The correlation between dose homogeneity index and target volume in intracavitary brachytherapy treatment plans of cervical cancer patients

Abstract

Aim: The aim is to calculate and correlate dose homogeneity index (DHI) with the target volume of intracavitary brachytherapy (ICBT) plans for cervical cancer patients. Introduction: In the case of brachytherapy, the dose distribution is heterogeneous as a very high radiation dose gradient is there in the vicinity of the radiation source. To assess the treatment plans, one of the objective tools is DHI which can give a choice for making a favorable plan with maximum homogeneous coverage of tumor and protects normal tissues at the same time. In this study, DHI was calculated and correlated with clinical target volume. Materials and Methods: Forty-five treatment plans of ICBT of cervical cancer patients were generated. DHI was calculated for all these treatment plans. These treatment plans were divided into six groups according to the volume of clinical targets, and data were analyzed to find out the correlation between DHI and clinical target volume. Results: The minimum, maximum, and mean values of DHI for all the treatment plans were 0.0045, 0.4998, and 0.2389, respectively. The minimum and maximum values of DHI was seen for clinical target volume of 19.99 cc and 37.32 cc, respectively. The volume of the clinical target varied from 15.41 cc to 44.32 cc, with an average value of 30.5 cc. Discussion: The lowest value of DHI was seen in the group having the lowest clinical target volume and the highest DHI was seen in the group having the largest clinical target volume. These observations suggest that homogeneity was worsening as the volume of tumor increases. Conclusion: DHI may be a good indicator to assess the quality of treatment plan during the planning.