Abstract

Purpose: Deep Inspiration Breath Hold (DIBH) is a well-established method in reducing their radiation of the heart and lung when treating Left sided Breast cancer with EBRT. There is, however, limited literature comparing different methods of DIBH. The purpose of our study is to compare the efficacy of Active Breathing Co-ordinator (ABC) against Voluntary Breath Hold (VBH).
Methods and Materials: 20 patients were selected whom had left sided Breast cancer and underwent EBRT. 10 patients underwent Active Breathing Coordinator (ABC) using specialized Elekta equipment and 10 performed Voluntary Breath Hold (VBH) following the JOVE protocol. All 20 patients had two CT simulation scans: one in FB and the other in DIBH. Treatment plans were generated using a tangential radiation therapy technique. A dosimetric comparison was made between the two plans as per EviQ guidelines. Measurements were collected for Lung V20 (%), Ipsilateral Lung Maximum Depth (cm), Heart V25 (%), Heart (Gy), and Contralateral Breast V3 (%). 9 patients had LAD mean values measured.
Results: When using the Mann-Whitney U test to compare ABC to VBH: the VBH technique yielded a median Heart (Gy) of 1.75 (IQR=1.15) and median Contralateral Breast V3 of 0.31% (IQR=0.89%). The ABC technique yielded a median Heart (Gy) of 1.44 (IQR=.60) and for the Contralateral Breast V3 a median of 0.00% (IQR=0.00%). The ABC technique was statistically superior with U=15.000 p =.008 (Heart (Gy)) and U=24.500 p=.035 (Contralateral Breast V3) respectively. None of the other parameters had statistically significant median differences.
When using the Wilcoxon signed-rank test to compare DIBH to FB: The VBH technique yielded a median Ipsilateral Lung max (cm) of 2.3, Ipsilateral Lung V20 of 13.92%, Lung V20 of 6.45%, Heart V25 of 2.41%, Heart (Gy) of 2.7, and LAD mean (Gy) of 23.4. The DIBH technique was statistically superior in these parameters and yielded a median Ipsilateral Lung max (cm) of 2.6 (Z=-3.072 p=.002), Ipsilateral Lung V20 of 12.33% (Z=-2.576 p=.01), Lung V20 of 5.84% (Z=-2.296 p=.01), Heart V25 of 0.26% (Z=- 3.921 p<.001), Heart (Gy) of 1.43 (Z=-3.921 p<.001), and LAD mean (Gy) of 7.7 (Z=-2.201 p=.028).
Conclusion: ABC is a superior breath hold technique when compared to VBH and will yield lesser long-term cardiac complications. However, it is a more expensive modality and can be poorly tolerated by patients. Surrounding structures incur significantly less radiation when using DIBH than FB which is consistent with previous studies in the literature. Further studies are required to confirm this data.