Probability of normal tissue complications for hematologic and gastrointestinal toxicity in postoperative whole pelvic radiotherapy for gynecologic malignancies using intensity-modulated proton therapy with robust optimization.
Takaaki Yoshimura, Ryota Yamada, Rumiko Kinoshita, Taeko Matsuura, Takahiro Kanehira, Hiroshi Tamura, Kentaro Nishioka, Koichi Yasuda, Hiroshi Taguchi, Norio Katoh, Keiji Kobashi, Takayuki Hashimoto, Hidefumi Aoyama
Journal of radiation research, 17 Mar. 2024, [International Magazine]
English, Scientific journal, This retrospective treatment-planning study was conducted to determine whether intensity-modulated proton therapy with robust optimization (ro-IMPT) reduces the risk of acute hematologic toxicity (H-T) and acute and late gastrointestinal toxicity (GI-T) in postoperative whole pelvic radiotherapy for gynecologic malignancies when compared with three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated X-ray (IMXT) and single-field optimization proton beam (SFO-PBT) therapies. All plans were created for 13 gynecologic-malignancy patients. The prescribed dose was 45 GyE in 25 fractions for 95% planning target volume in 3D-CRT, IMXT and SFO-PBT plans and for 99% clinical target volume (CTV) in ro-IMPT plans. The normal tissue complication probability (NTCP) of each toxicity was used as an in silico surrogate marker. Median estimated NTCP values for acute H-T and acute and late GI-T were 0.20, 0.94 and 0.58 × 10-1 in 3D-CRT; 0.19, 0.65 and 0.24 × 10-1 in IMXT; 0.04, 0.74 and 0.19 × 10-1 in SFO-PBT; and 0.06, 0.66 and 0.15 × 10-1 in ro-IMPT, respectively. Compared with 3D-CRT and IMXT plans, the ro-IMPT plan demonstrated significant reduction in acute H-T and late GI-T. The risk of acute GI-T in ro-IMPT plan is equivalent with IMXT plan. The ro-IMPT plan demonstrated potential clinical benefits for reducing the risk of acute H-T and late GI-T in the treatment of gynecologic malignances by reducing the dose to the bone marrow and bowel bag while maintaining adequate dose coverage to the CTV. Our results indicated that ro-IMPT may reduce acute H-T and late GI-T risk with potentially improving outcomes for postoperative gynecologic-malignancy patients with concurrent chemotherapy.

Impact of adaptive radiotherapy on survival in locally advanced nasopharyngeal carcinoma treated with concurrent chemoradiotherapy.
Yusuke Uchinami, Koichi Yasuda, Hideki Minatogawa, Yasuhiro Dekura, Noboru Nishikawa, Rumiko Kinoshita, Kentaro Nishioka, Norio Katoh, Takashi Mori, Manami Otsuka, Naoki Miyamoto, Ryusuke Suzuki, Keiji Kobashi, Yasushi Shimizu, Jun Taguchi, Nayuta Tsushima, Satoshi Kano, Akihiro Homma, Hidefumi Aoyama
Radiation oncology journal, 42, 1, 74, 82, Mar. 2024, [International Magazine]
English, Scientific journal, PURPOSE: To investigate the clinical significance of adaptive radiotherapy (ART) in locally advanced nasopharyngeal carcinoma treated with intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: Eligible patients were treated with concurrent chemoradiotherapy using IMRT. Planning computed tomography in ART was performed during radiotherapy, and replanning was performed. Since ART was started in May 2011 (ART group), patients who were treated without ART up to April 2011 (non-ART group) were used as the historical control. The Kaplan-Meier method was used to calculate overall survival (OS), locoregional recurrence-free survival (LRFS), progression-free survival (PFS), and distant metastasis-free survival (DMFS). LRFS for the primary tumor (LRFS_P) and regional lymph node (LRFS_LN) were also studied for more detailed analysis. Statistical significance was evaluated using the log-rank test for survival. RESULTS: The ART group tended to have higher radiation doses. The median follow-up period was 127 months (range, 10 to 211 months) in the non-ART group and 61.5 months (range, 5 to 129 months) in the ART group. Compared to the non-ART group, the ART group showed significantly higher 5-year PFS (53.8% vs. 81.3%, p = 0.015) and LRFS (61.2% vs. 85.3%, p = 0.024), but not OS (80.7% vs. 80.8%, p = 0.941) and DMFS (84.6% vs. 92.7%, p = 0.255). Five-year LRFS_P was higher in the ART group (61.3% vs. 90.6%, p = 0.005), but LRFS_LN did not show a significant difference (91.9% vs. 96.2%, p = 0.541). CONCLUSION: Although there were differences in the patient backgrounds between the two groups, this study suggests the potential effectiveness of ART in improving locoregional control, especially in the primary tumor.

Radiotherapy with or without chemotherapy for locally advanced head and neck cancer in elderly patients: analysis of the Head and Neck Cancer Registry of Japan.
Koichi Yasuda, Yusuke Uchinami, Satoshi Kano, Jun Taguchi, Daisuke Kawakita, Megumi Kitayama, Kentaro Nishioka, Takashi Mori, Fuki Koizumi, Yuri Fujii, Yasushi Shimizu, Keiji Kobashi, Seiichi Yoshimoto, Ken-Ichi Nibu, Akihiro Homma, Hidefumi Aoyama
International journal of clinical oncology, 29 Dec. 2023, [Domestic magazines]
English, Scientific journal, BACKGROUND: Whether concurrent chemotherapy with radiotherapy (CRT) is effective for elderly patients with head and neck cancer is a controversial topic. This study aimed to analyze the effectiveness of CRT vs. radiation therapy (RT) among elderly patients in Japan. METHODS: Data from the Head and Neck Cancer Registry of Japan were extracted and analyzed. Patients with locally advanced squamous cell carcinoma of the oropharynx, hypopharynx, or larynx who received definitive CRT or RT between 2011 and 2014 were included. RESULTS: CRT was administered to 78% of the 1057 patients aged ≥ 70 years and 67% of the 555 patients aged ≥ 75 years. For the patients aged ≥ 75 years, the overall survival (OS) rate was significantly better in the CRT group than in the RT group (P < 0.05), while the progression-free survival (PFS) rate was not significantly different (P > 0.05). The add-on effect of CRT was significantly poor in elderly patients (P < 0.05), and it was not a significant factor in the multivariate analysis for patients aged ≥ 75 years. After propensity score matching, there were no significant differences in the OS and PFS rates between the patients aged ≥ 70 years and those aged ≥ 75 years (all, P > 0.05). CONCLUSION: Although aggressive CRT is administered to elderly patients in Japan, its effectiveness is uncertain. Further prospective randomized trials are needed to verify whether CRT is superior to RT alone for elderly patients.

Daily fraction dose-adjusted radiotherapy policy to avoid prolonging the overall treatment time for early glottic squamous cell carcinoma: a single-institutional retrospective study.
Yasuhiro Dekura, Koichi Yasuda, Hideki Minatogawa, Yusuke Uchinami, Nayuta Tsushima, Takayoshi Suzuki, Satoshi Kano, Takashi Mori, Kentaro Nishioka, Keiji Kobashi, Norio Katoh, Akihiro Homma, Hidefumi Aoyama
Journal of radiation research, 10 Nov. 2023, [International Magazine]
English, Scientific journal, The objective of this study was to determine the outcomes of radical radiotherapy for early glottic squamous cell carcinoma (EGSCC) with the policy of increasing the fraction size during radiotherapy when the overall treatment time (OTT) was expected to be prolonged. Patients diagnosed with clinical T1-2N0M0 EGSCC, who were treated with radical radiotherapy between 2008 and 2019 at Hokkaido University Hospital, were included. Patients received 66 Gy in 33 fractions for T1 disease and 70 Gy in 35 fractions for T2 disease as our standard regimen (usual group [UG]). If the OTT was expected to extend for >1 week, the dose fraction size was increased from 2.0 to 2.5 Gy from the beginning or during radiotherapy (adjusted group [AG]). At this time, we performed a statistical analysis between UG and AG. In total, 116 patients were identified, and the treatment schedules of 29 patients were adjusted. The median follow-up was 60.9 months. In the T1 group, the cumulative 5-year local failure rate was 12.0% in the AG and 15.4% in the UG, and in the T2 group, the rate was 40.7% in the AG and 25.3% in the UG. There were no significant differences between the AG and UG. Similarly, no significant differences were observed for overall survival and progression-free survival rates. Our single-institutional retrospective analysis of EGSCC patients suggested that a method of adjusting the radiotherapy schedule to increase fraction size from the beginning or during the course may be effective in maintaining treatment outcomes.

Predicting the daily gastrointestinal doses of stereotactic body radiation therapy for pancreatic cancer based on the shortest distance between the tumor and the gastrointestinal tract using daily computed tomography images
Yusuke Uchinami, Takahiro Kanehira, Keiji Nakazato, Yoshihiro Fujita, Fuki Koizumi, Shuhei Takahashi, Manami Otsuka, Koichi Yasuda, Hiroshi Taguchi, Kentaro Nishioka, Naoki Miyamoto, Kohei Yokokawa, Ryusuke Suzuki, Keiji Kobashi, Keita Takahashi, Norio Katoh, Hidefumi Aoyama
BJR|Open, 5, 1, British Institute of Radiology, Aug. 2023
Scientific journal, Objectives:

We aimed to investigate whether daily computed tomography (CT) images could predict the daily gastroduodenal, small intestine, and large intestine doses of stereotactic body radiation therapy (SBRT) for pancreatic cancer based on the shortest distance between the gross tumor volume (GTV) and gastrointestinal (GI) tract.

