旋转摆位误差在单等中心容积旋转调强技术(VMAT)治疗多发脑转移中的靶区剂量评估

摘要/Abstract

摘要： 通过在治疗计划系统上模拟不同体积大小(1 cm、2 cm和3 cm直径)和距等中心距离(6 cm范围内)的肿瘤在已知旋转角度(0.5°、1°、1.5°和2°)的剂量分布来评估旋转摆位误差在单等中心容积旋转调强技术(VMAT)治疗多发脑转移中的靶区剂量学影响,同时对增加肿瘤区外扩以减少旋转摆位误差影响进行定量分析。结果表明,随旋转角度的增加,计划靶区(PTV)剂量覆盖率呈现明显降低趋势,肿瘤区(GTV)剂量覆盖率的变化趋势与PTV一致,但数值较PTV明显减小;随与等中心距离的增加,靶区剂量覆盖率呈现降低趋势,靶区体积越小,这种趋势越显著。GTV外扩2 mm得到PTV时,GTV剂量覆盖率降低的趋势得到显著改善,均在-5%以内。因此,建议在使用单等中心VMAT治疗多发脑转移时,优先采用六维治疗床进行旋转纠偏;若无六维床设备,可根据靶区的尺寸、与等中心的距离,结合临床旋转摆位误差和容差选择合适的外扩大小。

关键词: 旋转摆位误差, 单等中心, 多发脑转移, 六维治疗床

Abstract: The dose of the rotation setup deviation in single-isocenter VMAT for multiple brain lesions was evaluated by simulating rotations of known degrees (0.5°, 1°, 1.5°, and 2°) on the treatment planning system with varying tumor volume size (1 cm, 2 cm, and 3 cm) and distance to isocenter (up to 6 cm). A quantitative analysis of reducing the effect of the rotation setup deviation by increasing the tumor volume margin was done. With the increase of the rotation angle, the dose coverage of PTV decreased significantly, which was less for GTV. As the distance from the isocenter increased, the dose coverage rate decreased, and the smaller the target volume, the more significant it was. When the GTV was marginned by 2 mm, the decreasing trend of GTV dose coverage was significantly improved, all within -5%. It is recommended to use a six-dimensional couch top to correct the rotation setup deviation when using single-isocenter VMAT to treat patients with multiple brain metastases. For the organizations without a six-dimensional couch top, the appropriate margin should be considered according to the size of the target volume, the distance from the isocenter, and the clinical rotation setup deviation and tolerance.

Key words: rotation setup deviation, single-isocenter, multiple brain metastases, six-dimensional couch top

中图分类号:

R144

侯灵通, 姚升宇, 范盛韵. 旋转摆位误差在单等中心容积旋转调强技术(VMAT)治疗多发脑转移中的靶区剂量评估[J]. 辐射防护, 2025, 45(4): 396-402.

HOU Lingtong, YAO Shengyu, FAN Shengyun. Dose evaluation of the rotation setup deviation in the single-isocenter volume modulated arc therapy for multiple brain metastases[J]. RADIATION PROTECTION, 2025, 45(4): 396-402.

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