Body CT examinations in oncologic patients: the impact of subspecialty radiology on radiation exposure in the clinical practice. A quality care study.

PURPOSES

The primary objective of this retrospective study was to assess whether the CT dose delivered to oncologic patients was different in a subspecialty radiology department, compared to a general radiology department. The secondary explorative objective was to assess whether the objective image quality of CT examinations was different in the two settings.

MATERIALS AND METHODS

Chest and abdomen CT scans performed for oncologic indications were selected from a general radiology department and a subspecialty radiology department. By using a radiation dose management platform, we extracted and compared CT dose index (CTDI) and dose length product (DLP) both for each phase and for the entire CT exams. For objective image quality evaluation, we calculated the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) at the level of the liver and of the aorta. A P-value < 0.05 was considered significant.

RESULTS

A total of 7098 CT examinations were included. CTDI was evaluated in 12,804 phases; DLP in 10,713 phases and in 6714 examinations. The CTDI and DLP overall were significantly lower in the subspecialty radiology department compared to the general radiology department CTDI median (IQR) 5.19 (3.91-7.00) and 5.51 (4.17-7.72), DLP median and IQR of 490.0 (342.4-710.6) and 503.4 (359.9-728.8), p < 0.001 and p = 0.01, respectively. The objective image quality showed no significant difference in the general and subspecialty radiology departments, with median and IQR of 4.03 (2.82-5.51) and 3.84 (3.09-4.94) for SNR (p = 0.58); 4.81 (2.70-7.62) and 4.34 (3.05-6.25) for SNR (p = 0.30); 0.83 (0.20-1.89) and 1.00 (0.35-1.57) for CNR (p = 0.99); 2.23 (0.09-3.83) and 1.01 (0.15-2.84) for CNR (p = 0.24) with SNR (p = 0.58), SNR (p = 0.30), CNR (p = 0.99) and CNR (p = 0.24).

CONCLUSION

In a subspecialty radiology department, CT protocols are optimized compared to a general radiology department leading to lower doses to oncologic patients without significant objective image quality degradation.