Nieder Carsten, Grosu Anca L, Stark Sybille, Wiedenmann Nicole, Busch Raymonde, Kneschaurek Peter, Molls Michael
Department of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
Int J Radiat Oncol Biol Phys. 2006 Mar 15;64(4):1055-9. doi: 10.1016/j.ijrobp.2005.09.015. Epub 2005 Dec 9.
To examine retrospectively the maximum dose to the large skull base/intracranial arteries in fractionated stereotactic radiotherapy (FSRT) and intensity-modulated radiotherapy (IMRT), because of the potential risk of perfusion disturbances.
Overall, 56 patients with tumors adjacent to at least one major artery were analyzed. Our strategy was to perform FSRT with these criteria: 1.8 Gy per fraction, planning target volume (PTV) enclosed by the 95% isodose, maximum dose 107%. Dose limits were applied to established organs at risk, but not the vessels. If FSRT planning failed to meet any of these criteria, IMRT was planned with the same objectives.
In 31 patients (median PTV, 23 cm3), the FSRT plan fulfilled all criteria. No artery received a dose > or =105%. Twenty-five patients (median PTV, 39 cm3) needed IMRT planning. In 11 of 25 patients (median PTV, 85 cm3), no plan satisfying all our criteria could be calculated. Only in this group, moderately increased maximum vessel doses were observed (106-110%, n = 7, median PTV, 121 cm3). The median PTV dose gradient was 29% (significantly different from the 14 patients with satisfactory IMRT plans). Three of the four patients in this group had paranasal sinus tumors.
The doses to the major arteries should be calculated in IMRT planning for critical tumor locations if a dose gradient >13% within the PTV can not be avoided because the PTV is large or includes air cavities.
由于存在灌注紊乱的潜在风险，对分次立体定向放射治疗（FSRT）和调强放射治疗（IMRT）中大型颅底/颅内动脉的最大剂量进行回顾性研究。
总共分析了56例肿瘤紧邻至少一条主要动脉的患者。我们的策略是按照以下标准进行FSRT：每次分割剂量1.8 Gy，计划靶体积（PTV）由95%等剂量线包绕，最大剂量107%。对已确定的危及器官应用剂量限制，但不对血管进行限制。如果FSRT计划不符合这些标准中的任何一条，则以相同目标制定IMRT计划。
在31例患者（PTV中位数为23 cm³）中，FSRT计划符合所有标准。没有动脉接受的剂量≥105%。25例患者（PTV中位数为39 cm³）需要进行IMRT计划。在25例患者中的11例（PTV中位数为85 cm³）中，无法计算出满足我们所有标准的计划。仅在该组中观察到最大血管剂量适度增加（106 - 110%，n = 7，PTV中位数为121 cm³）。该组PTV剂量梯度中位数为29%（与14例IMRT计划满意的患者有显著差异）。该组4例患者中有3例患有鼻窦肿瘤。
对于关键肿瘤部位的IMRT计划，如果由于PTV较大或包含气腔而无法避免PTV内剂量梯度>13%，则应计算主要动脉的剂量。
