Assessment of Effective Dose Received in Various Computed Tomography Protocols and Factors Affecting It

Abstract

Purpose of Study: The purpose of the study was to evaluate the effect of patient characteristics and equipment-related factors on the computed tomography (CT) dose received by patients from positron emission tomography-CT (PET-CT) using system-generated dose-length product (DLP) values and also to check the effective dose (ED) received from various CT protocols at our institute. Materials and Methods: This retrospective study included 78 adult patients who underwent F-18 fluorodeoxyglucose whole-body PET-CT and were divided into three groups based on the area of primary cancerous lesion. In Group A, we had 44 patients who underwent PET-CT (head-and-neck protocol), in Group B, we had 24 patients who underwent PET-CT (whole body with brain protocol), and in Group C, we had 10 patients who underwent PET-CT (pelvis protocol). All of the patients under the study are of South Asian ethnicity. A majority of patients 53.85% were males and remaining 46.15% were females. The product of conversion factor (k-coefficient), as described in “American Association of Physicists in Medicine Report No. 96” and DL P value generated by the scanner, was used to calculate the ED. Moreover, we also performed regression analysis to check relation between body weight, height, scan range, tube current, Volume computed tomography dose index (CTDIvol), DLP, and ED. Results: The regression analysis shows that scan range, patient height, weight, tube current, and DLP were significantly correlated with ED ( P < 0.05 for all). Moreover, the DLP and conversion factor method estimated the ED from various groups. Patients under Group A (head-and-neck protocol), Group B (whole body with brain protocol), Group C (pelvis protocol) received an average ED of 22.45 mSv, 22.40 mSv, and 21.24 mSv, respectively. Conclusion: ED from CT component of PET-CT can be assessed as the product of scanner-generated DLP and conversion factor for selected range. Moreover, body weight, scan range, and tube current had an independent significant effect on ED received from CT.

A Comparison of the Mean CTDIvol and DLP Values for Adult Abdominal CT Examination for MTRH, Eldoret Hospital, St. Luke’s Hospital and Mediheal Hospital: A Retrospective Study

“…The study findings were also agreeable to the conclusion by 15 that variation in values reported by different CT scanners can vary between 10 and 15%. Dissimilar findings were reported by 16 who established that dose levels are not dependent on the equipment related factor of machine model. The difference in findings can be attributed to a number of institutional factors such radiology technicians given that the study was conducted in government referral hospital while the current study conducted among referral hospital and private hospitals.…”

Effective radiation dose reduction in total body PET/CT while improving diagnostic value

“…Rational selection of exposure condition and optimization of relation parameters can effectively reduce radiation dose in a PET/CT examination without affecting image quality. A previous report [22] found that patient ED mostly depends on scan range and tube current. Tonkopi, E. et al [23] proposed an approach that sped up X-ray tube rotation time, increasing X-ray beam coverage and noise index value to achieve radiation reduction in the CT component, up to 32% reduction with using optimized CT protocol.…”