乳腺癌术后胸壁电子线放射治疗单野与分野计划比较

目的：乳腺癌术后胸壁电子线放射治疗时单野与分野治疗对整个胸壁照射区剂量分布比较。方法：对乳腺癌根治术后病人进行模拟CT定位，用Varian的Eclipse治疗计划系统进行CT图像重建、靶区勾画。6MeV或9MeV电子线对所勾画的靶区进行单野和分野计划设计，计算并比较整个靶区的剂量分布。结果：乳腺癌术后胸壁照射由单野改成二野照射后，80％剂量曲线所包靶区体积由47％上升到84％，90％剂量曲线所包靶区体积由28％上升到72％。结论：进行乳腺癌根治术后大胸壁电子线照射时，单野照射剂量分布不均且靠近内乳区和腋中线区剂量严重不足，若在病人体表弯曲处进行分野，分野后进行二野照射则大大提高内乳区和腋中线区的剂量，提高了整个靶区的剂量，从而满足临床剂量要求。

Comparision of single- field irradiation planning and divided- field irradiation planning with the electron beam after mastectomy

Objective：To compare dose distribution of single - field irradiation and dose distribution divided - field irradiation with electron beam irradiate the entire chest wall after mastectomy for breast cancer. Methods： Patients of post - mastectomy took CT simulation, CT images were reconstructed and GTV （ gross target volume） was sketched with Varian eclipse planning system. To make planning of single - filed and divided - field with 6Mev and 9Mev electron beam and calculate dose distribution, then compare dose distribution of GTV for 6Mev planning and 9Mev planning. Results： Target area volume surrounded by 80% isodose line was from 47% up to 84% and target area volume surrounded by 90% isodose line from 28% up to 72% when the single - field irradiation was changed to the divided - field irradiation for chest wall post - mastectomy. Conclusion： Large chest wall after radical masteetomy electron irradiation, dose distribution is uneven with a single field irradiation and the dose is severe shortage wihin breast area and axillary near the median line, if the body surface is divided in bend , which is irradiated with two field, then dose is improved very much where is inside the breast and axillary midline area, which will improve the GTV dose to meet the requirement of clinical dose.