Methods:

Twelve patients with pancreatic cancer received SBRT of 40 Gy in five fractions. We recalculated the reference clinical SBRT plan (PLAN_ref) using daily CT images and calculated the shortest distance from the GTV to each GI tract. The maximum dose delivered to 0.5 cc (D_0.5cc) was evaluated for each planning at-risk volume of the GI tract. Spearman’s correlation test was used to determine the association between the daily change in the shortest distance (Δshortest distance) and the ratio of ΔD_0.5cc dose to D_0.5cc dose in PLAN_ref (ΔD_0.5cc/PLAN_ref) for quantitative analysis.

Results:

The median shortest distance in PLAN_ref was 0 mm in the gastroduodenum (interquartile range, 0–2.7), 16.7 mm in the small intestine (10.0–23.7), and 16.7 mm in the large intestine (8.3–28.1 mm). The D_0.5cc of PLAN_ref in the gastroduodenum was >30 Gy in all patients, with 10 (83.3%) having the highest dose. A significant association was found between the Δshortest distance and ΔD_0.5cc/ PLAN_ref in the small or large intestine (p < 0.001) but not in the gastroduodenum (p = 0.404).

Conclusions:

The gastroduodenum had a higher D_0.5cc and predicting the daily dose was difficult. Daily dose calculations of the GI tract are recommended for safe SBRT.

Advances in knowledge:

This study aimed to predict the daily doses in SBRT for pancreatic cancer from the shortest distance between the GTV and the gastrointestinal tract. Daily changes in the shortest distance can predict the daily dose to the small or large intestines, but not to the gastroduodenum.

Effectiveness of CT-image guidance in proton therapy for liver cancer and the importance of daily dose monitoring for tumors and organs at risk.
Yoshikazu Maeda, Keiji Kobashi, Yoshitaka Sato, Hiroyasu Tamamura, Kazutaka Yamamoto, Keiichiro Matsushita, Makoto Sasaki, Hitoshi Tatebe, Tomoko Asahi, Sae Matsumoto, Shigeyuki Takamatsu, Koichi Miyazaki, Rintaro Fujimoto, Yusuke Uchinami, Norio Katoh, Hidefumi Aoyama
Medical physics, 50, 6, 3274, 3288, 26 Apr. 2023, [International Magazine]
English, Scientific journal, BACKGROUND: It is important to have precise image guidance throughout proton therapy in order to take advantage of the therapy's physical selectivity. PURPOSE: We evaluated the effectiveness of computed tomography (CT)-image guidance in proton therapy for patients with hepatocellular carcinoma (HCC) by assessing daily proton dose distributions. The importance of daily CT image-guided registration and daily proton dose monitoring for tumors and organs at risk (OARs) was investigated. METHODS: A retrospective analysis was conducted using 570 sets of daily CT (dCT) images throughout whole treatment fractions for 38 HCC patients who underwent passive scattering proton therapy with either a 66 cobalt gray equivalent (GyE)/10 fractions (n = 19) or 76 GyE/20 fractions (n = 19) protocol. The actual daily delivered dose distributions were estimated by forward calculation using the dCT sets, their corresponding treatment plans, and the recorded daily couch correction information. We then evaluated the daily changes of the dose indices D99% , V30GyE , and Dmax for the tumor volumes, non-tumorous liver, and other OARs, that is, stomach, esophagus, duodenum, colon, respectively. Contours were created for all dCT sets. We validated the efficacy of the dCT-based tumor registrations (hereafter, "tumor registration") by comparing them with the bone registration and diaphragm registration as a simulation of the treatment based on the positioning using the conventional kV X-ray imaging. The dose distributions and the indices of three registrations were obtained by simulation using the same dCT sets. RESULTS: In the 66 GyE/10 fractions, the daily D99% value in both the tumor and diaphragm registrations agreed with the planned value with 3%-6% (SD), and the V30GyE value for the liver agreed within ±3%; the indices in the bone registration showed greater deterioration. Nevertheless, tumor-dose deterioration occurred in all registration methods for two cases due to daily changes of body shape and respiratory condition. In the 76 GyE/20 fractions, in particular for such a treatment that the dose constraints for the OARs have to be cared in the original planning, the daily D99% in the tumor registration was superior to that in the other registration (p < 0.001), indicating the effectiveness of the tumor registration. The dose constraints, set in the plan as the maximum dose for OARs (i.e., duodenum, stomach, colon, and esophagus) were maintained for 16 patients including seven treated with re-planning. For three patients, the daily Dmax increased gradually or changed randomly, resulting in an inter-fractional averaged Dmax higher than the constraints. The dose distribution would have been improved if re-planning had been conducted. The results of these retrospective analyses indicate the importance of daily dose monitoring followed by adaptive re-planning when needed. CONCLUSIONS: The tumor registration in proton treatment for HCC was effective to maintain the daily dose to the tumor and the dose constraints of OARs, particularly in the treatment where the maintenance for the dose constraints needs to be considered throughout the treatment. Nevertheless daily proton dose monitoring with daily CT imaging is important for more reliable and safer treatment.

Evaluation of short-term gastrointestinal motion and its impact on dosimetric parameters in stereotactic body radiation therapy for pancreatic cancer
Yusuke Uchinami, Takahiro Kanehira, Yoshihiro Fujita, Naoki Miyamoto, Kohei Yokokawa, Fuki Koizumi, Motoyasu Shido, Shuhei Takahashi, Manami Otsuka, Koichi Yasuda, Hiroshi Taguchi, Keiji Nakazato, Keiji Kobashi, Norio Katoh, Hidefumi Aoyama
Clinical and Translational Radiation Oncology, 39, 100576, 100576, Elsevier BV, Mar. 2023
Scientific journal

Study of hepatic toxicity in small liver tumors after photon or proton therapy based on factors predicting the benefits of proton.
Yusuke Uchinami, Norio Katoh, Daisuke Abo, Ryo Morita, Hiroshi Taguchi, Yoshihiro Fujita, Takahiro Kanehira, Ryusuke Suzuki, Naoki Miyamoto, Seishin Takao, Taeko Matsuura, Takuya Sho, Koji Ogawa, Tatsuya Orimo, Tatsuhiko Kakisaka, Keiji Kobashi, Hidefumi Aoyama
The British journal of radiology, 96, 1144, 20220720, 20220720, 12 Jan. 2023, [Peer-reviewed], [International Magazine]
English, Scientific journal, OBJECTIVES: In a previous study of hepatic toxicity, the following three factors were identified to predict the benefits of proton beam therapy (PBT) for hepatocellular carcinomas (HCC) with a maximum diameter of ≤5 cm and Child-pugh grade A (CP-A): number of tumors (one vs ≥2), the location of tumors (hepatic hilum or others), and the sum of the diameters of lesions. The aim of this study is to analyze the association between these three factors and hepatic toxicity. METHODS: We retrospectively reviewed patients of CP-A treated with PBT or photon stereotactic body radiotherapy (X-ray radiotherapy, XRT) for HCC ≤5 cm. For normal liver dose, the V5, V10, V20 (volumes receiving 5, 10, and 20 Gy at least), and the mean dose was evaluated. The albumin-bilirubin (ALBI) and CP score changes from the baseline were evaluated at 3 and 6 months after treatment. RESULTS: In 89 patients (XRT: 48, PBT: 41), those with two or three (2-3) predictive factors were higher normal liver doses than with zero or one (0-1) factor. In the PBT group, the ALBI score worsened more in patients with 2-3 factors than those with 0-1 factor, at 3 months (median 0.26 vs 0.02, p = 0.032) and at 6 months (median: 0.35 vs 0.10, p = 0.009). The ALBI score change in the XRT group and CP score change in either modality were not significantly different in the number of predictive factors. CONCLUSIONS: The predictive factor numbers predicted the ALBI score change in PBT but not in XRT. ADVANCES IN KNOWLEDGE: This study suggest that the number of predictive factors previously identified (0-1 vs 2-3) were significantly associated with dosimetric parameters of the normal liver in both modalities. In the proton group, the number of predictive factors was associated with a worsening ALBI score at 3 and 6 months, but these associations were not found in the photon SBRT group.

