Biological effect of dose distortion by fiducial markers in spot-scanning proton therapy with a limited number of fields:A simulation study

有限视场点扫描质子治疗中基准标记剂量畸变的生物学效应：模拟研究

• 批准号: 23791379
• 负责人: MATSUURA Taeko
• 金额: $ 2.66万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Young Scientists (B)
• 财政年份: 2011
• 资助国家: 日本
• 起止时间: 2011 至 2012
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-23791379/
• 关键词: 陽子線治療; スポットスキャニング照射法; 動体追跡; IGRT

In accurate proton spot-scanning therapy, continuous target tracking by fluoroscopic x ray during irradiation is beneficial not only for respiratory moving tumors of lung and liver but also for relatively stationary tumors of prostate. Implanted gold markers have been used with great effect for positioning the target volume by a fluoroscopy. However, recent studies have revealed that gold markers can cause a significant underdose in proton therapy. This research focuses on prostate cancer and explores the possibility that multiple-field irradiation improves the underdose effect by markers on tumor-control probability (TCP) by using a Monte Carlo simulation. It was found that the marker of 1.5 mm diameter does not affect the TCPs when two or more fields are used. On the other hand, if the marker diameter is 2 mm, more than two irradiation fields are required to suppress the decrease in TCP by less than 3%. It is recommended that 1.5-mm markers be used to avoid the reduction of TCP as well as to spare the surrounding critical organs, as long as the markers are visible on x-ray fluoroscopy. When 2-mm markers are implanted, more than two fields should be used and the markers should not be placed close to the distal edge of any of the beams.

在精确的质子点扫描治疗中，透视x线在照射过程中持续的靶标跟踪不仅有利于肺、肝等呼吸运动肿瘤，也有利于相对静止的前列腺肿瘤。植入金标记物用于透视定位靶体积，效果显著。然而，最近的研究表明，在质子治疗中，金标记物可能导致明显的剂量不足。本研究以前列腺癌为研究对象，通过蒙特卡罗模拟探讨了多场照射改善标记物对肿瘤控制概率（TCP）的剂量不足效应的可能性。当使用两个或多个字段时，发现1.5 mm直径的标记不会影响tcp。另一方面，如果标记物直径为2mm，则需要两个以上的辐照场才能抑制TCP的下降小于3%。建议使用1.5 mm标记物，以避免TCP的减少，并保留周围的关键器官，只要标记物在x线透视下可见。当植入2mm标记时，应使用两个以上的场，并且标记不应靠近任何梁的远端边缘。

项目成果

A study on a gated proton spot-scanning beam therapy integrated with a real-time tumor-monitoring: an initial phantom study using patient tumor trajectory data

门控质子点扫描束治疗与实时肿瘤监测相结合的研究：使用患者肿瘤轨迹数据的初始模型研究

• 发表时间: 2013
• 作者: Matsumoto S.;Batra S.;Saito K.;YasuiH.;Choudhuri R.;Gadisetti C.,Subramanian S.;Devasahayam N.;Munasinghe J.P.;Mitchell J.B.;and Krishna M.C.;T. Matsuura et al.
• 通讯作者: T. Matsuura et al.

Biological Effect of Dose Shadowing by Fiducial Markers in Spot Scanning Proton Therapy with a Limited Number of Fields

有限视场数点扫描质子治疗中基准标记剂量遮蔽的生物学效应

• 发表时间: 2012
• 作者: Matsumoto S.;Batra S.;Saito K.;YasuiH.;Choudhuri R.;Gadisetti C.,Subramanian S.;Devasahayam N.;Munasinghe J.P.;Mitchell J.B.;and Krishna M.C.;T. Matsuura et al.;T. Matsuura et al.
• 通讯作者: T. Matsuura et al.