Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Objectives: This study aimed to assess the precision of dose delivery to the target in adaptive carbon ion radiotherapy (CIRT) for locally advanced non-small cell lung cancer (LA-NSCLC) in cumulative dosimetry. Methods: Forty-six patients who received CIRT were included (64 Gy[relative biological effectiveness, RBE] in 16 fractions) with treatment plan computed tomography (CT) and weekly CT scans. Offline adaptive radiotherapy (ART) was administered if the dose distribution significantly worsened. Daily doses were calculated from weekly CTs and integrated into plan CT scans using deformable image registration. The dosimetry parameters were compared between the as-scheduled plan and adaptive replan in patients receiving ART. Survival outcomes and toxicity were compared between the ART and non-ART groups. Results: ART was implemented for 27 patients in whom adaptive replans significantly increased the median V98% of the clinical tumor volume from 96.5% to 98.1% and D98% from 60.5 to 62.7 Gy(RBE) compared with the as-scheduled plans (p < 0.001). The conformity and uniformity of the dose distribution improved (p < 0.001), with no significant differences in the doses to normal tissues (lungs, heart, esophagus, and spinal cord) from the as-scheduled plans (p > 0.05). The ART and non-ART groups demonstrated comparable local control, progression-free survival, and overall survival (p > 0.05). No grade 3 or higher radiation-related toxicities were observed. Conclusions: ART enhanced target dose coverage while maintaining acceptable normal tissue exposure, supporting weekly CT monitoring integration during CIRT for the timely intervention for anatomical variations, ensuring precise dose delivery in LA-NSCLC.

DOI： 10.3390/cancers17162709

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

We performed a risk assessment of soft errors in cardiac implantable electronic devices in carbon ion radiation therapy (CIRT) for prostate cancer treatment by conducting Monte Carlo simulations based on computed tomography images. Input files were generated using RT-PHITS. The risk of soft errors varied depending on irradiation conditions, particularly beam energy and irradiation direction. The estimated number of soft errors was 2.0. Therefore, the risk of soft errors attributable to CIRT for prostate cancer treatment is considered acceptable.

DOI： 10.1007/s10967-025-10249-1

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Other Link： https://link.springer.com/article/10.1007/s10967-025-10249-1/fulltext.html

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Radiological Technology  

DOI： 10.6009/jjrt.25-0401

PubMed

CiNii Research

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

The number of patients requiring breast reconstruction with artificial implants has been increasing, and so is the use of carbon-ion radiotherapy (CIRT). Consequently, a growing number of patients with artificial breast implants are expected to undergo CIRT. Because artificial breasts are composed of a silicone polymer gel with a silicon–oxygen backbone, which differs significantly from human tissues, the stopping power ratio for carbon beams cannot be accurately converted from CT values using standard CT-to-stopping power ratio tables (CT–SP tables). Incorrect stopping power ratios can lead to significant problems in CIRT, including erroneous calculations of carbon beam range. To address this, we measured the CT values and stopping power ratios of three commercial artificial breasts using a 380 MeV/u carbon beam. Our results revealed significant deviations from the CT–SP table values. For instance, calculations for treating lung cancer with incorrect stopping power ratios resulted in errors of approximately 5 mm in range calculations, adversely affecting dose distribution to the target. Although further studies with various products are needed, it is crucial to conduct thorough patient consultations and develop treatment plans using accurate stopping power ratios.

DOI： 10.1007/s12194-024-00860-4

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Other Link： https://link.springer.com/article/10.1007/s12194-024-00860-4/fulltext.html

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Background and purpose: To develop a normal tissue complication probability (NTCP) model for predicting grade ≥ 2 acute oral mucositis (AOM) in head and neck cancer patients undergoing carbon-ion radiation therapy (CIRT). Methods and materials: We retrospectively included 178 patients, collecting clinical, dose-volume histogram (DVH), radiomics, and dosiomics data. Patients were randomly divided into training (70%) and test sets (30%). Feature selection involved univariable logistic regression, least absolute shrinkage and selection operator regression, stepwise backward regression, and Spearman's correlation test, with the bootstrap method ensuring reliability. Multivariable models were built on the training set and evaluated using the test set. Results: The optimal NTCP model incorporated a DVH parameter (V<inf>37Gy [relative biological effectiveness, RBE]</inf>), radiomics, and dosiomics features, achieving an area under the curve (AUC) of 0.932 in the training set and 0.959 in the test set. This hybrid model outperformed those based on single DVH, radiomics, dosiomics, or clinical data (Bonferroni-adjusted p < 0.001 and ΔAUC > 0 for all comparisons in 1,000 bootstrap validations). Calibration curves showed strong agreement between predictions and outcomes. A 44.0 % AOM risk threshold was proposed, yielding accuracies of 87.1 % in the training set and 90.7 % in the test set. Conclusions: We developed the first NTCP model for estimating AOM risk in head and neck cancer patients undergoing CIRT and proposed a risk stratification. This model may assist in clinical decision-making and improve treatment planning for AOM prevention and management by identifying high-risk patients.

DOI： 10.1016/j.radonc.2025.110709

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publisher：Japan Society of Medical Physics  

<p>This is a review on history of medical physics in Radiological Physics and Technology published by JSRT and JSMP (https://www.jsmp.org/en/).</p>

DOI： 10.11323/jjmp.44.4_79

PubMed

CiNii Research

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：JCI Insight  

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor–deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

DOI： 10.1172/jci.insight.161282

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：Surgery Today  

The “bystander effect” is a transmission phenomenon mediating communication from target to non-target cells, as well as cell-to-cell interactions between neighboring and distantly located cells. In this narrative review, we describe the fundamental and clinical significance of the bystander effect with respect to cell-to-cell interactions in carcinogenesis, therapeutic response, and tissue regeneration. In carcinogenesis, the bystander effect mediates communications between tumor microenvironments and non-malignant epithelial cells and has been suggested to impact heterogeneous tumorigenic cells in tumors and cancerized fields. In therapeutic response, the bystander effect mediates communications between drug-sensitive and drug-resistant cells and may transmit both drug efficacy and resistance. Therefore, control of therapeutic response transmission via the bystander effect might offer a promising future cancer treatment. Finally, in tissue regeneration, circulating cells and stromal cells may differentiate into various cells for the purpose of tissue regeneration under direction of the bystander effect arising from surrounding cells in a defective space. We hope that the findings we present will promote the development of innovative cancer therapies and tissue regeneration methodologies from the viewpoint of cell-to-cell interactions through the bystander effect.

