Intensity-modulated radiotherapy versus three-dimensional conformal radiotherapy during deep inspiratory breath hold for left-sided whole-breast irradiation: A comparative analysis

Aim Deep inspiratory breath hold (DIBH) during left-breast irradiation helps to minimise cardiac irradiation by physically separating the heart from the left breast. The dose to organs-at-risk in intensity-modulated radiotherapy (IMRT) and opposed tangent three-dimensional conformal radiotherapy (3DCRT) during DIBH in patients with left-sided breast cancer was compared. Materials and methods A total of 20 consecutive patients with left-sided breast cancer had a computed tomography scan utilising DIBH. Mean volumes of the heart, left anterior descending coronary artery, total lung and right breast receiving 5-95% of the prescription dose were calculated. Results Target volume homogeneity was improved with IMRT and average mean dose to target was higher for 3DCRT (51·03 Gy) compared with IMRT (50·47 Gy, p<0·01). The average mean dose to the heart was lower with 3DCRT (87 versus 77 cGy, p<0·01). The average mean dose to the contralateral breast was also lower with 3DCRT (19 versus 17 cGy, p<0·01). Less monitor units (MUs) were required with 3DCRT with an average difference of 225 MU/fraction (p<0·01).