Room: AAPM ePoster Library
Purpose: The purpose of this research is to compare the impact of using high definition multi-leaf collimator (HD-MLC) versus the normal-sized multi-leaf collimator (MLC) on treatment plans of patients with lung lesions, who had been treated with stereotactic body radiation therapy (SBRT).
Methods: 50 treatment plans of 25 patients with HD MLCs and normal-sized MLCs, having leaf-widths 2.5 and 5 mm respectively, were compared to quantify dosimetric and radiobiological parameters by keeping all other parameters same. 18 of those had originally been planned with HD-MLC and 7 with normal MLC. Dosimetric parameters conformity indices (CI), gradient indices (GI) and heterogeneity indices (HI) were compared. The radiobiological parameters were evaluated by normal tissue complication probability (NTCP) and tumor control probability (TCP) based on the Niemierko’s equivalent uniform dose (EUD) method.
Results: The mean CI and HI values were higher by 1.07% and 5.30%, respectively for the HD-MLC as compared to the normal MLC while the mean GI value was lower by 1.57% for the HD-MLC relative to the normal MLC. The average EUD and TCP values were increased by 0.15% and 0.03%, respectively for the HD-MLC.
Conclusion: The results of this study showed that there is dosimetric and radiobiological merit of the HD-MLC over the normal MLC. However, the improvement was not consistent with all the plans and further research is in progress with a large cohort of patient cases in order to validate these preliminary results.
Not Applicable / None Entered.