A study on predicting cases that would benefit from proton beam therapy in primary liver tumors of less than or equal to 5 cm based on the estimated incidence of hepatic toxicity
Yusuke Uchinami, Norio Katoh, Ryusuke Suzuki, Takahiro Kanehira, Masaya Tamura, Seishin Takao, Taeko Matsuura, Naoki Miyamoto, Yoshihiro Fujita, Fuki Koizumi, Hiroshi Taguchi, Koichi Yasuda, Kentaro Nishioka, Isao Yokota, Keiji Kobashi, Hidefumi Aoyama
Clinical and Translational Radiation Oncology, 35, 70, 75, Elsevier BV, Jul. 2022, [Peer-reviewed], [International Magazine]
English, Scientific journal, Background: For small primary liver tumors, favorable outcomes have been reported with both of proton beam therapy (PBT) and X-ray therapy (XRT). However, no clear criteria have been proposed in the cases for which and when of PBT or XRT has to be used. The aim of this study is to investigate cases that would benefit from PBT based on the predicted rate of hepatic toxicity. Materials and methods: Eligible patients were those who underwent PBT for primary liver tumors with a maximum diameter of ≤ 5 cm and Child-Pugh grade A (n = 40). To compare the PBT-plan, the treatment plan using volumetric modulated arc therapy was generated as the XRT-plan. The rate of predicted hepatic toxicity was estimated using five normal tissue complication probability (NTCP) models with three different endpoints. The differences in NTCP values (ΔNTCP) were calculated to determine the relative advantage of PBT. Factors predicting benefits of PBT were analyzed by logistic regression analysis. Results: From the dose-volume histogram comparisons, an advantage of PBT was found in sparing of the normal liver receiving low doses. The factors predicting the benefit of PBT differed depending on the selected NTCP model. From the five models, the total tumor diameter (sum of the target tumors), location (hepatic hilum vs other), and number of tumors (1 vs 2) were significant factors. Conclusions: From the radiation-related hepatic toxicity, factors were identified to predict benefits of PBT in primary liver tumors with Child-Pugh grade A, with the maximum tumor diameter of ≤ 5 cm.

Dosimetric advantages of daily adaptive strategy in IMPT for high-risk prostate cancer.
Hiroshi Tamura, Keiji Kobashi, Kentaro Nishioka, Takaaki Yoshimura, Takayuki Hashimoto, Shinichi Shimizu, Yoichi M Ito, Yoshikazu Maeda, Makoto Sasaki, Kazutaka Yamamoto, Hiroyasu Tamamura, Hidefumi Aoyama, Hiroki Shirato
Journal of applied clinical medical physics, 23, 4, e13531, 19 Jan. 2022, [Peer-reviewed], [Corresponding author], [International Magazine]
English, Scientific journal, PURPOSE: To evaluate the dosimetric advantages of daily adaptive radiotherapy (DART) in intensity-modulated proton therapy (IMPT) for high-risk prostate cancer by comparing estimated doses of the conventional non-adaptive radiotherapy (NART) that irradiates according to an original treatment plan through the entire treatment and the DART that uses an adaptive treatment plan generated by using daily CT images acquired before each treatment. METHODS: Twenty-three patients with prostate cancer were included. A treatment plan with 63 Gy (relative biological effectiveness (RBE)) in 21 fractions was generated using treatment planning computed tomography (CT) images assuming that all patients had high-risk prostate cancer for which the clinical target volume (CTV) needs to include prostate and the seminal vesicle (SV) in our treatment protocol. Twenty-one adaptive treatment plans for each patient (total 483 data sets) were generated using daily CT images, and dose distributions were calculated. Using a 3 mm set-up uncertainty in the robust optimization, the doses to the CTV, prostate, SV, rectum, and bladder were compared. RESULTS: Estimated accumulated doses of NART and DART in the 23 patients were 60.81 ± 3.47 Gy (RBE) and 63.24 ± 1.04 Gy (RBE) for CTV D99 (p < 0.01), 62.99 ± 1.28 Gy (RBE) and 63.43 ± 1.33 Gy (RBE) for the prostate D99 (p = 0.2529), and 59.07 ± 5.19 Gy (RBE) and 63.17 ± 1.04 Gy (RBE) for SV D99 (p < 0.001). No significant differences were observed between NART and DART in the estimated accumulated dose for the rectum and bladder. CONCLUSION: Compared with the NART, DART was shown to be a useful approach that can maintain the dose coverage to the target without increasing the dose to the organs at risk (OAR) using the 3 mm set-up uncertainty in the robust optimization in patients with high-risk prostate cancer.

Prediction of liver Dmean for proton beam therapy using deep learning and contour-based data augmentation
Sira Jampa-ngern, Keiji Kobashi, Shinichi Shimizu, Seishin Takao, Keiji Nakazato, Hiroki Shirato
Journal of Radiation Research, Oxford University Press (OUP), 06 Oct. 2021, [Peer-reviewed], [Corresponding author], [International Magazine]
English, Scientific journal, Abstract

The prediction of liver Dmean with 3-dimensional radiation treatment planning (3DRTP) is time consuming in the selection of proton beam therapy (PBT), and deep learning prediction generally requires large and tumor-specific databases. We developed a simple dose prediction tool (SDP) using deep learning and a novel contour-based data augmentation (CDA) approach and assessed its usability. We trained the SDP to predict the liver Dmean immediately. Five and two computed tomography (CT) data sets of actual patients with liver cancer were used for the training and validation. Data augmentation was performed by artificially embedding 199 contours of virtual clinical target volume (CTV) into CT images for each patient. The data sets of the CTVs and OARs are labeled with liver Dmean for six different treatment plans using two-dimensional calculations assuming all tissue densities as 1.0. The test of the validated model was performed using 10 unlabeled CT data sets of actual patients. Contouring only of the liver and CTV was required as input. The mean relative error (MRE), the mean percentage error (MPE) and regression coefficient between the planned and predicted Dmean was 0.1637, 6.6%, and 0.9455, respectively. The mean time required for the inference of liver Dmean of the six different treatment plans for a patient was 4.47±0.13 seconds. We conclude that the SDP is cost-effective and usable for gross estimation of liver Dmean in the clinic although the accuracy should be improved further if we need the accuracy of liver Dmean to be compatible with 3DRTP.

A treatment planning study of urethra-sparing intensity-modulated proton therapy for localized prostate cancer.
Takaaki Yoshimura, Kentaro Nishioka, Takayuki Hashimoto, Kazuya Seki, Shouki Kogame, Sodai Tanaka, Takahiro Kanehira, Masaya Tamura, Seishin Takao, Taeko Matsuura, Keiji Kobashi, Fumi Kato, Hidefumi Aoyama, Shinichi Shimizu
Physics and imaging in radiation oncology, 20, 23, 29, Oct. 2021, [International Magazine]
English, Scientific journal, BACKGROUND AND PURPOSE: Urethra-sparing radiation therapy for localized prostate cancer can reduce the risk of radiation-induced genitourinary toxicity by intentionally underdosing the periurethral transitional zone. We aimed to compare the clinical impact of a urethra-sparing intensity-modulated proton therapy (US-IMPT) plan with that of conventional clinical plans without urethral dose reduction. MATERIALS AND METHODS: This study included 13 patients who had undergone proton beam therapy. The prescribed dose was 63 GyE in 21 fractions for 99% of the clinical target volume. To compare the clinical impact of the US-IMPT plan with that of the conventional clinical plan, tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated with a generalized equivalent uniform dose-based Lyman-Kutcher model using dose volume histograms. The endpoints of these model parameters for the rectum, bladder, and urethra were fistula, contraction, and urethral stricture, respectively. RESULTS: The mean NTCP value for the urethra in US-IMPT was significantly lower than that in the conventional clinical plan (0.6% vs. 1.2%, p < 0.05). There were no statistically significant differences between the conventional and US-IMPT plans regarding the mean minimum dose for the urethra with a 3-mm margin, TCP value, and NTCP value for the rectum and bladder. Additionally, the target dose coverage of all plans in the robustness analysis was within the clinically acceptable range. CONCLUSIONS: Compared with the conventional clinically applied plans, US-IMPT plans have potential clinical advantages and may reduce the risk of genitourinary toxicities, while maintaining the same TCP and NTCP in the rectum and bladder.

Assessment of the confidence interval in the multivariable normal tissue complication probability model for predicting radiation-induced liver disease in primary liver cancer.
Anussara Prayongrat, Natchalee Srimaneekarn, Sira Sriswasdi, Yoichi M Ito, Norio Katoh, Masaya Tamura, Yasuhiro Dekura, Chie Toramatsu, Chonlakiet Khorprasert, Napapat Amornwichet, Petch Alisanant, Yuichi Hirata, Anthony Hayter, Hiroki Shirato, Shinichi Shimizu, Keiji Kobashi
Journal of radiation research, 62, 3, 483, 493, 12 May 2021, [Peer-reviewed], [Last author, Corresponding author], [International Magazine]
English, Scientific journal, We developed a confidence interval-(CI) assessing model in multivariable normal tissue complication probability (NTCP) modeling for predicting radiation-induced liver disease (RILD) in primary liver cancer patients using clinical and dosimetric data. Both the mean NTCP and difference in the mean NTCP (ΔNTCP) between two treatment plans of different radiotherapy modalities were further evaluated and their CIs were assessed. Clinical data were retrospectively reviewed in 322 patients with hepatocellular carcinoma (n = 215) and intrahepatic cholangiocarcinoma (n = 107) treated with photon therapy. Dose-volume histograms of normal liver were reduced to mean liver dose (MLD) based on the fraction size-adjusted equivalent uniform dose. The most predictive variables were used to build the model based on multivariable logistic regression analysis with bootstrapping. Internal validation was performed using the cross-validation leave-one-out method. Both the mean NTCP and the mean ΔNTCP with 95% CIs were calculated from computationally generated multivariate random sets of NTCP model parameters using variance-covariance matrix information. RILD occurred in 108/322 patients (33.5%). The NTCP model with three clinical and one dosimetric parameter (tumor type, Child-Pugh class, hepatitis infection status and MLD) was most predictive, with an area under the receiver operative characteristics curve (AUC) of 0.79 (95% CI 0.74-0.84). In eight clinical subgroups based on the three clinical parameters, both the mean NTCP and the mean ΔNTCP with 95% CIs were able to be estimated computationally. The multivariable NTCP model with the assessment of 95% CIs has potential to improve the reliability of the NTCP model-based approach to select the appropriate radiotherapy modality for each patient.

