Precision Radiation Oncology最新文献

{"title":"Comparing simultaneous integrated boost whole-brain radiotherapy and local irradiation for brain metastases in lung cancer: A retrospective analysis.","authors":"Qian Bi, Jing Shen, Xin Lian, Wentai Zhang, Fuquan Zhang","doi":"10.1002/pro6.70035","DOIUrl":"10.1002/pro6.70035","url":null,"abstract":"<p><strong>Background: </strong>This study aimed to evaluate the differences between simultaneous integrated boost whole-brain radiotherapy (SIB-WBRT) and brain metastases local irradiation efficacy, and determine predictors of outcomes for lung cancer brain metastases patients in therapy.</p><p><strong>Methods: </strong>This retrospective analysis evaluated patients with brain metastases treated with SIB-WBRT (whole brain at 40 Gy/20 fractions, tumor boosted to 56-60 Gy/20 fractions) and localized irradiation (prescribed doses ranging from 20-60 Gy over 2-25 fractions, typically administered as 30 Gy/5 fractions, with a biologically effective dose [BED] of 28-100.8 Gy) at PUMCH between September 2015 and December 2021. The primary outcome was intracranial progression-free survival (iPFS), with secondary outcomes encompassing overall survival (OS), development of new intracranial lesions, and tumor control. Propensity score matching was employed to compare the two retrospective groups. Survival curves for iPFS, OS, new intracranial lesions, and tumor control were generated and estimated using the Kaplan-Meier approach. Cox proportional hazards modeling was applied to examine the relationships between pertinent variables and clinical outcomes.</p><p><strong>Results: </strong>After Propensity score matching, 59 patients were enrolled in each group (SIB-WBRT and local irradiation), with a total of 118 patients included in the analysis. No significant difference was observed between the 2 groups in iPFS (HR = 0.8, 95%CI: 0.4-1.3, <i>P</i> = 0.288), OS (HR = 1.1, 95%CI: 0.7-1.8, <i>P</i> = 0.653), or incidence of intracranial new lesions (HR = 0.6, 95%CI: 0.4-1.2, <i>P</i> = 0.144). However, a statistically significant difference was noted in local control time between the groups, with local irradiation brain metastases being superior (HR = 0.4, 95% CI: 0.2-0.8, <i>P</i> = 0.005). Tumor volume and other factors were related to local control.</p><p><strong>Conclusion: </strong>Compared to local irradiation, SIB-WBRT did not significantly improve iPFS in patients with brain metastases. Compared to SIB-WBRT, local irradiation improved local control. Tumor volume and other factors may be associated with local control.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"266-273"},"PeriodicalIF":3.6,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750304/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated quality assurance of HDR brachytherapy: Evaluation of Dwell-position accuracy and Dwell-time linearity via image processing of radiochromic films.","authors":"Qingqing Yuan, Suyan Bi, En Lou, YaJun Jia, Zhitao Dai","doi":"10.1002/pro6.70040","DOIUrl":"10.1002/pro6.70040","url":null,"abstract":"<p><strong>Purpose: </strong>To develop and validate a fully automated quality assurance method for high-dose rate (HDR) brachytherapy, enabling the precise evaluation of source dwell-position accuracy and dwell-time linearity using radiochromic film analysis and advanced image processing algorithms.</p><p><strong>Methods: </strong>A novel analytical framework was established to verify HDR source positional precision and dwell-time linearity. Radiochromic films were irradiated under predefined treatment plans. Image preprocessing involved grayscale conversion, median filtering, rotation correction, and absolute coordinate calibration. The centroid of each dwell position was determined using two-dimensional Gaussian fitting. Temporal linearity analysis employed radial grayscale summation within the radii of 250-400 pixels. Linearity was quantified using the coefficient of determination (R²), with R² approaching 1 indicating optimal performance.</p><p><strong>Results: </strong>Automated Gaussian fitting achieved sub-millimeter positional accuracy (maximum error ≤ 0.6 mm), eliminating manual intervention. Rotation correction algorithms effectively mitigated positional errors caused by film misalignment. Comparative analysis with commercial software yielded nearly identical results, validating the reliability of the method. Dwell-time analysis demonstrated excellent linearity (<i>R²≥</i>0.999) over summation radii ranging from 150 to 400 dpi.