Researcher Profile and Settings

Affiliation

• Faculty of Medicine　Global Center for BiomedicalScience and Engineering

Job Title

• Assistant Professor

Degree

• PhD（Hokkaido University）

Research funding number

• 70643914

J-Global ID

• 201301006481050234

Profile

• Born December 23, 1963 in Seattle, Washington, U.S.A.
  
  Moved to Austin, Texas 1976
  
  Attended Westlake High School 1978-1982
  
  Studied Computer Sciences at the University of Texas 1982-1986
  
  Moved to Sapporo, Japan in 1989

Research Interests

• Software   Monte Carlo SImulation   ai   

Research Areas

• Informatics / Software

Educational Organization

•  Bachelor's degree program　Departments of Medicine, School of Medicine
•  Master's degree program　Graduate School of Biomedical Science and Engineering
•  Doctoral (PhD) degree program　Graduate School of Biomedical Science and Engineering

Education

• 2003/05 - Today  Hokkaido University  Graduate School of Medicine
• 1982/09 - 1986/05  University of Texas at Austin  Natural Science  Computer Sciences

Research Activities

Published Papers

• Fully automatic software for detecting radiographic joint space narrowing progression in rheumatoid arthritis: phantom study and comparison with visual assessment

  Taichi Okino, Yafei Ou, Masayuki Ikebe, Kenichi Tamura, Kenneth Sutherland, Jun Fukae, Kazuhide Tanimura, Tamotsu Kamishima

  JAPANESE JOURNAL OF RADIOLOGY 41 (5) 510 - 520 1867-1071 2023/05 

  Purpose We have developed an in-house software equipped with partial image phase-only correlation (PIPOC) which can automatically quantify radiographic joint space narrowing (JSN) progression. The purpose of this study was to evaluate the software in phantom and clinical assessments. Materials and methods In the phantom assessment, the software's performance on radiographic images was compared to the joint space width (JSW) difference using a micrometer as ground truth. A phantom simulating a finger joint was scanned underwater. In the clinical assessment, 15 RA patients were included. The software measured the radiological progression of the finger joints between baseline and the 52nd week. The cases were also evaluated with the Genant-modified Sharp score (GSS), a conventional visual scoring method. We also quantitatively assessed these joints' synovial vascularity (SV) on power Doppler ultrasonography (0, 8, 20 and 52 weeks). Results In the phantom assessment, the PIPOC software could detect changes in JSN with a smallest detectable difference of 0.044 mm at 0.1 mm intervals. In the clinical assessment, the JSW change of the joints with GSS progression detected by the software was significantly greater than those without GSS progression (p = 0.004). The JSW change of joints with positive SV at baseline was significantly higher than those with negative SV (p = 0.024). Conclusion Our in-house software equipped with PIPOC can automatically and quantitatively detect slight radiographic changes of JSW in clinically inactive RA patients.
• Fully automatic software for detecting radiographic joint space narrowing progression in rheumatoid arthritis: phantom study and comparison with visual assessment.

  Taichi Okino, Yafei Ou, Masayuki Ikebe, Kenichi Tamura, Kenneth Sutherland, Jun Fukae, Kazuhide Tanimura, Tamotsu Kamishima

  Japanese journal of radiology 41 (5) 510 - 520 2023/05 

  PURPOSE: We have developed an in-house software equipped with partial image phase-only correlation (PIPOC) which can automatically quantify radiographic joint space narrowing (JSN) progression. The purpose of this study was to evaluate the software in phantom and clinical assessments. MATERIALS AND METHODS: In the phantom assessment, the software's performance on radiographic images was compared to the joint space width (JSW) difference using a micrometer as ground truth. A phantom simulating a finger joint was scanned underwater. In the clinical assessment, 15 RA patients were included. The software measured the radiological progression of the finger joints between baseline and the 52nd week. The cases were also evaluated with the Genant-modified Sharp score (GSS), a conventional visual scoring method. We also quantitatively assessed these joints' synovial vascularity (SV) on power Doppler ultrasonography (0, 8, 20 and 52 weeks). RESULTS: In the phantom assessment, the PIPOC software could detect changes in JSN with a smallest detectable difference of 0.044 mm at 0.1 mm intervals. In the clinical assessment, the JSW change of the joints with GSS progression detected by the software was significantly greater than those without GSS progression (p = 0.004). The JSW change of joints with positive SV at baseline was significantly higher than those with negative SV (p = 0.024). CONCLUSION: Our in-house software equipped with PIPOC can automatically and quantitatively detect slight radiographic changes of JSW in clinically inactive RA patients.
• A real-time measurement system for gene expression rhythms from deep tissues of freely moving mice under light-dark conditions.

  Nakaya M, Wakamatsu M, Motegi H, Ami Tanaka A, Sutherland K, Ishikawa M, Ozaki M, Shirato H, Hamada K, Hamada T* (* Correspondence).

  Biochemistry and Biophysics Reports 32 101344 - 101344 2022/09 [Refereed][Not invited]
   

  Clock gene expression in most organs of the living body exhibits a diurnal rhythm synchronized with the external 24 h light-dark (LD) cycle via circadian pacemaker suprachiasmatic nucleus (SCN). Disturbances in clock gene expression due to desynchronization of clock gene expression of the external LD cycle are risk factors for developing various diseases. Measuring the in vivo clock genes expression rhythm for a long duration under LD conditions can greatly contribute to understand the pathogenic mechanism of the disease caused by the disturbance of the biological rhythm. However, it is presently difficult to continuously measure gene expression for a long duration under LD conditions. In present study, we succeeded in measuring Period1 (Per1) gene expression under LD conditions using ultraviolet (UV) light with filter cut the visible light range. In addition, we succeeded in measuring the kinetic change of liver Per1 gene expression during the process of desynchronization of behavioral rhythm from the LD cycle by chronic administration of methamphetamine (MAP). In the future, by using this system to measure clock gene expression rhythms of brain tissues such as SCN and peripheral tissues under LD conditions, it could contribute to understand the onset mechanism of diseases induced by the desynchronization mechanism of biological rhythm to the LD cycle.
• Period1 gene expression in the olfactory bulb and liver of freely moving streptozotocin-treated diabetic mouse.

  Harumi Kanou, Kouki Nagasawa, Yuki Ishii, Aya Chishima, Juri Hayashi, Sanae Haga, Kenneth Sutherland, Masayori Ishikawa, Michitaka Ozaki, Hiroki Shirato, Kazuko Hamada, Toshiyuki Hamada

  Biochemical and biophysical research communications 560 14 - 20 2021/06/30 

  Clock genes express circadian rhythms in most organs. These rhythms are organized throughout the whole body, regulated by the suprachiasmatic nucleus (SCN) in the brain. Disturbance of these clock gene expression rhythms is a risk factor for diseases such as obesity. In the present study, to explore the role of clock genes in developing diabetes, we examined the effect of streptozotocin (STZ)-induced high glucose on Period1 (Per1) gene expression rhythm in the liver and the olfactory bub (OB) in the brain. We found a drastic increase of Per1 expression in both tissues after STZ injection while blood glucose content was low. After a rapid expression peak, Per1 expression showed no rhythm. Associated with an increase of glucose content, behavior became arrhythmic. Finally, we succeeded in detecting an increase of Per1 expression in mice hair follicles on day 1 after STZ administration, before the onset of symptoms. These results show that elevated Per1 expression by STZ plays an important role in the aggravation of diabetes.
• Stability of d-luciferin for bioluminescence to detect gene expression in freely moving mice for long durations.

  Kanako Nakajima, Kazuko Hamada, Ryoga Ito, Yukina Yoshida, Kenneth Sutherland, Masayori Ishikawa, Michitaka Ozaki, Hiroki Shirato, Toshiyuki Hamada

  Luminescence : the journal of biological and chemical luminescence 36 (1) 94 - 98 2021/02 

  Circadian disturbance of clock gene expression is a risk factor for diseases such as obesity, cancer, and sleep disorders. To study these diseases, it is necessary to monitor and analyze the expression rhythm of clock genes in the whole body for a long duration. The bioluminescent reporter enzyme firefly luciferase and its substrate d-luciferin have been used to generate optical signals from tissues in vivo with high sensitivity. However, little information is known about the stability of d-luciferin to detect gene expression in living animals for a long duration. In the present study, we examined the stability of a luciferin solution over 21 days. l-Luciferin, which is synthesized using racemization of d-luciferin, was at high concentrations after 21 days. In addition, we showed that bioluminescence of Period1 (Per1) expression in the liver was significantly decreased compared with the day 1 solution, although locomotor activity rhythm was not affected. These results showed that d-luciferin should be applied to the mouse within, at most, 7 days to detect bioluminescence of Per1 gene expression rhythm in vivo.
• Mouse period1 gene expression recording from olfactory bulb under free moving conditions with a portable optic fibre device.

  Ryoga Ito, Kazuko Hamada, Shigeru Kasahara, Yoshihiro Kikuchi, Kanako Nakajima, Kenneth Sutherland, Hiroki Shirato, Michitaka Ozaki, Masayori Ishikawa, Toshiyuki Hamada

  Luminescence : the journal of biological and chemical luminescence 35 (8) 1248 - 1253 2020/12 

  Because the disruption of circadian clock gene is a risk factor in many diseases such as obesity and cancer, it is important to monitor and analyzed the expression of the rhythm of the clock gene throughout the body over a long period of time. Although we previously reported on a new gene expression analysis system tracking a target position on the body surface of freely moving mice, the experimental apparatus required a large space. We have therefore developed an in vivo recording system using a portable photomultiplier tube (PMT) system attached to an optical fibre. Directly connecting the target area with the device, we could easily measure the photon counts in a very small space. However, little information is known about the characteristics of optical fibres when exposed to twisting/looping in association with a moving mouse and the effect of the surface of optical fibre. In the present study, we report on the characteristics of optical fibres to detect gene expression rhythm in freely moving mice. Using this portable optical device directly connected with a target area, we were able to measure the circadian rhythm of clock gene expression over a prolonged period in freely moving mice in a small space.
• Fully automatic quantitative software for assessment of minute finger joint space narrowing progression on radiographs: evaluation in rheumatoid arthritis patients with long-term sustained clinical low disease activity.

  Kazuki Kato, Kenneth Sutherland, Yuki Tanaka, Masaru Kato, Jun Fukae, Kazuhide Tanimura, Tamotsu Kamishima

  Japanese journal of radiology 38 (10) 979 - 986 2020/10 

  PURPOSE: Rheumatoid arthritis (RA) causes joint space narrowing (JSN) as a form of joint destruction. We developed an automatic system that can detect joint locations and compute the joint space difference index (JSDI), which was defined as the chronological change in JSN between two radiographs. This study aims to evaluate the application of "machine vision" for radiographic image of the finger joints. MATERIALS AND METHODS: Fifteen RA patients with long-term sustained clinical low disease activity were recruited. All patients underwent hand radiography and power Doppler ultrasonography (PDUS). The JSN was evaluated using the Genant-modified Sharp scoring (GSS) method and the automatic system. Synovial vascularity (SV) was assessed quantitatively using ultrasonography. RESULTS: There were no significant differences in the JSDI between the joints with JSN and those without JSN on GSS (p = 0.052). The JSDI of the joints with SV was significantly higher than those without SV (p = 0.043). The JSDI of the no therapeutic response group was significantly higher than those of the response group (p < 0.001). CONCLUSION: Our software can automatically evaluate temporal changes of JSN, which might free rheumatologists / radiologists from the burden of scoring hand radiography.
• Double recording system of Period1 gene expression rhythm in the olfactory bulb and liver in freely moving mouse.

