RapidPlan development of VMAT plans for cervical cancer patients in low- and middle-income countries

Abstract

Cervical cancer has a high incidence and mortality rate in low- and middle-income countries (LMICs) largely due to limited resources and insufficient staffing. Knowledge-based planning (KBP) could alleviate understaffing issues by streamlining the radiotherapy treatment planning process. Varian's KBP system (RapidPlan) was used to develop a model capable of producing volumetric modulated arc therapy (VMAT) plans for cervical cancer patients. Plan data from 46 patients previously treated at MD Anderson Cancer Center (MDACC) were used to create and train the model which was then applied to 32 patients excluded from the training process. Dose volume histogram (DVH) values for the planning target volume (PTV_High), bladder, rectum, and bowel were evaluated for the validation plans and found to have satisfied the required PTV coverage and organ-at-risk (OAR) dose constraints. The average value for PTV_High D95.0% was 48.0 Gy (sd = 3.0 Gy) for existing clinical plans and 48.4 Gy (sd = 2.6 Gy) for the validation plans. The mean dose for the bladder, rectum, and bowel was 39.8 Gy (sd = 3.9 Gy), 41.6 Gy (sd = 5.2 Gy), and 21.6 Gy (sd = 5.0 Gy) for existing clinical plans and 38.9 Gy (sd = 4.0 Gy), 40.3 Gy (sd = 4.8 Gy), and 21.5 Gy (sd = 4.6 Gy) for validation plans, respectively. A TOST test showed that the p values for the PTV_High D95.0% (p < 0.001), rectum V30Gy (p = 0.039), and mean dose to the bladder (p = 0.0014), rectum (p = 0.025), and bowel (p = 0.006) were statistically significant within a 5% equivalence margin of the clinical value thereby providing strong evidence of equivalence. Based on this statistical analysis, it was determined that the model was capable of generating treatable VMAT plans for cervical cancer patients.