Cardiac dose reduction using deep inspiratory breath hold (DIBH) in radiation treatment of left sided breast cancer patients with breast conservation surgery and modified radical mastectomy.

PURPOSE: Deep inspiration breath hold (DIBH) reduces heart and pulmonary doses during left-sided breast radiation therapy (RT); however, there is limited information whether the reduction in doses is similar in patients with modified radical MRM (MRM) and breast conservation surgery (BCS). The primary objective was to determine whether DIBH offers greater dosimetric reduction in cardiac doses in patients with MRM as compared to BCS with secondary objectives of documenting time consumed in counseling, simulation and planning such techniques. METHODS: Thirty patients with diagnosis of left sided breast cancer underwent CT simulation both free breathing (FB) and DIBH. Patients were grouped into two cohorts: MRM (n = 20) and BCS (n = 10). 3D-conformal plans were developed and FB was compared to DIBH for entire group (n = 30) and each cohort using Wilcoxon signed-rank tests for continuous variables and McNemar's test for discrete variables. The percent relative reduction conferred by DIBH in mean heart (Dmean heart) and left anterior descending artery dose (LADmean and LADmax), heart V25,V10, V2 and ipsilateral DmeanLung,V20, V12 were compared between the two cohorts using Wilcox rank-sum testing. A two-tailed p-value ≤ 0.05 was considered statistically significant. Time consumed during FB and DIBH from patient counseling to planning was documented. RESULTS: Patients undergoing BCS had comparable boost target coverage on DIBH and FB. For the overall group (n = 30), DIBH reduced Dmean heart and LAD dose, V25, V10 and V2 doses for the heart and Ipsilateral DmeanLung, V20, V12 which was statistically significant. For individual cohorts DIBH did not significantly reduce the lung (Ipsilateral DmeanLung, V20, V12) and LAD (LADmean and LADmax) doses for BCS while significant reduction in all cardiopulmonary doses was seen in MRM cohort. Despite significant reductions with DIBH in MRM, ipsilateral lung constraint of V12 < 15% was less commonly achieved in MRM (n = 11, 55%) requiring nodal radiation as compared to BCS (n = 3, 30%). Percent reduction in all cardiac and pulmonary dosimetric parameters with DIBH was similar in the MRM cohort as compared to BCS cohort. In total 73.1 ± 2.6 min was required for FB as compared to 108.1 ± 4.1 min in DIBH. CONCLUSION: DIBH led to significant reduction of cardiac doses in both MRM and BCS. Reduction of lung and LAD doses were significant in MRM cohort. All cardiac constraints were met with DIBH in both cohorts, lung constraints were less frequently met in MRM cohort requiring nodal radiation.

Comparison of set-up errors by breast size on wing board by portal imaging.

AIM: To quantify and compare setup errors between small and large breast patients undergoing intact breast radiotherapy. METHODS: 20 patients were inducted. 10 small/moderate size breast in arm I and 10 large breast in arm II. Two orthogonal and one lateral tangent portal images (PIs) were obtained and analyzed for systematic (Σ) and random (σ) errors. Effect of no action level (NAL) was also evaluated retrospectively. RESULTS: 142 PIs were analyzed. Σ(mm) was 3.2 versus 6.7 (p = 0.41) in the mediolateral (ML) direction, 2.1 versus 2.9 (p = 0.06) in the craniocaudal (CC) and 2.2 versus 3.6 (p = 0.08) in the anteroposterior (AP) direction in small and large breast, respectively. σ(mm) was 3.0, 3.3 and 3.3 for small breast and 4.1, 3.7 and 3.2 for large breast in the ML, CC and AP direction (p = 0.07, 0.86, 0.37), respectively. 3 D Σ(mm) was 2.7 versus 4.2 (p = 0.01) and σ(mm) was 2.5 versus 3.2 (p = 0.14) in arm I and II, respectively. The standard deviation (SD) of variations (mm) in breast contour depicted by central lung distance (CLD) was 5.9 versus 7.4 (p < 0.001), central flash distance (CFD) 6.6 versus 10.5 (p = 0.002), inferior central margin (ICM) 4 versus 4.9 (p < 0.001) in arm I and II, respectively. NAL showed a significant reduction of systematic error in large breast in the mediolateral direction only. CONCLUSION: Wing board can be used in a busy radiotherapy department for setting up breast patients with a margin of 1.1 cm, 0.76 cm and 0.71 cm for small breasts and 1.96 cm, 1.12 cm and 0.98 cm for large breast in the ML, AP and CC directions, respectively. The large PTV margin in the mediolateral direction in large breast can be reduced using NAL. Further research is needed to optimize positioning of large breasted women.