DOI： 10.1007/s00595-022-02524-5

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publisher：(一社)日本医用画像工学会  

宇宙物理や高エネルギー物理の分野で長い歴史をもつコンプトンカメラの技術を医療応用できれば,新たな核医学診断法を開拓できるかもしれない.一方で,ヒト撮像においてPETと同程度の解像度を実現するには,装置性能の向上が必要不可欠である.SPECTやPETは確立された性能評価技術を活用して装置開発が進められているが,コンプトンカメラは放射線の検出方式や検出器配置がさまざまであり,標準的な性能評価技術が存在しない.標準評価法があればさまざまなコンプトンカメラの検出器性能とイメージング性能を明らかにでき,装置性能の直接比較だけでなく,臨床機に要求される検出器性能の導出,有望な検出器の選定にも活用できると考えられる.そこで,量子科学技術研究開発機構が主体となって分野横断的な研究グループを組織し,医用コンプトンカメラを同一条件で性能比較できる標準評価法の開発に取り組んでいる.本稿では,この取り組みについて概説する.(著者抄録)

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：(一社)日本放射線影響学会  

炭素イオンの線エネルギー付与(LET)、二本鎖切断(DSB)クラスタの程度や殺細胞作用との相互関係について検討した。ヒト肺癌細胞株A549細胞にLET 13-100keV/μmの炭素イオンを照射し、誘発されたγH2AXフォーカス容積を高解像度画像技術で解析した。次に3317γH2AXフォーカスからデータを得た後、Gauss関数で1Gy炭素イオンが細胞核当り容積(Vth)以上に、γH2AXフォーカスを誘発する確率(p)を概算した。なお、殺細胞作用はクローン原性アッセイで評価した。その結果、殺細胞作用は様々なLET値でvth=0.7μm3におけるp値と高い一致が示され、双方の差異も平均4.7±2.2%の範囲内であった。さらに、これらの関係は拡大ブラッグピーク幅(30～120mm)にわたり、混合LETプロファイルを有する臨床適用の炭素イオンビームにも適合し、モンテカルロシミュレーションからの線量-平均LETを用いてp値を求めると、vth=0.7μm3における差の平均が1.6±1.2%であった。以上より、炭素イオン線の殺細胞作用はDSBクラスタを含むγH2AXの誘発能により予測されることが示唆され、本調査により、炭素イオン放射線治療計画におけるLET調節に際し生物学的基礎が得られた。

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：Frontiers in Psychiatry  

Backgrounds: Hikikomori, pathological social withdrawal, is becoming a crucial mental health issue in Japan and worldwide. We have developed a 3-day family intervention program for hikikomori sufferers based on Mental Health First Aid (MHFA) and Community Reinforcement and Family Training (CRAFT). This study aims to confirm the effectiveness of the 3-day program by a randomized controlled trial. Methods: This study was registered on the UMIN Clinical Trials Registry (UMIN000037289). Fifteen parents were assigned to the treat as usual (TAU) group (TAU only; Age Mean, 65.6; SD, 7.8), and 14 to the Program group (program + TAU; Age Mean, 67.9; SD, 8.6). This study was discontinued due to the COVID-19 pandemic; the recruitment rate was 36.3% of our target sample size of 80. Results: Perceived skills improved temporally and stigma temporally worsened in the TAU group. Confidence decreased and attitude showed no change in both groups. Aggressive behaviors of hikikomori sufferers were significantly worsened in the Program group; however, no serious domestic violence was reported. In the TAU group, Avoidance and irregular life patterns were improved. Activity levels were worsened in both groups. Two participants (16.7%) in the Program group and one participant (7.7%) in the TAU group reported actual behavioral changes (e.g., utilizing support). Conclusion: We could not draw general conclusions on the effectiveness of the program due to the study discontinuation. Nevertheless, this study indicates the necessity for revision of the program to improve family members’ confidence in engaging with hikikomori sufferers, with safer approaching by families.

DOI： 10.3389/fpsyt.2022.1029653

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Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publisher：(公社)日本アイソトープ協会  

粒子線治療におけるビームの可視化は,照射領域のずれをなくすことを可能とし,安全性の高い治療を行うために有用な手段である。著者らは,放射線診断の現場に広く用いられるイメージングプレートを用いて,制動放射線を指標としたビームイメージングを行った。その結果,高解像度なビーム像を得ることに成功した。さらに,得られた画像から飛程を推定する手法を開発し,標準偏差2.5mmの精度で治療用炭素線の飛程の推定が可能であることが示唆された。(著者抄録)

Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：Journal of Radiation Research  

According to guidelines, carbon-ion beam therapy is considered to carry a high safety risk for patients with cardiac implantable electronic devices (CIEDs), although the actual impacts remain unclear. In this study, we investigated the safety of carbon-ion beam therapy in patients with CIEDs. Patients with CIEDs who underwent carbon-ion therapy at Gunma University Heavy Ion Medical Center between June 2010 and December 2019 were identified and investigated for abnormalities in the operation of their CIEDs, such as oversensing and resetting during irradiation, and abnormalities in operation after treatment. In addition, the risk of irradiation from carbon-ion beam therapy was evaluated by model simulations. Twenty patients (22 sites) with CIEDs were identified, 19 with pacemakers and one with an implantable cardioverter-defibrillator (ICD). Treatments were completed without any problems, except for one case in which the treatment was discontinued because of worsening of the primary disease. Monte Carlo simulation indicated that the carbon beam irradiation produced neutrons at a constant and high level in the irradiation field. Nevertheless, with the distances between the CIEDs and the irradiation fields in the analyzed cases, the quantity of neutrons at the CIEDs was lower than that within the irradiation. Although carbon-ion beam therapy can be safely administered to patients with CIEDs, it is advisable to perform the therapy with sufficient preparation and backup devices because of the risks involved.

DOI： 10.1093/jrr/rrab105

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Authorship：Lead author,　Last author,　Corresponding author   Language：English   Publisher：(一社)日本放射線影響学会  

植込み型心臓電気デバイス(CIED)装着患者における、炭素イオン線治療(CIRT)の安全性について、後向きに検討した。2010年6月～2019年12月にかけ、当院でCIRTが施行されたCIED装着患者20例を調査対象とし、CIRTを2回行った2例を含む22例(男性15例、女性7例、年齢61～94歳)の患者データから、CIRT治療下ならびに経過観察期間に発生したCIEDの誤作動を調べ、CIRTによるリスクをモデルシミュレーションにより評価した。その結果、CIRT治療下/経過観察期間いずれにおいても、CIEDの誤動作は検出されなかった。また、モンテカルロシミュレーションにより、CIRTにより照射野に、中性子が一定数もしくは高レベルで産生され、CIEDと照射野間の距離が長くなると、CIEDにおける中性子量は照射野内よりも少なくなることが明らかにされた。本研究結果から、CIRTはCIED装着患者に対し安全に適用可能ではあるが、CIRTによるCIEDの誤動作リスクを考慮して適用することが肝要と考えられた。

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Purpose: Boron neutron capture therapy (BNCT) is a promising cancer treatment; however, it poses the risk of soft errors in cardiac implantable electronic devices (CIEDs). This study aimed to assess the occurrence of soft errors in CIEDs during BNCT and to correlate these errors with the neutron flux. Materials and methods: A field-programmable gate array (FPGA) was used as a surrogate for CIED to measure the soft errors under thermal and epithermal neutron irradiation. The neutron flux at the FPGA position was assessed using gold wire activation, and the effective soft-error cross-section was calculated. Results: The neutron flux exhibited a clear inverse relationship with distance from the irradiation center. The number of soft errors observed in the FPGA mirrored this trend, showing a significant reduction as the distance from the beam center increased. A strong linear correlation was identified between the thermal neutron flux and soft-error rate, and a consistent reaction cross-section was derived. Conclusion: This study provides foundational data on soft-error risks in electronic devices during BNCT. Our findings indicate that increasing the distance from the beam center significantly reduces the soft-error rate. These insights are crucial for developing robust radiotherapy safety guidelines for patients with implanted electronic devices.

