PURPOSE To report the achieved dosimetry in the ACCEL trial and compare the results to reported dosimetry from the major accelerated partial breast irradiation (APBI) phase III trials. METHODS The ACCEL trial was a single arm, phase II, prospective cohort study. A five-field, inverse-planned, IMRT strategy was employed using a class solution technique to increase planning consistency including high dose conformity and low normal tissue dose to the ipsilateral breast. RESULTS Between 2016 and 2019, 283 patients were treated with 27 Gy in five fractions in consecutive days. The average PTV conformity index was 1.1. For the ipsilateral breast, the median (range) volume receiving 95% and 50% of the prescription dose was 9.7% (3.2-22.4) and 30.3% (11.1-54.6), respectively. Compared to major APBI phase III trial constraints, this reduction in irradiated volume at the 95% and 50% isodose levels represents a reduction of 209 cm3 and 265 cm3, respectively. CONCLUSION The IMRT planning strategy employed in the ACCEL trial demonstrated consistent and superior dosimetry by comparison to conventionally used 3D CRT techniques. Future APBI trials should update dosimetric constraints.

中文翻译：

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ACCEL 试验的结果：加速部分乳房照射中的剂量测定

目的 报告 ACCEL 试验中实现的剂量测定，并将结果与​​主要加速部分乳房照射 (APBI) III 期试验报告的剂量测定进行比较。方法 ACCEL 试验是一项单组、II 期、前瞻性队列研究。采用五场、逆向计划的 IMRT 策略，使用类解决方案技术来提高计划一致性，包括对同侧乳房的高剂量一致性和低正常组织剂量。结果 2016 年至 2019 年间，283 名患者连续接受 5 次 27 Gy 治疗。平均 PTV 一致性指数为 1.1。对于同侧乳房，接受 95% 和 50% 处方剂量的中位（范围）体积分别为 9.7% (3.2-22.4) 和 30.3% (11.1-54.6)。与主要的 APBI III 期试验限制相比，在 95% 和 50% 等剂量水平下辐照体积的减少分别代表减少了 209 cm3 和 265 cm3。结论 与传统使用的 3D CRT 技术相比，ACCEL 试验中采用的 IMRT 计划策略证明了一致且优越的剂量测定。未来的 APBI 试验应更新剂量限制。