  Kazuko Hamada, Akari Oota, Ryoga Ito, Shigeru Kasahara, Kanako Nakajima, Yoshihiro Kikuchi, Kenneth Sutherland, Masayori Ishikawa, Hiroki Shirato, Michitaka Ozaki, Toshiyuki Hamada

  Biochemical and biophysical research communications 529 (4) 898 - 903 2020/09/03 

  Clock genes express circadian rhythms in most organs. These rhythms are organized throughout the whole body, regulated by the suprachiasmatic nucleus (SCN) in the brain. Disturbance of these clock gene expression rhythms is a risk factor for diseases such as obesity and cancer. To understand the mechanism of regulating clock gene expression rhythms in vivo, multiple real time recording systems are required. In the present study, we developed a double recording system of Period1 expression rhythm in peripheral tissue (liver) and the brain. In peripheral tissue, quantification of gene expression in a steadily moving target was achieved by using a photomultiplier tube (PMT) attached to a tissue contact optical sensor (TCS). Using this technique, we were able to analyze circadian rhythms of clock gene expression over a prolonged period in the liver and olfactory bub (OB) of the brain. The present double recording system has no effect on behavioral activity or rhythm. Our novel system thus successfully quantifies clock gene expression in deep areas of the body in freely moving mice for a period sufficient to analyze circadian dynamics. In addition, our double recording system can be widely applied to many areas of biomedical research, as well as applications beyond medicine.
• Quick and accurate selection of hand images among radiographs from various body parts using deep learning.

  Kohei Fujiwara, Wanxuan Fang, Taichi Okino, Kenneth Sutherland, Akira Furusaki, Akira Sagawa, Tamotsu Kamishima

  Journal of X-ray science and technology 28 (6) 1199 - 1206 2020 

  BACKGROUND: Although rheumatoid arthritis (RA) causes destruction of articular cartilage, early treatment significantly improves symptoms and delays progression. It is important to detect subtle damage for an early diagnosis. Recent software programs are comparable with the conventional human scoring method regarding detectability of the radiographic progression of RA. Thus, automatic and accurate selection of relevant images (e.g. hand images) among radiographic images of various body parts is necessary for serial analysis on a large scale. OBJECTIVE: In this study we examined whether deep learning can select target images from a large number of stored images retrieved from a picture archiving and communication system (PACS) including miscellaneous body parts of patients. METHODS: We selected 1,047 X-ray images including various body parts and divided them into two groups: 841 images for training and 206 images for testing. The training images were augmented and used to train a convolutional neural network (CNN) consisting of 4 convolution layers, 2 pooling layers and 2 fully connected layers. After training, we created software to classify the test images and examined the accuracy. RESULTS: The image extraction accuracy was 0.952 and 0.979 for unilateral hand and both hands, respectively. In addition, all 206 test images were perfectly classified into unilateral hand, both hands, and the others. CONCLUSIONS: Deep learning showed promise to enable efficiently automatic selection of target X-ray images of RA patients.
• Intravoxel incoherent motion MRI for discrimination of synovial proliferation in the hand arthritis: A prospective proof-of-concept study.

  Motoshi Fujimori, Koichi Murakami, Hiroyuki Sugimori, Yutong Lu, Kenneth Sutherland, Nozomi Oki, Takatoshi Aoki, Tamotsu Kamishima

  Journal of magnetic resonance imaging : JMRI 50 (4) 1199 - 1206 1053-1807 2019/10 [Refereed][Not invited]
   

  BACKGROUND: Postcontrast-enhanced MRI is currently the reference standard for synovial proliferation in rheumatoid arthritis (RA). However, the technique is somewhat invasive due to the use of gadolinium contrast agents, which may cause severe adverse/side effects. Intravoxel incoherent motion (IVIM) simultaneously permits quantification of perfusion as well as diffusion using a single imaging scan. PURPOSE/HYPOTHESIS: To test the capability of IVIM MRI for noninvasive discrimination of synovial proliferation in hand arthritis. STUDY TYPE: Prospective. SUBJECTS: Seven suspected RA patients (three women and four men; mean age, 61 years; range, 26-74 years). FIELD STRENGTH/SEQUENCE: 3 T/short tau inversion recovery (STIR), IVIM, postcontrast-enhanced MRI. ASSESSMENT: Region of interest (ROI) was identified based on STIR. Contrast-enhanced MRI was evaluated using a 5-point grading scale of 0 (water) to 4 (synovial proliferation) according to the degree of contrast enhancement within the ROI. For each ROI, we calculated the apparent diffusion coefficient (ADC) and IVIM parameters (molecular diffusion coefficient [D], perfusion fraction [f], and perfusion-related diffusion coefficient [D*]). These parameters were subsequently compared with ROI contrast enhancement grades. STATISTICAL TESTS: Spearman's rank correlation test and a receiver operating characteristic (ROC) curve. RESULTS: A total of 90 ROIs of suspected synovial proliferation and/or joint effusion were identified. ROI grades were correlated with ADC and D values (r S = -0.385, P < 0.001, r S = -0.458, P < 0.0001, respectively), but not with the f and D* values (r S = -0.010, P = 0.936, r S = -0.084, P = 0.505, respectively). The area under the curves (AUCs) of D values (0.708-0.888, P = 0.002-0.0002) were slightly larger than those of ADC values (0.692-0.791, P = 0.013-0.001) when comparing low- vs. high-contrast enhancement grades. DATA CONCLUSION: The IVIM parameter D and ADC may be useful for the noninvasive identification of synovial proliferation in hand arthritis. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:1199-1206.
• Detection of Fine Radiographic Progression in Finger Joint Space Narrowing Beyond Human Eyes: Phantom Experiment and Clinical Study with Rheumatoid Arthritis Patients.

  Kazuki Kato, Nobutoshi Yasojima, Kenichi Tamura, Shota Ichikawa, Kenneth Sutherland, Masaru Kato, Jun Fukae, Kazuhide Tanimura, Yuki Tanaka, Taichi Okino, Yutong Lu, Tamotsu Kamishima

  Scientific reports 9 (1) 8526 - 8526 2019/06/12 

  The visual assessment of joint space narrowing (JSN) on radiographs of rheumatoid arthritis (RA) patients such as the Genant-modified Sharp score (GSS) is widely accepted but limited by its subjectivity and insufficient sensitivity. We developed a software application which can assess JSN quantitatively using a temporal subtraction technique for radiographs, in which the chronological change in JSN between two radiographs was defined as the joint space difference index (JSDI). The aim of this study is to prove the superiority of the software in terms of detecting fine radiographic progression in finger JSN over human observers. A micrometer measurement apparatus that can adjust arbitrary joint space width (JSW) in a phantom joint was developed to define true JSW. We compared the smallest detectable changes in JSW between the JSDI and visual assessment using phantom images. In a clinical study, 222 finger joints without interval score change on GSS in 15 RA patients were examined. We compared the JSDI between joints with and without synovial vascularity (SV) on power Doppler ultrasonography during the follow-up period. True JSW difference was correlated with JSDI for JSW differences ranging from 0.10 to 1.00 mm at increments of 0.10 mm (R2 = 0.986 and P < 0.001). Rheumatologists were difficult to detect JSW difference of 0.30 mm or less. The JSDI of finger joints with SV was significantly higher than those without SV (P = 0.030). The software can detect fine differences in JSW that are visually unrecognizable.
• 3D Transformation Matrix Calculation and Pixel Intensity Normalization for the Dual Focus Tracking System

  Kenneth Sutherland, Toshiyuki Hamada, Masayori Ishikawa, Naoki Miyamoto, Masahiro Mizuta, Hiroyuki Date, Hiroki Shirato

  Journal of Medical and Biological Engineering 2019 [Refereed][Not invited]
  
• Investigation of energy absorption by clustered gold nanoparticles

  Jihun Kwon, Kenneth Sutherland, Anastasia Makarova, Taeko Matsuura, Takayuki Hashimoto, Hao Peng, Toshiyuki Toshito, Kikuo Umegaki, Hiroki Shirato, Shinichi Shimizu

  Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms 429 34 - 41 0168-583X 2018/08/15 [Refereed][Not invited]
   

  © 2018 Elsevier B.V. The utilization of gold nanoparticles (GNPs) as a radiation sensitizer has received broad attention. Although GNPs form clusters in living cells, most previous simulation studies have assumed a homogeneous distribution of GNPs. In this study, a GNP cluster was constructed for simulations and the impact of cluster formation on dose enhancement was examined. Energy absorption by the GNPs was compared between clustered and homogeneous distributions for several different GNP concentrations and diameters under 100 keV X-ray irradiations. Our simulations showed that clusters more efficiently absorbed the secondary electrons and photons produced by GNPs themselves. Furthermore, the impact of cluster formation on dose enhancement was more significant for smaller GNPs and higher concentrations. Our results suggest that previous simulations assuming a homogeneous GNP distribution have overestimated the dose enhancement, especially for smaller GNPs and higher concentrations. These findings should guide the selection of GNP size and concentration for effectively optimizing dose enhancement in future studies.
• Composite assessment of power Doppler ultrasonography and MRI in rheumatoid arthritis: a pilot study of predictive value in radiographic progression after one year.

  Fujimori M, Kamishima T, Kato M, Seno Y, Sutherland K, Sugimori H, Nishida M, Atsumi T

  The British journal of radiology 91 (1086) 20170748 - 20170748 0007-1285 2018/06 [Refereed][Not invited]
   

  OBJECTIVE: Power Doppler ultrasonography (PDUS) and MRI are independently useful to predict structural damage in patients with rheumatoid arthritis (RA). We hypothesize that there is a complementary relationship between these modalities. The aim of this study is, therefore, to investigate the usefulness of the predictive value of composite assessment of PDUS and contrast-enhanced MRI in radiographic outcomes in patients with RA. METHODS: 20 patients (17 females and 3 males) with RA on disease-modifying antirheumatic drugs underwent PDUS and MRI of both hands at baseline. Radiography of the bilateral hands was performed at baseline and at 1 year. Articular synovitis on PDUS was evaluated according to quantitative measurement. Synovitis, bone marrow edema and bone erosion were scored according to the RA MRI scoring method. The changes of joint space narrowing and bone erosion on radiograph were assessed by the Sharp/van der Heijde method. We applied t-statistics to combine the assessment of quantitative PDUS with semiquantitative MRI. RESULTS: Structural damage progression for radiography was not correlated with any evaluations for MRI, while it showed significant correlation with synovitis on PDUS (rs = 0.597, p = 0.005). The composite assessment of both modalities (synovitis for PDUS and bone marrow edema for MRI) was correlated with structural damage progression on radiograph (rs = 0.792, p < 0.0001). CONCLUSION: Composite assessment of PDUS and MRI may have a stronger predictive value in radiographic progression than PDUS or MRI alone in RA. Advances in knowledge: Composite assessment of PDUS and MRI may be an effective predictor of structural damage in RA.
• Quantification of hand synovitis in rheumatoid arthritis: Arterial mask subtraction reinforced with mutual information can improve accuracy of pixel-by-pixel time-intensity curve shape analysis in dynamic MRI.