Analysis of acute-phase toxicities of intensity-modulated proton therapy using a model-based approach in pharyngeal cancer patients.
Koichi Yasuda, Hideki Minatogawa, Yasuhiro Dekura, Seishin Takao, Masaya Tamura, Nayuta Tsushima, Takayoshi Suzuki, Satoshi Kano, Takatsugu Mizumachi, Takashi Mori, Kentaro Nishioka, Motoyasu Shido, Norio Katoh, Hiroshi Taguchi, Noriyuki Fujima, Rikiya Onimaru, Isao Yokota, Keiji Kobashi, Shinichi Shimizu, Akihiro Homma, Hiroki Shirato, Hidefumi Aoyama
Journal of radiation research, 62, 2, 329, 337, 10 Mar. 2021, [Peer-reviewed], [International Magazine]
English, Scientific journal, Pharyngeal cancer patients treated with intensity-modulated proton therapy (IMPT) using a model-based approach were retrospectively reviewed, and acute toxicities were analyzed. From June 2016 to March 2019, 15 pharyngeal (7 naso-, 5 oro- and 3 hypo-pharyngeal) cancer patients received IMPT with robust optimization. Simulation plans for IMPT and intensity-modulated X-ray therapy (IMXT) were generated before treatment. We also reviewed 127 pharyngeal cancer patients with IMXT in the same treatment period. In the simulation planning comparison, all of the normal-tissue complication probability values for dysphagia, dysgeusia, tube-feeding dependence and xerostomia were lower for IMPT than for IMXT in the 15 patients. After completing IMPT, 13 patients completed the evaluation, and 12 of these patients had a complete response. The proportions of patients who experienced grade 2 or worse acute toxicities in the IMPT and IMXT cohorts were 21.4 and 56.5% for dysphagia (P < 0.05), 46.7 and 76.3% for dysgeusia (P < 0.05), 73.3 and 62.8% for xerostomia (P = 0.43), 73.3 and 90.6% for mucositis (P = 0.08) and 66.7 and 76.4% for dermatitis (P = 0.42), respectively. Multivariate analysis revealed that IMPT was independently associated with a lower rate of grade 2 or worse dysphagia and dysgeusia. After propensity score matching, 12 pairs of IMPT and IMXT patients were selected. Dysphagia was also statistically lower in IMPT than in IMXT (P < 0.05). IMPT using a model-based approach may have clinical benefits for acute dysphagia.

The normal tissue complication probability model-based approach considering uncertainties for the selective use of radiation modality in primary liver cancer patients.
Prayongrat A, Kobashi K, Ito YM, Katoh N, Tamura M, Dekura Y, Toramatsu C, Khorprasert C, Amornwichet N, Alisanant P, Shirato H, Shimizu S
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, 135, 100, 106, Mar. 2019, [Peer-reviewed], [International Magazine]
English, Scientific journal, PURPOSE: To predict the probability of radiation-induced liver toxicity (RILT) and implement the normal tissue complication probability (NTCP) model-based approach considering confidence intervals (CIs) to select patients for new treatment techniques, such as proton beam therapy, based on a certain NTCP reduction (ΔNTCP) threshold for primary liver cancer patients. METHODS AND MATERIALS: Common Toxicity Criteria for Adverse Events (CTCAE) grade ≥2 RILT was scored. The Lyman NTCP models predicting the probability of CTCAE grade ≥2 RILT as a function of the fraction-size adjusted mean liver dose (MLD), using reference fraction size = 2 Gy/fraction and α/β ratio = 2 Gy, were fitted using the maximum likelihood method. At certain combinations of MLDs, ΔNTCP with a CI was evaluated by the delta method. RESULTS: Of the 239 patients, the incidence of CTCAE grade ≥2 RILT was 55% (46% in the Child-Pugh (CP)-A vs. 81% in the CP-B/C, p < 0.001). Among 180 CP-A patients, 40% who had viral hepatitis infections experienced toxicity vs. 32% in the nonhepatitis subgroup. The MLD was 18 Gy in the toxicity group vs. 16.1 Gy in the nontoxicity group (p = 0.002). The estimated NTCP model parameters specific to the patient subgroups and the ΔNTCP with CI assuming a particular CP classification and viral hepatitis infection status were considerably different which possible changed treatment decision. CONCLUSIONS: Patients with CP-A and viral hepatitis infection or CP-B/C cirrhosis had greater susceptibility to CTCAE grade ≥2 RILT. The estimated NTCP and ΔNTCP for individual patients along with a consideration of uncertainties improve the reliability of the NTCP model-based approach.

Uncertainties of Normal Tissue Complication Probability (NTCP) and NTCP Difference between Radiation Treatment Modalities for Radiation-Induced Liver Toxicity in Child-Pugh A Primary Liver Cancer Patients
A. Prayongrat, K. Kobashi, Y. Ito, N. Katoh, Y. Dekura, N. Amornwichet, S. Shimizu, H. Shirato
International Journal of Radiation Oncology*Biology*Physics, 102, 3, e65, e66, Elsevier BV, Nov. 2018, [Peer-reviewed]
English, Scientific journal

Selection of external beam radiotherapy approaches for precise and accurate cancer treatment
Hiroki Shirato, Quynh-Thu Le, Keiji Kobashi, Anussara Prayongrat, Seishin Takao, Shinichi Shimizu, Amato Giaccia, Lei Xing, Kikuo Umegaki
JOURNAL OF RADIATION RESEARCH, 59, suppl_1, I2, I10, OXFORD UNIV PRESS, Mar. 2018, [Peer-reviewed]
English, Scientific journal, Physically precise external-beam radiotherapy (EBRT) technologies may not translate to the best outcome in individual patients. On the other hand, clinical considerations alone are often insufficient to guide the selection of a specific EBRT approach in patients. We examine the ways in which to compare different EBRT approaches based on physical, biological and clinical considerations, and how they can be enhanced with the addition of biophysical models and machine-learning strategies. The process of selecting an EBRT modality is expected to improve in tandem with knowledge-based treatment planning.

Present developments in reaching an international consensus for a model-based approach to particle beam therapy.
Anussara Prayongrat, Kikuo Umegaki, Arjen van der Schaaf, Albert C Koong, Steven H Lin, Thomas Whitaker, Todd McNutt, Naruhiro Matsufuji, Edward Graves, Masahiko Mizuta, Kazuhiko Ogawa, Hiroyuki Date, Kensuke Moriwaki, Yoichi M Ito, Keiji Kobashi, Yasuhiro Dekura, Shinichi Shimizu, Hiroki Shirato
Journal of radiation research, 59, suppl_1, i72-i76, i76, 01 Mar. 2018, [Peer-reviewed], [International Magazine]
English, Scientific journal, Particle beam therapy (PBT), including proton and carbon ion therapy, is an emerging innovative treatment for cancer patients. Due to the high cost of and limited access to treatment, meticulous selection of patients who would benefit most from PBT, when compared with standard X-ray therapy (XRT), is necessary. Due to the cost and labor involved in randomized controlled trials, the model-based approach (MBA) is used as an alternative means of establishing scientific evidence in medicine, and it can be improved continuously. Good databases and reasonable models are crucial for the reliability of this approach. The tumor control probability and normal tissue complication probability models are good illustrations of the advantages of PBT, but pre-existing NTCP models have been derived from historical patient treatments from the XRT era. This highlights the necessity of prospectively analyzing specific treatment-related toxicities in order to develop PBT-compatible models. An international consensus has been reached at the Global Institution for Collaborative Research and Education (GI-CoRE) joint symposium, concluding that a systematically developed model is required for model accuracy and performance. Six important steps that need to be observed in these considerations include patient selection, treatment planning, beam delivery, dose verification, response assessment, and data analysis. Advanced technologies in radiotherapy and computer science can be integrated to improve the efficacy of a treatment. Model validation and appropriately defined thresholds in a cost-effectiveness centered manner, together with quality assurance in the treatment planning, have to be achieved prior to clinical implementation.

