Rosewall Tara, Chung Peter, Bayley Andrew, Lockwood Gina, Alasti Hamideh, Bristow Robert, Kong Vickie, Milosevic Michael, Catton Charles
Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ont., Canada.
Radiother Oncol. 2008 Jul;88(1):88-94. doi: 10.1016/j.radonc.2008.01.019. Epub 2008 Feb 14.
To quantify inter- and intrafraction prostate motion in a standard VacLok (VL) immobilization device or in the BodyFix (BF) system incorporating a compression element which may reduce abdominal movement.
Thirty-two patients were randomly assigned to VL or BF. Interfraction prostate motion >3 mm was corrected pre-treatment. EPIs were taken daily at the start and end of the first and last treatment beams. Interfraction and intrafraction prostate motion were measured for centre of mass (COM) and individual markers.
There were no significant differences in interfraction (p0.002) or intrafraction (p0.16) prostate motion with or without abdominal compression. Median intrafraction motion was slightly smaller than interfraction motion in the AP (7.0 mm vs. 7.6 mm) and SI direction (3.2 mm vs. 4.7 mm). The final image captured the maximal intrafraction displacement in only 40% of fractions. Our PTV incorporated >95% of total prostate motion.
Intrafraction motion became the major source of error during radiotherapy after online correction of interfraction prostate motion. The addition of 120 mbar abdominal compression to custom pelvic immobilization influenced neither interfraction nor intrafraction prostate motion.
量化在标准VacLok（VL）固定装置或包含可减少腹部运动的压缩元件的BodyFix（BF）系统中前列腺在分次治疗间和分次治疗内的运动。
32例患者被随机分配至VL组或BF组。对于分次治疗间前列腺运动>3 mm的情况，在治疗前进行校正。在首次和末次治疗射野开始和结束时每日采集回波平面成像（EPI）。测量质心（COM）和各个标记点的分次治疗间和分次治疗内前列腺运动。
无论有无腹部压迫，分次治疗间（p>0.002）或分次治疗内（p>0.16）前列腺运动均无显著差异。在前后（AP）方向（7.0 mm对7.6 mm）和头脚（SI）方向（3.2 mm对4.7 mm），分次治疗内运动的中位数略小于分次治疗间运动。最终图像仅在40%的分次中捕捉到了分次治疗内的最大位移。我们的计划靶体积（PTV）纳入了前列腺总运动的>95%。
在对分次治疗间前列腺运动进行在线校正后，分次治疗内运动成为放射治疗期间误差的主要来源。在定制盆腔固定基础上增加120毫巴的腹部压迫对分次治疗间和分次治疗内前列腺运动均无影响。