  Kobayashi Y, Kamishima T, Sugimori H, Ichikawa S, Noguchi A, Kono M, Iiyama T, Sutherland K, Atsumi T

  Journal of magnetic resonance imaging : JMRI 1053-1807 2018/03 [Refereed][Not invited]
   

  BACKGROUND: Synovitis, which is a hallmark of rheumatoid arthritis (RA), needs to be precisely quantified to determine the treatment plan. Time-intensity curve (TIC) shape analysis is an objective assessment method for characterizing the pixels as artery, inflamed synovium, or other tissues using dynamic contrast-enhanced MRI (DCE-MRI). PURPOSE/HYPOTHESIS: To assess the feasibility of our original arterial mask subtraction method (AMSM) with mutual information (MI) for quantification of synovitis in RA. STUDY TYPE: Prospective study. SUBJECTS: Ten RA patients (nine women and one man; mean age, 56.8 years; range, 38-67 years). FIELD STRENGTH/SEQUENCE: 3T/DCE-MRI. ASSESSMENT: After optimization of TIC shape analysis to the hand region, a combination of TIC shape analysis and AMSM was applied to synovial quantification. The MI between pre- and postcontrast images was utilized to determine the arterial mask phase objectively, which was compared with human subjective selection. The volume of objectively measured synovitis by software was compared with that of manual outlining by an experienced radiologist. Simple TIC shape analysis and TIC shape analysis combined with AMSM were compared in slices without synovitis according to subjective evaluation. STATISTICAL TESTS: Pearson's correlation coefficient, paired t-test and intraclass correlation coefficient (ICC). RESULTS: TIC shape analysis was successfully optimized in the hand region with a correlation coefficient of 0.725 (P < 0.01) with the results of manual assessment regarded as ground truth. Objective selection utilizing MI had substantial agreement (ICC = 0.734) with subjective selection. Correlation of synovial volumetry in combination with TIC shape analysis and AMSM with manual assessment was excellent (r = 0.922, P < 0.01). In addition, negative predictive ability in slices without synovitis pixels was significantly increased (P < 0.01). DATA CONCLUSIONS: The combination of TIC shape analysis and image subtraction reinforced with MI can accurately quantify synovitis of RA in the hand by eliminating arterial pixels. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.
• Power Doppler signal calibration in the finger joint between two models of ultrasound machine: a pilot study using a phantom and joints in patients with rheumatoid arthritis.

  Ryosuke Sakano, Katsumi Saito, Tamotsu Kamishima, Mutsumi Nishida, Tatsunori Horie, Atsushi Noguchi, Michihito Kono, Kenneth Sutherland, Tatsuya Atsumi

  Acta radiologica (Stockholm, Sweden : 1987) 58 (10) 1238 - 1244 0284-1851 2017/10 [Refereed][Not invited]
   

  Background Despite the advantages of ultrasound (US) in the management of rheumatoid arthritis (RA) patients, power Doppler (PD) US may be highly dependent on the type of US machine used. Purpose To present a method to calibrate the PD signal of two models of US machines by use of a flow phantom and finger joints of patients with RA. Material and Methods For the phantom study, the PD signal count was measured in the flow phantom perfusing blood mimicking fluid at various injection rates and pulse repetition frequencies (PRFs). The quantitative PD index was calculated with ImageJ. For the clinical study, the second and third metacarpophalangeal joints of five consecutive patients with RA were examined. The quantitative PD index was measured at various PRFs by use of two models of machine (the same models as the phantom study). Results For the phantom and clinical studies, negative correlations were found between the PRF and the quantitative PD index when the flow velocity was constant and positive correlations between flow velocity and the quantitative PD index at constant PRF. There was a significant difference in the depiction performance of synovial blood flow between the two models, which can be calibrated by adjusting the PRF values derived from the phantom study in each model. Conclusion Signal calibration of pannus vascularity between US machines may be possible by adjusting the PRF value according to flow phantom data. Different US machines can thus provide equivalent examination results concerning the pannus vascularity.
• Computer-Based Radiographic Quantification of Joint Space Narrowing Progression Using Sequential Hand Radiographs: Validation Study in Rheumatoid Arthritis Patients from Multiple Institutions

  Shota Ichikawa, Tamotsu Kamishima, Kenneth Sutherland, Jun Fukae, Kou Katayama, Yuko Aoki, Takanobu Okubo, Taichi Okino, Takahiko Kaneda, Satoshi Takagi, Kazuhide Tanimura

  JOURNAL OF DIGITAL IMAGING 30 (5) 648 - 656 0897-1889 2017/10 [Refereed][Not invited]
   

  We have developed a refined computer-based method to detect joint space narrowing (JSN) progression with the joint space narrowing progression index (JSNPI) by superimposing sequential hand radiographs. The purpose of this study is to assess the validity of a computer-based method using images obtained from multiple institutions in rheumatoid arthritis (RA) patients. Sequential hand radiographs of 42 patients (37 females and 5 males) with RA from two institutions were analyzed by a computer-based method and visual scoring systems as a standard of reference. The JSNPI above the smallest detectable difference (SDD) defined JSN progression on the joint level. The sensitivity and specificity of the computer-based method for JSN progression was calculated using the SDD and a receiver operating characteristic (ROC) curve. Out of 314 metacarpophalangeal joints, 34 joints progressed based on the SDD, while 11 joints widened. Twenty-one joints progressed in the computer-based method, 11 joints in the scoring systems, and 13 joints in both methods. Based on the SDD, we found lower sensitivity and higher specificity with 54.2 and 92.8%, respectively. At the most discriminant cutoff point according to the ROC curve, the sensitivity and specificity was 70.8 and 81.7%, respectively. The proposed computer-based method provides quantitative measurement of JSN progression using sequential hand radiographs and may be a useful tool in follow-up assessment of joint damage in RA patients.
• Cartilage quantification using contrast-enhanced MRI in the wrist of rheumatoid arthritis: cartilage loss is associated with bone marrow edema.

  Motoshi Fujimori, Satoko Nakamura, Kiminori Hasegawa, Kunihiro Ikeno, Shota Ichikawa, Kenneth Sutherland, Tamotsu Kamishima

  The British journal of radiology 90 (1077) 20170167 - 20170167 0007-1285 2017/08 [Refereed][Not invited]
   

  OBJECTIVE: To quantify wrist cartilage using contrast MRI and compare with the extent of adjacent synovitis and bone marrow edema (BME) in patients with rheumatoid arthritis (RA). METHODS: 18 patients with RA underwent post-contrast fat-suppressed T1weighted coronal imaging. Cartilage area at the centre of the scaphoid-capitate and radius-scaphoid joints was measured by in-house developed software. We defined cartilage as the pixels with signal intensity between two thresholds (lower: 0.4, 0.5 and 0.6 times the muscle signal, upper: 0.9, 1.0, 1.1, 1.2 and 1.3 times the muscle signal). We investigated the association of cartilage loss with synovitis and BME score derived from RA MRI scoring system. RESULTS: Cartilage area was correlated with BME score when thresholds were adequately set with lower threshold at 0.6 times the muscle signal and upper threshold at 1.2 times the muscle signal for both SC (rs=-0.469, p < 0.05) and RS (rs=-0.486, p < 0.05) joints, while it showed no significant correlation with synovitis score at any thresholds. CONCLUSION: Our software can accurately quantify cartilage in the wrist and BME associated with cartilage loss in patients with RA. Advances in knowledge: Our software can quantify cartilage using conventional MR images of the wrist. BME is associated with cartilage loss in RA patients.
• Visceral adipose tissue area measurement at a single level: can it represent visceral adipose tissue volume?

  Yusuke Noumura, Tamotsu Kamishima, Kenneth Sutherland, Hideho Nishimura

  The British journal of radiology 90 (1077) 20170253 - 20170253 0007-1285 2017/08 [Refereed][Not invited]
   

  OBJECTIVE: Measurement of visceral adipose tissue (VAT) needs to be accurate and sensitive to change for risk monitoring. The purpose of this study is to determine the CT slice location where VAT area can best reflect changes in VAT volume and body weight. METHODS: 60 plain abdominal CT images from 30 males [mean age (range) 51 (41-68) years, mean body weight (range) 71.1 (101.9-50.9) kg] who underwent workplace screenings twice within a 1-year interval were evaluated. Automatically calculated and manually corrected areas of the VAT of various scan levels using "freeform curve" region of interest on CT were recorded and compared with body weight changes. RESULTS: The strongest correlations of VAT area with VAT volume and body weight changes were shown in a slice 3 cm above the lower margin of L3 with r values of 0.853 and 0.902, respectively. CONCLUSION: VAT area measurement at a single level 3 cm above the lower margin of the L3 vertebra is feasible and can reflect changes in VAT volume and body weight. Advances in knowledge: As VAT area at a CT slice 3cm above the lower margin of L3 can best reflect interval changes in VAT volume and body weight, VAT area measurement should be selected at this location.
• Semi-Automated Quantification of Finger Joint Space Narrowing Using Tomosynthesis in Patients with Rheumatoid Arthritis

  Shota Ichikawa, Tamotsu Kamishima, Kenneth Sutherland, Hideki Kasahara, Yuka Shimizu, Motoshi Fujimori, Nobutoshi Yasojima, Yohei Ono, Takahiko Kaneda, Takao Koike

  JOURNAL OF DIGITAL IMAGING 30 (3) 369 - 375 0897-1889 2017/06 [Refereed][Not invited]
   

  The purpose of the study is to validate the semi-automated method using tomosynthesis images for the assessment of finger joint space narrowing (JSN) in patients with rheumatoid arthritis (RA), by using the semi-quantitative scoring method as the reference standard. Twenty patients (14 females and 6 males) with RA were included in this retrospective study. All patients underwent radiography and tomosynthesis of the bilateral hand and wrist. Two rheumatologists and a radiologist independently scored JSN with two modalities according to the Sharp/van der Heijde score. Two observers independently measured joint space width on tomosynthesis images using an in-house semi-automated method. More joints with JSN were revealed with tomosynthesis score (243 joints) and the semi-automated method (215 joints) than with radiography (120 joints), and the associations between tomosynthesis scores and radiography scores were demonstrated (P < 0.001). There was significant, negative correlation between measured joint space width and tomosynthesis scores with r = -0.606 (P < 0.001) in metacarpophalangeal joints and r = -0.518 (P < 0.001) in proximal interphalangeal joints. Inter-observer and intra-observer agreement of the semi-automated method using tomosynthesis images was in almost perfect agreement with intra-class correlation coefficient (ICC) values of 0.964 and 0.963, respectively. The semi-automated method using tomosynthesis images provided sensitive, quantitative, and reproducible measurement of finger joint space in patients with RA.
• A reliability study using computer-based analysis of finger joint space narrowing in rheumatoid arthritis patients.

  Katsuya Hatano, Tamotsu Kamishima, Kenneth Sutherland, Masaru Kato, Ikuma Nakagawa, Shota Ichikawa, Keisuke Kawauchi, Shota Saitou, Masaya Mukai

  Rheumatology international 37 (2) 189 - 195 0172-8172 2017/02 [Refereed][Not invited]
   

  The joint space difference index (JSDI) is a newly developed radiographic index which can quantitatively assess joint space narrowing progression of rheumatoid arthritis (RA) patients by using an image subtraction method on a computer. The aim of this study was to investigate the reliability of this method by non-experts utilizing RA image evaluation. Four non-experts assessed JSDI for radiographic images of 510 metacarpophalangeal joints from 51 RA patients twice with an interval of more than 2 weeks. Two rheumatologists and one radiologist as well as the four non-experts examined the joints by using the Sharp-van der Heijde Scoring (SHS) method. The radiologist and four non-experts repeated the scoring with an interval of more than 2 weeks. We calculated intra-/inter-observer reliability using the intra-class correlation coefficients (ICC) for JSDI and SHS scoring, respectively. The intra-/inter-observer reliabilities for the computer-based method were almost perfect (inter-observer ICC, 0.966-0.983; intra-observer ICC, 0.954-0.996). Contrary to this, intra-/inter-observer reliability for SHS by experts was moderate to almost perfect (inter-observer ICC, 0.556-0.849; intra-observer ICC, 0.589-0.839). The results suggest that our computer-based method has high reliability to detect finger joint space narrowing progression in RA patients.
• Pixel-by-Pixel Arterial Spin Labeling Blood Flow Pattern Variation Analysis for Discrimination of Rheumatoid Synovitis: A Pilot Study.

