Organ doses, effective dose, and cancer risk estimation from whole-body CT scans in PET-CT imaging

The integration of PET and CT technologies has revolutionized medical imaging, particularly in cancer management. However, the associated radiation exposure necessitates a detailed understanding of the risks involved. This study aims to quantify the effective dose (ED) and associated cancer risks from whole-body CT scans in PET-CT procedures.

Data from 500 patients (226 men and 274 women) undergoing PET-CT scans were analyzed. Two methods were employed to calculate the ED: The Dose Length Product (DLP) and the NCICT dosimetry system, which utilizes Monte Carlo simulations. Organ doses and ED were compared between genders, and the correlation between ED and patient age was examined.

The mean DLP was 516.4 ± 200 mGy cm, resulting in an ED of 7.76 ± 3.01 mSv using the DLP method, and 6.82 ± 2.56 mSv using NCICT. The thyroid received the highest organ dose, followed by the kidneys in females and the testes in males. A significant decrease in cancer risk with increasing age was observed for both genders.

This study emphasizes the importance of considering age in assessing the cancer risks from CT radiation in PET-CT scans, particularly for younger patients. It advises caution in recommending CT scans and suggests exploring alternative imaging modalities while adhering to ALARA principles to reduce exposure. It also paves the way for future research aimed at either eliminating or reducing the CT dose component in PET/CT scans, thereby enhancing the overall safety and efficacy of this imaging modality.