Abstract
BackgroundIn radiation oncology, automation of treatment planning has reported the potential to improve plan quality and increase planning efficiency. We performed a comprehensive dosimetric evaluation of the new Personalized algorithm implemented in Pinnacle3 for full planning automation of VMAT prostate cancer treatments.Material and MethodsThirteen low-risk prostate (without lymph-nodes irradiation) and 13 high-risk prostate (with lymph-nodes irradiation) treatments were retrospectively taken from our clinical database and re-optimized using two different automated engines implemented in the Pinnacle treatment system. These two automated engines, the currently used Autoplanning and the new Personalized are both template-based algorithms that use a wish-list to formulate the planning goals and an iterative approach able to mimic the planning procedure usually adopted by experienced planners. In addition, the new Personalized module integrates a new engine, the Feasibility module, able to generate an “a priori” DVH prediction of the achievability of planning goals. Comparison between clinically accepted manually generated (MP) and automated plans generated with both Autoplanning (AP) and Personalized engines (Pers) were performed using dose-volume histogram metrics and conformity indexes. Three different normal tissue complication probabilities (NTCPs) models were used for rectal toxicity evaluation. The planning efficiency and the accuracy of dose delivery were assessed for all plans.ResultsFor similar targets coverage, Pers plans reported a significant increase of dose conformity and less irradiation of healthy tissue, with significant dose reduction for rectum, bladder, and femurs. On average, Pers plans decreased rectal mean dose by 11.3 and 8.3 Gy for low-risk and high-risk cohorts, respectively. Similarly, the Pers plans decreased the bladder mean doses by 7.3 and 7.6 Gy for low-risk and high-risk cohorts, respectively. The integral dose was reduced by 11–16% with respect to MP plans. Overall planning times were dramatically reduced to about 7 and 15 min for Pers plans. Despite the increased complexity, all plans passed the 3%/2 mm γ-analysis for dose verification.ConclusionsThe Personalized engine provided an overall increase of plan quality, in terms of dose conformity and sparing of normal tissues for prostate cancer patients. The Feasibility “a priori” DVH prediction module provided OARs dose sparing well beyond the clinical objectives. The new Pinnacle Personalized algorithms outperformed the currently used Autoplanning ones as solution for treatment planning automation.
Highlights
In radiation oncology, the quality of treatment planning has a major impact on clinical outcomes as well demonstrated in several clinical trials [1, 2]
This study aimed to provide a comprehensive dosimetric evaluation of Pinnacle Personalized potential for the radiotherapy of prostate cancer in the two scenarios of low-risk and high-risk prostate cancer
The dose conformity was significantly better with AP and Pers plans than with manual VMAT plans (MP) plans in both scenarios, with Pers plans outperforming the AP plans and demonstrating a higher capability to better conform the doses to target volumes, especially to the complex concave lymph-nodal volumes
Summary
The quality of treatment planning has a major impact on clinical outcomes as well demonstrated in several clinical trials [1, 2]. Despite the worldwide implementation of the ICRU83 guidelines [3], local treatment planning protocols still have a major impact on plan quality. The relationship between the plan quality and the clinical outcomes has been recently reported, proving that failures to adhere to protocol guidelines are associated with reduced local control and survival and potentially increased toxicity [5]. An analysis of frequency and clinical severity of quality deficiencies in planning on the RTOG126 protocol demonstrated the critical impact of suboptimal plans on rectal complications [6]. Automation of treatment planning has reported the potential to improve plan quality and increase planning efficiency. We performed a comprehensive dosimetric evaluation of the new Personalized algorithm implemented in Pinnacle for full planning automation of VMAT prostate cancer treatments
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