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Development of intensity modulated radiation therapy (IMRT) based on radiobiology

基于放射生物学的调强放射治疗（IMRT）的发展

基本信息

批准号：
14570887
负责人：
NISHIMURA Yasumasa
金额：
$ 2.18万
依托单位：
Kinki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14570887/
关键词：
quality assurance intensity modulated radiotherapy radiation biology xerostomia malignant glioma head and neck cancer PTV margin dose-rate effect 高精度照射法ファントム治療計画

项目摘要

A method of quality assurance in IMRT at our hospital was established. The measured dose distribution in phantoms were consistent with the calculated dose distribution within a difference of 2-4%. We measured the intrafraction and interfraction organ motions and set-up errors for patients with head and neck cancer. Based on the measured systematic and random errors, a planning target volume (PTV) margin of 5 mm was appropriate for our IMRT system.It took 15-20 min for a single fraction of IMRT, which may cause a dose-rate effect or sublethal damage repair during a farction. Cell survival curves of SCCVII tumors and CHO cells irradiated with IMRT and conventional beams were compared. Below the range of 10 Gy, no significant difference in cell survival curves were detected.IMRT using the simultaneous integrated boost (SIB) method was designed for treating malignant gliomas. IMRT delivered 70 Gy/28 fractions/daily 2.5 Gy to the gross tumor volume (GTV) and 56 Gy/28 fractions/daily 2.0 Gy to the surrounding edema defined as the clinical target volume annulus (CTV-a). Although this treatment was feasible both physically and clinically, the local control was not improved.The patterns of local-regional recurrence in patients with head and neck cancer treated by parotid-sparing IMRT were analyzed. The mean doses to the contra- and ipsi-lateral parotid glands were 24.0 Gy and 30.3 Gy, respectively Among the 33 patients, 19 patients (58%) showed only grade-0,1 xerostomia. Thus, parotid-sparing IMRT could reduce the incidence of xerostomia. However, some recurrences were noted at the margin of PTV. PTV delineation in IMRT should be cautious enough.

建立了我院调强放疗质量保证的方法。体模中测量的剂量分布与计算的剂量分布一致，差异为2- 4%。我们测量了头颈部癌症患者的分次内和分次间器官运动和摆位误差。根据测量的系统误差和随机误差，我们的IMRT系统的计划靶区（PTV）裕度为5 mm是合适的，单次IMRT需要15-20 min，这可能导致剂量率效应或在一次照射中造成亚致死损伤修复。比较了SCCVII肿瘤和CHO细胞经IMRT和常规射线照射后的细胞存活曲线。在10戈伊以下，细胞存活曲线无显著差异。调强放射治疗对大体肿瘤体积（GTV）给予70戈伊/28次/日2.5戈伊，对周围水肿（定义为临床靶体积环（CTV-a））给予56戈伊/28次/日2.0戈伊。虽然这种治疗在物理和临床上都是可行的，但局部控制并没有得到改善。本文分析了保留腮腺的调强放疗治疗头颈部癌患者的局部复发模式。对侧腮腺平均受照剂量为24.0戈伊，同侧腮腺平均受照剂量为30.3戈伊。因此，保留腮腺的调强放疗可以降低口干症的发生率。然而，在PTV边缘观察到一些复发。调强放疗中PTV的勾画应足够谨慎。