Influence of the contrast agents on treatment planning dose calculations of prostate and rectal cancers

AimThe aim of the present study is to quantify differences in dose calculations caused by using CA and determine if the resulting differences are clinically significant.BackgroundThe influence of contrast agents (CA) on radiation dose calculations must be taken into account in treatment planning.Materials and methodsEleven patients with pelvic cancers were included in this study and two sets of CTs were taken for each patient (without and with CA) in the same position and coordinates. Both sets of images were transferred to the DosiSoft ISOgray treatment planning system for contouring and calculating the dose distribution and monitor units (MUs) with Collapsed Cone and Superposition algorithms, respectively. All plans were generated on pre-contrast CT and subsequently copied to the post-contrast CT. Radiation dose calculations from the two sets of CTs were compared using a paired sample t-test.ResultsThe results showed a statistically insignificant difference between pre- and post-contrast CT treatment plans for target volume and OARs (p[[ce:hsp sp="0.25"/]]>[[ce:hsp sp="0.25"/]]0.05), except bladder organ in the prostate region (p[[ce:hsp sp="0.25"/]