Assessing the uncertainty in a normal tissue complication probability difference ('NTCP): Radiation-induced liver disease (RILD) in liver tumour patients treated with proton vs X-ray therapy
Keiji Kobashi, Anussara Prayongrat, Takuya Kimoto, Chie Toramatsu, Yasuhiro Dekura, Norio Katoh, Shinichi Shimizu, Yoichi M Ito, Hiroki Shirato
Journal of Radiation Research, 59, suppl_1, i50, i57, Oxford University Press, 01 Mar. 2018, [Peer-reviewed], [Lead author]
English, Scientific journal, Modern radiotherapy technologies such as proton beam therapy (PBT) permit dose escalation to the tumour and minimize unnecessary doses to normal tissues. To achieve appropriate patient selection for PBT, a normal tissue complication probability (NTCP) model can be applied to estimate the risk of treatment-related toxicity relative to X-ray therapy (XRT). A methodology for estimating the difference in NTCP ('NTCP), including its uncertainty as a function of dose to normal tissue, is described in this study using the Delta method, a statistical method for evaluating the variance of functions, considering the variance-covariance matrix. We used a virtual individual patient dataset of radiation-induced liver disease (RILD) in liver tumour patients who were treated with XRT as a study model. As an alternative option for individual patient data, dose-bin data, which consists of the number of patients who developed toxicity in each dose level/bin and the total number of patients in that dose level/bin, are useful for multi-institutional data sharing. It provides comparable accuracy with individual patient data when using the Delta method. With reliable NTCP models, the 'NTCP with uncertainty might potentially guide the use of PBT
however, clinical validation and a cost-effectiveness study are needed to determine the appropriate 'NTCP threshold.

Dual Isotope SPECT Study With Epilepsy Patients Using Semiconductor SPECT System
Tohru Shiga, Atsuro Suzuki, Kotarou Sakurai, Tsugiko Kurita, Wataru Takeuchi, Takuya Toyonaga, Kenji Hirata, Keiji Kobashi, Chietsugu Katoh, Naoki Kubo, Nagara Tamaki
CLINICAL NUCLEAR MEDICINE, 42, 9, 663, 668, LIPPINCOTT WILLIAMS & WILKINS, Sep. 2017, [Peer-reviewed]
English, Scientific journal, Purpose We developed a prototype CdTe SPECT system with 4-pixel matched collimator for brain study. This system provides high-energy-resolution (6.6%), high-sensitivity (220 cps/MBq/head), and high-spatial-resolution images. The aim of this study was to evaluate dual-isotope study of CBF and central benzodiazepine receptor (BZR) images using Tc-99m-ECD and I-123-IMZ with the new SPECT system in patients with epilepsy comparing with single-isotope study using the conventional scintillation gamma camera.Methods This study included 13 patients with partial epilepsy. The BZR images were acquired at 3 hours after I-123-IMZ injection for 20 minutes. The images of IMZ were acquired with a conventional 3-head scintillation gamma camera. After BZR image acquisition with the conventional camera, Tc-99m-ECD was injected, and CBF and BZR images were acquired simultaneously 5 minutes after ECD injection with the new SPECT system. The CBF images were also acquired with the conventional camera on separate days. The findings were visually analyzed, and 3D-SSP maximum Z scores of lesions were compared between the 2 studies.Results There were 47 abnormal lesions on BZR images and 60 abnormal lesions on CBF images in the single-isotope study with the conventional camera. Dual-isotope study with the new system showed concordant abnormal findings of 46 of 47 lesions on BZR and 54 of 60 lesions on CBF images with the single-isotope study with the conventional camera. There was high agreement between the 2 studies in both BZR and CBF findings (Cohen values = 0.96 for BZR and 0.78 for CBF). In semiquantitative analysis, maximum Z scores of dual-isotope study with the new system strongly correlated with those of single-isotope study with the conventional camera (BZR: r = 0.82, P < 0.05, CBF: r = 0.87, P < 0.05).Conclusions Our new SPECT system permits dual-isotope study for pixel-by-pixel analysis of CBF and BZR information with the same pathophysiological condition in patients with epilepsy.

Quantitative Measurement of Dual-Radioisotopes of Technetium-99m and Iodine-123 in Blood Samples With a Cadmium-Telluride-Based Counting Device
Atsuro Suzuki, Wataru Takeuchi, Takafumi Ishitsu, Isao Takahashi, Yuichiro Ueno, Keiji Kobashi, Naoki Kubo, Tohru Shiga, Nagara Tamaki
IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES, 1, 3, 238, 245, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, May 2017, [Peer-reviewed]
English, Scientific journal, Our previous study demonstrated that a cadmium telluride (CdTe)-based single-photon emission computed tomography (SPECT) system with good energy resolution could provide dual-radioisotope SPECT images of a patient who had been administered with two kinds of radioisotope simultaneously. To obtain two quantitative physiological parametric images from these radioisotope images by using compartment model analysis, the concentrations of the dual-radioisotope in the blood sample need to be measured. In this paper, a CdTe-based well counter was developed to measure the concentrations of a dual-radioisotope of Tc-99m and I-123, and its performance was evaluated. The counter consists of four detector panels. Each detector panel consists of two detector modules, and each module has 16 x 16 CdTe detector pixels with a pitch of 2.5 mm; the eight detector modules give our system a field of view (x x y x z) of 4 x 4 x 8 cm(3). The crosstalk correction coefficient alpha, which is the ratio of the count rate in the Tc-99m-energy window to that in the I-123-energy window, was obtained by measuring the single-radioisotope solution of I-123. When the dual-radioisotope of 99mTc and 123I was measured, the true count rate of 99mTc was obtained by subtracting the crosstalk count rate (alpha x the count rate of I-123) from the uncorrected count rate of 99mTc. To evaluate the measurement accuracy, dual-and single-radioisotope solutions were measured, and the mean percentage error of the measured count rate of dual-radioisotope solutions to that of the single-radioisotope solution was obtained. The energy resolutions full width at half maximum of the CdTe-based well counter were 6.95% and 6.93% at 140.5 keV and 159 keV, respectively, and were higher than that of a conventional NaI (Tl) scintillation detector (10% at 140.5 keV). The count loss in the CdTe detector was 1.7% at 44 kcps. For the dual-radioisotope measurement, the percentage errors (mean percentage% +/- standard deviation%, N = 3) of the count rate of Tc-99m and I-123 at a high count rate (Tc-99m: 44 kcps, I-123: 28 kcps) were -1.9% +/- 0.0% and -3.5% +/- 1.1%, respectively. On the other hand, the percentage errors of the count rate of Tc-99m and I-123 at a low count rate Tc-99m: 3 kcps, I-123: 4 kcps) were -0.4% +/- 0.3% and 0.2% +/- 0.6%, respectively. The CdTe-based well counter measured each concentration of Tc-99m and I-123 in mixed solutions with high accuracy.

Monte Carlo-based scatter correction considering the tailing effect of a CdTe detector for dual-isotope brain SPECT imaging
Atsuro Suzuki, Wataru Takeuchi, Yuichiro Ueno, Keiji Kobashi, Takuya Toyonaga, Tohru Shiga, Nagara Tamaki
BIOMEDICAL PHYSICS & ENGINEERING EXPRESS, 2, 4, IOP PUBLISHING LTD, Aug. 2016, [Peer-reviewed]
English, Scientific journal, A Monte Carlo (MC)-based scatter correctionmethod considering the tailing effect of aCdTe detector was developed for dual-isotope brain single-photon emission computed tomography (SPECT) imaging using technetium-99m(Tc-99m) and iodine-123 (I-123), and its accuracywas validated bymeasuring phantoms. The tailing effectwasmodeled by convolutions of energy spectra obtained by geometry and tracking (GEANT) simulation with energy smoothing kernels. In our experimental phantomstudies, quantitative accuracy and image contrast in the reconstructed image of dual-isotope-filled phantoms with ourMC-based scatter correctionmethod (Dual_SC) were compared with those of single-isotopefilled phantoms (Single_SC). The quantitative accuracy was evaluated by the percent error between the estimated activity concentration and true activity concentration. In our six-compartment phantom studywith six different activity concentrations, themean absolute percent errors of Tc-99m for Single_SC andDual_SCwere 1.7% and 2.8%, respectively, while those of I-123 for Single_SCandDual_SCwere 4.8% and 5.6%, respectively. In our striatal phantomstudy, the percent errors in the background regions for Single_SCandDual_SCwere less than2% for both Tc-99m and I-123. The image contrast was evaluated by the percent contrast of a cold or hot spot region to a background region. In our cold rod phantom study, themean percent contrasts in the cold rod regions of 99mTc for Single_SCandDual_SCwere 66.2% and 65.0%, respectively, while those of I-123 for Single_SCandDual_SCwere 59.3% and 61.6%, respectively. In our striatal phantomstudy, the percent contrasts in the striatal regions of 99m Tc for Single_SCandDual_SCwere 56.1% and 56.1%, respectively, while those of I-123 for Single_SCand Dual_SCwere 39.8% and 40.0%, respectively. In conclusion, dual-isotope imaging with theCdTe-based brain SPECTsystemand ourMC-based scatter correctionmethod can provide comparable quantitative accuracy and image contrast to those of single-isotope imaging.