DOI： 10.1007/s11604-026-01993-9

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Other Link： https://link.springer.com/article/10.1007/s11604-026-01993-9

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Background

The anatomical changes during carbon ion radiotherapy (CIRT) for head and neck cancers frequently require plan adaptations with adaptive re-planning. However, the details of the anatomical changes and their rates are not clear. The purpose of this study was to retrospectively evaluate the factors that require re-planning during CIRT for head and neck cancers.

Methods

Thirty-seven patients who underwent 146 computed tomography (CT) scans and CIRT for head and neck cancers were evaluated retrospectively. To evaluate the re-planning situation, the frequency of the plan adaptation, reasons for plan adaptations, and causes of dose-distribution distortion were evaluated. Dose distributions were evaluated for two cases in which re-planning was carried out due to changes in tumor size and density on the beam path.

Results

The main cause for dose-distribution distortion was a change in tumor size for 11 of 13 patients who underwent plan adaptation. Of the tumor-size changes, 64% were due to tumor expansion. For two patients, adaptive re-planning on weekly CT images resulted in a dose distribution equivalent to the original treatment plan in terms of target coverage and sparing of organs at risk.

Conclusion

In CIRT for head and neck cancers, the main cause of dose-distribution distortion requiring re-planning was an increase in tumor size soon after treatment initiation.

DOI： 10.3389/fonc.2026.1543304

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Institute of Anticancer Research  

Background/Aim: This study aimed to evaluate whether the predictive performance of tumor control probability (TCP) by carbon ion radiotherapy (CIRT) could be improved by incorporating cancer type-specific carbon ion sensitivity data obtained from non-small cell lung cancer (NSCLC). Materials and Methods: A TCP model based on the linear-quadratic (LQ) formalism and fractionated irradiation was employed, with n defined as an index of inter-tumor heterogeneity on radiosensitivity. The LQ model parameters a and 0 for NSCLC were obtained from 13 cell lines subjected to carbon ion irradiation under clinically relevant conditions, followed by clonogenic assays. The human salivary gland (HSG) cell line was used as a control. The a and 0 values were incorporated into the TCP model, and agreement with the clinical data (i.e., the local control rates for 48 NSCLCs treated with CIRT, as previously reported) was evaluated using the coefficient of determination (R²) derived from least-squares fitting. Results: When e was set to 0.20, the NSCLC-derived TCP curve showed better agreement with the clinical data than the HSG cell-derived TCP curve (R²: 0.72 vs. 0.53, respectively). Similarly, when e was set to 0.15, the NSCLC-derived curve showed better agreement with the clinical data (R²: 0.56 vs. 0.38, respectively). Furthermore, when weighting factors of 1, 3, and 10 were applied to the two data points with TCP=1.0, the NSCLC-derived TCP curve showed consistently better agreement with the clinical data than the HSG cell-derived TCP curve (R²: 0.74 vs. 0.55, 0.78 vs. 0.63, and 0.79 vs. 0.65, respectively). Conclusion: Incorporation of cancer type-specific carbon ion sensitivity data can improve the predictive performance of TCP modeling compared with the conventional HSG cell-based approach.

DOI： 10.21873/anticanres.17927

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Institute of Anticancer Research  

Background/Aim: In carbon-ion radiotherapy (CIRT), a low dose-averaged linear energy transfer (LET<inf>d</inf>) within the tumor has been suggested as a potential unfavorable prognostic factor for local recurrence. However, inter-fractional variations in LET<inf>d</inf> during daily CIRT sessions remain unelucidated. This study aimed to investigate inter-fractional variations in LET<inf>d</inf> profiles during CIRT for pancreatic cancer. Patients and Methods: Seven patients with locally advanced pancreatic cancer treated with CIRT were retrospectively analyzed. Treatment plans delivering 55.2 Gy (relative biological effectiveness) in 12 fractions were generated based on computed tomography (CT) images (Plan-CT). For each CIRT session, in-room CT images were acquired immediately after irradiation and referred to as Daily-CT; all 12 series of images were deformably registered to the Plan-CT. LET<inf>d</inf> parameters (L<inf>98%</inf>, L<inf>95%</inf>, L<inf>50%</inf>, and L<inf>2%</inf>) for target volumes were compared between Plan-CT and Daily-CT (L<inf>X%</inf> was defined as the minimum LET<inf>d</inf> delivered to X% of the target volume). Results: The L<inf>50%</inf> and L<inf>2%</inf> values for the planning target volumes were significantly lower on Daily-CT than on Plan-CT, although the differences were modest. Meanwhile, no significant differences were observed for L<inf>98%</inf> and L<inf>95%</inf>. One patient exhibited a consistent decrease in LET<inf>d</inf> on Daily-CT across all LET<inf>d</inf> parameters and target volumes examined. For this patient, increased bowel gas within the beam path was observed during daily sessions, which caused a distal shift of the LET<inf>d</inf> distribution, which then reduced LET<inf>d</inf> coverage of the target volumes. Conclusion: During CIRT for pancreatic cancer, inter-fractional variations in LET<inf>d</inf> profiles may be more pronounced at larger target volumes and at lower L<inf>X%</inf> values. Although the variations were modest in most cases, inter-fractional changes in bowel gas within the beam path are a potential risk factor for reduced LET<inf>d</inf> coverage.

DOI： 10.21873/anticanres.17961

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Nuclear reactions between proton irradiation and boron via p + ¹¹ B→3α (boron proton-capture reaction; BPCR) and n + ¹⁰ B→α+ ⁷ Li (boron neutron-capture reaction; BNCR) enhance the cell-killing effects of proton beam irradiation (PBI); however, which reaction exerts superior sensitization effects remains unclear. Therefore, we evaluated the efficacy of the BPCR and BNCR in enhancing the cell-killing effects of PBI. Human osteosarcoma (MG-63) and glioma (U-251 MG) cells were irradiated with PBI with and without boronophenylalanine (BPA) enriched with &gt; 95% ¹⁰ B ( ¹⁰ B-BPA) for BNCR and BPA with natural isotopic abundance of boron (80% ¹¹ B + 20% ¹⁰ B; N-BPA) for BPCR. Sensitizer enhancement ratios (SERs) were obtained by comparing the doses that yielded a surviving fraction of 10% (D ₁₀ ). The D ₁₀ values for PBI alone, PBI with ¹⁰ B-BPA, and PBI with N-BPA were 5.67, 4.85, and 5.51 and 5.21, 4.65, and 5.18 for MG-63 and U-251 MG cells, respectively. SERs of PBI with ¹⁰ B-BPA and N-BPA were 1.17 and 1.03 and 1.12 and 1.01 for MG-63 and U-251 MG cells, respectively. Our results indicate that ¹⁰ B-BPA-associated BNCR may be a better sensitizer for PBI than N-BPA-associated BPCR, which warrants further investigation into the clinical use of ¹⁰ B-enriched BPA.

