Department of Radiation Oncology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, USA.
Int J Radiat Oncol Biol Phys. 2012 May 1;83(1):e75-80. doi: 10.1016/j.ijrobp.2011.11.029. Epub 2012 Feb 11.
To evaluate bladder and rectal doses using two-dimensional (2D) and 3D treatment planning for vaginal cuff high-dose rate (HDR) in endometrial cancer.
Ninety-one consecutive patients treated between 2000 and 2007 were evaluated. Seventy-one and 20 patients underwent 2D and 3D planning, respectively. Each patient received six fractions prescribed at 0.5 cm to the superior 3 cm of the vagina. International Commission on Radiation Units and Measurements (ICRU) doses were calculated for 2D patients. Maximum and 2-cc doses were calculated for 3D patients. Organ doses were normalized to prescription dose.
Bladder maximum doses were 178% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were no different than ICRU doses (p = 0.22). Two-cubic centimeter doses were 59% of maximum doses (p < 0.0001). Rectal maximum doses were 137% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 87% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 64% of maximum doses (p < 0.0001). Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final bladder dose to within 10% for 44%, 59%, 83%, 82%, and 89% of patients by using the ICRU dose, and for 45%, 55%, 80%, 85%, and 85% of patients by using the maximum dose, and for 37%, 68%, 79%, 79%, and 84% of patients by using the 2-cc dose. Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final rectal dose to within 10% for 100%, 100%, 100%, 100%, and 100% of patients by using the ICRU dose, and for 60%, 65%, 70%, 75%, and 75% of patients by using the maximum dose, and for 68%, 95%, 84%, 84%, and 84% of patients by using the 2-cc dose.
Doses to organs at risk vary depending on the calculation method. In some cases, final dose accuracy appears to plateau after the third fraction, indicating that simulation and planning may not be necessary in all fractions. A clinically relevant level of accuracy should be determined and further research conducted to address this issue.
评估阴道高位（HDR）子宫内膜癌二维（2D）和三维（3D）治疗计划的膀胱和直肠剂量。
评估了 2000 年至 2007 年间连续治疗的 91 例患者。71 例和 20 例患者分别接受了 2D 和 3D 规划。每位患者接受了六个分次剂量，在阴道上 3 厘米的上方 0.5 厘米处规定剂量。为 2D 患者计算了国际辐射单位和测量委员会（ICRU）剂量。为 3D 患者计算了最大剂量和 2-cc 剂量。器官剂量归一化为规定剂量。
膀胱最大剂量为 ICRU 剂量的 178%（p<0.0001）。2-cc 剂量与 ICRU 剂量无差异（p=0.22）。2-cc 剂量为最大剂量的 59%（p<0.0001）。直肠最大剂量为 ICRU 剂量的 137%（p<0.0001）。2-cc 剂量为 ICRU 剂量的 87%（p<0.0001）。2-cc 剂量为最大剂量的 64%（p<0.0001）。使用前 1、2、3、4 或 5 个分数，我们使用 ICRU 剂量预测最终膀胱剂量，对于 44%、59%、83%、82%和 89%的患者，预测值在 10%以内，使用最大剂量预测 45%、55%、80%、85%和 85%的患者，使用 2-cc 剂量预测 37%、68%、79%、79%和 84%的患者。使用前 1、2、3、4 或 5 个分数，我们使用 ICRU 剂量预测最终直肠剂量，对于 100%、100%、100%、100%和 100%的患者，预测值在 10%以内，对于 60%、65%、70%、75%和 75%的患者，使用最大剂量预测，对于 68%、95%、84%、84%和 84%的患者，使用 2-cc 剂量预测。
危险器官的剂量取决于计算方法。在某些情况下，第三次分割后，最终剂量的准确性似乎趋于平稳，这表明模拟和计划在所有分割中可能不是必需的。应确定一个具有临床意义的准确水平，并进行进一步研究以解决这个问题。
