Kishan Amar U, Tyran Marguerite, Weng Julius, Upadhyaya Shrinivasa, Lamb James, Steinberg Michael, King Christopher, Cao Minsong
1 Department of Radiation Oncology, University of California , Los Angeles , USA.
2 Department of Urology, University of California , Los Angeles , USA.
Br J Radiol. 2019 Jul;92(1099):20181001. doi: 10.1259/bjr.20181001. Epub 2019 Apr 3.
To evaluate the dosimetric ramifications of simultaneously irradiating the prostate and pelvic lymph nodes (PLNs) with a stereotactic body radiotherapy approach based on rigid registration to intraprostatic markers (IPMs).
Nineteen patients received concurrent SBRT to the prostate and PLNs on a phase II clinical trial. The translational and rotation shifts required for rigid registration to bony anatomy and changes in bladder and rectal anatomy were compared between patients with > 90% and < 90% coverage of the nodal clinical target volume (CTV ) as drawn on fractional kilovoltage cone-beam CTs. Stepwise multivariable regression models evaluated relationships between these anatomical parameters and the change in VCTV.
The average VCTV per patient was 92.4 % (IQR, 90.2 - 96.4 %). For five patients (26.3%), the average was 85.0 % (IQR, 82.4-88.3 %). The left-right and superior-inferior translational shifts, sagittal rotational shift, and change in bladder volume were significantly different ( < 0.05 for all via Student's -test). Changes in bladder height, left/right shift, superior/inferior shift, 3-D shift, and axial rotation as significant predictors of change in dosing of VCTV.
While simultaneous SBRT to the prostate and PLNs based on rigid registration to IPMs provides adequate PLN coverage in most instances, overall coverage may be lower than anticipated if anatomy is unstable. Careful evaluation of bladder filling on kV-CBCT before treatment may be the most practical method for estimating accuracy prior to treatment.
Simultaneous SBRT to the prostate and PLNs based on rigid registration to IPMs provides adequate PLN coverage in most instances.
基于对前列腺内标志物（IPM）的刚性配准，采用立体定向体部放射治疗方法同时照射前列腺和盆腔淋巴结（PLN），评估其剂量学影响。
19例患者在一项II期临床试验中接受了前列腺和PLN的同步立体定向体部放射治疗（SBRT）。比较在分次千伏锥形束CT上绘制的淋巴结临床靶体积（CTV）覆盖率>90%和<90%的患者，在刚性配准到骨骼解剖结构时所需的平移和旋转偏移以及膀胱和直肠解剖结构的变化。逐步多变量回归模型评估这些解剖学参数与CTV变化之间的关系。
每位患者的平均CTV为92.4%（四分位间距，90.2 - 96.4%）。5例患者（26.3%）的平均值为85.0%（四分位间距，82.4 - 88.3%）。左右和上下平移偏移、矢状面旋转偏移以及膀胱体积变化存在显著差异（所有通过Student's t检验，P<0.05）。膀胱高度、左右偏移、上下偏移、三维偏移和轴向旋转的变化是CTV剂量变化的显著预测因素。
基于对IPM的刚性配准同时对前列腺和PLN进行SBRT在大多数情况下可提供足够的PLN覆盖，但如果解剖结构不稳定，总体覆盖可能低于预期。治疗前在千伏锥形束CT上仔细评估膀胱充盈情况可能是估计治疗前准确性的最实用方法。
基于对IPM的刚性配准同时对前列腺和PLN进行SBRT在大多数情况下可提供足够的PLN覆盖。
