Modulated volumetric arc therapy for total marrow irradiation: A feasibility study in the oncology hospital of CMN SXXI from a medical physics approach.

Abstract

The objective of this study is to explore the use of volumetric arc therapy (VMAT) to perform total marrow irradiation (TMI) and compare its results to the standard TBI technique in the Mexican public health system. The standard total body irradiation (TBI) technique is used with chemotherapy as a method of a pre-transplant conditioning of the bone marrow. In this technique, the whole body of the patient is considered to be PTV and irradiated generating toxicities and raising concerns about possible development of radio-induced tumors. Through the use of simulation tomography of 12 patients previously treated with TBI, twelve different treatment plans were created with the proposed TMI technique and compared with the conventional protocol, the treatment plans were evaluated with a dose volume histogram analysis and quality assurance was evaluated with a portal dosimetry system using the gamma index criteria 3%/3mm. Experimental results show an increasing dose to 99% of PTV of up to 41.1% by using TMI with the VMAT technique. The mean average dose to PTV was increased up to 19.3%. The use of the new TMI technique caused an improvement in the mean average dose to 99% of the PTV as well the homogeneity of the dose distribution prescribed at the PTV while leading to a better reproducibility of the treatment. The Qa of all the plans met the criterion of gamma index 3mm-3%. The results analysis shows that the proposed TMI technique is feasible and applicable in the Mexican public health system.