Department of Radiation Oncology, Rush University Medical Center, Chicago, IL, USA.
Am J Clin Oncol. 2009 Oct;32(5):460-6. doi: 10.1097/COC.0b013e3181967d89.
Static field intensity modulated radiation therapy (IMRT) has demonstrated dosimetric and clinical benefits over 3-dimensional conformal radiation therapy. TomoTherapy is a unique form of IMRT that may offer further improvements.
The study population consisted of 15 patients with low-risk prostate cancer treated at Rush University with TomoTherapy (n = 7) or IMRT (n = 8). For each patient, both a TomoTherapy plan and an IMRT plan were generated using identical planning objectives. The planning target volume (PTV) was defined as the prostate and proximal seminal vesicles plus a margin. The prescription dose was 7740 cGy in 43 fractions. Radiation Therapy Oncology Group (RTOG) normal tissue guidelines were used as constraints, and the PTV coverage was made equivalent for the paired plans by equalizing the PTV V100. RTOG benchmark DVH values for the rectum and bladder and mean dose to the penile bulb were recorded. The volume of PTV receiving ≥ 105% of the prescription dose was measured.
The mean DVH values for each of the RTOG constraints for rectum and bladder were significantly improved using TomoTherapy. The volume of the PTV that received at least 105% of the dose was higher with IMRT (11.7% vs. 0.2%, <0.001). The mean dose to the penile bulb was higher with TomoTherapy (40.4 Gy vs. 27.4 Gy, P = 0.005).
TomoTherapy offers a more favorable dose distribution to the bladder and rectum, as well as improved target homogeneity in comparison with IMRT.
静磁场强度调制放射治疗（IMRT）在剂量学和临床方面优于 3 维适形放射治疗。TomoTherapy 是一种独特的 IMRT 形式，可能会提供进一步的改进。
研究人群由 15 名低危前列腺癌患者组成，他们在 Rush 大学接受 TomoTherapy（n = 7）或 IMRT（n = 8）治疗。对于每个患者，都使用相同的计划目标生成了 TomoTherapy 计划和 IMRT 计划。计划靶区（PTV）定义为前列腺和近端精囊加上一个边界。处方剂量为 7740cGy，分为 43 个部分。使用放射治疗肿瘤学组（RTOG）正常组织指南作为约束条件，并通过使 PTVV100 相等来使配对计划的 PTV 覆盖范围相等。记录了直肠和膀胱的 RTOG 基准剂量体积直方图（DVH）值和阴茎球的平均剂量。测量了接受处方剂量≥105%的 PTV 体积。
使用 TomoTherapy 时，直肠和膀胱的每个 RTOG 约束条件的平均 DVH 值均得到显著改善。接受至少 105%剂量的 PTV 体积更高（11.7%对 0.2%，<0.001）。TomoTherapy 组的阴茎球平均剂量更高（40.4Gy 对 27.4Gy，P = 0.005）。
与 IMRT 相比，TomoTherapy 为膀胱和直肠提供了更有利的剂量分布，并改善了靶区均匀性。