DOI： 10.1038/s41598-025-27619-0

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Other Link： https://www.nature.com/articles/s41598-025-27619-0

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/nss/mic/rtsd57106.2025.11287255

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Purpose: This study aims to enhance carbon-ion range estimation using a Compton camera, improved through artificial neural network (ANN)-based event classification. Methods: A Monte Carlo simulation was developed in Geant4. Carbon ions irradiated to a PMMA phantom and 511 keV gamma-rays emitted were detected by silicon/cadmium telluride (Si/CdTe) Compton cameras. An ANN was trained to identify true Compton events. Following event selection, the annihilation photon distribution was reconstructed using the list-mode maximum-likelihood expectation–maximization algorithm. The beam range was estimated by identifying the peak position of the emission profile along the beam axis. This method was compared to traditional approach based on geometric constraints and energy thresholds. Results: ANN-based event selection significantly improved the true Compton event ratio and the accuracy of range estimation. Across a phantom position range from –15 mm to 30 mm, the proposed method achieved a phantom position mean error of less than 3 mm, outperforming the traditional method, which showed a maximum error of 4.3 mm. Conclusions: The integration of ANN-based event classification with Compton imaging improves the precision of online range monitoring for carbon-ion therapy. This approach demonstrates strong potential for clinical application, offering enhanced accuracy and reliability in particle therapy dose verification.

DOI： 10.1016/j.ejmp.2025.105193

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

Soft errors in terrestrial applications are typically evaluated by irradiating semiconductor chips with high-energy neutrons or protons. We propose an alternative method using clinical carbon beam facilities, where carbon ions are irradiated onto an acrylic block to generate secondary particles. Test chips are irradiated with neutrons emitted from the block, while charged particles with high linear energy transfer (LET), such as alpha particles, are shielded by Pb blocks. To evaluate the shielding effect, we investigated the dependence of single event upset (SEU) rates and single event transient (SET) pulse widths on Pb thickness. The SEU rate stabilized at 4 cm, but the total SET rate at this thickness was 70% higher than that at 8 cm. This increase was mainly due to an increased number of pulses shorter than 245 ps, likely caused by direct ionization from charged particles. We then compared our method with white neutron (WN) irradiation using six types of 65 nm flip-flops (FFs) to validate its effectiveness. The SEU rates showed the correlation coefficient of 0.98 and differed by less than 1%. SET pulses longer than 245 ps were similar in both cases, while shorter pulses occurred more often with WNs. This difference is attributed to a higher fraction of medium-energy neutrons in the WN spectrum. These findings indicate that clinical carbon beam facilities offer a practical alternative for soft-error evaluation, particularly when the contribution of medium-energy neutrons is limited.

DOI： 10.1109/tns.2025.3611382

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Background and purpose: Acute oral mucositis (AOM) is a critical adverse event in head and neck cancer (HNC) requiring early intervention during carbon ion radiotherapy (CIRT). Considering external irradiation and internal mucosal heterogeneity, this study developed a classification model integrating maximum dose (Dmax) and dose-volume-based radiomics (RaV<inf>x</inf>) for early identification of grade ≥ 2 AOM. Methods and materials: We retrospectively analyzed 190 HNC patients treated with CIRT (training: test = 7:3). Radiomic features were extracted from the entire oral mucosa and dose-specific subregions [RaV<inf>x</inf>, 10–50 Gy(RBE) in 10-Gy increments]. Feature selection employed logistic regression, random forest, and XGBoost, followed by Spearman's correlation test. Six two-stage models were developed: Stage 1 stratified patients into high- and low-dose groups using a Dmax threshold (Dmax model), while Stage 2 further classified high-dose patients using a support vector machine (SVM) with selected RaV<inf>x</inf> features (RaV<inf>x</inf>-SVM model). Classification performance was assessed in training and test sets using bootstrap validation. Results: Grade ≥ 2 AOM occurred in 61.6 % of patients. The Dmax model with a 50 Gy(RBE) threshold achieved 87.2 % accuracy but had a high false-positive rate (FPR = 31.4 %). The RaV<inf>x</inf>-SVM model reduced false positives, with the RaV<inf>40 Gy(RBE)</inf>-SVM-model performing best. The integrated Dmax<inf>50</inf>&RaV<inf>40 Gy(RBE)</inf>-SVM model achieved 97.0 % accuracy (FPR 2.0 %) in training and 96.5 % mean accuracy (mean FPR 4.7 %) in the test. Conclusions: Dose-volume radiomics effectively identified low-risk AOM patients in the high-dose group. The integrated model demonstrated high accuracy in identifying HNC patients with grade ≥ 2 AOM during CIRT.

DOI： 10.1016/j.phro.2025.100842

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

An accelerator-based neutron source (ABNS) for boron neutron capture therapy (BNCT) is under development at the University of Osaka, Japan. It can supply a sufficiently intense epi-thermal neutron flux of ~8 × 108 n/s/cm2 and, at the same time, enable the whole-body dose to be substantially suppressed (~0.26 Sv/irradiation) by employing a p-Li reaction as a neutron emission reaction. At present, we are designing all the equipment to be implemented in the BNCT machine. Previously, prior to the design of the real machine, we carried out mock-up experiments to demonstrate epi-thermal neutron production and check our neutronics design code system with a prototype beam shaping assembly (BSA). The series of experiments was conducted with a Dynamitron accelerator at Birmingham University, UK. Based on the experimental results, the first neutronics design of the real machine was completed. The design result was described, together with details of the neutronics design goal and design code system. Now, our p-liquid Li-based ABNS-BNCT system is planned to be constructed in the Institute of Free Electron Laser at the University of Osaka, Osaka, Japan.

DOI： 10.3390/app151810248

Scopus

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Boron neutron capture therapy (BNCT) can selectively destroy tumor cells while minimizing damage to normal tissue through boron neutron capture reactions. Real-time determination and localization of the in-vivo boron dose during treatment is a critical challenge in BNCT. A promising solution involves imaging the 478 keV prompt gamma rays emitted from these capture reactions. This study presents a comprehensive simulation-based design of a Si/TlBr semiconductor Compton camera system for 478 keV prompt gamma-ray imaging in clinical BNCT. The design process includes optimization of detector geometry using isotropic, monoenergetic 478 keV gamma-ray sources; development of neutron and photon shielding under therapeutic neutron beam irradiation of a head phantom; and evaluation of imaging performance under clinically relevant conditions with low in-vivo ¹⁰B concentrations. The results provide valuable insights to support the further development of Compton camera systems for BNCT applications.

DOI： 10.35848/1347-4065/ae02d5

Web of Science

Scopus

Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ae02d5/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Purpose: To evaluate the effects of dose-averaged linear energy transfer (LET<inf>d</inf>) profiles on local control (LC) of pancreatic cancer treated with carbon ion radiation therapy (CIRT). Methods and Materials: Data from patients with inoperable pancreatic cancer, treated with CIRT and concurrent chemotherapy between 2013 and 2021, were analyzed retrospectively. The prescribed dose was 55.2 Gy (relative biological effectiveness), administered in 12 fractions. The LET<inf>d</inf> of CIRT plans were calculated using a previously reported in-house pipeline. The association between tumor LET<inf>d</inf> profiles and local recurrence (LR) was analyzed. Results: The study analyzed 106 patients. The 2-year cumulative LR rate was 20.2% (95% confidence interval [CI], 12.8%-28.9%). Analysis of LET<inf>d</inf> parameters using a Fine-Gray regression model showed that the minimum LET<inf>d</inf> (L<inf>min</inf>) for the clinical target volume (CTV) had a significant effect on LR (P = .023). According to the cut-off value of 42.2 keV/µm, determined by time-dependent receiver operating characteristic analysis at 18 months, patients with low CTV L<inf>min</inf> had a significantly greater cumulative LR rate than those with high CTV L<inf>min</inf> (P = .020; 2-year cumulative LR rate, 32.4% [95% CI, 16.6%-49.3%] vs 12.7% [95% CI, 5.8%-22.5%]). Cause-specific proportional hazards models identified CTV L<inf>min</inf> as a significant predictor of LR (hazard ratio, 0.83; [95% CI, 0.71-0.98]; P = .030). CTV L<inf>min</inf> showed a strong, significant negative correlation with CTV (P < .0001, r = –0.52). Conclusions: This is the largest study investigating the association between tumor LET<inf>d</inf> profiles and LC post-CIRT. The results suggest that low LET<inf>d</inf> within the CTV is associated with poor LC in patients with pancreatic cancer treated with CIRT.

