Intensity-Modulated Radiation Therapy (IMRT) Versus Rapidarc in the Treatment of Carcinoma Left Breast – Finding the Optimal Radiation Therapy Technique

This study aimed to evaluate the dosimetric variations and treatment efficacy between intensity-modulated radiotherapy (IMRT) and double-arc RapidArc for irradiation of carcinoma left breast, focusing on adequate target coverage, sparing of organs at risk (OARs), delivered monitor units (MUs) per fraction, and treatment delivery time. This prospective, observational study was conducted on 30 patients with carcinoma left breast. All these patients were treated with adjuvant radiation therapy.  We generated two plans for each of these patients: IMRT and double-arc RapidArc technique. The target volume and OARs were analyzed using dose-volume histograms (DVHs). The average MUs and the treatment time were used as markers to assess the efficacy of treatment delivery. The planning target volume parameters such as homogeneity and conformity index were similar for all the plans with both techniques. With IMRT, statistically significantly better sparing of I/L lung, heart, C/L breast, C/L lung, and esophagus were achieved as compared to RapidArc. We found that RapidArc resulted in significantly lower MUs (535.05 ± 105.42) than IMRT (913.57 ± 129.35). Treatment delivery time was statistically shorter with RapidArc as compared to IMRT (p=0.001).  This study concluded that both IMRT and RapidArc plans have similar target coverage in terms of homogeneity and conformality indexes. Better OARs sparing was noticed with IMRT while RapidArc enabled higher efficacy with lower MUs and shorter treatment delivery time. However, further studies are needed to establish these dosimetric advantages being translated to improvements in the clinical outcomes of these patients.