SU‐E‐T‐823: Implication of the Spatial Resolution of the Conventional Dose‐Volume Histogram Analysis in the Radiation Therapy Treatments

Abstract

Purpose: The detection of the local‐spots of interest is important in evaluation of radiotherapy treatment plans. The conventional dose‐volume histogram (DVH) analysis loses the spatial information of the dose‐distribution such as “hot” and “cold” spots in the evaluation process. However, the cDVH can be resolved into the components of spatial‐DVHs (sDVHs; x‐,y‐ and zDVHs respectively). The objective of this work was to assess the accuracy of IMRT plans using a noble approach of sDVH analysis in the open‐source software system, Histogram Analysis in Radiation Therapy, HART (J Appl Clin Med Phys, Vol.11 (1), p. 3013, 2010). Method and Materials:The contours of the regions‐of‐interest along z‐direction were reformatted to generate contours along x‐, and y‐ planes respectively, using RTOG format of the IMRT plans of 10 head and neck cancer patients (N=10). The dose computed along z‐planes of the CT slices were used to compute dose‐volume matrices along x‐,y‐ and z‐planes respectively, using the user‐friendly HART program. The sDVH data‐points were validated with the cumulative‐DVH (cDVH) statistics of the corresponding organs. The sDVH statistics were utilized to assess the dose‐distribution in organs‐at‐risk such as salivary glands and larynx. Results: HART extracted more than 7000 sDVH statistics in 15–20 minutes for 20–30 organs using the dual‐core processor of 3GB RAM. The hot‐spots estimated from the sDVH analyses, were consistent with the cDVH analyses at higher resolution (1 mm). The low‐density hot‐spots (< 5% per slice) were symmetrically polarized in 3D‐space in 57 ±12% and 93 ±2% of the slices (N=10) of parotid glands and larynx respectively, however high‐density hot‐spots were detected in 90 ±8% of the slices (N=10) of the submandibular glands. Conclusions: The sDVH analysis is an accurate and efficient approach for the in‐depth analysis of the radiotherapy plans and the radio‐biological outcomes of the treatments, using the HART program.