  Taro Sakashita, Tamotsu Kamishima, Hiroyuki Sugimori, Minghui Tang, Atsushi Noguchi, Michihito Kono, Kenneth Sutherland, Tatsuya Atsumi

  Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 16 (1) 78 - 83 1347-3182 2017/01/10 [Refereed][Not invited]
   

  We examined the capability of a gray-scale arterial spin labeling blood flow pattern variation (BFPV) map with two different post labeling delay (PLD) times to discriminate pannus in patients with rheumatoid arthritis (RA) at 3T. There was a statistically significant difference in the BFPV values between artery, pannus, and surrounding tissue. Furthermore, the color-coded BFPV map was able to accurately distinguish pannus from other tissues. These results suggest this approach may be capable of identifying pannus noninvasively.
• Performance of computer-based analysis using temporal subtraction to assess joint space narrowing progression in rheumatoid patients

  Shota Ichikawa, Tamotsu Kamishima, Kenneth Sutherland, Takanobu Okubo, Kou Katayama

  RHEUMATOLOGY INTERNATIONAL 36 (1) 101 - 108 0172-8172 2016/01 [Refereed][Not invited]
   

  Our computer-based method can detect the chronological change in joint space width between baseline and follow-up images as the joint space difference index (JSDI). The aim of this study was to verify the sensitivity and specificity of our computer-based method in assessment of joint space narrowing progression in rheumatoid patients. Twenty-seven patients (24 women and 3 men) with rheumatoid arthritis underwent radiography of the bilateral hand at baseline and at 1 year. The joint space narrowing (JSN) of a total of 252 metacarpophalangeal (MCP) joints and 229 carpal joints was assessed by our computer-based method, setting the Sharp/van der Heijde method as the gold standard. We constructed a receiver operating characteristic curve by using the Sharp/van der Heijde method as the gold standard and set the optimal cutoff on JSDI for MCP, carpal, and MCP/carpal joints. We then calculated the sensitivity and specificity for each cutoff in assessment of JSN progression. At the most discriminant cutoff, the sensitivity and specificity of the computer-based method for MCP joints was 78.6 versus 85.3 %, respectively (AUC = 0.837; P < 0.001). Carpal joints revealed a lower sensitivity and specificity with 64.7 and 86.8 % (AUC = 0.775; P < 0.001). Furthermore, the sensitivity and specificity for MCP/carpal joints was 71.0 versus 83.6 %, respectively (AUC = 0.778; P < 0.001). The computer-based method presented a reliable assessment of JSN progression with high sensitivity and specificity and may be useful in follow-up assessment of the joint damage in rheumatoid patients.
• Tomosynthesis can facilitate accurate measurement of joint space width under the condition of the oblique incidence of X-rays in patients with rheumatoid arthritis

  Yohei Ono, Rina Kashihara, Nobutoshi Yasojima, Hideki Kasahara, Yuka Shimizu, Kenichi Tamura, Kaori Tsutsumi, Kenneth Sutherland, Takao Koike, Tamotsu Kamishima

  BRITISH JOURNAL OF RADIOLOGY 89 (1062) 20150967  0007-1285 2016 [Refereed][Not invited]
   

  Objective: Accurate evaluation of joint space width (JSW) is important in the assessment of rheumatoid arthritis (RA). In clinical radiography of bilateral hands, the oblique incidence of X-rays is unavoidable, which may cause perceptional or measurement error of JSW. The objective of this study was to examine whether tomosynthesis, a recently developed modality, can facilitate a more accurate evaluation of JSW than radiography under the condition of oblique incidence of X-rays. Methods: We investigated quantitative errors derived from the oblique incidence of X-rays by imaging phantoms simulating various finger joint spaces using radiographs and tomosynthesis images. We then compared the qualitative results of the modified total Sharp score of a total of 320 joints from 20 patients with RA between these modalities. Results: A quantitative error was prominent when the location of the phantom was shifted along the JSW direction. Modified total Sharp scores of tomosynthesis images were significantly higher than those of radiography, that is to say JSW was regarded as narrower in tomosynthesis than in radiography when finger joints were located where the oblique incidence of X-rays is expected in the JSW direction. Conclusion: Tomosynthesis can facilitate accurate evaluation of JSW in finger joints of patients with RA, even with oblique incidence of X-rays. Advances in knowledge: Accurate evaluation of JSW is necessary for the management of patients with RA. Through phantom and clinical studies, we demonstrate that tomosynthesis may achieve more accurate evaluation of JSW.
• Radiographic quantifications of joint space narrowing progression by computer-based approach using temporal subtraction in rheumatoid wrist

  Shota Ichikawa, Tamotsu Kamishima, Kenneth Sutherland, Takanobu Okubo, Kou Katayama

  BRITISH JOURNAL OF RADIOLOGY 89 (1057) 20150403  0007-1285 2016 [Refereed][Not invited]
   

  Objective: To investigate the validity of a computerbased method using temporal subtraction in carpal joints of patients with rheumatoid arthritis (RA), which can detect the difference in joint space between two images with the joint space difference index (JSDI). Methods: The study consisted of 43 patients with RA (39 females and 4 males) who underwent radiography at baseline and at 1-year follow-up. The joint space narrowing (JSN) of carpal joints on bilateral hand radiographs was assessed by our computer-based method, using the Sharp/ van der Heijde method as the standard of reference. We compared the JSDI of joints with JSN progression in the follow-up period with that of those without JSN progression. In addition, we examined whether there is a significant difference in JSDI in terms of laterality or topology of the joint. Results: The JSDI of joints with JSN progression was significantly higher than that of those without JSN progression (Mann-Whitney U test, p < 0.001). There was no statistically significant difference in the JSDI between the left and right carpal joints, which was analysed for five different joints altogether and each joint separately (Mann-Whitney U test, p > 0.05). There was statistically significant difference in JSDI among different joints (Kruskal-Wallis test, p = 0.003). Conclusion: These results suggest that our computerbased method may be useful to recognize the JSN progression on radiographs of rheumatoid wrists. Advances in knowledge: The computer-based temporal subtraction method can detect the JSN progression in the wrist, which is the single most commonly involved site in RA.
• Accurate quantitative assessment of synovitis in rheumatoid arthritis using pixel-by-pixel, time-intensity curve shape analysis

  Taro Sakashita, Tamotsu Kamishima, Yuto Kobayashi, Hiroyuki Sugimori, Minghui Tang, Kenneth Sutherland, Atsushi Noguchi, Michihito Kono, Tatsuya Atsumi

  BRITISH JOURNAL OF RADIOLOGY 89 (1061) 20151000  0007-1285 2016 [Refereed][Not invited]
   

  Objective: To improve on the reproducibility and sensitivity of the assessment of patients with rheumatoid arthritis (RA), two semi-automated measurement methods of the area of enhancing pannus (AEP), based on thresholding (AEP_THRES) and pixel-by-pixel time-intensity curve analysis (AEP_TIC), were evaluated as an alternative for the gold-standard manual contouring method (AEP_MANUAL). Methods: 8 patients (7 females and 1 male) with RA of the wrist or finger joints participated in the study. A three-dimensional contrast-enhanced dynamic sequence was used at 3 T. After identifying the most relevant time-intensity curve (TIC) shape in terms of synovitis by comparing with the synovitis score using the RA-MRI scoring system, three different approaches for measuring the AEP were performed. Spearman's test of rank correlation was used to compare AEPs via two semi-automated methods (AEP_THRES and AEP_TIC) against manual segmentation (AEP_MANUAL) in the entire hand region as well as the wrist and the finger regions. Results: The TIC shape of "washout after fast initial enhancement" had excellent correlation with synovitis score (r = 0.809). The correlation coefficient between AEP_TIC and AEP_MANUAL was evaluated to be better than that of AEP_THRES and AEP_MANUAL in the wrist region (AEP_THRES: r = 0.716, AEP_TIC: r = 0.815), whereas these were of comparable accuracy for the entire hand and the finger regions. Conclusion: This study suggests that TIC analysis may be an alternative to manual contouring for pannus quantification and provides important clinical information of the extent of the disease in patients with RA. Advances in knowledge: TIC shape analysis can be applied for new quantitative assessment for RA synovitis in the wrist.
• Dose distribution of electrons from gold nanoparticles by proton beam irradiation

  Jihun Kwon, Kenneth Sutherland, Takayuki Hashimoto, Hiroyuki Date

  International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2015 (4) 49 - 53 2015 [Refereed][Not invited]
  
• Development of a wavelength-separated type scintillator with optical fiber dosimeter to compensate for the Cerenkov radiation effect

  Masayori Ishikawa, Naomi Nagase, Taeko Matsuura, Junichi Hiratsuka, Ryusuke Suzuki, Naoki Miyamoto, Kenneth Sutherland, Katsuhisa Fujita, Hiroki Shirato

  Journal of Radiation Research Oxford University Press 56 (2) 372 - 381 0449-3060 2015 [Refereed][Not invited]
   

  The scintillator with optical fiber (SOF) dosimeter consists of a miniature scintillator mounted on the tip of an optical fiber. The scintillator of the current SOF dosimeter is a 1-mm diameter hemisphere. For a scintillation dosimeter coupled with an optical fiber, measurement accuracy is influenced by signals due to Cerenkov radiation in the optical fiber. We have implemented a spectral filtering technique for compensating for the Cerenkov radiation effect specifically for our plastic scintillator-based dosimeter, using a wavelength-separated counting method. A dichroic mirror was used for separating input light signals. Individual signal counting wasperformed for high- and low-wavelength light signals. To confirm the accuracy, measurements with variousamounts of Cerenkov radiation were performed by changing the incident direction while keeping the Ir-192 source-to-dosimeter distance constant, resulting in a fluctuation of <5%. Optical fiber bending was alsoaddressed; no bending effect was observed for our wavelength-separated SOF dosimeter.
• 教育講座－モンテカルロシミュレーションの放射線技術への利用－３．モンテカルロシミュレーションの放射線医療への応用

  ケネス・サザランド, 白石 祐太, 伊達 広行

  日本放射線技術学会雑誌 70 (8) 827 - 838 2014/08 [Not refereed][Invited]
  
• 一方向X線透視による低被曝・省スペース型動体追跡装置の開発

  宮本直樹, 石川正純, SUTHERLAND Kenneth, 鈴木隆介, 松浦妙子, 高尾聖心, 寅松千枝, 二本木英明, 清水伸一, 梅垣菊男, 白土博樹

  医学物理 Supplement 32 (3) 281 - 282 1345-5362 2012/09/13 [Not refereed][Not invited]
  
• 体内複数マーカを用いた高精度ゲーティング照射法の基礎検討

  大友可奈子, 宮本直樹, SUTHERLAND Kenneth, 鈴木隆介, 松浦妙子, 鬼丸力也, 清水伸一, 梅垣菊男, 白土博樹, 石川正純

  医学物理 Supplement 32 (3) 155 - 156 1345-5362 2012/09/13 [Not refereed][Not invited]
  
• 陽子線スキャニング照射における体内マーカーによる線量遮蔽のTCPを用いた評価

  前田憲一郎, 松浦妙子, 高尾聖心, SUTHERLAND Kenneth, 寅松千枝, 二本木英明, 宮本直樹, 石川正純, 清水伸一, 梅垣菊男, 白土博樹

  医学物理 Supplement 32 (3) 101 - 102 1345-5362 2012/09/13 [Not refereed][Not invited]
  
• Biological effect of dose distortion by fiducial markers in spot-scanning proton therapy with a limited number of fields: a simulation study.