Simultaneous Tc-99m and I-123 dual-radionuclide imaging with a solid-state detector-based brain-SPECT system and energy-based scatter correction
Wataru Takeuchi, Atsuro Suzuki, Tohru Shiga, Naoki Kubo, Yuichi Morimoto, Yuichiro Ueno, Keiji Kobashi, Kikuo Umegaki, Nagara Tamaki
EJNMMI PHYSICS, 3, 1, 10, SPRINGER, Jun. 2016, [Peer-reviewed]
English, Scientific journal, Background: A brain single-photon emission computed tomography (SPECT) system using cadmium telluride (CdTe) solid-state detectors was previously developed. This CdTe-SPECT system is suitable for simultaneous dual-radionuclide imaging due to its fine energy resolution (6.6 %). However, the problems of down-scatter and low-energy tail due to the spectral characteristics of a pixelated solid-state detector should be addressed. The objective of this work was to develop a system for simultaneous Tc-99m and I-123 brain studies and evaluate its accuracy.Methods: A scatter correction method using five energy windows (FiveEWs) was developed. The windows are Tc-lower, Tc-main, shared sub-window of Tc-upper and I-lower, I-main, and I-upper. This FiveEW method uses pre-measured responses for primary gamma rays from each radionuclide to compensate for the overestimation of scatter by the triple-energy window method that is used. Two phantom experiments and a healthy volunteer experiment were conducted using the CdTe-SPECT system. A cylindrical phantom and a six-compartment phantom with five different mixtures of Tc-99m and I-123 and a cold one were scanned. The quantitative accuracy was evaluated using 18 regions of interest for each phantom. In the volunteer study, five healthy volunteers were injected with Tc-99m human serum albumin diethylene triamine pentaacetic acid (HSA-D) and scanned (single acquisition). They were then injected with I-123 N-isopropyl-4-iodoamphetamine hydrochloride (IMP) and scanned again (dual acquisition). The counts of the Tc-99m images for the single and dual acquisitions were compared.Results: In the cylindrical phantom experiments, the percentage difference (PD) between the single and dual acquisitions was 5.7 +/- 4.0 % (mean +/- standard deviation). In the six-compartment phantom experiment, the PDs between measured and injected activity for Tc-99m and I-123 were 14.4 +/- 11.0 and 2.3 +/- 1.8 %, respectively. In the volunteer study, the PD between the single and dual acquisitions was 4.5 +/- 3.4 %.Conclusions: This CdTe-SPECT system using the FiveEW method can provide accurate simultaneous dual-radionuclide imaging. A solid-state detector SPECT system using the FiveEW method will permit quantitative simultaneous Tc-99m and I-123 study to become clinically applicable.

High Reproducibility of FMISO PET with high-definition semiconductor PET in patients with head and neck cancer.
Tohru Shiga, Shozo Okamoto, Wataru Takeuchi, Atsuro Suzuki, Koichi Yasuda, Keiichi Magota, Shiro Watanabe, Kenji Hirata, Yuji Kuge, Keiji Kobashi, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 57, SOC NUCLEAR MEDICINE INC, May 2016, [Peer-reviewed]
English

A semiconductor based well counter for measurement of a dual-radioisotope in blood sample
Atsuro Suzuki, Wataru Takeuchi, Takafumi Ishitsu, Yuichiro Ueno, Keiji Kobashi, Tohru Shiga, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 57, SOC NUCLEAR MEDICINE INC, May 2016, [Peer-reviewed]
English

New SPECT scanner with semiconductor detectors enables quantitative dual tracer diagnostic imaging of CBF and Dopamine transporter imaging in patients with cognitive disorder.
Takuya Toyonaga, Tohru Shiga, Atsuro Suzuki, Wataru Takeuchi, Shin Nakagawa, Kenji Hirata, Yuko Uchiyama, Osamu Manabe, Kentaro Kobayashi, Shiro Watanabe, Keiji Kobashi, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 57, SOC NUCLEAR MEDICINE INC, May 2016, [Peer-reviewed]
English

Use of convolutional neural network as the first step of fully automated tumor detection on 11C-methionine brain PET
Hirata Kenji, Takeuchi Wataru, Yamaguchi Shigeru, Kobayashi Hiroyuki, Terasaka Shunsuke, Toyonaga Takuya, Watanabe Shiro, Kobayashi Kentaro, Manabe Osamu, Kobashi Keiji, Shiga Tohru, Tamaki Nagara
JOURNAL OF NUCLEAR MEDICINE, 57, 01 May 2016, [Peer-reviewed]

A nine-pixel matched collimator for low- and medium-energy SPECT imaging
Atsuro Suzuki, Wataru Takeuchi, Yuichi Morimoto, Yuichiro Ueno, Keiji Kobashi, Tohru Shiga, Nagara Tamaki
BIOMEDICAL PHYSICS & ENGINEERING EXPRESS, 2, 1, IOP PUBLISHING LTD, Feb. 2016, [Peer-reviewed]
English, Scientific journal, For low-and medium-energy SPECT imaging without collimator exchange, a wide-aperture parallelhole collimator-called a 'nine-pixel matched collimator (9-PMC)'-was developed. The hole size of the 9-PMC is matched to nine detector pixels, giving nine (3. x. 3) pixels per collimator hole. The 9-PMC was designed to reduce the penetration of medium-energy gamma rays. The performance of the 9-PMC for Tc-99m and In-111 gamma-ray energy was experimentally evaluated and compared with that of a low-energy collimator. A CdTe detector with 1.4 mm pitch was used in conjunction with the 9-PMC. A four-pixel matched collimator ('4-PMC' hereafter) with hole size matched to four detector pixels was also used as a high-sensitivity low-energy collimator. Hole pitch, hole length and septum thickness of the 4-PMC/9-PMC were 2.8/4.2 mm, 26.0/33.4 mm and 0.4/1.0 mm, respectively. The system sensitivities of the 4-PMC and 9-PMC for Tc-99m gamma rays were 221 cps MBq(-1) and 211 cps MBq(-1), respectively. For the 4-PMC, system sensitivities for 171 and 245 keV In-111 gamma rays were 232 cps MBq(-1) and 503 cps MBq(-1), respectively, while for the 9-PMC, the system sensitivities for 171 and 245 keV In-111 gamma rays were 145 cps MBq(-1) and 106 cps MBq(-1), respectively. Spatial resolution of the collimator was analyzed by using modulation transfer functions (MTFs) obtained from the line-source profiles. The results of this analysis demonstrate that the 9-PMC for Tc-99m had frequency ranges for similar (or higher) and lower MTF values compared with those for the 4-PMC, while the 9-PMC for In-111 had higher MTF values than those for the 4-PMC at a wide frequency range. Hot-sphere phantom images showed that the image contrast of the 9-PMC for Tc-99m gamma rays is comparable to that of the 4-PMC, while that of the 9-PMC for In-111 gamma rays is higher than that of the 4-PMC. The developed SPECT with the 9-PMC and CdTe detector provided higher image quality for In-111 gamma rays, or comparable image quality for Tc-99m gamma rays, compared with that of a low-energy collimator.

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads
Atsuro Suzuki, Wataru Takeuchi, Takafumi Ishitsu, Yuichi Morimoto, Keiji Kobashi, Yuichiro Ueno
ANNALS OF NUCLEAR MEDICINE, 29, 8, 682, 696, SPRINGER, Oct. 2015, [Peer-reviewed]
English, Scientific journal, To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations.In the simulation study, the tilt angle of the detector heads relative to the axis was 45A degrees. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison.The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT.PT-SPECT provides improved image resolution at not only upper but also at central slices of the cerebrum.

Collimator for Variable Sensitivity and Spatial Resolution Without the Need for Exchange
Kubo N, Tsuchiya K, Shiga T, Kojima S, Suzuki A, Ueno Y, Kobashi K, Tamaki N
IEEE Trans Nucl Sci., 61, 5, 2489, 2493, IEEE, Oct. 2014, [Peer-reviewed]
English, Scientific journal, A new design of collimator is proposed that has variable sensitivity and spatial resolution, eliminating the need for exchanging collimators in a gamma camera. Using Monte Carlo simulations, the present article evaluates the shielding of undesirable gamma rays in a parallel-hole collimator. It consists of a number of layers of rectangular holes. These layers consist of alternately stacked fixed and movable collimators. In high-resolution mode, the movable collimators are shifted by half the aperture pitch along the diagonal direction. The first collimator (type A) has 50 layers with fixed thicknesses of 1.2 mm. The second collimator (type B) has 25 layers with a thickness of 1.0 mm on the object side and 25 layers with a thickness of 1.4 mm on the opposite side. The third collimator (type C) has 20 layers with non-uniform thicknesses. The ratios of the maximum artificial peak to the main-peak are calculated for point-source responses. The ratios for types A, B, and C collimators are 0.78, 0.08, and 0.03, respectively. The same performance for shielding undesirable gamma rays is achieved in the type C collimator as for a conventional collimator.

