Comparative Study on Effective Dose and Cancer Risk in Dual-tracer Hybrid Imaging - International Commission on...

Dual-tracer hybrid imaging is used for concurrent evaluation of two distinct molecular biomarkers, enhancing diagnostic capabilities. However, concerns about increased radiation exposure to patients arise with this technique. This study investigates the representative radiation doses and cancer risks associated with dual-tracer imaging and explores personalized dosimetry approaches.

A literature-based protocol identification was performed to obtain the required dosimetric inputs. Dose coefficients were applied to convert tracer activities into effective dose estimates. Internal dose assessments using reference phantom models were compared with personalized dosimetry results obtained through GATE-based Monte Carlo simulations specific to dual-tracer positron emission tomography. In addition, complementary computed tomography (CT) imaging was performed, and cancer risks were quantified using the BEIR VII risk model.

Whole-body CT dose estimates closely matched those from the MIRDct tool, with a maximum discrepancy of 9.2%. Among the tracers evaluated, ²⁰¹Tl resulted in the highest effective dose and cancer risk, while ^81mKr and ¹³N-ammonia exhibited the lowest doses. Personalized dosimetry for dual-tracer imaging with ^¹⁸F-fludeoxyglucose (FDG) and ⁶⁸Ga-PSMA showed a maximum deviation of 5.6% from phantom-based models. The total effective dose reached up to 34 mSv.

The study emphasizes the importance of addressing increased radiation doses and harmonizing dual-tracer hybrid imaging protocols. Personalized dosimetry enhances patient-specific risk assessments and safety by providing more accurate estimates of radiation exposure and associated cancer risks.