  Matsuura T, Maeda K, Sutherland K, Takayanagi T, Shimizu S, Takao S, Miyamoto N, Nihongi H, Toramatsu C, Nagamine Y, Fujimoto R, Suzuki R, Ishikawa M, Umegaki K, Shirato H

  Medical physics 9 39 (9) 5584 - 5591 0094-2405 2012/09 [Refereed][Not invited]
   

  Purpose: In accurate proton spot-scanning therapy, continuous target tracking by fluoroscopic X-ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy, especially for the cases of liver and prostate with the targets surrounded by water-equivalent tissues. However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This paper focuses on prostate cancer and explores the possibility that multiple-field irradiation improves the underdose effect by markers on Tumor-Control Probability (TCP). Methods: A Monte Carlo simulation was performed to evaluate the dose distortion effect. A spherical gold marker was placed at several characteristic points in a water phantom. Markers were with two different diameters of 2 mm and 1.5 mm, both visible on fluoroscopy. Three beam arrangements of SFUD (single-field uniform dose) were examined: one lateral field, two opposite lateral fields, and three fields (two opposite lateral fields + anterior field). The Relative Biological Effectiveness (RBE) was set to 1.1 and a dose of 74 Gy (RBE) was delivered to the target of a typical prostate size in 37 fractions. The ratios of TCP to that without the marker (TCPr) were compared with the parameters of the marker sizes, number of fields, and marker positions. To take into account the dependence of biological parameters in TCP model, α/β values of 1.5, 3, and 10 Gy (RBE) were considered. Results: It was found that the marker of 1.5 mm diameter does not affect the TCPs with all α/β values when two or more fields are used. On the other hand, if the marker diameter is φ2 mm, more than two irradiation fields are required to suppress the decrease in TCP from TCPr by less than 3%. This is especially true when multiple (two or three) markers are used for alignment of a patient. Conclusions: It is recommended that φ1.5 mm markers be used to avoid the reduction of TCP as well as to spare the surrounding critical organs, as long as the markers are visible on X-ray fluoroscopy. When φ2 mm markers are implanted, more than two fields should be used and the markers should not be placed close to the distal edge of any of the beams.
• Improvement of tracking accuracy and stability by recursive image processing in real-time tumor-tracking radiotherapy system

  Miyamoto Naoki, Sutherland Kenneth, Suzuki Ryusuke, Matsuura Taeko, Toramatsu Chie, Takao Seishin, Nihongi Hideaki, Kinoshita Rumiko, Shimizu Shinichi, Onimaru Rikiya, Umegaki Kikuo, Shirato Hiroki, Ishikawa Masayori

  MEDICAL IMAGING 2012: IMAGE-GUIDED PROCEDURES, ROBOTIC INTERVENTIONS, AND MODELING 8316 83160  0277-786X 2012 [Refereed][Not invited]
  
• Optimization of fluoroscopy parameters using pattern matching prediction in the real-time tumor-tracking radiotherapy system.

  Miyamoto N, Ishikawa M, Bengua G, Sutherland K, Suzuki R, Kimura S, Shimizu S, Onimaru R, Shirato H

  Physics in medicine and biology 15 56 (15) 4803 - 4813 0031-9155 2011/08 [Refereed][Not invited]
   

  In the real-time tumor-tracking radiotherapy system, fluoroscopy is used to determine the real-time position of internal fiducial markers. The pattern recognition score (PRS) ranging from 0 to 100 is computed by a template pattern matching technique in order to determine the marker position on the fluoroscopic image. The PRS depends on the quality of the fluoroscopic image. However, the fluoroscopy parameters such as tube voltage, current and exposure duration are selected manually and empirically in the clinical situation. This may result in an unnecessary imaging dose from the fluoroscopy or loss of the marker because of too much or insufficient x-ray exposure. In this study, a novel optimization method is proposed in order to minimize the fluoroscopic dose while keeping the image quality usable for marker tracking. The PRS can be predicted in a region where the marker appears to move in the fluoroscopic image by the proposed method. The predicted PRS can be utilized to judge whether the marker can be tracked with accuracy. In this paper, experiments were performed to show the feasibility of the PRS prediction method under various conditions. The predicted PRS showed good agreement with the measured PRS. The root mean square error between the predicted PRS and the measured PRS was within 1.44. An experiment using a motion controller and an anthropomorphic chest phantom was also performed in order to imitate a clinical fluoroscopy situation. The result shows that the proposed prediction method is expected to be applicable in a real clinical situation.
• A feasibility study of a molecular-based patient setup verification method using a parallel-plane PET system.

  Yamaguchi S, Ishikawa M, Bengua G, Sutherland K, Nishio T, Tanabe S, Miyamoto N, Suzuki R, Shirato H

  Physics in medicine and biology 4 56 (4) 965 - 977 0031-9155 2011/02 [Refereed][Not invited]
   

  A feasibility study of a novel PET-based molecular image guided radiation therapy (m-IGRT) system was conducted by comparing PET-based registration with radiographic registration. We selected a pair of opposing parallel-plane PET systems for the practical implementation. Five different sizes of 18F cylindrical sources (diameter: 8, 12, 16, 24, 32 mm) were used to determine setup errors. PET data acquisition times were 1, 3 and 5 min. Image registration was performed by 5 observers. Setup errors from the PET system were compared with setup errors from image intensifier-based fluoroscopy. The in-plane and cross-plane FWHM of the profile of a 2 mm diameter sources for the parallel-plane PET system were approximately 1.8 mm and 8.1 mm, respectively. The majority of the mean registration errors obtained from the PET-based registration were not significantly different from those obtained from the radiographic registration. Acquisition time did not appear to result in significant differences in the mean registration error. The mean registration error for the PET-based registration was found to be 0.93±0.33 mm. This is not statistically different from the radiographic registration which had mean registration error of 0.92±0.27 mm. Our results suggest that m-IGRT is feasible for clinical use with a parallel plane PET-based registration.
• Detection of patient setup errors with a portal image - DRR registration software application

  Kenneth Sutherland, Masayori Ishikawa, Gerard Bengua, Yoichi M. Ito, Yoshiko Miyamoto, Hiroki Shirato

  JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS 12 (3) 2 - 15 1526-9914 2011 [Refereed][Not invited]
   

  The purpose of this study was to evaluate a custom portal image - digitally reconstructed radiograph (DRR) registration software application. The software works by transforming the portal image into the coordinate space of the DRR image using three control points placed on each image by the user, and displaying the fused image. In order to test statistically that the software actually improves setup error estimation, an intra-and interobserver phantom study was performed. Portal images of anthropomorphic thoracic and pelvis phantoms with virtually placed irradiation fields at known setup errors were prepared. A group of five doctors was first asked to estimate the setup errors by examining the portal and DRR image side-by-side, not using the software. A second group of four technicians then estimated the same set of images using the registration software. These two groups of human subjects were then compared with an auto-registration feature of the software, which is based on the mutual information between the portal and DRR images. For the thoracic case, the average distance between the actual setup error and the estimated error was 4.3 +/- 3.0 mm for doctors using the side-by-side method, 2.1 +/- 2.4 mm for technicians using the registration method, and 0.8 +/- 0.4 mm for the automatic algorithm. For the pelvis case, the average distance between the actual setup error and estimated error was 2.0 +/- 0.5 mm for the doctors using the side-by-side method, 2.5 +/- 0.4 mm for technicians using the registration method, and 2.0 +/- 1.0 mm for the automatic algorithm. The ability of humans to estimate offset values improved statistically using our software for the chest phantom that we tested. Setup error estimation was further improved using our automatic error estimation algorithm. Estimations were not statistically different for the pelvis case. Consistency improved using the software for both the chest and pelvis phantoms. We also tested the automatic algorithm with a database of over 5,000 clinical cases from our hospital. The algorithm performed well for head and breast but performed poorly for pelvis cases, probably due to lack of contrast in the megavoltage portal image. The software incorporates an original algorithm to fuse portal and DRR images, which we describe in detail. The offset optimization algorithm used in the automatic mode of operation is also unique, and may be useful if the contrast of the portal images can be improved.
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• Optimization of fluoroscopy parameters using pattern matching prediction in the real-time tumor-tracking radiotherapy system.

  Miyamoto N, Ishikawa M, Bengua G, Sutherland K, Suzuki R, Kimura S, Shimizu S, Onimaru R, Shirato H

  Phys Med Biol 56 (15) 4803 - 13 1361-6560 2011 [Refereed][Not invited]
   

  In the real-time tumor-tracking radiotherapy system, fluoroscopy is used to determine the real-time position of internal fiducial markers. The pattern recognition score (PRS) ranging from 0 to 100 is computed by a template pattern matching technique in order to determine the marker position on the fluoroscopic image. The PRS depends on the quality of the fluoroscopic image. However, the fluoroscopy parameters such as tube voltage, current and exposure duration are selected manually and empirically in the clinical situation. This may result in an unnecessary imaging dose from the fluoroscopy or loss of the marker because of too much or insufficient x-ray exposure. In this study, a novel optimization method is proposed in order to minimize the fluoroscopic dose while keeping the image quality usable for marker tracking. The PRS can be predicted in a region where the marker appears to move in the fluoroscopic image by the proposed method. The predicted PRS can be utilized to judge whether the marker can be tracked with accuracy. In this paper, experiments were performed to show the feasibility of the PRS prediction method under various conditions. The predicted PRS showed good agreement with the measured PRS. The root mean square error between the predicted PRS and the measured PRS was within 1.44. An experiment using a motion controller and an anthropomorphic chest phantom was also performed in order to imitate a clinical fluoroscopy situation. The result shows that the proposed prediction method is expected to be applicable in a real clinical situation.
• The impact of 18F-fluoromisonidazole PET for H&N cancer and the applying for IMRT

  YASUDA KOICHI, HASEGAWA MASAICHI, ONIMARU RIKIYA, KINOSHITA RUMIKO, KATO NORIO, TAGUCHI HIROSHI, SHIMIZU SHIN'ICHI, INOUE TETSUYA, ONODERA SHUNSUKE, MIZOGUCHI FUMIKI, AOYAMA HIDEFUMI, SHIRATO HIROKI, SHIGA SATORU, OKAMOTO SHOZO, TAMAKI NAGARA, ISHIKAWA MASAZUMI, SUTHERLAND KENNETH, BENGUA GERARD, MIYAMOTO NAOKI, SUZUKI TAKASUKE

  Jpn J Radiol 28 (Supplement 1) 14  1867-1071 2010/07/25 [Not refereed][Not invited]
  
• 生物学的効果を考慮した治療計画—Dose Volume Histogram解析による考察—

  関原和正, 石川正純, SUTHERLAND Kenneth, BENGUA Gerard, 宮本直樹, 鈴木隆介, 清水伸一, 白土博樹

  Jpn J Radiol 28 (Supplement 1) 15  1867-1071 2010/07/25 [Not refereed][Not invited]
  
• Evaluation of the effectiveness of the stereotactic body frame in reducing respiratory intrafractional organ motion using the real-time tumor-tracking radiotherapy system.

