AbstractsBiology & Animal Science

A Verification of Deformable Dose and Treatment Planning Software in the Evaluation of Dose to Targets and Normal Structures in SBRT Patients

by Adam M Dalhart




Institution: University of Toledo Health Science Campus
Department: Biomedical Sciences (Medical Physics)
Degree: MS
Year: 2014
Keywords: Health Sciences; Medical Imaging; MIM, Deformable, Fusion, Pinnacle
Record ID: 2032774
Full text PDF: http://rave.ohiolink.edu/etdc/view?acc_num=mco1404777373


Abstract

The purpose of this research is to quantify whether it is necessary to recalculate dose distributions on CBCTs in order to evaluate dose to normal structures, or if using the planned distribution is acceptable on dose software platform. Patients with different treatment sites were taken into account to test the adaptive therapy used at the University of Toledo. KV CBCT images obtained prior to each SBRT fraction were evaluated for 4 liver, 4 lung and 3 chest wall metastatic lesions. These CBCTs were then brought into a dose deformation software program, the contours transferred and modified, and the planned dose distributions transferred to the CBCT. The dose distributions were then recalculated in a treatment planning software using a CT density table that corrected for the CBCT HUs. The planned dose distribution was transferred to the CT in the dose deformation software and the dose to each structure was then compared using a DVH comparison. From the CBCTs for liver patients, 33 out of 115 tabulated values that deviate from the planning system by more than 4%; of those 33, the percentage difference of 8 data points are above 10%. Of the lung patients, 63/155 tabulated values that have a percentage difference from the planning system of more than 4%. Of those 63, 13 deviate by over 10%. Lastly, 32/98 tabulated values for the chest wall patients have a percentage difference from the planning system of more than 4%, with 19 of these having a deviation of 10% or greater. It was determined that the dose deformation software is not recommended for the evaluation of the dose delivered to targets and normal structures. The preferred method is to re-compute the dose distribution in the planning system for an accurate representation of delivered dose. It may, however, be used to obtain a rough estimate of the dose delivered to targets and normal structures.