Department of Radiation Oncology, Hospital of University of Pennsylvania, Philadelphia, PA 19104, USA.
Int J Radiat Oncol Biol Phys. 2011 Dec 1;81(5):1302-9. doi: 10.1016/j.ijrobp.2010.08.052. Epub 2010 Oct 29.
To prospectively investigate intrafraction prostate motion during radiofrequency-guided prostate radiotherapy with implanted electromagnetic transponders when daily endorectal balloon (ERB) is used.
Intrafraction prostate motion from 24 patients in 787 treatment sessions was evaluated based on three-dimensional (3D), lateral, cranial-caudal (CC), and anterior-posterior (AP) displacements. The mean percentage of time with 3D, lateral, CC, and AP prostate displacements>2, 3, 4, 5, 6, 7, 8, 9, and 10 mm in 1 minute intervals was calculated for up to 6 minutes of treatment time. Correlation between the mean percentage time with 3D prostate displacement>3 mm vs. treatment week was investigated.
The percentage of time with 3D prostate movement>2, 3, and 4 mm increased with elapsed treatment time (p<0.05). Prostate movement>5 mm was independent of elapsed treatment time (p=0.11). The overall mean time with prostate excursions>3 mm was 5%. Directional analysis showed negligible lateral prostate motion; AP and CC motion were comparable. The fraction of time with 3D prostate movement>3 mm did not depend on treatment week of (p>0.05) over a 4-minute mean treatment time.
Daily endorectal balloon consistently stabilizes the prostate, preventing clinically significant displacement (>5 mm). A 3-mm internal margin may sufficiently account for 95% of intrafraction prostate movement for up to 6 minutes of treatment time. Directional analysis suggests that the lateral internal margin could be further reduced to 2 mm.
前瞻性研究植入电磁传感器的经直肠内球囊引导的前列腺放射治疗中，每日内直肠球囊（ERB）应用时前列腺的分次内运动。
基于三维（3D）、侧向、头脚（CC）和前后（AP）位移，评估了 24 例患者的 787 个治疗疗程中的分次内前列腺运动。计算了 3D、侧向、CC 和 AP 前列腺位移>2、3、4、5、6、7、8、9 和 10 毫米的 3D 前列腺位移>3 毫米的平均时间百分比与治疗周的相关性。
3D 前列腺运动>2、3 和 4 毫米的时间百分比随着治疗时间的延长而增加（p<0.05）。前列腺运动>5 毫米与治疗时间无关（p=0.11）。前列腺运动>3 毫米的总平均时间为 5%。方向分析显示，侧向前列腺运动可忽略不计；AP 和 CC 运动相当。3D 前列腺运动>3 毫米的时间比例不依赖于治疗周（p>0.05），在 4 分钟的平均治疗时间内。
每日内直肠球囊可稳定前列腺，防止临床上明显的位移（>5 毫米）。3 毫米的内部边界可能足以解释 95%的治疗时间内的前列腺运动，最长可达 6 分钟。方向分析表明，侧向内部边界可以进一步减少到 2 毫米。
