Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna, Austria.
Department of Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna/Allgemeines Krankenhaus der Stadt Wien, Vienna, Austria.
Int J Radiat Oncol Biol Phys. 2014 Mar 1;88(3):715-22. doi: 10.1016/j.ijrobp.2013.11.241.
To assess the dosimetric differences among volumetric modulated arc therapy (VMAT), scanned proton therapy (intensity-modulated proton therapy, IMPT), scanned carbon-ion therapy (intensity-modulated carbon-ion therapy, IMIT), and low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy (BT) treatment of localized prostate cancer.
Ten patients were considered for this planning study. For external beam radiation therapy (EBRT), planning target volume was created by adding a margin of 5 mm (lateral/anterior-posterior) and 8 mm (superior-inferior) to the clinical target volume. Bladder wall (BW), rectal wall (RW), femoral heads, urethra, and pelvic tissue were considered as organs at risk. For VMAT and IMPT, 78 Gy(relative biological effectiveness, RBE)/2 Gy were prescribed. The IMIT was based on 66 Gy(RBE)/20 fractions. The clinical target volume planning aims for HDR-BT ((192)Ir) and LDR-BT ((125)I) were D(90%) ≥34 Gy in 8.5 Gy per fraction and D(90%) ≥145 Gy. Both physical and RBE-weighted dose distributions for protons and carbon-ions were converted to dose distributions based on 2-Gy(IsoE) fractions. From these dose distributions various dose and dose-volume parameters were extracted.
Rectal wall exposure 30-70 Gy(IsoE) was reduced for IMIT, LDR-BT, and HDR-BT when compared with VMAT and IMPT. The high-dose region of the BW dose-volume histogram above 50 Gy(IsoE) of IMPT resembled the VMAT shape, whereas all other techniques showed a significantly lower high-dose region. For all 3 EBRT techniques similar urethra D(mean) around 74 Gy(IsoE) were obtained. The LDR-BT results were approximately 30 Gy(IsoE) higher, HDR-BT 10 Gy(IsoE) lower. Normal tissue and femoral head sparing was best with BT.
Despite the different EBRT prescription and fractionation schemes, the high-dose regions of BW and RW expressed in Gy(IsoE) were on the same order of magnitude. Brachytherapy techniques were clearly superior in terms of BW, RW, and normal tissue sparing, with lowest values for HDR-BT.
评估容积调强弧形治疗（VMAT）、扫描质子治疗（强度调制质子治疗，IMPT）、扫描碳离子治疗（强度调制碳离子治疗，IMIT）以及低剂量率（LDR）和高剂量率（HDR）近距离治疗局部前列腺癌的剂量学差异。
本研究纳入了 10 名患者。对于外照射放射治疗（EBRT），通过在临床靶区（CTV）上增加 5mm（侧/前后）和 8mm（上/下）的边缘来创建计划靶区（PTV）。膀胱壁（BW）、直肠壁（RW）、股骨头、尿道和骨盆组织被认为是危及器官。对于 VMAT 和 IMPT，规定 78Gy（相对生物效应，RBE）/2Gy。IMIT 基于 66Gy（RBE）/20 个分次。HDR-BT（（192）Ir）和 LDR-BT（（125）I）的临床靶区计划目标是每个分次 8.5Gy 时 D（90%）≥34Gy 和 D（90%）≥145Gy。质子和碳离子的物理剂量和 RBE 加权剂量分布均转换为基于 2Gy（IsoE）分次的剂量分布。从这些剂量分布中提取了各种剂量和剂量体积参数。
与 VMAT 和 IMPT 相比，IMIT、LDR-BT 和 HDR-BT 降低了直肠壁 30-70Gy（IsoE）的照射剂量。IMPTDose-volume histogram 中 BW 剂量高于 50Gy（IsoE）的高剂量区域类似于 VMAT 形状，而所有其他技术均显示出明显较低的高剂量区域。对于所有 3 种 EBRT 技术，获得的尿道 D（均值）约为 74Gy（IsoE）。LDR-BT 结果约高 30Gy（IsoE），HDR-BT 低 10Gy（IsoE）。BT 在保护 BW、RW 和正常组织方面具有最佳效果。
尽管 EBRT 处方和分割方案不同，但 BW 和 RW 的 Gy（IsoE）高剂量区域处于同一数量级。在 BW、RW 和正常组织保护方面，近距离治疗技术明显优于 HDR-BT，HDR-BT 的剂量最低。
