Purpose: To investigate the use of a Plan Quality Prediction Software in improving patient specific quality assurance (PSQA) passing rates.
Methods: Five prostate patients, whose clinical boost plans were generated using Pinnacle³ v16.2.1 (Philips, Amsterdam, Netherlands) and had failed institutional PSQA tolerances (95% passing at 3%/2mm, global gamma criteria), were investigated. PlanIQ (Sun Nuclear Corp., Melbourne, FL) was utilized to retroactively investigate the difference between the clinical DVH for the Bladder, Rectum, and Penile Bulb and the feasibility DVH. These differences were compared with five patients whose clinical QA passed institutional criteria. Three re-plans were created in Pinnacle³ v16.4.2 for each failing plan: 1.) pushing the DVHs to represent the DVHs of the clinical plan, 2.) using PlanIQ to set planning objectives, and 3.) using PlanIQ but restricting the minimum segment area. PSQA was measured for each re-plan and the relationship between plan passing rates was analyzed.
Results: Comparing the failing and passing clinical plans, no significance was found in the difference between the clinical DVH and feasibility DVH for the Bladder or Rectum. However, at a feasibility score of 0.1, the difference between the clinical DVH and feasibility DVH for the Penile Bulb was found to be significant (p=0.032) with the failing plans exhibiting an average DVH difference of -2.23±0.88 Gy and the passing plans exhibiting an average DVH difference of -0.57±0.44 Gy. After re-planning these cases in v16.4.2, improved PSQA passing rates for failing plans were found when using PlanIQ, with average improvement of 1.1±2.5%. Combining PlanIQ with a restricted minimum segment area showed further improvement in PSQA passing rates, with average improvement of 2.6±1.7%.
Conclusion: PSQA passing rates are influenced by many factors, but PlanIQ was shown to be a useful tool in improving PSQA passing rates for failing plans especially when combined with restricted segment areas.