Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut.
Tulane University School of Medicine, New Orleans, Louisiana.
Pract Radiat Oncol. 2011 Apr-Jun;1(2):126-34. doi: 10.1016/j.prro.2010.11.002. Epub 2011 Apr 8.
To describe and compare a novel, modified dynamic conformal arc (MDCA) technique for lung stereotactic body radiation therapy with the standard noncoplanar beam (NCB) technique based on stereotactic body radiation therapy (SBRT) coverage, dose conformality, normal tissue constraints, and treatment time.
Twenty consecutive medically inoperable patients with early stage, peripheral, non-small cell lung cancer treated with SBRT using an NCB technique were re-planned with a novel MDCA technique. Treatment plans were compared based on Radiation Therapy Oncology Group (RTOG) 0236 criteria for planning treatment volume (PTV) coverage and normal tissue dose constraints, as well as high- and moderate-dose conformality. Treatment times necessary to deliver the NCB plans were compared with the times of a separate group of 12 consecutive patients treated with the MDCA technique at our institution.
The MDCA technique resulted in improved coverage of the cranial and caudal regions of the PTV and generated plans that were significantly more conformal by all high-dose criteria proposed by the RTOG protocol. In terms of moderate-dose criteria, MDCA plans had a significantly lower maximum dose (2 cm from the PTV), whereas the ratio of the 50% dose volume to the volume of the PTV was equivalent between the 2 techniques. All normal tissue dose constraints proposed in the RTOG 0236 protocol were met by each plan, although the median lung V20 and mean lung dose were slightly higher in the MDCA plans, whereas the chest wall dose was slightly lower. A 42% reduction in treatment time was observed when patients treated with the NCB technique were compared with a separate cohort of 12 patients treated with the MDCA technique (P < .0001).
The new MDCA technique described in this study resulted in enhanced PTV coverage, improved high- and moderate-dose conformality, simplified treatment planning, and reduced treatment time compared with results using the standard NCB technique.
描述并比较一种新的改良动态适形弧形（MDCA）技术与基于立体定向体部放射治疗（SBRT）覆盖范围、剂量适形性、正常组织约束和治疗时间的标准非共面射束（NCB）技术用于肺部立体定向体部放射治疗的情况。
对 20 例因医学原因无法手术的早期、周围性、非小细胞肺癌患者，采用 NCB 技术进行 SBRT 治疗，对其进行新的 MDCA 技术再计划。根据 RTOG 0236 计划靶区（PTV）覆盖和正常组织剂量约束以及高剂量和中剂量适形性的标准，对治疗计划进行比较，并比较了在我院采用 MDCA 技术治疗的 12 例连续患者所需的治疗时间与 NCB 计划所需的治疗时间。
MDCA 技术可改善 PTV 颅顶和尾端区域的覆盖范围，并通过 RTOG 方案提出的所有高剂量标准生成更符合适形性的计划。在中剂量标准方面，MDCA 计划的最大剂量（距 PTV 2cm 处）显著降低，而两种技术的 50%剂量体积与 PTV 体积比相当。RTOG 0236 方案中提出的所有正常组织剂量限制均由每个计划满足，尽管 MDCA 计划的中位数肺 V20 和平均肺剂量略高，而胸壁剂量略低。与采用 NCB 技术治疗的患者相比，采用 MDCA 技术治疗的 12 例患者的治疗时间减少了 42%（P<0.0001）。
与标准 NCB 技术相比，本研究中描述的新 MDCA 技术可提高 PTV 覆盖范围、改善高剂量和中剂量适形性、简化治疗计划和缩短治疗时间。
