局部晚期胰腺癌（LAPC）患者剂量递增立体定向体部放射治疗（SBRT）的剂量学可行性研究：是时候提高标准了。
Dosimetric Feasibility Study of Dose Escalated Stereotactic Body Radiation Therapy (SBRT) in Locally Advanced Pancreatic Cancer (LAPC) Patients: It Is Time to Raise the Bar.
作者信息
Mazzarotto Renzo, Simoni Nicola, Guariglia Stefania, Rossi Gabriella, Micera Renato, De Robertis Riccardo, Pierelli Alessio, Zivelonghi Emanuele, Malleo Giuseppe, Paiella Salvatore, Salvia Roberto, Cavedon Carlo, Milella Michele, Bassi Claudio
机构信息
Department of Radiation Oncology, University of Verona Hospital Trust, Verona, Italy.
Department of Medical Physics, University of Verona Hospital Trust, Verona, Italy.
出版信息
Front Oncol. 2020 Dec 17;10:600940. doi: 10.3389/fonc.2020.600940. eCollection 2020.
BACKGROUND AND OBJECTIVE
To assess the dosimetric feasibility of a stereotactic body radiotherapy (SBRT) dose escalated protocol, with a simultaneous integrated boost (SIB) and a simultaneous integrated protection (SIP) approach, in patients with locally advanced pancreatic cancer (LAPC).
MATERIAL AND METHODS
Twenty LAPC lesions, previously treated with SBRT at our Institution, were re-planned. The original prescribed and administered dose was 50/30/25 Gy in five fractions to PTV (tumor-vessel interface [TVI])/PTV (tumor volume)/PTV (overlap area between PTV and planning organs at risk volume [PRV]), respectively. At re-planning, the prescribed dose was escalated up to 60/40/33 Gy in five fractions to PTV/PTV/PTV, respectively. All plans were performed using an inspiration breath hold (IBH) technique and generated with volumetric modulated arc therapy (VMAT). Well-established and accepted OAR dose constraints were used (D < 33 Gy for luminal OARs and D < 38 Gy for corresponding PRV). The primary end-point was to achieve a median dose equal to the prescription dose for the PTV with D≥ 95% (95% of prescription dose is the minimum dose), and a coverage for PTV and PTV of D≥95%, with minor deviations in OAR dose constraints in < 10% of the plans.
RESULTS
PTV median (± SD) dose/D/conformity index (CI) were 60.54 (± 0.85) Gy/58.96 (± 0.86) Gy/0.99 (± 0.01), respectively; whilst PTV median (± SD) dose/D were 44.51 (± 2.69) Gy/38.44 (± 0.82) Gy, and PTV median (± SD) dose/D were 35.18 (± 1.42) Gy/33.01 (± 0.84) Gy, respectively. With regard to OARs, median (± SD) maximum dose (D) to duodenum/stomach/bowel was 29.31 (± 5.72) Gy/25.29 (± 6.90) Gy/27.03 (± 5.67) Gy, respectively. A minor acceptable deviation was found for a single plan (bowel and duodenum D=34.8 Gy). V38 < 0.5 cc was achieved for all PRV luminal OARs.
CONCLUSIONS
In LAPC patients SBRT, with a SIB/SIP dose escalation approach up to 60/40/33 Gy in five fractions to PTV/PTV/PTV, respectively, is dosimetrically feasible with adequate PTVs coverage and respect for OAR dose constraints.
背景与目的
评估立体定向体部放射治疗（SBRT）剂量递增方案（采用同步整合加量（SIB）和同步整合保护（SIP）方法）用于局部晚期胰腺癌（LAPC）患者的剂量学可行性。
材料与方法
对本机构先前接受过SBRT治疗的20例LAPC病灶进行重新计划。原规定及给予的剂量分别为：肿瘤血管界面（TVI）的计划靶体积（PTV）50 Gy分5次、肿瘤体积的PTV 30 Gy分5次、PTV与危及器官计划体积（PRV）重叠区域的PTV 25 Gy分5次。重新计划时，规定剂量分别递增至PTV/PTV/PTV的60 Gy/40 Gy/33 Gy分5次。所有计划均采用吸气屏气（IBH）技术并通过容积调强弧形治疗（VMAT）生成。使用既定且公认的危及器官剂量限制（管腔内危及器官D < 33 Gy，相应PRV的D < 38 Gy）。主要终点是PTV的中位剂量等于处方剂量且D≥95%（95%处方剂量为最小剂量），PTV和PTV的覆盖率D≥95%，且<10%的计划中危及器官剂量限制有微小偏差。
结果
PTV中位（±标准差）剂量/D/适形指数（CI）分别为60.54（±0.85）Gy/58.96（±0.86）Gy/0.99（±0.01）；而PTV中位（±标准差）剂量/D为44.51（±2.69）Gy/38.44（±0.82）Gy，PTV中位（±标准差）剂量/D为35.18（±1.42）Gy/33.01（±0.84）Gy。关于危及器官，十二指肠/胃/肠的中位（±标准差）最大剂量（D）分别为29.31（±5.72）Gy/25.29（±6.90）Gy/27.03（±5.67）Gy。在单个计划中发现一个可接受的微小偏差（肠和十二指肠D = 34.8 Gy）。所有PRV管腔内危及器官均实现V38 < 0.5 cc。
结论
在LAPC患者中，SBRT采用SIB/SIP剂量递增方法，分别给予PTV/PTV/PTV的60 Gy/40 Gy/33 Gy分5次，在剂量学上是可行的，PTV覆盖率充足且符合危及器官剂量限制。
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