  Bengua G, Ishikawa M, Sutherland K, Horita K, Yamazaki R, Fujita K, Onimaru R, Katoh N, Inoue T, Onodera S, Shirato H

  International journal of radiation oncology, biology, physics 2 77 630 - 636 0360-3016 2010/06 [Refereed][Not invited]
  
• A parameter study of pencil beam proton dose distributions for the treatment of ocular melanoma utilizing spot scanning

  Kenneth Sutherland, Satoshi Miyajima, Hiroyuki Date, Hiroki Shirato, Masayori Ishikawa, Masao Murakami, Mitsuru Yamagiwa, Paul Bolton, Toshiki Tajima

  Radiological Physics and Technology 3 (1) 16 - 22 1865-0333 2010/01 [Refereed][Not invited]
   

  The results of Monte Carlo calculated dose distributions of proton treatment of ocular melanoma are presented. An efficient spot scanning method utilizing active energy modulation, which also minimizes the number of target spots was developed. We simulated various parameter values for the particle energy spread and the pencil beam diameter in order to determine values suitable for medical treatment. We found that a 2.5-mm-diameter proton beam with a 5% Gaussian energy spread was suitable for treatment of ocular melanoma while preserving vision for the typical case that we simulated. The energy spectra and the required proton current were also calculated and are reported. The results are intended to serve as a guideline for a new class of low-cost, compact accelerators. © 2009 Japanese Society of Radiological Technology and Japan Society of Medical Physics.
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• Evaluation of the effectiveness of the stereotactic body frame in reducing respiratory intrafractional organ motion using the real-time tumor-tracking radiotherapy system.

  Bengua G, Ishikawa M, Sutherland K, Horita K, Yamazaki R, Fujita K, Onimaru R, Katoh N, Inoue T, Onodera S, Shirato H

  Int J Radiat Oncol Biol Phys 77 (2) 630 - 6 1879-355X 2010 [Refereed][Not invited]
  
• 動体追跡装置におけるコントラスト‐ノイズ比の測定方法の検討

  木村傑, 宮本直樹, 石川正純, SUTHERLAND Kenneth, BENGUA Gerard, 鈴木隆介, 清水伸一, 青山英史, 鬼丸力也, 白土博樹

  医学物理 Supplement 29 (3) 148-149  1345-5362 2009/09 [Not refereed][Not invited]
  
• 動体追跡装置を用いた肺定位照射時の投与線量解析—動体追跡データに基づくDVH解析—

  石川正純, サザランド ケネス, ベングア ジェラード, 鈴木隆介, 宮本直樹, 加藤徳雄, 清水伸一, 鬼丸力也, 青山英史, 白土博樹

  日本放射線腫よう学会誌 21 (Supplement 1) 158  1040-9564 2009/08/19 [Not refereed][Not invited]
  
• 体内臓器同期照射を目的とした次世代動体追跡装置の開発〜透視画像の歪みと位置計算誤差〜

  宮本直樹, SUTHERLAND Kenneth, 石川正純, 鈴木隆介, BENGUA Gerard, 木村傑, 清水伸一, 青山英史, 鬼丸力也, 白土博樹

  医学物理 Supplement 29 (2) 192-193  1345-5362 2009/04 [Not refereed][Not invited]
  
• 体内臓器同期照射を目的とした次世代動体追跡装置の開発〜デジタル画像機器としての定量的評価〜

  木村傑, 石川正純, SUTHERLAND Kenneth, 宮本直樹, BENGUA Gerard, 鈴木隆介, 清水伸一, 青山英史, 鬼丸力也, 白土博樹

  医学物理 Supplement 29 (2) 196-197  1345-5362 2009/04 [Not refereed][Not invited]
  
• 体内臓器同期照射を目的とした次世代動体追跡装置の開発〜複数マーカ追跡への挑戦〜

  石川正純, SUTHERLAND Kenneth, 宮本直樹, BENGUA Gerard, 清水伸一, 青山英史, 鬼丸力也, 木村傑, 白土博樹

  医学物理 Supplement 29 (2) 194-195  1345-5362 2009/04 [Not refereed][Not invited]
  
• A feasibility study of novel plastic scintillation dosimetry with pulse counting mode

  M. Ishikawa, G. Bengua, K. Sutherland, J. Hiratsuka, N. Katoh, S. Shimizu, H. Aoyama, K. Fujita, R. Yamazaki, K. Horita, H. Shirato

  Physics in Medicine and Biology 54 2079 - 2092 2009 [Refereed][Not invited]
  
• SOF線量計によるIr‐192高線量率密封小線源治療時のin‐vivoリアルタイム線量測定

  石川正純, 平塚純一, 長瀬尚巳, GERARD Bengua, KENNETH Sutherland, 加藤徳雄, 清水伸一, 鬼丸力也, 青山英史, 白土博樹

  日本放射線腫よう学会誌 20 (Supplement 1) 251  1040-9564 2008/09/22 [Not refereed][Not invited]
  
• LG-DRR patient setup verification for routine clinical application

  KENNETH SUTHERLAND, ISHIKAWA MASAZUMI, GERARD BENGUA, ONIMARU RIKIYA, SHIMIZU SHIN'ICHI, AOYAMA HIDEFUMI, FUJITA KATSUHISA, YAMASAKI SATOI, SHIRATO HIROKI

  日本放射線腫よう学会誌 20 (Supplement 1) 264  1040-9564 2008/09/22 [Not refereed][Not invited]
  
• 分子イメージングを利用した患者位置確認のための対向型Open‐PET装置の製作と基礎検討

  棚邊哲史, 石川正純, 山口哲, 武島嗣英, GERARD Bengua, KENNETH Sutherland, 加藤徳雄, 清水伸一, 鬼丸力也, 白土博樹

  日本放射線腫よう学会誌 20 (Supplement 1) 268  1040-9564 2008/09/22 [Not refereed][Not invited]
  
• RTRT-based evaluation of the effectiveness of the stereotactic body frame in reducing intrafraction organ motion

  Bengua G, Ishikawa M, Sutherland K, Horita K, Yamazaki R, Fujita K, Onimaru R, Shimizu S, Shirato

  International Journal of Radiation Oncology Biology Physics 72 (1) S610 - S611 0360-3016 2008 [Refereed][Not invited]
  
• A simple parallelization of GEANT4 on a PC cluster with static scheduling for dose calculations

  K. Sutherland, S. Miyajima, H. Date

  FIRST EUROPEAN WORKSHOP ON MONTE CARLO TREATMENT PLANNING 74 (012020) 1742-6588 2007 [Refereed][Not invited]
   

  We discuss our experience improving the speed of Monte Carlo dose distribution calculations with GEANT4. First we customized the core geometry library to navigate voxelized CT volumes more efficiently. This resulted in a speed improvement of more than two orders of magnitude in our case. We then tried to run the simulation in parallel. However, we found that existing parallelizations of GEANT4 such as TOP-C (Task Oriented Parallel C/C++) did not scale well. We determined that the poor performance was due to excessive network traffic. We abandoned the master/slave model employed in TOP-C in favour of "static scheduling" parallelism where the event list is divided evenly among the processes. Our implementation used only a few low-level MPI calls. With this method, we achieved a linear speed improvement on our cluster of 23 machines. The simulation executes efficiently because there is almost no network traffic during the simulation. Using our customized GEANT4 navigation library running on our cluster with our parallelization method, we achieved a combined speed improvement factor of more than 3000, reducing our simulation time from several days to a few minutes. Although we did not consider issues such as fault tolerance or load sharing, our approach is well suited for many kinds of Monte Carlo simulations on a homogenous cluster of local PCs.
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• Spatial distributions of dose enhancement around a gold nanoparticle at several depths of proton Bragg peak

  Jihun Kwon, Kenneth Sutherland, Takayuki Hashimoto, Hiroki Shirato, Hiroyuki Date  Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms  384-  113  -120  2016/10/01  [Not refereed][Not invited]
   

  © 2016 Elsevier B.V. Gold nanoparticles (GNPs) have been recognized as a promising candidate for a radiation sensitizer. A proton beam incident on a GNP can produce secondary electrons, resulting in an enhancement of the dose around the GNP. However, little is known about the spatial distribution of dose enhancement around the GNP, especially in the direction along the incident proton. The purpose of this study is to determine the spatial distribution of dose enhancement by taking the incident direction into account. Two steps of calculation were conducted using the Geant4 Monte Carlo simulation toolkit. First, the energy spectra of 100 and 195 MeV protons colliding with a GNP were calculated at the Bragg peak and three other depths around the peak in liquid water. Second, the GNP was bombarded by protons with the obtained energy spectra. Radial dose distributions were computed along the incident beam direction. The spatial distributions of the dose enhancement factor (DEF) and subtracted dose (D sub ) were then evaluated. The spatial DEF distributions showed hot spots in the distal radial region from the proton beam axis. The spatial D sub distribution isotropically spread out around the GNP. Low energy protons caused higher and wider dose enhancement. The macroscopic dose enhancement in clinical applications was also evaluated. The results suggest that the consideration of the spatial distribution of GNPs in treatment planning will maximize the potential of GNPs.
• In vivo imaging of clock gene expression in multiple tissues of freely moving mice

  Toshiyuki Hamada, Kenneth Sutherland, Masayori Ishikawa, Masayori Ishikawa, Masayori Ishikawa, Masayori Ishikawa, Naoki Miyamoto, Sato Honma, Hiroki Shirato, Hiroki Shirato, Ken Ichi Honma  Nature Communications  7-  11705  -11705  2016/06/10  [Not refereed][Not invited]
   

  Clock genes are expressed throughout the body, although how they oscillate in unrestrained animals is not known. Here, we show an in vivo imaging technique that enables long-term simultaneous imaging of multiple tissues. We use dual-focal 3D tracking and signal-intensity calibration to follow gene expression in a target area. We measure circadian rhythms of clock genes in the olfactory bulb, right and left ears and cortices, and the skin. In addition, the kinetic relationship between gene expression and physiological responses to experimental cues is monitored. Under stable conditions gene expression is in phase in all tissues. In response to a long-duration light pulse, the olfactory bulb shifts faster than other tissues. In Cry1 - / - Cry2 - / - arrhythmic mice circadian oscillation is absent in all tissues. Thus, our system successfully tracks circadian rhythms in clock genes in multiple tissues in unrestrained mice.
• Dose Enhancement by Gold Nanoparticles Around the Bragg Peak of Proton Beams

  J. Kwon, K. Sutherland, T. Hashimoto, H. Peng, L. Xing, H. Shirato, H. Date  MEDICAL PHYSICS  43-  (6)  3787  -+  2016/06  [Not refereed][Not invited]
  
• 新規動体追跡技術により可能になる3D imagingによる自由行動マウスの全身の遺伝子発現追跡定量法の開発

  浜田 俊幸, 石川 正純, Sutherland Kenneth, 宮本 直樹, 白土 博樹, 本間 さと, 本間 研一  バイオイメージング  24-  (2)  114  -114  2015/09  [Not refereed][Not invited]
  
