Rapid Selection of Patients Suitable for Deep Inspiration Breath-Hold Using an Automatic Delineating System and RapidPlan Model in Patients With Left Breast Cancer Undergoing Adjuvant Radiation Therapy With IMRT

Abstract

PurposeThis study aimed to determine whether radiotherapy plans created using an automatic delineating system and a RapidPlan (RP) module could rapidly and accurately predict heart doses and benefit from deep inspiratory breath-hold (DIBH)in left breast cancer patients. Methods and MaterialsOne hundred thirty-six clinically approved free breathing (FB) plans for patients with left breast cancer were included, defined as manual delineation–manual plan (MD–MP). A total of 104/136 plans were selected for RP model training. A total of 32/136 patients were automatically delineated by software, after which the RP generated plans, defined as automatic delineation–RapidPlan (AD–RP). In addition, 40 patients who used DIBH were included to analyze differences in heart benefits from DIBH. ResultsTwo RP models were established for post breast-conserving surgery (BCS) and post modified radical mastectomy (MRM). There were no significant differences in most of the dosimetric parameters between the MD–MP and AD–RP. The heart doses of the two plans were strongly correlated in patients after BCS (0.80 ≤ r ≤ 0.88, P < 0.05) and moderately correlated in patients after MRM (0.46 ≤ r ≤ 0.58, P < 0.05). The RP model predicted the mean heart dose (MHD) within ± 59.67 cGy and ± 63.32 cGy for patients who underwent the two surgeries described above. The heart benefits from DIBH were significantly greater in patients with FB-MHD ≥ 4 Gy than in those with FB-MHD < 4 Gy. ConclusionsThe combined automatic delineation RP model allows for the rapid and accurate prediction of heart dose under FB in patients with left breast cancer. FB-MHD ≥ 4 Gy can be used as a dose threshold to select patients suitable for DIBH.