</p><p><strong>Conclusions: </strong>This study presents a robust and fully automated quality assurance (QA) solution for HDR brachytherapy that simultaneously verifies sub-millimeter-level dwell-position accuracy and temporal linearity. The integration of radiochromic film dosimetry with algorithmic image processing eliminates manual intervention and standardizes QA workflows, representing a substantial advancement in treatment safety and efficiency.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"10 2","pages":"137-146"},"PeriodicalIF":3.6,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13292168/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148333227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemoradioimmunotherapy versus chemoimmunotherapy or chemoradiotherapy in extensive-stage small-cell lung cancer: A retrospective analysis of survival outcomes.","authors":"Jinmin Han, Ying Hua, Xue Wu, Xiufeng Tang, Chengxin Liu","doi":"10.1002/pro6.70043","DOIUrl":"10.1002/pro6.70043","url":null,"abstract":"<p><strong>Background and purpose: </strong>Current evidence is insufficient to define the value of thoracic radiotherapy (TRT) following chemoimmunotherapy (CT-IO) in extensive-stage small-cell lung cancer (ES-SCLC). We aimed to ascertain whether incorporating immunotherapy (IO) could improve survival and explore the efficacy of TRT in combination with CT-IO among patients with ES-SCLC.</p><p><strong>Methods: </strong>Clinical data were retrospectively analyzed. Patients were classified into two groups: IO and chemoradiotherapy (CRT). Within the IO group, we further defined two subgroups: CT-IO and chemoradioimmunotherapy (CRT-IO) groups.</p><p><strong>Results: </strong>A total of 206 patients were enrolled in this study. The median overall survival was 22.2 months in the CRT-IO group, which was longer than the 16.0 months observed in the CT-IO group (<i>P</i> = 0.002) and 19.0 months noted in the CRT group (<i>P</i> = 0.208). The objective response rate (ORR) in the CRT-IO group (69.8%) was better than that in the CT-IO (68.9 %, <i>P</i> = 0.929) and CRT (59.3 %, <i>P</i> = 0.227) groups.</p><p><strong>Conclusions: </strong>Considering the trend toward prolonged survival and a higher ORR in the CRT-IO group, TRT may be feasible in IO era. Considering the economic factors and physical conditions, CRT may be an option for patients with ES-SCLC.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"295-303"},"PeriodicalIF":3.6,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750307/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the trade-off between plan complexity, dosimetric accuracy, and treatment efficiency: Role of aperture shape controller settings in HyperArc for intracranial oligometastases.","authors":"Huipeng Meng, Yanlong Zhang, Xinrui Wang, Pengfei Liu, Weihua Zhu, Shixiong Huang, Yining Yang","doi":"10.1002/pro6.70034","DOIUrl":"10.1002/pro6.70034","url":null,"abstract":"<p><strong>Purpose: </strong>To evaluate the impact of different aperture shape controller (ASC) stratification strategies on the dosimetric quality and treatment efficiency of HyperArc plans for intracranial oligometastases.</p><p><strong>Methods: </strong>This retrospective study analyzed 17 patients with 1-3 intracranial oligometastases. For each patient, the HyperArc plans were reoptimized using six ASC strength settings (off, very low, low, moderate, high, and very high). Evaluations encompassed planning target volume (PTV) and organ at risk (OAR) dosimetric parameters (Paddick Conformity Index [Paddick CI], Gradient Index [GI], D_2cm, OAR D_max/D_mean, Gamma passing rate), and treatment efficiency parameters (monitor units [MUs], segment number [SN], Modulation Complexity Score [MCS], Average Leaf Trajectory [ALT], and aperture irregularity [AI]).</p><p><strong>Results: </strong>No statistically significant differences were observed in the PTV and OAR dosimetric parameters or gamma passing rates among the ASC strategy groups (<i>p</i> > 0.05), indicating a minimal impact of the ASC on plan dosimetric quality. In addition, SN, MCS, and ALT demonstrated no significant intergroup differences (<i>p</i> > 0.05). However, AI improved with moderate and high ASC strength. Critically, the total MUs differed significantly among the groups (<i>F</i> = 2.904, <i>p</i> < 0.05), with high ASC strength causing significantly lower MUs than ASC-off (<i>p</i> < 0.05), suggesting enhanced treatment efficiency.