High-sensitivity brain SPECT system using cadmium telluride (CdTe) semiconductor detector and 4-pixel matched collimator
Atsuro Suzuki, Wataru Takeuchi, Takafumi Ishitsu, Katsutoshi Tsuchiya, Yuichi Morimoto, Yuichiro Ueno, Keiji Kobashi, Naoki Kubo, Tohru Shiga, Nagara Tamaki
PHYSICS IN MEDICINE AND BIOLOGY, 58, 21, 7715, 7731, IOP PUBLISHING LTD, Nov. 2013, [Peer-reviewed]
English, Scientific journal, For high-sensitivity brain imaging, we have developed a two-head single-photon emission computed tomography (SPECT) system using a CdTe semiconductor detector and 4-pixel matched collimator (4-PMC). The term, '4-PMC' indicates that the collimator hole size is matched to a 2 x 2 array of detector pixels. By contrast, a 1-pixelmatched collimator (1-PMC) is defined as a collimator whose hole size is matched to one detector pixel. The performance of the higher-sensitivity 4-PMC was experimentally compared with that of the 1-PMC. The sensitivities of the 1-PMC and 4-PMC were 70 cps/MBq/head and 220 cps/MBq/head, respectively. The SPECT system using the 4-PMC provides superior image resolution in cold and hot rods phantom with the same activity and scan time to that of the 1-PMC. In addition, with half the usual scan time the 4-PMC provides comparable image quality to that of the 1-PMC. Furthermore, Tc-99m-ECD brain perfusion images of healthy volunteers obtained using the 4-PMC demonstrated acceptable image quality for clinical diagnosis. In conclusion, our CdTe SPECT system equipped with the higher-sensitivity 4-PMC can provide better spatial resolution than the 1-PMC either in half the imaging time with the same administered activity, or alternatively, in the same imaging time with half the activity.

A four-pixel matched collimator for high-sensitivity SPECT imaging
Atsuro Suzuki, Wataru Takeuchi, Takafumi Ishitsu, Katsutoshi Tsuchiya, Yuichiro Ueno, Keiji Kobashi
PHYSICS IN MEDICINE AND BIOLOGY, 58, 7, 2199, 2217, IOP PUBLISHING LTD, Apr. 2013, [Peer-reviewed]
English, Scientific journal, We propose a wide aperture parallel-hole collimator that we call a 4-pixel matched collimator (4-PMC) for high-sensitivity SPECT imaging. The hole size of the 4-PMC is matched to four detector pixels; that is, there are four (2 x 2) pixels per collimator hole. By contrast, a 1-pixel matched collimator (1-PMC) is defined as a collimator whose hole size is matched to one detector pixel. We evaluated four types of collimator (high-resolution collimator versions and high-sensitivity collimator versions of both 4-PMC and 1-PMC) by simulation. SPECT images of a cylindrical phantom with cold spots in the noise-free condition demonstrated that the 4-PMC provided a higher-contrast image than the 1-PMC for the same collimator version. In addition, SPECT images at the noise level corresponding to a human cerebral blood flow study suggested that the high-sensitivity version of the 4-PMC provided the highest contrast image among the four collimator types. In conclusion, the high-sensitivity SPECT system using the 4-PMC can improve the trade-off between spatial resolution and sensitivity and will consequently provide improved image contrast for clinical studies of the human brain compared with the SPECT system using the 1-PMC.

First clinical application of a prototype CdTe SPECT system with 4-pixel matched collimator for brain study
Morimoto Yuichi, Suzuki Atsuro, Takeuchi Wataru, Ishitsu Takafumi, Ueno Yuichiro, Kobashi Keiji, Kubo Naoki, Kuge Yuji, Shiga Tohru, Tamaki Nagara
JOURNAL OF NUCLEAR MEDICINE, 53, 01 May 2012, [Peer-reviewed]

Optimization of energy window setting of the semiconductor PET for clinical FDG studies
Tohru Shiga, Wataru Takeuchi, Yuichi Morimoto, Naoki Kubo, Kenji Hirata, Keiji Kobashi, Naoya Hattori, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 53, SOC NUCLEAR MEDICINE INC, May 2012, [Peer-reviewed]
English

Scatter correction for high energy resolution semiconductor human brain PET
Wataru Takeuchi, Yuichi Morimoto, Atsuro Suzuki, Yuichiro Ueno, Keiji Kobashi, Naoya Hattori, Naoki Kubo, Tohru Shiga, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 53, SOC NUCLEAR MEDICINE INC, May 2012, [Peer-reviewed]
English

Clinical applicability of high-sensitivity CdTe SPECT system with 4-pixel matched collimator
Kubo Naoki, Suzuki Atsuro, Ishitsu Takafumi, Ueno Yuichiro, Kobashi Keiji, Shiga Tohru, Kuge Yuji, Tamaki Nagara
JOURNAL OF NUCLEAR MEDICINE, 52, 01 May 2011, [Peer-reviewed]

Optimization of energy window setting of the semiconductor PET for human FDG studies
Tohru Shiga, Wataru Takeuchi, Naoki Kubo, Kenji Hirata, Naoya Hattori, Reiko Usui, Yuichi Morimoto, Keiji Kobashi, Kikuo Umegaki, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 52, SOC NUCLEAR MEDICINE INC, May 2011, [Peer-reviewed]
English

Accurate imaging of intratumoral FDG distribution with semiconductor human brain-PET: Evaluation by autoradiographic study in rats
Wataru Takeuchi, Toshiyuki Hatano, Sonji Zhao, Yan Zhao, Yuichi Morimoto, Norihito Kuno, Keiji Kobashi, Yuji Kuge, Nagara Tamaki
JOURNAL OF NUCLEAR MEDICINE, 52, SOC NUCLEAR MEDICINE INC, May 2011, [Peer-reviewed]
English

A newly designed multi-layer collimator for variable sensitivity and spatial resolution
Kubo Naoki, Tsuchiya Katsutoshi, Kojima Shinichi, Suzuki Atsuro, Ueno Yuichiro, Kobashi Keiji, Tamaki Nagara
JOURNAL OF NUCLEAR MEDICINE, 52, 01 May 2011, [Peer-reviewed]

Artifact reduction method for SPECT system with 4-pixel matched collimator
Ishitsu Takafumi, Suzuki Atsuro, Tsuchiya Katsutoshi, Ueno Yuichiro, Kobashi Keiji
JOURNAL OF NUCLEAR MEDICINE, 52, 01 May 2011, [Peer-reviewed], [Last author]

Biparametric correction methods using two shapers for In/CdTe/Pt radiation detector
Tomoyuki Seino, Takafumi Ishitsu, Yuichiro Ueno, Keiji Kobashi
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 629, 1, 170, 174, ELSEVIER SCIENCE BV, Feb. 2011, [Peer-reviewed], [Last author]
English, Scientific journal, Biparametric correction methods have reportedly been used to improve the energy resolutions of CdTe or CdZnTe radiation detectors. There are two methods for the correction. One is a method that uses the rise time and pulse height, and the other is a method that uses two pulse heights acquired from a fast and a slow shaper. The latter one for a 2.3-mm-thick In/CdTe/Pt radiation detector was investigated for this paper. The polarization effect resulting in short-term instability in the energy spectrum should be resolved before an In/CdTe/Pt detector is used. A pulsed bias voltage shutdown technique was used with the two shaper biparametric correction method to overcome both the polarization effect and the incomplete carrier collection. An energy resolution of 4.6% for a 122 keV peak was observed for a 2.3-mm-thick In/CdTe/Pt detector at 35 degrees C for 2 h after applying a bias voltage of -800 V. Furthermore, the energy resolutions are improved for all the photo peaks when a constant correction factor is applied to the five photo peaks in the energy range 59.5-1333 keV. (C) 2010 Elsevier B.V. All rights reserved.

Development of high-sensitivity SPECT system with 4-pixel matched collimator and pixelated CdTe detectors
Atsuro Suzuki, Kaori Hattori, Takafumi Ishitsu, Katsutoshi Tsuchiya, Keiji Kobashi
JOURNAL OF NUCLEAR MEDICINE, 51, SOC NUCLEAR MEDICINE INC, May 2010, [Peer-reviewed], [Last author]
English

Physical performance of a prototype semiconductor PET scanner featuring high energy resolution with MAP based reconstruction
Kobashi Keiji, Takeuchi Wataru, Morimoto Yuichi, Ishitsu Takafumi, Ueno Yuichiro, Matsuzaki Kazuki, Kubo Naoki, Katoh Chietsugu, Shiga Tohru, Tamaki Nagara
JOURNAL OF NUCLEAR MEDICINE, 51, May 2010, [Peer-reviewed]

Basic performance and stability of a CdTe solid-state detector panel
Katsutoshi Tsuchiya, Isao Takahashi, Tsuneaki Kawaguchi, Kazuma Yokoi, Yuuichi Morimoto, Takafumi Ishitsu, Atsurou Suzuki, Yuuichirou Ueno, Keiji Kobashi
ANNALS OF NUCLEAR MEDICINE, 24, 4, 301, 311, SPRINGER, May 2010, [Peer-reviewed], [Last author]
English, Scientific journal, We have developed a prototype gamma camera system (R1-M) using a cadmium telluride (CdTe) detector panel and evaluated the basic performance and the spectral stability.The CdTe panel consists of 5-mm-thick crystals. The field of view is 134 x 268 mm comprising 18,432 pixels with a pixel pitch of 1.4 mm. Replaceable small CdTe modules are mounted on to the circuit board by dedicated zero insertion force connectors. To make the readout circuit compact, the matrix read out is processed by dedicated ASICs. The panel is equipped with a cold-air cooling system. The temperature and humidity in the panel were kept at 20A degrees C and below 70% relative humidity. CdTe polarization was suppressed by the bias refresh technique to stabilize the detector. We also produced three dedicated square pixel-matched collimators: LEGP (20 mm-thick), LEHR (27 mm-thick), and LEUHR (35 mm-thick). We evaluated their basic performance (energy resolution, system resolution, and sensitivity) and the spectral stability in terms of short-term (several hours of continuous acquisition) and long-term (infrequent measurements over more than a year) activity.The intrinsic energy resolution (FWHM) acquired with Tc-99m (140.5 keV) was 6.6%. The spatial resolutions (FWHM at a distance of 100 mm) with LEGP, LEHR, and LEUHR collimators were 5.7, 4.9, and 4.2 mm, and the sensitivities were 71, 39, and 23 cps/MBq, respectively. The energy peak position and the intrinsic energy resolution after several hours of operation were nearly the same as the values a few minutes after the system was powered on; the variation of the peak position was < 0.2%, and that of the resolution was about 0.3%. Infrequent measurements conducted over a year showed that the variations of the energy peak position and the intrinsic energy resolution of the system were at a similar level to those described above.The basic performance of the CdTe-gamma camera system was evaluated, and its stability was verified. It was shown that the camera could be operated daily for several months without calibration.

