Purpose: Develop a method for determining the skin dose contribution of CT to the total skin dose for procedures performed in a hybrid CT/Angiography suite and incorporate the results into a previously validated fluoroscopic peak skin dose (PSD) calculator.
Methods: Optically stimulated luminescent dosimeter (OSLD) arrays were created to investigate the dose distribution for two separate arrangements using an anthropomorphic phantom. The first arrangement used a flat area array (45 x 25 cm²) placed beneath the phantom and was exposed to a 160-mm volume CT scan. The second arrangement used a larger ring array (86.5 x 5.5 cm²) around the abdominal region of the phantom and was exposed to 160-mm volume CT scans. Scans were repeated for five arrays at different volume CT dose index (CTDI(vol)) values.
Results: The OSLDs were read using a microStar™ dosimetry system and dose distribution maps were created using Matlab™. The maps for the OSLD ring arrays were used to generate an equation relating CTDI(vol) to the OSLD dose by averaging the dose to the 30 posterior OSLDs for each CTDI(vol) value. A good linear relationship (R²= 0.9968) was seen between CTDI(vol) and OSLD dose.
Conclusion: The CT contribution to the total skin dose from a patient procedure in the hybrid CT/Angiography suite can be estimated by applying the best fit equation generated from these results then using an OSLD dose conversion factor. The CT dose estimation will be included in a fluoroscopy skin dose calculator that was developed to determine the skin dose from angiography exams, providing a total skin dose for procedures performed in the hybrid CT/Angiography suite. Total skin dose calculations will be validated by direct measurement of patient doses using flat OSLD arrays placed under patients during clinical procedures to assess dosimetry in a hybrid CT/Angiography suite.