• 新規4D imagingによる自由行動マウスの全身の時計遺伝子発現制御機構の解析

  浜田 俊幸, Sutherland Kenneth, 石川 正純, 宮本 直樹, 本間 さと, 白土 博樹, 本間 研一  日本薬学会年会要旨集  135年会-  (2)  290  -290  2015/03  [Not refereed][Not invited]
  
• A motion-compensated image filter for low-dose fluoroscopy in a real-time tumor-tracking radiotherapy system

  Naoki Miyamoto, Masayori Ishikawa, Kenneth Sutherland, Ryusuke Suzuki, Taeko Matsuura, Chie Toramatsu, Seishin Takao, Hideaki Nihongi, Shinichi Shimizu, Kikuo Umegaki, Hiroki Shirato  Journal of Radiation Research  56-  (1)  186  -196  2014/01/01  [Not refereed][Not invited]
   

  © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology. In the real-time tumor-tracking radiotherapy system, a surrogate fiducial marker inserted in or near the tumor is detected by fluoroscopy to realize respiratory-gated radiotherapy. The imaging dose caused by fluoroscopy should be minimized. In this work, an image processing technique is proposed for tracing a moving marker in low-dose imaging. The proposed tracking technique is a combination of a motion-compensated recursive filter and template pattern matching. The proposed image filter can reduce motion artifacts resulting from the recursive process based on the determination of the region of interest for the next frame according to the current marker position in the fluoroscopic images. The effectiveness of the proposed technique and the expected clinical benefit were examined by phantom experimental studies with actual tumor trajectories generated from clinical patient data. It was demonstrated that the marker motion could be traced in low-dose imaging by applying the proposed algorithm with acceptable registration error and high pattern recognition score in all trajectories, although some traj ectories were not able to be tracked with the conventional spatial filters or without image filters. The positional accuracy is expected to be kept within ±2 mm. The total computation time required to determine the marker position is a few milliseconds. The proposed image processing technique is applicable for imaging dose reduction.
• 覚醒マウス嗅球および皮膚における時計遺伝子発現の4Dイメージング

  浜田俊幸, 石川正純, SUTHERLAND K, 宮本直樹, 白土博樹, 本間さと, 本間研一  日本生理学雑誌  75-  (4)  206  -207  2013/07/01  [Not refereed][Not invited]
  
• What is the appropriate size criterion for proton radiotherapy for hepatocellular carcinoma? A dosimetric comparison of spot-scanning proton therapy versus intensity-modulated radiation therapy

  Chie Toramatsu, Norio Katoh, Shinichi Shimizu, Hideaki Nihongi, Taeko Matsuura, Seishin Takao, Naoki Miyamoto, Ryusuke Suzuki, Kenneth Sutherland, Rumiko Kinoshita, Rikiya Onimaru, Masayori Ishikawa, Kikuo Umegaki, Hiroki Shirato  Radiation Oncology  8-  2013/03/05  [Not refereed][Not invited]
   

  Background: We performed a dosimetric comparison of spot-scanning proton therapy (SSPT) and intensity-modulated radiation therapy (IMRT) for hepatocellular carcinoma (HCC) to investigate the impact of tumor size on the risk of radiation induced liver disease (RILD).Methods: A number of alternative plans were generated for 10 patients with HCC. The gross tumor volumes (GTV) varied from 20.1 to 2194.5 cm 3 . Assuming all GTVs were spherical, the nominal diameter was calculated and ranged from 3.4 to 16.1 cm. The prescription dose was 60 Gy for IMRT or 60 cobalt Gy-equivalents for SSPT with 95% planning target volume (PTV) coverage. Using IMRT and SSPT techniques, extensive comparative planning was conducted. All plans were evaluated by the risk of RILD estimated using the Lyman-normal-tissue complication probability model.Results: For IMRT the risk of RILD increased drastically between 6.3-7.8 cm nominal diameter of GTV. When the nominal diameter of GTV was more than 6.3 cm, the average risk of RILD was 94.5% for IMRT and 6.2% for SSPT.Conclusions: Regarding the risk of RILD, HCC can be more safely treated with SSPT, especially if its nominal diameter is more than 6.3 cm. © 2013 Toramatsu et al.; licensee BioMed Central Ltd.
• SU‐E‐T‐448: Effectiveness of An In‐Gate Beam Tracking Method in Spot‐Scanning Proton Therapy

  T. Matsuura, Y. Fujii, R. Fujimoto, M. Umezawa, N. Miyamoto, K. Sutherland, S. Takao, H. Nihongi, C. Toramatsu, S. Shimizu, K. U. Megaki, H. Shirato  Medical Physics  40-  308  2013/01/01  [Not refereed][Not invited]
   

  Purpose: To mitigate the impact of tumor motion in spot‐scanning proton beam therapy, the gating technique has been considered as a powerful tool. Although residual tumor motion of a few millimeters of gate volume can still cause a dose error, the error can be minimized by repainting. However, a larger number of paintings also results in the prolongation of treatment time. We propose a method which improves the dose uniformity while minimally increasing the number of paintings. Methods: Lateral beam tracking was applied in conjunction with gating. A simulation study was performed using the VQA treatment planning system (Hitachi Ltd., Japan) to assess the effectiveness of this method. A gated proton beam provided by a synchrotron was irradiated to spherical clinical target volumes (CTVs) with a diameter of 5 cm located at 10 cm and 15 cm depth in a heterogeneous phantom. The system delay time was 66 ms. Gate width was set to 2 mm. Rigid motion was assumed for CTVs which were shifted in synchronization with 20 patients' tumor trajectory data. A dose of 2 Gy was prescribed with the minimum repainting scheme. The cases that fulfilled the ICRU 50 criteria (CTVmax < 107% and CTVmin > 95%) were accepted. Results: When only gating was used, 12 and 16 out of 20 cases were accepted for targets at 10 cm and 15 cm depth, respectively. On the other hand, when beam tracking was also applied, all cases were accepted for both target depths. Conclusion: The results suggest that the application of lateral beam tracking in gate volume can improve the dose uniformity without (or minimally) increasing the number of paintings. A simulation including non‐rigid patient motion will be considered in the future. © 2013, American Association of Physicists in Medicine. All rights reserved.
• Integration of a real-time tumor monitoring system into gated proton spot-scanning beam therapy: An initial phantom study using patient tumor trajectory data

  Taeko Matsuura, Taeko Matsuura, Taeko Matsuura, Naoki Miyamoto, Naoki Miyamoto, Naoki Miyamoto, Shinichi Shimizu, Shinichi Shimizu, Yusuke Fujii, Yusuke Fujii, Masumi Umezawa, Masumi Umezawa, Seishin Takao, Seishin Takao, Hideaki Nihongi, Hideaki Nihongi, Chie Toramatsu, Chie Toramatsu, Kenneth Sutherland, Kenneth Sutherland, Ryusuke Suzuki, Ryusuke Suzuki, Masayori Ishikawa, Masayori Ishikawa, Rumiko Kinoshita, Kenichiro Maeda, Kenichiro Maeda, Kikuo Umegaki, Hiroki Shirato  Medical Physics  40-  (7)  071729  -071729  2013/01/01  [Not refereed][Not invited]
   

  Purpose: In spot-scanning proton therapy, the interplay effect between tumor motion and beam delivery leads to deterioration of the dose distribution. To mitigate the impact of tumor motion, gating in combination with repainting is one of the most promising methods that have been proposed. This study focused on a synchrotron-based spot-scanning proton therapy system integrated with real-time tumor monitoring. The authors investigated the effectiveness of gating in terms of both the delivered dose distribution and irradiation time by conducting simulations with patients' motion data. The clinically acceptable range of adjustable irradiation control parameters was explored. Also, the relation between the dose error and the characteristics of tumor motion was investigated. Methods: A simulation study was performed using a water phantom. A gated proton beam was irradiated to a clinical target volume (CTV) of 5 × 5 × 5 cm 3 , in synchronization with lung cancer patients' tumor trajectory data. With varying parameters of gate width, spot spacing, and delivered dose per spot at one time, both dose uniformity and irradiation time were calculated for 397 tumor trajectory data from 78 patients. In addition, the authors placed an energy absorber upstream of the phantom and varied the thickness to examine the effect of changing the size of the Bragg peak and the number of required energy layers. The parameters with which 95% of the tumor trajectory data fulfill our defined criteria were accepted. Next, correlation coefficients were calculated between the maximum dose error and the tumor motion characteristics that were extracted from the tumor trajectory data. Results: With the assumed CTV, the largest percentage of the data fulfilled the criteria when the gate width was ±2 mm. Larger spot spacing was preferred because it increased the number of paintings. With a prescribed dose of 2 Gy, it was difficult to fulfill the criteria for the target with a very small effective depth (the sum of an assumed energy absorber's thickness and the target depth in the phantom) because of the sharpness of the Bragg peak. However, even shallow targets could be successfully irradiated by employing an adequate number of paintings and by placing an energy absorber of sufficient thickness to make the effective target depth more than 12 cm. The authors also observed that motion in the beam direction was the main cause of dose distortion, followed by motion in the lateral plane perpendicular to the scan direction. Conclusions: The results suggested that by properly adjusting irradiation control parameters, gated proton spot-scanning beam therapy can be robust to target motion. This is an important first step toward establishing treatment plans in real patient geometry. © 2013 American Association of Physicists in Medicine.
• SU‐E‐J‐57: A Feasibility Study On Molecular‐Imaging‐Based Real‐Time Tumor Tracking for Gated Radiotherapy

  M. Ishikawa, S. Tanabe, S. Yamaguchi, N. Ukon, T. Yamanaka, K. Sutherland, N. Miyamoto, R. Suzuki, N. Katoh, K. Yasuda, H. Shirato  Medical Physics  40-  162  2013/01/01  [Not refereed][Not invited]
   

  Purpose: Molecular imaging is one of the important modalities in delineating tumors particularly in radiotherapy treatment planning. If the real‐time tumor position can be detected using molecular imaging during radiotherapy, it may be helpful for gated irradiation. A feasibility study on a beam gating system for radiotherapy using real‐time molecular imaging was conducted by the prototype and simulating a parallel plane PET system. Methods: Assuming that the motion of the positron source is constrained to the central plane, the source position can be calculated from a cross point of the Line of Response (LOR) and the central plane between detector surfaces. If a positron source is located at the ISO center, distribution of the cross points might be blurred due to random/scattered coincidence. Center Located Ratio (CLR) was defined as a ratio of LORs passing through the ISO center divided by the entire LORs. When dislocation for perpendicular direction is occurred, a distribution of cross points will be spread out and associated decrease of CLR value will be expected. Results: The behavior between real measurement and simulation was similar on proto‐type experiments, however, the Result from simulation for demonstrator might be different from actual measurement. RTRT system recognizes the position of a gold marker in the rate of 30 fps using two X‐ray television systems. It is shown that 15,000 events per second will be needed for an appropriate gating irradiation to recognize discrepancy over 2mm of time resolution in the parallel plane PET system demonstrator. Conclusion: A feasibility study was carried out to verify the potential for gating irradiation of tumors with real‐time molecular imaging using a parallel plane PET system. For an parallel plane PET system demonstrator, the possibility of detecting the tumor position with an accuracy of 2 mm from the ISO center with 500 events. This research was a part of the “Innovation COE Program for Future Drug Discovery and Medical Care” project and partially supported by the Grant‐in‐Aid for Project for Developing Innovation Systems of the Japanese Ministry of Education, Culture, Sports, Science and Technology. © 2013, American Association of Physicists in Medicine. All rights reserved.
• Improvement of tracking accuracy and stability by recursive image processing in real-time tumor-tracking radiotherapy system