</p><p><strong>Conclusions: </strong>ASC stratification strategies do not significantly compromise plan dosimetric quality in HyperArc treatment for intracranial oligometastases; however, these can markedly optimize treatment efficiency, particularly by reducing MUs. Considering both plan complexity and treatment efficiency, a moderate or high ASC strength is recommended to maintain high-quality radiotherapy while improving workflow efficiency.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"284-294"},"PeriodicalIF":3.6,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750308/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Intra-fractional respiratory motion on dose distribution in lattice radiotherapy for liver tumors.","authors":"Kuo Li, Yong Yin, Tonghai Liu, Tianyuan Dai, Jian Zhu, Zhenjiang Li","doi":"10.1002/pro6.70044","DOIUrl":"10.1002/pro6.70044","url":null,"abstract":"<p><strong>Purpose: </strong>To quantify the detrimental impact of respiratory motion on the critical \"peak-and-valley\" dose distribution in lattice radiotherapy (LRT) for liver tumors, to thereby evaluate the necessity of motion management.</p><p><strong>Methods: </strong>This study assessed the data of 24 patients with liver cancer who underwent free-breathing 4D-CT simulation, for which a 2×2×2 vertices LRT tree was constructed. Volumetric Modulated Arc Therapy (VMAT) plans were generated based on the results of free-breathing CT. The delivered dose distribution under respiratory motion was then simulated by dividing the planned dose into 10 equal subcomponents, applying phase-specific isocenter shifts derived from 4D-CT displacement measurements, and summing the deformed doses. The metrics analyzed included the vertex dose deviation, valley-to-peak dose ratio (VPDR), and low-dose bath volumes.</p><p><strong>Results: </strong>The analysis revealed a mean 3D respiratory motion error of 8.59 mm, with predominant displacement in the superior-inferior (SI) direction (6.78±3.15 mm). Respiratory motion significantly degraded the LRT dose distributions; specifically, the vertices mean dose (D_mean) decreased from 50.19 Gy to 42.26 Gy, while the maximum dose (D_max) from 58.94 Gy to 52.63 Gy. Crucially, the VPDR increased in all directions, with the most pronounced increase observed in the SI direction (0.14±0.04 to 0.18±0.06, representing a 28.6% increase), escalating exponentially when motion error exceeded 8 mm. Increases in the left-right (LR) (0.41 to 0.44, increasing 7.3%) and antero-posterior (AP) (0.41 to 0.45, increasing 9.8%) directions were comparatively smaller. The motion also paradoxically altered the low-dose regions; while the absolute V_40%, V_20%, and V_10% volumes decreased by approximately 10 cm³ in the delivered plan, normalization to match the prescription coverage revealed significant increases in these volumes (minimum increases: V_40% by 3.59 cm³, V_20% by 15.85 cm³ and V_10% by 92.29 cm³).</p><p><strong>Conclusion: </strong>Respiratory motion severely degrades essential spatial fractionation during liver LRT, particularly when exceeding 8 mm and occurring predominantly in the SI direction. This motion reduces peak vertex doses, increases the VPDR (homogenizing the dose distribution), and disrupts the low-dose bath volumes critical for normal tissue sparing and the bystander effect.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"274-283"},"PeriodicalIF":3.6,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750313/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficacy and safety evaluation of radiotherapy approach based on spatially fractionated radiotherapy and stereotactic core ablative radiation therapy technologies for bone metastatic malignant tumors with soft tissue formation: A randomized controlled phase II trial.","authors":"Yuxiang Kou, Ke Xu, Kunli Zhu, Shumei Jiang, Rui Feng, Xue Dou, Lei Xu, Xiang Zhang, Fang Shi, Xijun Liu, Zhe Gong, Jinbo Yue","doi":"10.1002/pro6.70036","DOIUrl":"10.1002/pro6.70036","url":null,"abstract":"<p><strong>Objective: </strong>Spatially fractionated radiation therapy (SFRT) and stereotactic core ablative radiation therapy (SCART), two novel radiotherapy techniques, have demonstrated distinct advantages in the treatment of large-volume tumors. Both approaches allow precise delivery of high-dose radiation to the tumor core while sparing surrounding organs at risk. The objective of this study is to evaluate the efficacy and safety of these two techniques for the treatment of bone metastases accompanied by soft tissue formation.