Martinez A, Gonzalez J, Stromberg J, Edmundson G, Plunkett M, Gustafson G, Brown D, Yan D, Vicini F, Brabbins D
Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI 48073, USA.
Int J Radiat Oncol Biol Phys. 1995 Dec 1;33(5):1019-27. doi: 10.1016/0360-3016(95)00254-5.
To improve treatment results on prostatic adenocarcinoma, conformal radiation therapy (CRT) has been used. Two major drawbacks of external CRT are: (a) internal organ motion/daily set-up variations, and (b) exclusion of several patients for CRT based on poor geometrical relationships as identified by three dimensional (3D) treatment planning. To overcome the above problems, we began the first prospective Phase I/II dose-escalating clinical trial of conformal brachytherapy (CB) and concurrent external beam irradiation.
Fifty-nine patients with T2b-T3c prostatic adenocarcinoma received 176 transperineal ultrasound-guided conformal high-dose rate (HDR) boost implants. All patients received concomitant external beam pelvic irradiation. Dose escalation of the three HDR-CB fractions proceeded as follows: 5.5 Gy (30 patients), 6 Gy (20 patients), and 6.5 Gy (9 patients). The CB dose was prescribed to the prostate contour as outlined using an online biplanar transrectal ultrasound probe. The urethra, anterior rectal wall, and prostate boundaries were identified individually and outlined at 5 mm intervals from the base to the apex of the gland. The CB using real-time ultrasound guidance with interactive online isodose distributions was performed on an outpatient basis. As needles were placed into the prostate, corrections for prostate displacement were recorded and the isodose distributions were recalculated to represent the new relationship between the needles, prostate, and normal structures. No computerized tomography (CT) planning or implant preplanning was required.
No patient was rejected based on poor geometrical relation of pelvic structures. In every implant performed, prostate displacement was noted. Craniocaudal motion of the gland ranged from 0.5-2.0 cm (mean = 1.0 cm), whereas lateral displacement was 0.1-0.4 cm. With the interactive online planning system, organ motion was immediately detected, accounted for, and corrected prior to each HDR treatment. The rectal dose has ranged from 45 to 87%, and the urethral dose from 97 to 112% of the prostate dose. It is significant to note that operator dependence has been completely removed because the interactive online planning system uniformly guides the physicians.
With ultrasound guidance and the interactive online dosimetry system, organ motion (as compared to external beam) is insignificant because it can be corrected during the procedure without increasing target volume margins. Common pitfalls of brachytherapy, including operator dependence and difficulty with reproducibility, have been eliminated with the intraoperative online planning system.
为提高前列腺腺癌的治疗效果，采用了适形放射治疗（CRT）。外照射CRT的两个主要缺点是：（a）体内器官运动/每日摆位变化，以及（b）基于三维（3D）治疗计划所确定的不良几何关系而将部分患者排除在CRT之外。为克服上述问题，我们开展了首例适形近距离放射治疗（CB）与同期外照射联合的前瞻性I/II期剂量递增临床试验。
59例T2b - T3c期前列腺腺癌患者接受了176次经会阴超声引导的适形高剂量率（HDR）后装植入治疗。所有患者均接受了同期盆腔外照射。三次HDR - CB分次剂量递增如下：5.5 Gy（30例患者）、6 Gy（20例患者）和6.5 Gy（9例患者）。CB剂量根据使用在线双平面经直肠超声探头勾勒出的前列腺轮廓进行处方。分别识别尿道、直肠前壁和前列腺边界，并从腺体基部至尖部以5 mm间隔进行勾勒。基于实时超声引导及交互式在线等剂量分布的CB在门诊进行。当针插入前列腺时，记录前列腺位移的校正情况，并重新计算等剂量分布以体现针、前列腺和正常结构之间的新关系。无需计算机断层扫描（CT）计划或植入前计划。
没有患者因盆腔结构几何关系不佳而被排除。在每次植入过程中，均观察到前列腺位移。腺体的头脚向运动范围为0.5 - 2.0 cm（平均 = 1.0 cm），而横向位移为0.1 - 0.4 cm。借助交互式在线计划系统，在每次HDR治疗前可立即检测、考虑并校正器官运动。直肠剂量为前列腺剂量的45%至87%，尿道剂量为前列腺剂量的97%至112%。值得注意的是，由于交互式在线计划系统能统一指导医生，完全消除了对操作者的依赖。
借助超声引导和交互式在线剂量测定系统，器官运动（与外照射相比）并不显著，因为在操作过程中可对其进行校正而无需增加靶体积边界。术中在线计划系统消除了近距离放射治疗的常见陷阱，包括对操作者的依赖和可重复性困难。