  Naoki Miyamoto, Kenneth Sutherland, Ryusuke Suzuki, Taeko Matsuura, Chie Toramatsu, Seishin Takao, Hideaki Nihongi, Rumiko Kinoshita, Shinichi Shimizu, Rikiya Onimaru, Kikuo Umegaki, Hiroki Shirato, Masayori Ishikawa  Progress in Biomedical Optics and Imaging - Proceedings of SPIE  8316-  83160  2012/05/01  [Not refereed][Not invited]
   

  In the real-time tumor-tracking radiotherapy (RTRT) system, the fiducial markers are inserted in or near the target tumor in order monitor the respiratory-induced motion of tumors. During radiation treatment, the markers are detected by continuous fluoroscopy operated at 30 frames/sec. The marker position is determined by means of a template pattern matching technique which is based on the normalized cross correlation. With high tube voltage, large current and long exposure, the fiducial marker will be recognized accurately, however, the radiation dose due to X-ray fluoroscopy increases. On the other hand, by decreasing the fluoroscopy parameter settings, the fiducial marker could be lost because the effect of statistical noise is increased. In the respiratory-gated radiotherapy, the error of the image guidance will induce the reduction of the irradiation efficiency and accuracy. In order to track the marker stably and accurately in low dose fluoroscopy, we propose the application of a recursive filter. The effectiveness of the image processing is investigated by tracking the static marker and the dynamic marker. The results suggest that the stability and the accuracy of the marker tracking can be improved by applying the recursive image filter in low dose imaging. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• リアルタイム分子イメージングを用いた治療ビームゲーティングに関する基礎検討

  右近直之, 棚邊哲史, 棚邊哲史, 山中琢, 山口哲, SUTHERLAND Kenneth, 鈴木隆介, 宮本直樹, 白土博樹, 石川正純  医学物理 Supplement  32-  (3)  2012
• MO‐F‐213AB‐04: Biological Effect of Dose Shadowing by Fiducial Markers in Spot Scanning Proton Therapy with a Limited Number of Fields

  T. Matsuura, K. Maeda, K. Sutherland, T. Takayanagi, S. Shimizu, S. Takao, H. Nihongi, C. Toramatsu, N. Miyamoto, Y. Nagamine, R. Fujimoto, K. Umegaki, H. Shirato  Medical Physics  39-  3872  2012/01/01  [Not refereed][Not invited]
   

  Purpose: In spot scanning proton therapy, accurate patient positioning before and during treatment is essential. A small gold ball marker is suitable as a fiducial for prostate treatment. However, it has been pointed out that the marker causes dose shadowing because the protons are scattered with their energy quickly diminished. In this research we explore the possibility that the biological effect of dose shadowing can be mitigated with a limited number of fields. Methods: The proton dose distribution in prostate was simulated using Geant4. The simulations include the Hokkaido University spot scanning nozzle and a water phantom positioned isocentrically. The PTV was delineated at the center of the phantom and a gold ball of 2 mm in diameter was placed at the middle of the PTV. The plan was created by single‐field optimization and each of the following beam arrangements was investigated; (1) single lateral field (2) two lateral fields (3) two lateral + one anterior fields (4) four‐field box. The dose prescription was D95 = 74 GyE (37 fr). The minimum dose and tumor control probability (TCP) were compared for the four beam arrangements. Results: For (1)–(4), the minimum dose values were 55%, 77%, 78%, and 84% of the prescribed dose, respectively. The reduction of the TCP values from those in the absence of the gold marker were 50%, 2%, 1.1%, and 0.7%, using the TCP model by Wang et al. (Int.J.Radiat.Oncol.Biol.Phys. 55, 2003) and 2%, 0.7%, 0.5%, and 0.4%, using the biological parameters in Levegrün et al. (Int.J.RadiatOncol.Biol.Phys. 51, 2001), respectively. Conclusions: Although dose shadowing by the gold marker is locally non‐negligible, the size of the affected domain is tiny. It was found that with a minimum number of fields, the TCP nearly recovers to the value without the gold marker. © 2012, American Association of Physicists in Medicine. All rights reserved.
• SU‐E‐J‐42: Motion Adaptive Image Filter for Low Dose X‐Ray Fluoroscopy in the Real‐Time Tumor‐Tracking Radiotherapy System

  N. Miyamoto, M. Ishikawa, K. Sutherland, R. Suzuki, T. Matsuura, S. Takao, C. Toramatsu, H. Nihongi, S. Shimizu, R. Onimaru, K. Umegaki, H. Shirato  Medical Physics  39-  3661  -3662  2012/01/01  [Not refereed][Not invited]
   

  Purpose: In the real‐time tumor‐tracking radiotherapy system, fiducial markers are detected by X‐ray fluoroscopy. The fluoroscopic parameters should be optimized as low as possible in order to reduce unnecessary imaging dose. However, the fiducial markers could not be recognized due to effect of statistical noise in low dose imaging. Image processing is envisioned to be a solution to improve image quality and to maintain tracking accuracy. In this study, a recursive image filter adapted to target motion is proposed. Methods: A fluoroscopy system was used for the experiment. A spherical gold marker was used as a fiducial marker. About 450 fluoroscopic images of the marker were recorded. In order to mimic respiratory motion of the marker, the images were shifted sequentially. The tube voltage, current and exposure duration were fixed at 65 kV, 50 mA and 2.5 msec as low dose imaging condition, respectively. The tube current was 100 mA as high dose imaging. A pattern recognition score (PRS) ranging from 0 to 100 and image registration error were investigated by performing template pattern matching to each sequential image. The results with and without image processing were compared. Results: In low dose imaging, theimage registration error and the PRS without the image processing were 2.15±1.21 pixel and 46.67±6.40, respectively. Those with the image processing were 1.48±0.82 pixel and 67.80±4.51, respectively. There was nosignificant difference in the image registration error and the PRS between the results of low dose imaging with the image processing and that of high dose imaging without the image processing. Conclusions: The results showed that the recursive filter was effective in order to maintain marker tracking stability and accuracy in low dose fluoroscopy. © 2012, American Association of Physicists in Medicine. All rights reserved.
• 診断X線領域における極微小光ファイバ線量計の基礎特性評価(第66回総会学術大会放射線防護・管理関連演題発表後抄録)

  江口 菜弥帆, 石川 正純, 作原 祐介, 阿保 大介, 太田 真緒, Sutherland Kenneth, 白土 博樹  放射線防護分科会会誌  0-  (31)  2010/10/14  [Not refereed][Not invited]
  
• 鼻腔・副鼻腔癌に対する超選択的動注を併用した根治的化学放射線療法

  長谷川雅一, 安田耕一, 吉田大介, 加藤徳雄, 鬼丸力也, 浅野剛, 白土博樹, 本間明宏, 折舘伸彦, 福田諭, 石川正純, BENGUA Gerard, SUTHERLAND Kenneth, 宮本直樹, 鈴木隆介  Jpn J Radiol  28-  (Supplement 1)  7  2010/07/25  [Not refereed][Not invited]
  
• 診断X線領域における極微小SOF線量計による被曝線量評価

  石川正純, 江口菜弥帆, 作原大介, 阿保大介, 太田真緒, SUTHERLAND Kenneth, BENGUA Gerard, 鈴木隆介, 宮本直樹, 白土博樹  日本医学放射線学会総会抄録集  69th-  S378  2010/02/28  [Not refereed][Not invited]
  
• 診断X線領域における極微小光ファイバ線量計の基礎特性評価

  江口 菜弥帆, 石川 正純, 作原 祐介, 阿保 大介, 太田 真緒, Sutherland Kenneth, 白土 博樹  日本放射線技術学会総会学術大会予稿集  66回-  153  -154  2010/02
• Conceptual Design of PET-linac System for Molecular-guided Radiotherapy

  M. Ishikawa, S. Yamaguchi, S. Tanabe, G. Bengua, K. Sutherland, R. Suzuki, N. Miyamoto, K. Nishijima, N. Katoh, H. Shirato  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  78-  (3)  S674  -S674  2010  [Not refereed][Not invited]
  
• Improvement of Tracking Accuracy and Stability with Utilizing a Color Image Intensifier in Real-time Tumor-tracking Radiotherapy System

  N. Miyamoto, M. Ishikawa, G. Bengua, K. Sutherland, R. Suzuki, H. Shirato  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  78-  (3)  S678  -S678  2010  [Not refereed][Not invited]
  
• Feasibility Study on Molecular-imaging Based Tracking System for Lung Cancer Treatment

  S. Tanabe, M. Ishikawa, S. Yamaguchi, G. Bengua, K. Sutherland, R. Suzuki, N. Miyamoto, N. Katoh, R. Onimaru, H. Shirato  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  78-  (3)  S749  -S749  2010  [Not refereed][Not invited]
  
• 動体追跡放射線治療におけるX線透視条件の最適化

  宮本直樹, SUTHERLAND Kenneth, 石川正純, 鈴木隆介, BENGUA Gerard, 木村傑, 清水伸一, 青山英史, 鬼丸力也, 白土博樹  医学物理 Supplement  29-  (3)  150-151  2009/09  [Not refereed][Not invited]
  
• 対向型PET装置を用いた患者位置確認システムの開発—GEANT4基礎シミュレーション—

  山口哲, 石川正純, 棚邊哲史, BENGUA Gerard, SUTHERLAND Kenneth, 青山英史, 武島嗣英, 白土博樹  医学物理 Supplement  29-  (3)  174-175  2009/09  [Not refereed][Not invited]
  
• 第3部 PET装置開発の展望(28)照射位置確認のためのOpen‐PET装置の開発—画像再構成の基礎シミュレーション—

  山口哲, 石川正純, 棚邊哲史, BENGUA Gerard, SUTHERLAND Kenneth, 青山英史, 武島嗣英, 白土博樹  NIRS−R (Natl Inst Radiol Sci)  (60)  137-138  2009/03  [Not refereed][Not invited]
  
• 放射線治療用頭頸部固定具(シェル)使用時による固定精度の評価

  高森清華, 堀田賢治, 斎藤英一, 山崎理衣, 藤田勝久, SUTHERLAND Kenneth, 石川正純  日本放射線技術学会総会学術大会予稿集  65th-  242  2009/02/27  [Not refereed][Not invited]
  
• Detection of Patient Set-up Errors with a Portal Image - DRR Registration Software System

  K. Sutherland, M. Ishikawa, G. Bengua, H. Shirato  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  75-  (3)  S600  -S600  2009  [Not refereed][Not invited]
  
• 患者位置確認のためのイメージング装置の開発—Open‐PET装置の基礎シミュレーション—

  山口哲, 石川正純, 棚邊哲史, GERARD Bengua, KENNETH Sutherland, 青山英史, 武島嗣英, 白土博樹  日本放射線腫よう学会誌  20-  (Supplement 1)  267  2008/09/22  [Not refereed][Not invited]
  
• Development of Molecular Imaging Device for patient setup : Preliminary simulation of Open-PET

  YAMAGUCHI Satoshi, ISHIKAWA Masayori, TANABE Satoshi, BENGUA Gerard, SUTHERLAND Kenneth, AOYAMA Hidefumi, TAKESHIMA Tuguhide, SHIRATO Hiroki  医学物理 : 日本医学物理学会機関誌 = Japanese journal of medical physics : an official journal of Japan Society of Medical Physics  28-  256  -257  2008/04/01  [Not refereed][Not invited]
  

Educational Activities

Teaching Experience