DOI： 10.1016/j.ijrobp.2025.07.1406

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.7759/cureus.83835

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Secondary electron bremsstrahlung (SEB) has been proposed for range verification in particle therapy. However, the uncertainty in range-shift estimation due to high statistical noise under small numbers of carbon ion irradiation remains unclear. This simulation study evaluated the uncertainty of SEB-based range-shift estimations under conditions with limited numbers of carbon ions. The SEB images were generated by irradiating an acrylic target with monoenergetic carbon-ion beams and calculating the energy deposited onto a cadmium telluride pixel detector in simulation. Estimated range shifts were derived from the obtained SEB images using our proposed range-shift estimation method. As a result, the uncertainty was 1.4 mm for 10⁸ ions and 4.4 mm for 10⁷ ions. The results suggested that improving the sensitivity of the detector is effective in reducing the uncertainty.

DOI： 10.35848/1347-4065/adc21b

Scopus

Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/adc21b/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Thermal neutrons generated in the body during proton beam therapy (PBT) can be used to cause boron neutron capture reactions and have recently been proposed as neutron capture enhanced PBT (NCEPBT). However, the cell killing effect of NCEPBT remains underexplored. Here, we show an increase in the cell killing effect of NCEPBT. Using Monte Carlo simulations, we showed that neutrons generated by proton beam irradiation are uniformly spread on tissue culture plates. Human salivary gland tumor cell line (HSG), human osteosarcoma cell line (MG63), human tongue squamous cell carcinoma cell line (SAS), and human malignant melanoma cell line (G-361) were irradiated with X-rays, proton beams, and proton beams with ¹⁰B-enriched boronophenylalanine (boron concentration of 20 and 80 ppm). The relative biological effectiveness (RBE) values of proton beams alone, proton beams with 20 ppm boron, and proton beams with 80 ppm boron for HSG, MG63, SAS, and G-361 were 1.02, 1.07, and 1.23; 1.01, 1.08, and 1.44; 1.05, 1.09, and 1.46; and 1.04, 1.13, and 1.63, respectively. NCEPBT with high boron concentration showed high RBE and a high sensitizing effect. Our results confirm an increase in the cell killing effect of NCEPBT, should aid in its clinical use, and warrant its further investigation.

DOI： 10.1038/s41598-024-79045-3

Scopus

Other Link： https://www.nature.com/articles/s41598-024-79045-3

Language：English   Publishing type：Research paper (scientific journal)  

A compact, convenient dosimeter device for a convenient dose-distribution profiling tool were developed using aluminum-enriched phosphate glass. The composition of the phosphate glass were modified by adding an additional 0.2 mol % aluminum impurity, which allowed the phosphate glass to be used as a real-time scintillator with broadband radioluminescence under various types of radiation exposure, including X-rays, without large build-up effects. Real-time radiation monitoring was accomplished on a submillimeter scale by using aluminum-enriched phosphate glass beads. Ion beam analysis confirmed that the aluminum-enriched phosphate glass contained no heavy elements. Optical fiber dosimetry based on the aluminum-enriched phosphate glass was demonstrated, and stable radioluminescence was visualized under X-ray irradiation.

DOI： 10.1016/j.nimb.2024.165447

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.ijrobp.2024.07.874

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

A thin diamond membrane energy-dispersive dosimeter 50 μm thick was fabricated for estimating clinical dose distribution. In contrast to conventional semiconductors, diamond wide-bandgap semiconductors are expected to have excellent radiation tolerance and biological compatibility based on the linear relationship of stopping power ratio for clinical carbon particles. Linear energy transfer (LET) spectra were obtained along with the Bragg curve for a clinical carbon beam generated at Gunma University Heavy Ion Medical Center. The relative biological effectiveness (RBE) distributions were estimated from the LET spectra for both the mono-energy and spread-out Bragg peak irradiation configurations. The diamond detector was also used as a solid ionization chamber to obtain the radiation-induced current (RIC) distribution, which represents the physical dose distribution. The clinical dose distribution was estimated from the RIC and RBE distributions as proof of concept for the clinical carbon beam therapy field with a single-chip diamond energy-dispersive dosimeter.

DOI： 10.1016/j.nimb.2024.165430

Scopus

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

The increasing use of cardiac implantable electronic devices (CIEDs) has raised concerns regarding potential soft errors during radiotherapy. Soft errors in CIEDs can lead to device malfunction, risking serious complications, such as ventricular tachycardia, that may require cardiopulmonary resuscitation. This study aimed to assess and compare the risks of soft errors in CIEDs exposed to radiation therapy using field-programmable gate arrays (FPGAs). The FPGAs were placed on an acrylic phantom and subjected to 10 min of X-ray or carbon-beam irradiation. The number of memory inversions, counted as soft errors, was studied for X-ray energies of 6, 10, or 15 MV and carbon beam energies of 290, 380, or 400 MeV/u, utilizing a 4-cm range shifter and a 6-cm spread-out Bragg peak for carbon beams. The results indicated that soft errors were minimal with X-rays below 10 MV but increased for 15 MV X-rays, and increasing the carbon beam energy correlated with more soft errors. In the measurement with a 400 MeV/u carbon beam, soft errors significantly increased with the smaller irradiation field, probably due to blocking the carbon ions by the collimator and increased neutron generation. And soft errors decreased with increasing distance from the center of the irradiation field to the FPGAs. Based on the experimental results using 15MV X-rays, it was shown that carbon-ion therapy could also be performed with acceptable risk. These observations may be associated with variations in the neutron generation sources, necessitating further verification through simulations and alternative methodologies. Although further studies are necessary to verify the impact of circuit design and relationship to malfunctions in clinical devices because this study used only one type of FPGA, this study contributes crucial foundational data for understanding the risk of soft errors in CIEDs during radiation therapy.

DOI： 10.1016/j.nimb.2024.165384

Scopus

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

Introduction: While carbon ion radiotherapy is highly effective in cancer treatment, it has a high risk of causing soft error, which leads to malfunctions in cardiac implantable electrical devices (CIEDs). To predict the risk of malfunction prior to treatment, it is necessary to measure the reaction cross-sections and contributions to the soft error of secondary particles generated during treatments. Methods: A field-programmable gate array was used instead of CIEDs to measure soft errors by varying the energy spectrum of secondary particles. Results and discussion: The reaction cross-sections measured for each secondary particle were 3.0 × 10-9, 2.0 × 10-9, 1.3 × 10-8, and 1.5 × 10-8 [cm2/Mb] for thermal neutrons, intermediate-energy neutrons, high-energy neutrons above 10 MeV, and protons, respectively. The contribution of high-energy neutrons was the largest among them. Our study indicates that to reduce the risk of soft errors, secure distance and appropriate irradiation directions are necessary.