</p><p><strong>Method: </strong>Patients with bone metastases accompanied by soft tissue formation will be recruited and assigned to the control or experimental groups. The control group will receive conventional radiotherapy (CRT) with 30 Gy delivered in 10 fractions, while the experimental group will undergo tumor core irradiation using SFRT or SCART with a single dose of 8-12 Gy, followed by whole-bone metastatic lesion radiotherapy with 25-40 Gy delivered in 5 fractions. The primary endpoint is the objective response rate, and secondary endpoints include the pain relief, safety, and local control rates.</p><p><strong>Discussion: </strong>This study evaluates the efficacy and tolerability of using SFRT/SCART for treating bone metastases with soft tissue formation, with the expectation of improving local tumor control and reducing treatment-related toxicities.</p><p><strong>Trial registration: </strong>The study was registered at ClinicalTrials.gov with the Identifier: NCT06987370 (Registered May 16, 2025).</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"260-265"},"PeriodicalIF":3.6,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750312/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial: 2^nd collection of special issue in innovations, advances, and challenges in precision radiation oncology physics.","authors":"Fada Guan, Sabrina Campelo, Zhuoran Jiang, Lawrence Bronk","doi":"10.1002/pro6.70039","DOIUrl":"10.1002/pro6.70039","url":null,"abstract":"","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"232-233"},"PeriodicalIF":2.1,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750305/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tomotherapy for sinonasal teratocarcinosarcoma with SMARCA4 deletion and CTNNB1 mutation: A case report and literature review.","authors":"Siyu Xie, Chenyu Ren, Lei Yang, Fanglei Duan, Yang Liu, Yue Zhao, Peng Xu, Shun Lu, Jie Zhou","doi":"10.1002/pro6.70038","DOIUrl":"10.1002/pro6.70038","url":null,"abstract":"<p><p>Sinonasal teratocarcinosarcoma (SNTCS) is a rare and aggressive malignant tumor that is difficult to diagnose and lacks a standard therapeutic strategies. Here, we report a case of SNTCS harboring a <i>SMARCA4</i> deletion and a <i>CTNNB1</i> mutation. Following incomplete surgical resection, the patient received synchronous postoperative chemotherapy with tomotherapy (TOMO) radiation and achieved a complete response lasting for > 47 months with tolerated side effects. This case suggests that <i>SMARCA4</i> deletion and <i>CTNNB1</i> mutation may be key molecular events in the development of SNTCS, potentially providing valuable clues for its diagnosis. Moreover, to the best of our knowledge, this is the first case demonstrating that TOMO technology can be a beneficial option for SNTCS radiotherapy.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"314-318"},"PeriodicalIF":3.6,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750310/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a real-time multi-scenario monitoring method for respiratory motion based on capacitive sensors.","authors":"Yongqiang Wang, Bing Li, Xuhua Xiao, Zhaoyang Lou, Kangdong Liu, Hong Ge","doi":"10.1002/pro6.70037","DOIUrl":"10.1002/pro6.70037","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to improve the accuracy of the tumor radiotherapy dose and reduce the irradiation dose to the surrounding organs, by developing a versatile respiratory motion monitoring system with multi-scenario applications to enhance the clinical efficacy of radiotherapy for thoracic and abdominal tumors.</p><p><strong>Methods: </strong>The respiratory motion monitoring system comprised an airbag structure integrated with a parallel-plate capacitive sensor. The airbag comprised a polymer balloon encapsulated in a nonelastic flexible membrane, and had a projected area of 120 mm × 120 mm. The capacitive sensor adopts a concentric configuration of beryllium copper (thickness: 0.1 mm, diameter: 10 mm) and oxygen-free copper (thickness: 1 mm, diameter: 10 mm) foils. Real-time monitoring of the respiratory motion was achieved by detecting the capacitance variations corresponding to changes in the internal air pressure within the airbag. The system performance was rigorously evaluated using a dynamic thorax phantom capable of simulating various patterns, including sinusoidal and fourth-power cosine waveforms.