Beard C J, Kijewski P, Bussière M, Gelman R, Gladstone D, Shaffer K, Plunkett M, Castello P, Coleman C N
Joint Center for Radiation Therapy, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Int J Radiat Oncol Biol Phys. 1996 Jan 15;34(2):451-8. doi: 10.1016/0360-3016(95)02081-0.
To quantify prostate and seminal vesicle positional changes (target motion) between treatment planning and delivery, and to identify the factors contributing to target motion.
Thirty patients with adenocarcinoma of the prostate were prospectively evaluated by analyzing two sequential planning computerized tomography (CT) scans (S1, obtained prior to treatment, and S2, obtained during the fourth week of treatment) for each patient. All anatomical volumes of interest (soft tissue and bony) were reconstructed from transverse CT images and projected onto anterior and lateral beam's-eye view projections. Positional changes between S1 and S2 were eliminated by applying a rigid body translation and rotation. Target motion was then measured by recording the positional change between S1 and S2 at the edges (right, left, superior, inferior). Potential correlation of target motion with bladder volume, rectal volume, and rectal diameter changes were evaluated by linear regression analysis.
Neither the prostate nor seminal vesicles remained fixed with respect to bony anatomy between S1 and S2. The distribution of positional changes were generally small (< 0.5 cm), but maximum displacements of 1.5-2.2 cm did occur, particularly in the lateral view. In this study, bladder volume changes between the scans were small and did not correlate with target motion (P = 0.67). Both rectal volume and rectal diameter changes correlated with target motion for both the prostate (p = 0.004 and 0.005, respectively) and seminal vesicles (p < 0.001 and < 0.001, respectively). However, neither the initial rectal volume nor the initial rectal diameter could be used to predict subsequent target motion when evaluated either singly or as part of a multiple regression model.
Target motion occurs during the course of treatment planning and delivery and should be considered when designing conformal radiation fields. Although the target position at the time of planning CT may differ substantially from the mean treatment position, target motion cannot be predicted by evaluating simply measured parameters from a single scan, or double scan sequence.
量化治疗计划与治疗实施之间前列腺和精囊的位置变化（靶区运动），并确定导致靶区运动的因素。
对30例前列腺腺癌患者进行前瞻性评估，分析每位患者的两次连续计划计算机断层扫描（CT）（S1，治疗前获得；S2，治疗第四周获得）。从横向CT图像重建所有感兴趣的解剖体积（软组织和骨骼），并投影到前后和侧方射野视角投影上。通过应用刚体平移和旋转消除S1和S2之间的位置变化。然后通过记录S1和S2在边缘（右、左、上、下）的位置变化来测量靶区运动。通过线性回归分析评估靶区运动与膀胱体积、直肠体积和直肠直径变化之间的潜在相关性。
在S1和S2之间，前列腺和精囊相对于骨骼解剖结构均未保持固定。位置变化的分布通常较小（<0.5 cm），但确实出现了1.5 - 2.2 cm的最大位移，特别是在侧视图中。在本研究中，扫描之间的膀胱体积变化较小，且与靶区运动无关（P = 0.67）。直肠体积和直肠直径变化与前列腺（分别为p = 0.004和0.005）和精囊（分别为p < 0.001和< 0.001）的靶区运动均相关。然而，单独评估或作为多元回归模型的一部分时，初始直肠体积和初始直肠直径均不能用于预测后续的靶区运动。
靶区运动发生在治疗计划和治疗实施过程中，在设计适形放射野时应予以考虑。尽管计划CT时的靶区位置可能与平均治疗位置有很大差异，但仅通过评估单次扫描或双次扫描序列的简单测量参数无法预测靶区运动。