DOI： 10.1109/ojemb.2024.3358989

Scopus

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Boron neutron capture therapy (BNCT) is a high-dose-intensive radiation therapy that has gained popularity due to advancements in accelerator neutron sources. To determine the dose for BNCT, it is necessary to know the difficult-to-determine boron concentration and neutron fluence. To estimate this dose, we propose a method of measuring the prompt γ-rays (PGs) from the boron neutron capture reaction (BNCR) using a Compton camera. We performed a fundamental experiment to verify basic imaging performance and the ability to discern the PGs from 511 keV annihilation γ-rays. A Si/CdTe Compton camera was used to image the BNCR and showed an energy peak of 478 keV PGs, separate from the annihilation γ-ray peak. The Compton camera could visualize the boron target with low neutron intensity and high boron concentration. This study experimentally confirms the ability of Si/CdTe Compton cameras to image BNCRs.

DOI： 10.1038/s41598-023-49955-9

Scopus

Other Link： https://www.nature.com/articles/s41598-023-49955-9

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/nssmicrtsd49126.2023.10338039

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Dosimeters with excellent energy resolution are required to improve quality control and assurance (QA/QC) for heavy-ion cancer therapy, in which multiple species of ions are expected to be used. The conventional ionization chamber that is widely used for QA/QC generally does not support quality discrimination for different radiation species, and several types of energy-dispersive dosimeters are being studied for this application, including silicon semiconductors on insulator devices. Other wide bandgap semiconductors with good radiation hardness, including SiC and diamond, are being studied for use in cancer therapy ion fields. In this study, a 4H-SiC Schottky barrier diode was used for energy-dispersive dosimetry in the clinical carbon therapy field at Gunma University Medical Center for Heavy Ion Beam Medicine. The relative biological effectiveness was estimated from the linear energy transfer spectra for a pristine carbon beam with an energy of 290 MeV/n and a spread-out Bragg peak beam using the linear-quadratic model. The results showed that the SiC-based dosimeter could be used in the detailed characterization of the clinical dose distribution of carbon ion cancer therapy fields.

DOI： 10.1016/j.nimb.2023.06.013

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Real-time physical dose evaluation was performed using radiation-tolerant SiC Schottky barrier diodes (SBDs). The radiation-induced current (RIC) generated in the SBD was measured under clinical carbon beam irradiation. A SiC SBD semiconductor detector (epitaxial layer, 69 µm thick; impurity concentration, 9.1 × 10¹⁴ cm⁻³; electrodes, 1 mm²) was used. The SiC SBD was irradiated with carbon ions having energy of 290 MeV/n at a maximum flux of therapeutic intensity (1 × 10⁹ particles per second) at the Gunma University Heavy Ion Medical Center. The transition of the RIC value at any depth point in the Bragg curve was evaluated by changing the thickness of a water tank placed in front of the SiC SBD. The RIC from the SiC SBD was obtained with an applied voltage of up to 100 V for each moderator thickness. The physical dose distribution was also measured using a commercial ionization chamber. The Bragg peak was determined from the RIC distribution, and the transition was similar to that observed using the commercial ionization chamber.

DOI： 10.1016/j.nimb.2023.04.009

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Anticancer Research USA Inc.  

Background/Aim: This study aimed to develop an improved algorithm for linear energy transfer (LET) estimation in carbon ion radiotherapy (CIRT) using relative biological effectiveness (RBE) and to establish a clinical pipeline for LET assessment. Materials and Methods: New approximation functions for LET versus RBE were developed for the overkill region. LET estimation performance was examined at two facilities (A and B) using archival- and Monte Carlo simulation-derived LET data, respectively, as a reference. A clinical pipeline for LET assessment was developed using Python and treatment planning systems (TPS). Results: In dataset A, LET estimation accuracy in the overkill region was improved by 80.0%. In dataset B, estimation accuracy was 2.3%±0.67% across 5 data points examined. LET distribution and LET-volume histograms were visualized for multiple CIRT plans. Conclusion: The new algorithm showed a greater LET estimation performance at multiple facilities using the same TPS. A clinical pipeline for LET assessment was established.

DOI： 10.21873/anticanres.16468

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

A G2000 glass scintillator (G2000-SC) was used to determine the carbon profile and range of a 290-MeV/n carbon beam used in heavy-ion therapy because it was sensitive enough to detect single-ion hits at hundreds of mega electron Volts. An electron-multiplying charge-coupled device camera was used to detect the ion luminescence generated during the irradiation of G2000-SC with the beam. The resulting image showed that the position of the Bragg peak can be determined. The beam passes through the 112-mm-thick water phantom and stops 5.73 ± 0.03 mm from the incident side to the G2000-SC. Additionally, the location of the Bragg peak was simulated when irradiating G2000-SC with the beam using the Monte Carlo code particle and heavy ion transport system (PHITS). Simulation results show that the incident beam stops at 5.60 mm after entering G2000-SC. The beam stop location obtained from images and the PHITS code is defined at 80% distal fall-off from the Bragg peak position. Consequently, G2000-SC provided effective profile measurements of therapeutic carbon beams.

DOI： 10.1016/j.apradiso.2023.110753

Scopus

PubMed

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cancers  

Carbon-ion radiotherapy (CIRT) is one of the most effective radiotherapeutic modalities. This study aimed to select robust-beam configurations (BC) by water equivalent thickness (WET) analysis in passive CIRT for pancreatic cancer. The study analyzed 110 computed tomography (CT) images and 600 dose distributions of eight patients with pancreatic cancer. The robustness in the beam range was evaluated using both planning and daily CT images, and two robust BCs for the rotating gantry and fixed port were selected. The planned, daily, and accumulated doses were calculated and compared after bone matching (BM) and tumor matching (TM). The dose-volume parameters for the target and organs at risk (OARs) were evaluated. Posterior oblique beams (120-240°) in the supine position and anteroposterior beams (0° and 180°) in the prone position were the most robust to WET changes. The mean CTV V95% reductions with TM were -3.8% and -5.2% with the BC for gantry and the BC for fixed ports, respectively. Despite ensuring robustness, the dose to the OARs increased slightly with WET-based BCs but remained below the dose constraint. The robustness of dose distribution can be improved by BCs that are robust to ΔWET. Robust BC with TM improves the accuracy of passive CIRT for pancreatic cancer.

DOI： 10.3390/cancers15092520

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Non-invasive range measurement of particle beams is important to prevent deviation of the irradiated area in particle therapy. In this study, we made an experiment of imaging carbon-ion beams by setting the projection ranges into an acrylic target from 4.29 cm to 7.65 cm by a pitch of 0.21 cm. Secondary electron bremsstrahlung (SEB) generated on the beam trajectories were detected for the imaging by use of a pinhole camera system consisting of a pinhole collimator and a position-sensitive cadmium-telluride semiconductor detector (CdTe imager). Beam images were acquired, and their profiles along the longitudinal axis were numerically analyzed, to obtain a suitable parameter that was strongly correlated with the set range. Then we could propose a scheme to measure the particle beam range in the target during irradiation by use of the CdTe imager. As a result, the range shift can be measured in the case of the acrylic target with an accuracy of 0.1 cm.

