South C P, Khoo V S, Naismith O, Norman A, Dearnaley D P
Department of Physics, Royal Marsden NHS Foundation Trust, London, UK.
Clin Oncol (R Coll Radiol). 2008 Feb;20(1):15-21. doi: 10.1016/j.clon.2007.10.012. Epub 2007 Dec 3.
To compare the radiotherapy planning techniques from two multicentre randomised external beam radiotherapy trials in the UK of conformal radiotherapy vs intensity-modulated radiotherapy (IMRT).
Sixteen sequential patients with histologically confirmed localised prostate cancer treated in the conventional or hypofractionated IMRT trial (CHHiP) were planned using both the CHHiP and Medical Research Council RT-01 planning protocols to 74 Gy in 37 daily fractions. The CHHiP plan used a single phase simple forward planned three-field IMRT plan for easy multicentre adoption. The RT-01 plan used two phases: three-field conformal radiotherapy plan to 64 Gy followed by a six-field boost of 10 Gy. After coverage of the planning target volumes according to the respective trial protocols, the dose to the rectum and bladder was assessed for the two planning techniques.
There was acceptable planning target volume coverage by both the CHHiP and RT-01 plans. All CHHiP plans produced lower mean irradiated rectal volumes at all measured dose levels compared with the RT-01 plans, particularly for irradiated rectal volumes at 50 and 70 Gy (P<0.05). In the cases when a CHHiP plan failed to meet its own trial dose constraints, the volumes of irradiated rectum were less than if an RT-01 planning technique had been used. The CHHiP plans gave lower mean irradiated bladder volumes at both 50 and 60 Gy, but higher volumes at 74 Gy. These differences in irradiated bladder volumes were significant at the 60 and 74 Gy dose levels (P<0.05) in favour of the CHHiP and RT-01 plans, respectively.
The forward planned CHHiP IMRT planning solution gives more favourable rectal sparing than the RT-01 plan. This is important to limit any potential increase in late rectal toxicity for prostate cancer patients treated with high-dose conventional or hypofractionated schedules.
比较英国两项多中心随机外照射放疗试验中适形放疗与调强放疗（IMRT）的放疗计划技术。
在常规或大分割IMRT试验（CHHiP）中接受治疗的16例经组织学确诊的局限性前列腺癌连续患者，分别使用CHHiP和医学研究委员会RT - 01计划方案进行计划，给予37次分割、总剂量74 Gy的照射。CHHiP计划采用单相简单正向计划的三野IMRT计划，便于多中心采用。RT - 01计划采用两个阶段：64 Gy的三野适形放疗计划，随后是10 Gy的六野加量。根据各自试验方案覆盖计划靶体积后，评估两种计划技术对直肠和膀胱的剂量。
CHHiP计划和RT - 01计划对计划靶体积的覆盖均可接受。与RT - 01计划相比，所有CHHiP计划在所有测量剂量水平下产生的平均照射直肠体积均较低，尤其是在50 Gy和70 Gy时的照射直肠体积（P<0.05）。当CHHiP计划未能满足其自身试验剂量约束时，照射直肠的体积小于使用RT - 01计划技术时的体积。CHHiP计划在50 Gy和60 Gy时的平均照射膀胱体积较低，但在74 Gy时较高。这些照射膀胱体积的差异在60 Gy和74 Gy剂量水平时具有统计学意义（P<0.05），分别有利于CHHiP计划和RT - 01计划。
正向计划的CHHiP IMRT计划方案比RT - 01计划更有利于减少直肠受量。这对于限制接受高剂量常规或大分割方案治疗的前列腺癌患者晚期直肠毒性的任何潜在增加非常重要。
