Department of Radiation Oncology, M. D. Anderson Cancer Center Orlando, Orlando, FL 32806, USA.
Radiother Oncol. 2011 Apr;99(1):37-43. doi: 10.1016/j.radonc.2011.02.012. Epub 2011 Mar 30.
To evaluate differences in target motion during prostate irradiation in the prone versus supine position using electromagnetic tracking to measure prostate mobility.
MATERIALS/METHODS: Twenty patients received prostate radiotherapy in the supine position utilizing the Calypso Localization System® for prostate positioning and monitoring. For each patient, 10 treatment fractions were followed by a session in which the patient was repositioned prone, and prostate mobility was tracked. The fraction of time that the prostate was displaced by >3, 5, 7, and 10mm was calculated for each patient, for both positions (400 tracking sessions).
Clear patterns of respiratory motion were seen in the prone tracks due to the influence of increased abdominal motion. Averaged over all patients, the prostate was displaced >3 and 5mm for 37.8% and 10.1% of the total tracking time in the prone position, respectively. In the supine position, the prostate was displaced >3 and 5mm for 12.6% and 2.9%, respectively. With both patient setups, inferior and posterior drifts of the prostate position were observed. Averaged over all prone tracking sessions, the prostate was displaced >3mm in the posterior and inferior directions for 11.7% and 9.5% of the total time, respectively.
With real-time tracking of the prostate, it is possible to study the effects of different setup positions on the prostate mobility. The percentage of time the prostate moved >3 and 5mm was increased by a factor of three in the prone versus supine position. For larger displacements (>7 mm) no difference in prostate mobility was observed between prone and supine positions. To reduce rectal toxicity, radiotherapy in the prone position may be a suitable alternative provided respiratory motion is accounted for during treatment. Acute and late toxicity results remain to be evaluated for both patient positions.
利用电磁跟踪测量前列腺运动，评估前列腺放疗时俯卧位与仰卧位靶区运动的差异。
材料/方法：20 例患者接受仰卧位前列腺放疗，采用 Calypso 定位系统®进行前列腺定位和监测。对于每位患者，在接受 10 次分次治疗后，进行一次患者重新俯卧位的治疗，并对前列腺运动进行跟踪。计算每位患者在两种体位（400 次跟踪）下，前列腺位移超过 3、5、7 和 10mm 的时间比例。
由于腹部运动增加的影响，在俯卧位跟踪中可明显观察到呼吸运动的模式。所有患者的平均结果显示，在俯卧位时，前列腺位移超过 3mm 和 5mm 的时间比例分别为 37.8%和 10.1%。在仰卧位时，前列腺位移超过 3mm 和 5mm 的时间比例分别为 12.6%和 2.9%。对于两种患者设置，均观察到前列腺位置的下和后向漂移。所有俯卧位跟踪的平均结果显示，前列腺在后方和下方的位移超过 3mm 的时间比例分别为总时间的 11.7%和 9.5%。
通过实时跟踪前列腺，可以研究不同设置体位对前列腺运动的影响。与仰卧位相比，俯卧位时前列腺位移超过 3mm 和 5mm 的时间比例增加了三倍。对于更大的位移（>7mm），在俯卧位和仰卧位之间未观察到前列腺运动的差异。为了降低直肠毒性，在考虑治疗期间呼吸运动的情况下，俯卧位放疗可能是一种合适的替代方法。对于两种患者体位，仍需要评估急性和晚期毒性的结果。
