Purpose: The benefits of deep-inspiration breath-hold (DIBH) radiation technique (RT) for left breast patients (LBPs) are well known, but there is little awareness about challenges and risks associated with this technique. We propose the upfront criterion, based on estimation of heart V20Gy (volume of the heart which receives 20 Gy), to select the LBPs for free breathing (FB) RT.
Methods: 38 patients, who were referred for adjuvant radiotherapy after left breast conserving surgery were analyzed in this study. All patients were simulated in the supine position and immobilized with breast board. Minimal computer tomography (CT) scan including heart volume was acquired for all patients. Heart V20Gy was estimated using pre-selection heart V20Gy method (based of maximum heart distance included in the field), and FB CT was acquired for patient with V20Gy<5% and DIBH for patients with V20Gy>5%. Using this selection, 23 patients were selected for FB RT and 15 patients for DIBH RT. The prescription doses were 42.56 Gy/16 Fx and 40.05 Gy/15 Fx. Patients were treated with tangential conformal fields with a multileaf collimator using 6 MV and 10 MV. To avoid hot spots field-in-field techniques was used. All plans were normalized for V95%>=95% with maximum dose of 107%.
Results: All 23 pre-selected for FB RT patients complied the criterion calculated V20Gy <5% with mean V20Gy = 1.11 Gy. Mean heart doses were in the range of 0.94 – 3.67 Gy with an average of 1.89 ± 0.84 Gy. 87% of the FB RT patients had mean heart dose of <3 Gy.
Conclusion: This work demonstrates the assessment of pre-selection criterion, based on evaluation of heart V20Gy, with respect to selecting the treatment technique of FB or DIBH for LBPs in order to avoid unnecessary complexity from simulation to treatment and also reducing the patient burden on DIBH techniques.
Not Applicable / None Entered.