An audit of patient radiation in low-dose CT pulmonary angiography

Abstract

Objectives: Assesment of radiation dose implementing low-dose CTPA protocols. Method: Retrospective analysis of radiation dose in two groups of adult patients, who underwent CECT chest and who were scanned by low-dose CTPA protocol from April 2014 to June 2015. Dose reduction techniques in CTPA included low kVp and iterative reconstruction. The values for CT dose index/volume and the dose-length product (DLP) were available from patients’ information sheet. Effective dose (ED) was calculated by multiplying DLP by body-specific conversion factor, k factor, 0.014. Statistical analysis using SPSS 16 was done for mean DLP, ED as well as paired T-test for comparison of groups. Results: DLP for CECT chest protocol was 218 mGy cm. Mean DLP value when applying low-dose CTPA technique was 166.2 mGy cm. The ED from CECT chest protocol was 1.6–6.3 mSv, while using low-dose CTPA protocol it ranged from 1.2 to 4.3 mSv. Statistically significant reduction of 23% of mean effective dose was achieved in Group 2. P value is less than 0.01. Conclusions: Low-dose CTPA protocol results in ED values that are significantly lower than CECT chest protocol and within accepted range for international radiation dose of CTPA.

Keywords

• Low dose CT
• PE
• CTPA
• Radiation dose