Yeboah C, Sandison G A
Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Alberta, Canada.
Phys Med Biol. 2002 Jul 7;47(13):2247-61. doi: 10.1088/0031-9155/47/13/305.
The merits of intensity-modulated very-high energy electron therapy (VHEET) and intensity-modulated proton therapy (IMPT) in relation to intensity-modulated x-ray therapy (IMXT) with respect to the treatment of the prostate have been quantified. Optimized dose distributions were designed for 5-11 beams of 250 MeV VHEET and 15 MV IMXT as well as 1-9 beam ports of IMPT. In the case of the comparison between 250 MeV VHEET and 15 MV IMXT, it was found that the quality of target coverage achievable with VHEET was comparable to or sometimes better than that provided by IMXT. However, VHEET provided an improvement over IMXT in the dose sparing of the sensitive structures and normal tissues. Compared to IMXT, VHEET decreased the mean rectal dose and bladder dose by up to 10% of the prescribed target dose, while reducing by up to 12% of the prescribed target dose the integral dose to normal tissues. In quantifying the merits of IMPT relative to IMXT, it was found that using intensity-modulated proton beams for inverse planning instead of intensity-modulated photon beams improved target dose homogeneity by up to 1.3% of the prescribed target dose, while reducing the mean rectal dose, bladder dose, and normal tissue integral dose by up to 27%, 30% and 28% of the prescribed target dose respectively. The comparison of optimized planning for IMPT and VHEET showed that the quality of target coverage achievable with IMPT is comparable to or better (by up to 1.3% of the prescribed target dose) than that provided by VHEET. Compared to VHEET, IMPT delivered a mean rectal dose and a bladder dose that was lower by up to 17% and 23% of prescribed target dose respectively, and also reduced the integral dose to normal tissues by up to 17% of the prescribed target dose. These results indicate that of the three modalities the greatest dose escalation will be possible with IMPT, then VHEET, and then IMXT. It follows that IMPT will result in the highest probability of complication-free tumour control, while IMXT will provide the lowest probability.
在前列腺治疗方面，已对调强甚高能电子治疗（VHEET）和调强质子治疗（IMPT）相对于调强X线治疗（IMXT）的优点进行了量化。针对250 MeV的VHEET的5 - 11束、15 MV的IMXT以及IMPT的1 - 9个射野端口设计了优化的剂量分布。在比较250 MeV的VHEET和15 MV的IMXT时发现，VHEET可实现的靶区覆盖质量与IMXT相当，有时甚至更好。然而，VHEET在对敏感结构和正常组织的剂量 sparing方面比IMXT有所改进。与IMXT相比，VHEET使直肠平均剂量和膀胱剂量降低了规定靶剂量的10%，同时使正常组织的积分剂量降低了规定靶剂量的12%。在量化IMPT相对于IMXT的优点时发现，使用调强质子束进行逆向计划而非调强光子束，可使靶剂量均匀性提高规定靶剂量的1.3%，同时使直肠平均剂量、膀胱剂量和正常组织积分剂量分别降低规定靶剂量的27%、30%和28%。对IMPT和VHEET的优化计划比较表明，IMPT可实现的靶区覆盖质量与VHEET相当或更好（高出规定靶剂量的1.3%）。与VHEET相比，IMPT的直肠平均剂量和膀胱剂量分别降低了规定靶剂量的17%和23%，还使正常组织的积分剂量降低了规定靶剂量的17%。这些结果表明，在这三种治疗方式中，IMPT实现的剂量提升最大，其次是VHEET，然后是IMXT。由此可见，IMPT导致无并发症肿瘤控制的概率最高，而IMXT提供的概率最低。
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