Bignardi Mario, Cozzi Luca, Fogliata Antonella, Lattuada Paola, Mancosu Pietro, Navarria Piera, Urso Gaetano, Vigorito Sabrina, Scorsetti Marta
Istituto Clinico Humanitas, Radiation Oncology, Rozzano, Italy.
Int J Radiat Oncol Biol Phys. 2009 Dec 1;75(5):1570-7. doi: 10.1016/j.ijrobp.2009.05.035. Epub 2009 Oct 31.
A planning study was performed comparing volumetric modulated arcs, RapidArc (RA), fixed beam IMRT (IM), and conformal radiotherapy (CRT) with multiple static fields or short conformal arcs in a series of patients treated with hypofractionated stereotactic body radiation therapy (SBRT) for solitary or oligo-metastases from different tumors to abdominal lymph nodes.
Fourteen patients were included in the study. Dose prescription was set to 45 Gy (mean dose to clinical target volume [CTV]) in six fractions of 7.5 Gy. Objectives for CTV and planning target volume (PTV) were as follows: Dose(min) >95%, Dose(max) <107%. For organs at risk the following objectives were used: Maximum dose to spine <18 Gy; V(15Gy) <35% for both kidneys, V(36Gy) <1% for duodenum, V(36Gy) <3% for stomach and small bowel, V(15Gy) <(total liver volume--700 cm(3)) for liver. Dose-volume histograms were evaluated to assess plan quality.
Planning objectives on CTV and PTV were achieved by all techniques. Use of RA improved PTV coverage (V(95%) = 90.2% +/- 5.2% for RA compared with 82.5% +/- 9.6% and 84.5% +/- 8.2% for CRT and IM, respectively). Most planning objectives for organs at risk were met by all techniques except for the duodenum, small bowel, and stomach, in which the CRT plans exceeded the dose/volume constraints in some patients. The MU/fraction values were as follows: 2186 +/- 211 for RA, 2583 +/- 699 for IM, and 1554 +/- 153 for CRT. Effective treatment time resulted as follows: 3.7 +/- 0.4 min for RA, 10.6 +/- 1.2 min for IM, and 6.3 +/- 0.5 min for CRT.
Delivery of SBRT by RA showed improvements in conformal avoidance with respect to standard conformal irradiation. Delivery parameters confirmed logistical advantages of RA, particularly compared with IM.
进行一项计划研究，比较容积调强弧形放疗（VMAT）、螺旋断层放疗（RA）、固定野调强放疗（IM）以及适形放疗（CRT，采用多个静态野或短适形弧）在一系列接受大分割立体定向体部放疗（SBRT）治疗不同肿瘤至腹部淋巴结的孤立或寡转移患者中的应用。
14例患者纳入研究。剂量处方设定为45 Gy（临床靶区[CTV]平均剂量），分6次给予，每次7.5 Gy。CTV和计划靶区（PTV）的目标如下：剂量（最小值）>95%，剂量（最大值）<107%。对于危及器官，采用以下目标：脊柱最大剂量<18 Gy；双肾V（15 Gy）<35%，十二指肠V（36 Gy）<1%，胃和小肠V（36 Gy）<3%，肝脏V（15 Gy）<（肝脏总体积 - 700 cm³）。评估剂量体积直方图以评估计划质量。
所有技术均实现了CTV和PTV的计划目标。RA的使用改善了PTV覆盖情况（RA的V（95%） = 90.2% ± 5.2%，而CRT和IM分别为82.5% ± 9.6%和84.5% ± 8.2%）。除十二指肠、小肠和胃外，所有技术均满足了大多数危及器官的计划目标，其中CRT计划在部分患者中超出了剂量/体积限制。每次分割的MU值如下：RA为2186 ± 211，IM为2583 ± 699，CRT为1554 ± 153。有效治疗时间如下：RA为3.7 ± 0.4分钟，IM为10.6 ± 1.2分钟，CRT为6.3 ± 0.5分钟。
与标准适形放疗相比，RA进行SBRT在适形规避方面有所改善。递送参数证实了RA的后勤优势，特别是与IM相比。
