Department of Radiation Oncology, Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
Department of Urology, Jefferson Medical College and Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
Pract Radiat Oncol. 2011 Apr-Jun;1(2):105-14. doi: 10.1016/j.prro.2010.10.005. Epub 2011 Apr 8.
Radiation therapy (RT) is delivered as adjuvant and salvage therapy after radical prostatectomy for prostate cancer. Interest in dose escalation in this setting may necessitate more advanced RT techniques, such as intensity modulation. This study was designed to compare intensity-modulated radiation therapy (IMRT) versus 3-dimensional conformal radiation therapy (3DCRT) planning.
Twenty patients were identified who received post--radical prostatectomy RT with 4-field, 3DCRT plans to 68.4 Gy. Contours were revised to comply with the European Organization for Research and Treatment of Cancer consensus guidelines. The IMRT plans with 5 versus 9 coplanar fields were compared for 10 patients. Then the 9-field IMRT plans were compared to 3DCRT in all 20 patients. Differences in dose-volume histogram values were evaluated using 2-tailed paired t tests. Cone beam computed tomographic images were analyzed to evaluate rectum doses in the treatment position during the RT course. The IMRT plans to 72.0 Gy were compared to 3DCRT to 68.4 Gy to be able to consider potential use in dose escalation.
The 9-field IMRT plans (vs 3DCRT) improved bladder mean dose and volume receiving 65 Gy or more (V65), as well as rectum mean dose (31.6 Gy vs 36.1 Gy; P < .001), volume receiving 75% or more of the prescription dose (24.4% vs 31.0%; P < .001), and V65 (10.5% vs 20.0%; P < .001). Advantages of IMRT were at the cost of small increases in maximum point doses delivered to the bladder and rectum. Cone beam computed tomographic images (n = 132) were analyzed for 8 patients; rectum mean dose and V65 were also improved by IMRT on these scans. IMRT allowed increasing dose to 72.0 Gy with similar bladder and rectum mean doses, V65, and V40 compared to 3DCRT to a total dose of 68.4 Gy.
The IMRT improves dosimetric parameters for the rectum and bladder, which may allow dose escalation after radical prostatectomy. Future studies should determine whether these advantages translate into improved clinical outcomes for prostate cancer patients.
放射治疗（RT）是前列腺癌根治术后辅助和挽救治疗的手段。在这种情况下，人们对提高剂量的兴趣可能需要更先进的 RT 技术，如强度调制。本研究旨在比较调强放疗（IMRT）与三维适形放疗（3DCRT）的计划。
共 20 例患者接受了根治性前列腺切除术后的 RT，采用 4 野 3DCRT 方案，剂量为 68.4 Gy。将轮廓修改为符合欧洲癌症研究与治疗组织的共识指南。比较了 10 例患者 5 个与 9 个共面野的 IMRT 计划。然后，在所有 20 例患者中比较了 9 野 IMRT 计划与 3DCRT。使用双侧配对 t 检验评估剂量-体积直方图值的差异。对锥形束 CT 图像进行分析，以评估在 RT 过程中治疗位置的直肠剂量。将 72.0 Gy 的 IMRT 计划与 68.4 Gy 的 3DCRT 进行比较，以考虑潜在的剂量升级。
9 野 IMRT 计划（与 3DCRT 相比）改善了膀胱平均剂量和 65 Gy 或更高剂量的体积（V65）、直肠平均剂量（31.6 Gy 比 36.1 Gy；P <.001）、接受处方剂量 75%或更高的体积（24.4%比 31.0%；P <.001）和 V65（10.5%比 20.0%；P <.001）。IMRT 的优势是以膀胱和直肠接受的最大点剂量略有增加为代价。对 8 例患者的 132 个锥形束 CT 图像进行了分析；在这些扫描中，IMRT 还改善了直肠平均剂量和 V65。与 3DCRT 总剂量为 68.4 Gy 相比，IMRT 可使 72.0 Gy 的剂量增加，同时保持膀胱和直肠平均剂量、V65 和 V40 相似。
IMRT 改善了直肠和膀胱的剂量学参数，这可能允许在根治性前列腺切除术后提高剂量。未来的研究应确定这些优势是否转化为前列腺癌患者的临床结局改善。
