乳腺癌保乳术后全乳野中野适形调强放射治疗技术

Field in field technology in total breast IMRT after breast conserving surgery on breast cancer

目的:探讨乳腺癌保乳术后全乳野中野适形调强照射技术方法,并与常规全乳切线野照射技术进行剂量学对比。方法:选取22例早期乳腺癌保乳术后患者在CT模拟机下对乳腺部位行薄层定位扫描,将定位图像传输至治疗计划系统进行全乳野中野计划设计:在全乳两切线适形野的基础上挡去高剂量区部分,另设计2-4个小跳数射野以降低靶区最高剂量和调整高剂量区的范围及所在位置。处方剂量50Gy/25次,要求95%的靶区接受处方剂量;然后利用其CT模拟定位资料按照常规切线野射野方法在治疗计划上模拟常规切线野治疗计划,对野中野计划和常规射野计划进行靶区适形性、靶区均匀性和危及器官受量的比较。结果:野中野适形调强放射治疗技术的适形度、均匀性优于常规切线野照射,靶区内超过110%处方剂量的体积明显小于常规切线野技术。减少了肺组织V20的体积,降低了心脏的平均剂量和受照体积。结论:乳腺癌保乳术后全乳野中野适形调强放射治疗技术是一种有益的全乳照射技术。

Objective：To research the method of field in field technology in intensity modulation adiation therapy （IMRT） after breast conserving surgery（BCS） on breast cancer, and make a dosimetric comparison with the conventional tangential irradiation for total breast radiotherapy. Methods： Total of 22 patients with early stage breast cancer were selected for this study. Their breast position were scan thinly with CT - sim scanner. Transfered the CT images to TPS and made the field in field in IMRT plans. Given two tangential conformal beams and shadowed the high dose regions. Added 2-4 beams with same gantry angle in order to reduce Dmax in targets and adjusted ranges and positions of the high dose regions. The total prescription dose was 50 Gy by 2.0 Gy per fraction. The 95% of PTV endure the prescription dose. Make a comparable plan to use the same CT images with conventional tangential beam in TPS. Between two plans, conformality,uniformity of target and dose of the risk organs were compared. Results： Conformality, uniformity of PTV in the plan which used the field in field technology were higher than that used the conventional tangential beam technology, and the volume above 110% prescription dose in target was lower obviously than the technology on conventional tangential irradiation, and the former had lower V20 of the lung tissues, and the average dose and the volume of heart were reduced at the former. Conclusion： The field in field technology in total breast IMRT is beneficial after BCS on breast cancer.