DOI： 10.1088/1748-0221/18/04/c04008

Scopus

Other Link： https://iopscience.iop.org/article/10.1088/1748-0221/18/04/C04008/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

The strong cell killing effect of high linear energy transfer (LET) carbon ions is dependent on lethal DNA damage. Our recent studies suggest that induction of clusters of double-strand breaks (DSBs) in close proximity is one of the potential mechanisms. However, the relationship between LET, the degree of DSB clustering and the cell killing effect of carbon ions remains unclear. Here, we used high-resolution imaging technology to analyze the volume of γH2AX foci induced by monoenergetic carbon ions with a clinically-relevant range of LET (13–100 keV/μm). We obtained data from 3317 γH2AX foci and used a gaussian function to approximate the probability (p) that 1 Gy-carbon ions induce γH2AX foci of a given volume (vth) or greater per nucleus. Cell killing effects were assessed in clonogenic assays. The cell killing effect showed high concordance with p at vth = 0.7 μm3 across various LET values; the difference between the two was 4.7% ± 2.2%. This relationship was also true for clinical carbon ion beams harboring a mixed LET profile throughout a spread-out Bragg peak width (30–120 mm), with the difference at vth = 0.7 μm3 being 1.6% ± 1.2% when a Monte Carlo simulation-derived dose-averaged LET was used to calculate p. These data indicate that the cell killing effect of carbon ions is predictable by the ability of carbon ions to induce γH2AX foci containing clustered DSBs, which is linked to LET, providing the biological basis for LET modulation in the planning of carbon ion radiotherapy.

DOI： 10.1093/jrr/rrac098

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

The purpose of this study is to evaluate the effect of a lead radiation shield on the ability of a beam imaging device consist of an imaging plate (IP) and a collimator by Monte Carlo simulations. Simulations were performed using PHITS. A carbon-ion beam was injected to an acrylic target. A tungsten collimator having a pinhole was placed at the distance of 31.2 cm from the beam. A lead radiation shield was placed on the tungsten collimator. An IP was placed under the collimator. Beam images were acquired by recording the position distribution of energy deposition on the IP. We confirmed that therapeutic carbon-ion beam images could be acquired using the imaging device combining the IP and collimator. It was found that removal of the lead shield had no effect on the imaging results.

DOI： 10.1088/1748-0221/18/01/c01071

Scopus

Other Link： https://iopscience.iop.org/article/10.1088/1748-0221/18/01/C01071/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Real-time monitoring of clinical carbon beams from a synchrotron accelerator was accomplished by using aluminum-enriched phosphate glass with a silver activator. Build-up effects are often observed in commercially available silver-containing phosphate glass that strongly limit the use of the glass in real-time dosimetry in clinical particle therapy fields. In this study, we modified the composition of silver-containing phosphate glass by adding an additional 0.2 mol% aluminum impurity to cause broadband radioluminescence under clinical carbon beam exposure. Convenient real-time radiation monitoring was accomplished on submillimeter scales by using aluminum-enriched silver-containing phosphate glass beads. Optical fiber dosimetry using the aluminum-enriched silver-containing phosphate glass was demonstrated, and stable radioluminescence was visualized for each bunch of 290 MeV u⁻¹ from a synchrotron under different beam fluxes up to 3 × 10⁹ particles/spill (clinical beam conditions).

DOI： 10.35848/1347-4065/aca457

Scopus

Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/aca457/pdf

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

The possibility of real-time monitoring of clinical carbon beams was investigated by analyzing ion beam induced luminescence (IBIL) using phosphate glass (PG) with a dopant of europium (Eu). Phosphate glass with a silver activator (PG: Ag) is known as a substrate for personal dosimeters. Several trials are being made by utilizing PG: Ag as an in-situ diagnostic tool for the clinical radiation therapy field. However, silvers are not actively responding to the radiation during the irradiation because of their build-up effect. In this study, we introduced a co-activator of europium, which is expected to coexist with silvers and have a scintillator property for real-time response. IBIL was successfully visualized with each bunch of 290 MeV/n from synchrotron under different beam intensity from 6.0×10⁶ to 3.0×10⁹ (clinical beam condition) counts/spill. IBIL measurement at each position of Bragg peak suggested that developed PG:Ag-beads with Eu co-activators have successfully demonstrated real-time radiation monitoring of clinical carbon beams.

DOI： 10.1088/1742-6596/2326/1/012012

Scopus

Other Link： https://iopscience.iop.org/article/10.1088/1742-6596/2326/1/012012/pdf

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

A radiation-tolerant silicon carbide (SiC) based dosimeter was developed for the measurement of linear energy transfer (LET) distributions along the Bragg curve for pristine and spread-out Bragg peak (SOBP) clinical carbon beam. Since the conventional ionized chamber is not suitable and effective for LET measurement, several energy-dispersive dosimeters are being developed and tested in the clinical field. While most of the detector lacks radiation hardness against carbon beam, we have utilized wide-bandgap semiconductors of SiC with different epitaxial layers from 25, 69, and 170 μm as a dosimeter for the clinical carbon field at Gunma University Heavy Ion Medical Center (GHMC). LET spectra were obtained not only for pristine carbon beams with an energy of 290 MeV/n but also SOBP conditions. It was confirmed through the changes in LET distribution, primally carbons and fragments are identified, and those energy depositions are successfully obtained by the fabricated SiC dosimeter. The distribution of relative biological effectiveness (RBE) was estimated from LET through biological estimation models. Results suggested that SiC-based dosimeter is successful in being utilized in the detailed characterization of the clinical carbon therapy field.

DOI： 10.1088/1742-6596/2326/1/012015

Scopus

Other Link： https://iopscience.iop.org/article/10.1088/1742-6596/2326/1/012015/pdf

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Sensors  

The history of Compton cameras began with the detection of radiation sources originally for applications in astronomy. A Compton camera is a promising γ-ray detector that operates in the wide energy range of a few tens of keV to MeV. The γ-ray detection method of a Compton camera is based on Compton scattering kinematics, which is used to determine the direction and energy of the γ-rays without using a mechanical collimator. Although the Compton camera was originally designed for astrophysical applications, it was later applied in medical imaging as well. Moreover, its application in environmental radiation measurements is also under study. Although a few review papers regarding Compton cameras have been published, they either focus very specifically on the detectors used in such cameras or the particular applications of Compton cameras. Thus, the aim of this paper is to review the features and types of Compton cameras and introduce their applications, associated imaging algorithms, improvement scopes, and their future aspects.

