Electron and proton FLASH beam dosimetry using unified alanine, EBT-XD, and HD-V2 Gafchromic film dosimeters

IF 3.2 2区医学 Q1 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING

Medical physics Pub Date : 2025-09-25 DOI:10.1002/mp.70022

Seongmoon Jung, In Jung Kim, Chul-Young Yi, Yun Ho Kim, Young Min Seong, Rukundo Solomon, Sang Hyoun Choi, Young-jae Jang, Se Byeong Lee, Chae-Eon Kim, Sang-il Pak, Jong In Park

{"title":"Electron and proton FLASH beam dosimetry using unified alanine, EBT-XD, and HD-V2 Gafchromic film dosimeters","authors":"Seongmoon Jung, In Jung Kim, Chul-Young Yi, Yun Ho Kim, Young Min Seong, Rukundo Solomon, Sang Hyoun Choi, Young-jae Jang, Se Byeong Lee, Chae-Eon Kim, Sang-il Pak, Jong In Park","doi":"10.1002/mp.70022","DOIUrl":null,"url":null,"abstract":"<div>\n \n \n <section>\n \n <h3> Background</h3>\n \n <p>Ultra-high dose rate (UHDR) radiotherapy, or FLASH RT, has shown potential to spare normal tissues while maintaining tumor control. However, accurate dosimetry at UHDR remains challenging, as conventional ionization chambers suffer from recombination effects. Although radiochromic films and alanine dosimeters have both been investigated independently for FLASH dosimetry, their separate use hinders robust validation and direct comparison of their measurements.</p>\n </section>\n \n <section>\n \n <h3> Purpose</h3>\n \n <p>This study aims to develop and evaluate a unified dosimeter containing both alanine and radiochromic film for electron and proton FLASH beam dosimetry. The design allows for simultaneous, co-located irradiation of both dosimeter types, enabling a direct comparison between them. This configuration eliminates confounding factors such as positional offsets, alignment errors, and beam fluctuations, thereby facilitating the validation of measurements and enhancing confidence in FLASH dosimetry.</p>\n </section>\n \n <section>\n \n <h3> Methods</h3>\n \n <p>The unified alanine and EBT-XD/HD-V2 film dosimeter was designed with the same outer dimensions as the Advanced Markus chamber (PTW-Freiburg), allowing compatibility with commercial QA phantoms. Alanine and film dosimeters were calibrated under conventional electron and proton beams, traceable to absorbed dose to water from Co-60 gamma rays. The unified dosimeter was used to measure dose from a 9 MeV electron FLASH beam (Varian Clinac iX) and a 230 MeV proton FLASH beam (IBA machine), with alanine and film irradiated simultaneously at the same location.</p>\n </section>\n \n <section>\n \n <h3> Results</h3>\n \n <p>The alanine dosimeter measured the dose per pulse, instantaneous dose rate, and mean dose rate at a source-to-surface distance of 100 cm for the electron FLASH beam as 0.99 <span></span><math>\n <semantics>\n <mo>±</mo>\n <annotation>$ \\pm $</annotation>\n </semantics></math> 0.02 Gy/pulse, 2.48 <span></span><math>\n <semantics>\n <mo>×</mo>\n <annotation>$ \\times $</annotation>\n </semantics></math> 10<sup>5</sup> Gy/s, and 357 Gy/s, respectively. The EBT-XD film showed good agreement (within a 2.0% relative difference) in the 10–30-Gy range, whereas the HD-V2 indicated a larger difference (up to 5.9%) compared to the alanine dosimeter. The mean dose rate for the proton FLASH beam, measured by the alanine dosimeter, was 115.4<span></span><math>\n <semantics>\n <mrow>\n <mspace></mspace>\n <mo>±</mo>\n </mrow>\n <annotation>$\\; \\pm $</annotation>\n </semantics></math> 1.1 Gy/s. The EBT-XD showed a 4.3% relative difference with the alanine dosimeter in the 10–30-Gy range.</p>\n </section>\n \n <section>\n \n <h3> Conclusions</h3>\n \n <p>The unified alanine and film dosimeters enabled simultaneous irradiation of the alanine and the films, with combined relative standard uncertainties of 2.4% (<i>k</i> = 1) for the alanine dosimeter and 3.5% (<i>k</i> = 1) for the EBT-XD films at the electron FLASH beam. For the proton FLASH beam, these uncertainties were 3.2% (<i>k</i> = 1) for both the alanine dosimeter and the EBT-XD films. Until dosimetry guidelines for the FLASH RT community are established by a working group such as AAPM TG-359, the dosimetry protocol proposed in this study can serve as a promising approach for FLASH RT facilities worldwide.</p>\n </section>\n </div>","PeriodicalId":18384,"journal":{"name":"Medical physics","volume":"52 10","pages":""},"PeriodicalIF":3.2000,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://aapm.onlinelibrary.wiley.com/doi/epdf/10.1002/mp.70022","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Medical physics","FirstCategoryId":"3","ListUrlMain":"https://aapm.onlinelibrary.wiley.com/doi/10.1002/mp.70022","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}

引用次数: 0

Abstract

Background

Ultra-high dose rate (UHDR) radiotherapy, or FLASH RT, has shown potential to spare normal tissues while maintaining tumor control. However, accurate dosimetry at UHDR remains challenging, as conventional ionization chambers suffer from recombination effects. Although radiochromic films and alanine dosimeters have both been investigated independently for FLASH dosimetry, their separate use hinders robust validation and direct comparison of their measurements.

