St Clair W H, Adams J A, Bues M, Fullerton B C, La Shell Sean, Kooy H M, Loeffler J S, Tarbell N J
Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Int J Radiat Oncol Biol Phys. 2004 Mar 1;58(3):727-34. doi: 10.1016/S0360-3016(03)01574-8.
To compare treatment plans from standard photon therapy to intensity modulated X-rays (IMRT) and protons for craniospinal axis irradiation and posterior fossa boost in a patient with medulloblastoma.
Proton planning was accomplished using an in-house 3D planning system. IMRT plans were developed using the KonRad treatment planning system with 6-MV photons.
Substantial normal-tissue dose sparing was realized with IMRT and proton treatment of the posterior fossa and spinal column. For example, the dose to 90% of the cochlea was reduced from 101.2% of the prescribed posterior fossa boost dose from conventional X-rays to 33.4% and 2.4% from IMRT and protons, respectively. Dose to 50% of the heart volume was reduced from 72.2% for conventional X-rays to 29.5% for IMRT and 0.5% for protons. Long-term toxicity with emphasis on hearing and endocrine and cardiac function should be substantially improved secondary to nontarget tissue sparing achieved with protons.
The present study clearly demonstrates the advantage of conformal radiation methods for the treatment of posterior fossa and spinal column in children with medulloblastoma, when compared to conventional X-rays. Of the two conformal treatment methods evaluated, protons were found to be superior to IMRT.
比较标准光子治疗、调强X线（IMRT）和质子治疗对一名髓母细胞瘤患者进行颅脊髓轴照射和后颅窝加量照射的治疗计划。
使用内部三维计划系统完成质子计划。使用KonRad治疗计划系统和6兆伏光子制定IMRT计划。
IMRT和质子治疗后颅窝和脊柱时可实现显著的正常组织剂量 sparing。例如，耳蜗90%的剂量从传统X线规定的后颅窝加量剂量的101.2%分别降至IMRT的33.4%和质子的2.4%。心脏体积50%的剂量从传统X线的72.2%降至IMRT的29.5%和质子的0.5%。由于质子实现了非靶组织 sparing，长期毒性（重点是听力、内分泌和心脏功能）应得到显著改善。
本研究清楚地证明了与传统X线相比，适形放射治疗方法在治疗儿童髓母细胞瘤后颅窝和脊柱方面的优势。在评估的两种适形治疗方法中，发现质子优于IMRT。
