比较适形调强放疗技术与 CyberKnife 立体定向体部放疗治疗低危前列腺癌的治疗计划研究。
A treatment planning study comparing IMRT techniques and cyber knife for stereotactic body radiotherapy of low-risk prostate carcinoma.
机构信息
Department of Radiation Oncology of the University Hospital Muenster, Albert-Schweitzer-Campus 1, Gebäude 1, 48149, Muenster, Germany.
出版信息
Radiat Oncol. 2019 Aug 9;14(1):143. doi: 10.1186/s13014-019-1353-6.
PURPOSE
Comparing radiation treatment plans by using the same safety margins and dose objectives for all techniques, to ascertain the optimal radiation technique for the stereotactic body radiotherapy (SBRT) of low-risk prostate cancer.
MATERIAL AND METHODS
Treatment plans for 27 randomly selected patients were compared using intensity-modulated (IMRT) techniques as Sliding Window (SW), volumetric modulated arc therapy (VMAT), and helical tomotherapy (HT), as well as Cyber Knife (CK) system. The target dose was calculated to 36.25 Gy delivered in five fractions over 1 week. Dosimetric indices for target volume and organs at risk (OAR) as well as normal tissue complication probability (NTCP) of late rectal and urinary bladder toxicities were analyzed.
RESULTS
The CK provided lower homogeneity in the target volume, but higher values for most of the conformity indices compared to the IMRT approaches. The SW demonstrated superior rectum sparing at medium-to-high dose range (V18 Gy - V32.6 Gy) compared to other techniques (p < 0.05). The whole urinary bladder experienced the best shielding by SW and VMAT at the medium dose (V18 Gy, p < 0.05 versus CK), however we obtained no relevant differences between techniques at the high dose. Generally, the CK demonstrated significantly superior rectum and bladder exposure at V18 Gy as compared to HT, SW, and VMAT. For the rectum, mean NTCP values were significantly superior for HT (NTCP = 2.3%, p < 0.05), and for urinary bladder, the NTCP showed no significant advantages for any technique.
CONCLUSION
No absolute dosimetric advantage was revealed to choose between CK or IMRT techniques for the SBRT of low-grade prostate cancer. Using the same safety margins and dose objectives, IMRT techniques demonstrated superior sparing of the rectum and bladder at a medium dose compared to CK. Comparing different IMRT approaches SW displayed superior rectum sparing at a medium-to-high dose range, whereas both SW and RA revealed superior bladder sparing compared to HT. HT demonstrated a significantly lower NTCP outcome compared to CK or IMRT techniques regarding the rectum. Radiation plans can be optimized further by an individual modification of dose objectives independent of the treatment plan strategy.
目的
通过对所有技术使用相同的安全边界和剂量目标来比较放射治疗计划，以确定低危前列腺癌立体定向体放射治疗（SBRT）的最佳放射技术。
材料和方法
比较了 27 名随机选择的患者的治疗计划，使用强度调制（IMRT）技术，如滑动窗口（SW）、容积调制弧形治疗（VMAT）和螺旋断层治疗（HT），以及 CyberKnife（CK）系统。靶区剂量计算为 36.25Gy，每周 5 次分割。分析了靶区和危及器官（OAR）的剂量学指标，以及晚期直肠和膀胱毒性的正常组织并发症概率（NTCP）。
结果
CK 提供了较低的靶区均匀性，但与 IMRT 方法相比，大多数适形指数的值更高。SW 在中至高剂量范围（V18Gy-V32.6Gy）中显示出更好的直肠保护，优于其他技术（p<0.05）。SW 和 VMAT 在中剂量时为整个膀胱提供了最佳的屏蔽效果（V18Gy，与 CK 相比 p<0.05），但在高剂量时，各技术之间没有明显差异。一般来说，CK 在 V18Gy 时对直肠和膀胱的暴露明显优于 HT、SW 和 VMAT。对于直肠，HT 的平均 NTCP 值明显较高（NTCP=2.3%，p<0.05），对于膀胱，任何技术的 NTCP 均无明显优势。
结论
对于低级别前列腺癌的 SBRT，在 CK 或 IMRT 技术之间没有发现绝对的剂量优势。使用相同的安全边界和剂量目标，IMRT 技术在中剂量时对直肠和膀胱的保护优于 CK。比较不同的 IMRT 方法，SW 在中至高剂量范围内显示出更好的直肠保护，而 SW 和 RA 均显示出优于 HT 的膀胱保护。HT 与 CK 或 IMRT 技术相比，直肠的 NTCP 结果明显较低。可以通过独立于治疗计划策略的剂量目标的个体修改来进一步优化放射计划。
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