</p><p><strong>Results: </strong>The capacitive sensor-based respiratory motion monitoring system demonstrated a displacement measurement range of up to 10 mm, capable of detecting movements as small as 0.1 mm (signal-to-noise ratio: 2.18). Real-time displacement conversion was performed using the fitted model <i>y</i> = a<i>x</i>+b<i>x</i> ³ (a = 26.105 ± 0.398, b = 285.868 ± 22.147). The system exhibited a high stability, with a standard deviation of only 0.0011 in capacitance measurements over 10 repeated tests with a 5 mm amplitude sinusoidal waveform, and further maintained the amplitude consistency within 2.25%-96.05% of the maximum value throughout 10 min of continuous operation. A reliable performance was confirmed across various respiratory waveforms, including sinusoidal and fourth-power cosine profiles. Furthermore, the non-metallic airbag structure enhances the adaptability to multiple clinical scenarios. However, two types of signal distortions were observed, originating from the airbag deformation and the limitations of the capacitive sensor electrode, both of which are thoroughly explained in the manuscript.</p><p><strong>Conclusion: </strong>Overall, this study developed a capacitive sensor and airbag-based respiratory monitoring system that combines the advantages of abdominal pressure belts with infrared-based monitoring technologies. This integrated approach offers a cost-effective, structurally simple, and versatile solution for monitoring respiratory motion across multiple clinical scenarios.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"251-259"},"PeriodicalIF":3.6,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750315/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental design and control methods for dose rate optimization in a synchrotron-based proton therapy beamline.","authors":"Jason Tang, Daniel Liu, Jacob Mathew, Sabrina Campelo, Lawrence Bronk, Paige Taylor, Yuting Li, Fada Guan","doi":"10.1002/pro6.70032","DOIUrl":"10.1002/pro6.70032","url":null,"abstract":"<p><strong>Background: </strong>Ultra-high dose rate radiotherapy (typically defined >40 Gy/s) has shown promise for enhanced normal tissue sparing while maintaining tumor control, termed the FLASH effect when this biological response is observed. However, precise dose rate control remains a technical challenge in proton therapy systems, particularly for research applications investigating dose rate effects.</p><p><strong>Purpose: </strong>To develop and validate a passive beam modulation technique using tungsten scatterers for controllable dose rate adjustment in a synchrotron-based proton therapy beamline without modifying accelerator parameters.</p><p><strong>Methods: </strong>We investigated dose rate modulation using tungsten foils of varying thicknesses (0.1-3.5 mm) positioned upstream in an 87.2 MeV experimental proton beamline. Monte Carlo simulations using Geant4 were performed to model the dose rate variation as a function of the tungsten scatter's thickness. Experimental validation was conducted using an Advanced Markus ionization chamber for dose rate measurements and EBT-XD radiochromic films for lateral dose profile analysis. Five tungsten thicknesses were tested with full-spill deliveries (∼1400 monitor units (MUs), and ∼100 milliseconds (ms) pulse width).</p><p><strong>Results: </strong>An inverse exponential relationship between dose rate and scatterer thickness was observed, with measured dose rates ranging from 288.9±0.7 Gy/s (0.1 mm tungsten) to 10.2±0.2 Gy/s (3.5 mm tungsten). Experimental measurements validated the accuracy of Monte Carlo predictions at the standard condition (1400 MU delivered in 100 ms) by falling within the 95% confidence intervals. Lateral beam profiles demonstrated progressive broadening with increased scatterer thickness, and the film measurements showed good agreements with Monte Carlo simulation (<2% difference at beam center).</p><p><strong>Conclusions: </strong>Tungsten scatterer thickness modulation provides a practical, controllable method for dose rate adjustment spanning conventional to FLASH regimes. This passive approach enables precise dose rate control for preclinical radiobiological research without requiring modifications of accelerator structure and parameters.</p>","PeriodicalId":32406,"journal":{"name":"Precision Radiation Oncology","volume":"9 4","pages":"234-241"},"PeriodicalIF":3.6,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12750309/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145879073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}