DOI： 10.3390/s22197374

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

In particle therapy, bioabsorbable polyglycolic acid (PGA) spacer was developed to reduce the healthy organ irradiation dose, especially in the gastrointestinal tract. The PGA spacer is safe and effective; however, there are no reports that have confirmed whether the PGA spacer which inserted in the body actually stops the carbon-ion (C-ion) beams. Here, we visualized and confirmed that the PGA spacer stops the C-ion beams in the body based on the dose distribution using auto-activation positron emission tomography (AAPET). A 59-year-old dedifferentiated retroperitoneal liposarcoma patient underwent C-ion radiotherapy (C-ion RT) on referral. A month before C-ion RT initiation, the patient underwent PGA spacer placement. Postoperatively, the patient received 4.4 Gy (RBE) per fraction of C-ion RT, followed by AAPET. AAPET revealed lower positron emitter concentrations at the distal tissue ventral to the PGA spacer than in the planning target volume. In observing the efficacy of the PGA spacer, the AAPET images and the average count per second of the positron emitter suggested that the PGA spacer stopped the C-ion beams in the body in accordance with the dose distribution. Therefore, AAPET was useful in confirming the PGA spacer’s effectiveness in this study, and the PGA spacer stopped the C-ion beams.

DOI： 10.3390/tomography8050195

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Radioisotope Association  

DOI： 10.3769/radioisotopes.71.109

CiNii Books

CiNii Research

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Purpose: This study aimed to explore the prognostic factors associated with acute radiation dermatitis (ARD). A normal tissue complication probability (NTCP) model for ARD in patients with head and neck cancer treated with carbon ion radiation therapy was developed. Materials and methods: A total of 187 patients were included in the analysis, and the endpoint was ≥grade 2 ARD. The biological and physical dose–surface parameters associated with ARD were used in the logistic regression model. The mean areas under the receiver operating characteristic curve in the internal cross-validation and Akaike's corrected Information Criterion were examined for model evaluation and selection. The multivariate logistic regression NTCP models were established based on factors with weak correlation. Results: Tumor volume, planning target volume to the skin, radiation technique and all dose–surface parameters were significantly associated with ARD (P < .05). Models with high performance for grade 2 to 3 ARD were constructed. The most significant prognostic predictors were S<inf>40</inf> <inf>Gy</inf> <inf>(</inf><inf>relative biological effectiveness</inf><inf>,</inf> <inf>RBE</inf><inf>)</inf> and S<inf>20</inf> <inf>Gy</inf> (absolute surface area receiving RBE-weighted dose of 40 Gy (RBE) or physical dose of 20 Gy). The internal cross-validation–based areas under the receiver operating characteristic curve for models with S<inf>40</inf> <inf>Gy</inf> <inf>(</inf><inf>RBE</inf><inf>)</inf> and S<inf>20</inf> <inf>Gy</inf> were 0.78 and 0.77, respectively. The biological and physical dose–surface parameters had similar performance at various dose levels. However, the performance of the multivariate NTCP models based on 2 factors was not better than that of the univariate models. Conclusions: NTCP models for ARD may provide a basis for the development of individualized treatment strategies and reduce the incidence of severe ARD in patients with head and neck cancer receiving carbon ion radiation therapy. Furthermore, biological and physical dose–surface parameter-based models are comparable. However, further validation with more evaluation parameters is warranted.

DOI： 10.1016/j.ijrobp.2022.03.002

Scopus

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Clinical Medicine  

Image-guided adaptive brachytherapy (IGABT) using intracavitary and interstitial (IC/IS) techniques plays a pivotal role in definitive radiotherapy for locally advanced cervical cancers. However, the training opportunities for interstitial needle application are limited, preventing this technique from becoming widespread. This study aimed to develop a training simulator for IC/IS brachytherapy. The simulator consists of a soft silicone tumor phantom and acrylic tube mimicking the vagina; it has high visibility because of translucent materials and is compatible with computed tomography (CT) and magnetic resonance imaging (MRI). A patient harboring a typical bulky and irregular-shaped cervical tumor was selected from 495 in-house IGABT-treated candidates, and a tumor phantom (68 × 49 × 45 mm) modeled on this patient was produced from three-dimensional real-scale measurements of the MRI-based high-risk clinical target volume at first brachytherapy. In trial use by two physicians with different levels of IGABT skills, a Fletcher-Suit Asian Pacific applicator, and a Venezia applicator with interstitial needles were nicely applied to the simulator, facilitating successful creation of CT-based treatment plans consistent with clinical practice. Thus, the training simulator can be useful for the training of IC/IS brachytherapy, and warrants further research employing a greater number of phantoms and practitioners to verify its educational value.

DOI： 10.3390/jcm11113103

Scopus

PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP Sciences  

Radiological technologists in nuclear medicine departments (NMRTs) are exposed to higher radiation doses than other nuclear medicine staff. Consequently, the Australian Radiation Protection and Nuclear Safety Agency recommends using a 0.5-mm lead equivalence protective apron (PA) for staff with radiation exposure &gt; 800 MBq of ^99mTc. However, 0.5 mm PA is heavy and cumbersome to use. We evaluated the effectiveness of a 0.25 mm lead equivalence lightweight protective apron (L-PA) for NMRT radiation exposure during daily nuclear medicine procedures. The work was performed both with a phantom and in a real situation in our study. The phantom study was conducted with five radioisotopes (RI) placed 0.5 m from the human phantom with and without L-PA. In the clinical study, NMRT recorded the radiation dose for 20 days inside and outside the L-PA using clinical agents (140 examinations). In the phantom study, L-PA decreased the measured doses by 63% with ²⁰¹Tl, 41% with ^99mTc, 27% with ⁶⁷Ga, 33% with ¹²³I, and 10% with ¹³¹I. In the clinical study, L-PA reduced the average dose per day by 43%. Therefore, L-PA could have sufficient shielding ability for daily work, mainly using ^99mTc, and could be recommended by considering PA weight.

DOI： 10.1051/radiopro/2022006

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese  

Language：Japanese  

J-GLOBAL

Event date： 2024.12

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Event date： 2023.11 - 2023.12

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Event date： 2022.11 - 2022.12

Language：English   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Event date： 2022.11

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Language：Japanese   Presentation type：Oral presentation (general)  

Language：Japanese  

Language：English   Publisher：(一社)日本放射線影響学会  

Language：Japanese   Publisher：(一社)日本医用画像工学会  

宇宙物理や高エネルギー物理の分野で長い歴史をもつコンプトンカメラの技術を医療応用できれば,新たな核医学診断法を開拓できるかもしれない.一方で,ヒト撮像においてPETと同程度の解像度を実現するには,装置性能の向上が必要不可欠である.SPECTやPETは確立された性能評価技術を活用して装置開発が進められているが,コンプトンカメラは放射線の検出方式や検出器配置がさまざまであり,標準的な性能評価技術が存在しない.標準評価法があればさまざまなコンプトンカメラの検出器性能とイメージング性能を明らかにでき,装置性能の直接比較だけでなく,臨床機に要求される検出器性能の導出,有望な検出器の選定にも活用できると考えられる.そこで,量子科学技術研究開発機構が主体となって分野横断的な研究グループを組織し,医用コンプトンカメラを同一条件で性能比較できる標準評価法の開発に取り組んでいる.本稿では,この取り組みについて概説する.(著者抄録)

J-GLOBAL

J-GLOBAL

J-GLOBAL

J-GLOBAL

J-GLOBAL

Language：Japanese   Publisher：(公社)応用物理学会放射線分科会  

J-GLOBAL

J-GLOBAL

J-GLOBAL

Language：Japanese   Publisher：公益社団法人 日本アイソトープ協会  

DOI： 10.50955/happyokai.2.0_95

CiNii Research

J-GLOBAL