A Sophisticated Maximum Capacity Analysis for Large Turbine Generators Considering Limitation of Temperature
K. Ide, K. Hattori, K. Takahashi, K. Kobashi, T. Watanabe
IEEE Transactions on Energy Conversion, 20, 1, 166, 172, Institute of Electrical and Electronics Engineers (IEEE), Mar. 2005, [Peer-reviewed]
Scientific journal

A new biomechanical model based approach on brain shift compensation
K Kobashi, Papademetris, X, JS Duncan
MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION - MICCAI 2003, PT 1, 2878, 59, 66, SPRINGER-VERLAG BERLIN, 2003, [Peer-reviewed], [Lead author, Corresponding author]
English, International conference proceedings, We propose a new algorithm for biomechanical model-based brain shift compensation in image guided neurosurgery. It can be used to update preoperative images with intraoperatively acquired information. We derive a model equation with regard to external forces acting on the brain surface during neurosurgery which can be consistently integrated with intraopearatively acquired information, assuming that these forces induce a linear biomechanical response. We treat external forces on the brain boundaries as unknown variables and then estimate them within a framework of inverse finite element analysis. By incorporating additional constraints from prior knowledge, we can solve the derived equations to obtain reasonable estimation results on boundary forces and the entire displacement field. This algorithm is especially beneficial in reducing navigation error of deeper brain structures by updating preoperative images using only exposed surface displacement. In this paper, we describe the derivation of the equations and present examples of two dimensional synthetic data, where the estimated displacement errors are reduced by fifty percent, compared to the standard approach.

Normal Tissue Complication Probability for Hematologic and Gastrointestinal Toxicity in Postoperative Whole Pelvic Radiotherapy for Gynecologic Malignancies using Intensity Modulated Proton Therapy with Robust Optimization
T. Yoshimura, R. Yamada, R. Kinoshita, H. Tamura, T. Matsuura, S. Takao, M. Tamura, S. Tanaka, N. Nagae, K. Kobashi, H. Aoyama, S. Shimizu, International Journal of Radiation Oncology*Biology*Physics, 108, 3, e494, e494, Nov. 2020, [Peer-reviewed]
Elsevier BV, Summary international conference

放射線治療における数値指標の医学物理的利用
清水伸一, 小橋啓司, 伊藤陽一, PRAYONGRAT Anussara, 加藤徳雄, 安田耕一, 出倉康裕, 木元拓也, 白土博樹, 日本放射線腫瘍学会高精度放射線外部照射部会学術大会プログラム・抄録集, 31st (CD-ROM), 39, 2018
Japanese

3D-SSP analysis revealed dual isotope SPECT of CBF and BZR with high sensitivity semiconductor system equivalent findings to single isotope SPECT with conventional high resolution SPECT system in patients with epilepsy.
Tohru Shiga, Atsuro Suzuki, Kotarou Sakurai, Kurita Tsugiko, Wataru Takeuchi, Takuya Toyonaga, Kenji Hirata, Chietsugu Katoh, Keiji Kobashi, Nagara Tamaki, JOURNAL OF NUCLEAR MEDICINE, 58, May 2017, [Peer-reviewed]
SOC NUCLEAR MEDICINE INC, English, Summary international conference

深層学習(deep learning)による脳腫瘍メチオニンPETの腫瘍・非腫瘍スライスの自動判定　　　　　　　　　　　　　　　
平田 健司, 竹内 渉, 山口 秀, 小林 浩之, 寺坂 俊介, 豊永 拓哉, 渡邊 史郎, 小林 健太郎, 小橋 啓司, 志賀 哲, 玉木 長良, 核医学, 53, Suppl., S309, S309, Oct. 2016
(一社)日本核医学会, Japanese

半導体SPECTを用いた123I-IFPと99mTc-ECDの2核種同時収集の検討　　　　　　　　　　　　　　　
豊永 拓哉, 志賀 哲, 鈴木 敦郎, 竹内 渉, 平田 健司, 内山 裕子, 真鍋 治, 小林 健太郎, 渡邊 史郎, 小橋 啓司, 玉木 長良, JSMI Report, 9, 2, 112, 112, Apr. 2016
日本分子イメージング学会, Japanese

深層学習(deep learning)による脳腫瘍メチオニンPETの腫瘍・非腫瘍スライスの自動判定
平田健司, 竹内渉, 山口秀, 小林浩之, 寺坂俊介, 豊永拓哉, 渡邊史郎, 小林健太郎, 小橋啓司, 志賀哲, 玉木長良, 核医学(Web), 53, Supplement, 1263(J‐STAGE), 2016
Japanese

半導体PETを用いた頭頸部癌FMISO‐PETの再現性
志賀哲, 岡本祥三, 安田耕一, 孫田恵一, 久下裕司, 竹内渉, 鈴木敦郎, 小橋啓司, 小橋啓司, 玉木長良, 核医学, 52, 3, 265, 265, 30 Sep. 2015
(一社)日本核医学会, Japanese

エネルギー分解能の高い半導体PETに向けた散乱補正の開発
竹内渉, 森本裕一, 鈴木敦郎, 小橋啓司, 久保直樹, 志賀哲, 服部直也, 玉木長良, 核医学, 49, 3, 270, 31 Aug. 2012
Japanese

半導体PET装置での脳FDG PET検査におけるエネルギーウインドウの最適化
志賀哲, 竹内渉, 久保直樹, 平田健司, 服部直也, 臼居礼子, 森本裕一, 小橋啓司, 梅垣菊雄, 玉木長良, 核医学, 48, 3, 351, 30 Sep. 2011
Japanese

高感度化4ピクセルマッチドコリメータを使用した半導体SPECT装置の検証
久保直樹, 鈴木敦郎, 石津崇章, 上野雄一郎, 小橋啓司, 志賀哲, 久下裕司, 玉木長良, 核医学, 48, 3, 304, 305, 30 Sep. 2011
Japanese

Research and development towards advanced diagnosis systems to overcome three major diseases
越智 久晃, 森本 裕一, 小橋 啓司, 日立評論, 93, 3, 315, 319, Mar. 2011
日立評論社, Japanese

Scatter Correction for Semiconductor-PET system
TAKEUCHI Wataru, MORIMOTO Yuichi, SUZUKI Atsuro, TSUCHIYA Kazutoshi, TAKAHASHI Isao, KOBASHI Keiji, KUBO Naoki, KATOH Chietsugu, SHIGA Tohru, TAMAKI Nagara, 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, 0, 51, 52, 01 Apr. 2008
Japanese

Iterative Reconstruction Method using Prior Information and System Response Function
TAKEUCHI Wataru, MORIMOTO Yuichi, SUZUKI Atsuro, MATSUZAKI Kazuki, KOJIMA Shinichi, KOBASHI Keiji, KUBO Naoki, KATOH Chietsugu, SHIGA Tohru, TAMAKI Nagara, 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, 0, 53, 54, 01 Apr. 2008
Japanese

Jun. 2020 - Present
Japanese Society for Radiation Oncology　　　　　　　　　　　　　　　

An Integrated Approach for Uncertainty Reduction of DIR-based Dose Accumulation in Adaptive Radiotherapy
Grants-in-Aid for Scientific Research
01 Apr. 2024 - 31 Mar. 2027
小橋 啓司, 橋本 孝之, 吉村 高明, 西岡 健太郎
Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 24K10878

肺癌に対する陽子線治療の選択基準確立に向けた心肺相互作用勘案NTCPモデル構築
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
青山 英史, 鈴木 隆介, 宮本 直樹, 高尾 聖心, 金平 孝博, 橋本 孝之, 小橋 啓司, 西岡 健太郎, 田口 大志
日本学術振興会, 基盤研究(B), 北海道大学, 22H03008

AIを活用した小児がん陽子線照射のトリプルハイブリッド遠隔治療計画システムの開発
科学研究費助成事業
01 Apr. 2022 - 31 Mar. 2025
橋本 孝之, 高尾 聖心, 小橋 啓司, 吉村 高明, 西岡 健太郎
日本学術振興会, 基盤研究(C), 北海道大学, 22K07631