Purpose

This study aims to develop and evaluate a unified dosimeter containing both alanine and radiochromic film for electron and proton FLASH beam dosimetry. The design allows for simultaneous, co-located irradiation of both dosimeter types, enabling a direct comparison between them. This configuration eliminates confounding factors such as positional offsets, alignment errors, and beam fluctuations, thereby facilitating the validation of measurements and enhancing confidence in FLASH dosimetry.

Methods

The unified alanine and EBT-XD/HD-V2 film dosimeter was designed with the same outer dimensions as the Advanced Markus chamber (PTW-Freiburg), allowing compatibility with commercial QA phantoms. Alanine and film dosimeters were calibrated under conventional electron and proton beams, traceable to absorbed dose to water from Co-60 gamma rays. The unified dosimeter was used to measure dose from a 9 MeV electron FLASH beam (Varian Clinac iX) and a 230 MeV proton FLASH beam (IBA machine), with alanine and film irradiated simultaneously at the same location.

Results

The alanine dosimeter measured the dose per pulse, instantaneous dose rate, and mean dose rate at a source-to-surface distance of 100 cm for the electron FLASH beam as 0.99 $\pm$ 0.02 Gy/pulse, 2.48 $\times$ 10⁵ Gy/s, and 357 Gy/s, respectively. The EBT-XD film showed good agreement (within a 2.0% relative difference) in the 10–30-Gy range, whereas the HD-V2 indicated a larger difference (up to 5.9%) compared to the alanine dosimeter. The mean dose rate for the proton FLASH beam, measured by the alanine dosimeter, was 115.4 $\pm$ 1.1 Gy/s. The EBT-XD showed a 4.3% relative difference with the alanine dosimeter in the 10–30-Gy range.

Conclusions

The unified alanine and film dosimeters enabled simultaneous irradiation of the alanine and the films, with combined relative standard uncertainties of 2.4% (k = 1) for the alanine dosimeter and 3.5% (k = 1) for the EBT-XD films at the electron FLASH beam. For the proton FLASH beam, these uncertainties were 3.2% (k = 1) for both the alanine dosimeter and the EBT-XD films. Until dosimetry guidelines for the FLASH RT community are established by a working group such as AAPM TG-359, the dosimetry protocol proposed in this study can serve as a promising approach for FLASH RT facilities worldwide.

Abstract Image

查看原文本刊更多论文

使用统一的丙氨酸、EBT-XD和HD-V2荧光膜剂量计进行电子和质子闪光束剂量测定

超高剂量率放疗（UHDR）或FLASH RT已显示出在维持肿瘤控制的同时保留正常组织的潜力。然而，由于传统的电离室受到重组效应的影响，UHDR的精确剂量测定仍然具有挑战性。虽然放射性致色膜和丙氨酸剂量计都被独立研究用于FLASH剂量测定，但它们的单独使用阻碍了其测量结果的可靠验证和直接比较。目的研制一种含丙氨酸和放射致变色膜的统一剂量计，用于电子和质子闪光束剂量测定。该设计允许两种剂量计类型同时在同一地点进行照射，从而可以对它们进行直接比较。这种配置消除了位置偏移、对准误差和光束波动等混杂因素，从而促进了测量结果的验证，增强了FLASH剂量测定的可信度。方法设计统一的丙氨酸和EBT-XD/HD-V2膜剂量计，其外尺寸与先进Markus腔（PTW-Freiburg）相同，可与商用QA模兼容。丙氨酸和膜剂量计在传统的电子和质子束下校准，可追溯到Co-60伽马射线对水的吸收剂量。采用统一剂量计测量了9 MeV电子闪射束（Varian Clinac iX）和230 MeV质子闪射束（IBA机）在同一位置同时辐照丙氨酸和膜的剂量。结果丙氨酸剂量计测得电子闪光束的每脉冲剂量、瞬时剂量率和源-表面距离100 cm处的平均剂量率分别为0.99±$ \pm $ 0.02 Gy/脉冲、2.48 × $ \ × $ 105 Gy/s和357 Gy/s。EBT-XD薄膜在10-30-Gy范围内显示出良好的一致性（在2.0%的相对差异内），而HD-V2与丙氨酸剂量计相比显示出更大的差异（高达5.9%）。丙氨酸剂量计测得质子闪光束的平均剂量率为115.4±$\；\pm $ 1.1 Gy/s在10 - 30 gy范围内，EBT-XD与丙氨酸剂量计的相对差异为4.3%。结论采用统一的丙氨酸和膜剂量计，可以同时辐照丙氨酸和膜，在电子闪光束下，丙氨酸剂量计的相对标准不确定度为2.4% (k = 1)， EBT-XD膜的相对标准不确定度为3.5% （k = 1）。对于质子闪光束，丙氨酸剂量计和EBT-XD薄膜的不确定度均为3.2% （k = 1）。在AAPM TG-359等工作组为FLASH RT社区制定剂量学指南之前，本研究提出的剂量学方案可以作为全球FLASH RT设施的一种有前途的方法。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Medical physics 医学-核医学

CiteScore

6.80

自引率

15.80%

发文量

660

审稿时长

1.7 months

期刊介绍： Medical Physics publishes original, high impact physics, imaging science, and engineering research that advances patient diagnosis and therapy through contributions in 1) Basic science developments with high potential for clinical translation 2) Clinical applications of cutting edge engineering and physics innovations 3) Broadly applicable and innovative clinical physics developments Medical Physics is a journal of global scope and reach. By publishing in Medical Physics your research will reach an international, multidisciplinary audience including practicing medical physicists as well as physics- and engineering based translational scientists. We work closely with authors of promising articles to improve their quality.