Department of Radiation Oncology, University of Florida, Gainesville, Florida, USA.
Int J Radiat Oncol Biol Phys. 2012 Aug 1;83(5):1549-57. doi: 10.1016/j.ijrobp.2011.10.014. Epub 2012 Jan 21.
To compare three-dimensional conformal proton radiotherapy (3DCPT), intensity-modulated photon radiotherapy (IMRT), and 3D conformal photon radiotherapy (3DCRT) to predict the optimal RT technique for retroperitoneal sarcomas.
3DCRT, IMRT, and 3DCPT plans were created for treating eight patients with retroperitoneal or intra-abdominal sarcomas. The clinical target volume (CTV) included the gross tumor plus a 2-cm margin, limited by bone and intact fascial planes. For photon plans, the planning target volume (PTV) included a uniform expansion of 5 mm. For the proton plans, the PTV was nonuniform and beam-specific. The prescription dose was 50.4 Gy/Cobalt gray equivalent CGE. Plans were normalized so that >95% of the CTV received 100% of the dose.
The CTV was covered adequately by all techniques. The median conformity index was 0.69 for 3DCPT, 0.75 for IMRT, and 0.51 for 3DCRT. The median inhomogeneity coefficient was 0.062 for 3DCPT, 0.066 for IMRT, and 0.073 for 3DCRT. The bowel median volume receiving 15 Gy (V15) was 16.4% for 3DCPT, 52.2% for IMRT, and 66.1% for 3DCRT. The bowel median V45 was 6.3% for 3DCPT, 4.7% for IMRT, and 15.6% for 3DCRT. The median ipsilateral mean kidney dose was 22.5 CGE for 3DCPT, 34.1 Gy for IMRT, and 37.8 Gy for 3DCRT. The median contralateral mean kidney dose was 0 CGE for 3DCPT, 6.4 Gy for IMRT, and 11 Gy for 3DCRT. The median contralateral kidney V5 was 0% for 3DCPT, 49.9% for IMRT, and 99.7% for 3DCRT. Regardless of technique, the median mean liver dose was <30 Gy, and the median cord V50 was 0%. The median integral dose was 126 J for 3DCPT, 400 J for IMRT, and 432 J for 3DCRT.
IMRT and 3DCPT result in plans that are more conformal and homogenous than 3DCRT. Based on Quantitative Analysis of Normal Tissue Effects in Clinic benchmarks, the dosimetric advantage of proton therapy may be less gastrointestinal and genitourinary toxicity.
比较三维适形质子放疗（3DCPT）、调强光子放疗（IMRT）和三维适形光子放疗（3DCRT），以预测腹膜后肉瘤的最佳放疗技术。
为 8 例腹膜后或腹腔内肉瘤患者制定 3DCRT、IMRT 和 3DCPT 计划。临床靶区（CTV）包括大体肿瘤加 2cm 边界，受骨和完整筋膜平面限制。对于光子计划，计划靶区（PTV）包括 5mm 的均匀扩展。对于质子计划，PTV 是非均匀的和束特定的。处方剂量为 50.4Gy/钴当量 CGE。计划归一化为使>95%的 CTV 接受 100%的剂量。
所有技术均能充分覆盖 CTV。3DCPT 的中位适形性指数为 0.69，IMRT 为 0.75，3DCRT 为 0.51。3DCPT 的中位不均匀性系数为 0.062，IMRT 为 0.066，3DCRT 为 0.073。3DCPT 的肠中位 15Gy 体积（V15）为 16.4%，IMRT 为 52.2%，3DCRT 为 66.1%。3DCPT 的肠中位 V45 为 6.3%，IMRT 为 4.7%，3DCRT 为 15.6%。3DCPT 的同侧平均肾脏剂量为 22.5CGE，IMRT 为 34.1Gy，3DCRT 为 37.8Gy。3DCPT 的对侧平均肾脏剂量为 0CGE，IMRT 为 6.4Gy，3DCRT 为 11Gy。3DCPT 的对侧肾脏 V5 为 0%，IMRT 为 49.9%，3DCRT 为 99.7%。无论采用何种技术，中位平均肝脏剂量均<30Gy，中位脊髓 V50 为 0%。中位积分剂量为 3DCPT 为 126J，IMRT 为 400J，3DCRT 为 432J。
与 3DCRT 相比，IMRT 和 3DCPT 可使计划更具适形性和均匀性。根据临床基准的正常组织效应定量分析，质子治疗的剂量学优势可能是胃肠道和泌尿生殖系统毒性较低。
