Effective Radiation Exposure Research Articles

Not Every Low-Dose Is Low-Dose: Impact of Revising Low-Dose CT Protocol on Mean Effective Radiation Exposure

Introduction: According to the American Urological Association imaging guidelines, patients presenting with renal colic should undergo low-dose (LD) rather than standard-dose (SD) noncontrast CT. The aim of the present study was to assess how often physicians ordered LD CT scans and to calculate mean effective radiation exposure (ERE) from CT scans from dose length products, and determine mean cumulative ERE over 1-year follow-up period. Methods: After obtaining ethics approval, a retrospective chart review was conducted for patients with renal colic presenting to the emergency department between August 1, 2015 and July 31, 2016 (Phase I) and between April 1, 2019 and October 1, 2019 (Phase II). All imaging studies performed within 1-year of initial presentation were cataloged. Results: In Phase I, 146 patients, with mean age of 51 years and mean body mass index (BMI) of 28.6 kg/m2, underwent 220 CT scans. In Phase II, 225 patients, with mean age of 55 years and mean BMI of 26.7 kg/m2, underwent 273 CT scans. Urologists were the only physicians ordering LD CT scans and they ordered significantly more LD than SD CT scans (71.3% vs 28.7%, p < 0.001). In Phase II, after revision of LD CT scan protocol in March 2019, the mean ERE per LD CT significantly decreased (6.5 vs 1.6 mSv, p < 0.001). In addition, there were significant differences in mean ERE from LD CT scans between two hospitals in the same health system (1.6 vs 7.8 mSv, p < 0.001). The mean cumulative ERE in Phase II over the 1-year period was 19.3 mSv, with 6.9% of patients exceeding 50 mSv. Conclusions: Although LD CT scans are being ordered, a small percentage of patients continue to exceed the 50 mSv annual threshold. It is important to keep track of mean ERE of LD CT scans and collaborate with medical physicists and the diagnostic imaging department to further refine LD CT scan protocols since not every low-dose is low-dose.

Effective radiation exposure evaluation during a one year follow-up of urolithiasis patients after extracorporeal shock wave lithotripsy.

IntroductionTo determine and evaluate the effective radiation exposure during a one year follow-up of urolithiasis patients following the SWL (extracorporeal shock wave lithotripsy) treatment.Material and methodsTotal Effective Radiation Exposure (ERE) doses for each of the 129 patients: 44 kidney stone patients, 41 ureter stone patients, and 44 multiple stone location patients were calculated by adding up the radiation doses of each ionizing radiation session including images (IVU, KUB, CT) throughout a one year follow-up period following the SWL.ResultsTotal mean ERE values for the kidney stone group was calculated as 15, 91 mSv (5.10-27.60), for the ureter group as 13.32 mSv (5.10-24.70), and in the multiple stone location group as 27.02 mSv (9.41-54.85). There was no statistically significant differences between the kidney and ureter groups in terms of the ERE dose values (p = 0.221) (p >0.05). In the comparison of the kidney and ureter stone groups with the multiple stone location group; however, there was a statistically significant difference (p = 0.000) (p <0.05).ConclusionsERE doses should be a factor to be considered right at the initiation of any diagnostic and/or therapeutic procedure. Especially in the case of multiple stone locations, due to the high exposure to ionized radiation, different imaging modalities with low dose and/or totally without a dose should be employed in the diagnosis, treatment, and follow-up bearing the aim to optimize diagnosis while minimizing the radiation dose as much as possible.

Effective Radiation Exposure in Evaluation and Follow-up of Patients With Urolithiasis

To quantify the effective radiation dose associated with the evaluation and follow-up of patients with urolithiasis. Retrospective review was performed for consecutive patients presenting to a tertiary stone clinic with acute stone episodes between November 2007 and December 2008, and had at least 2 years of follow-up. Number and modality of imaging studies were collected. Effective radiation exposure (ERE) doses were calculated from the dose length product values reported with each computed tomography (CT) scan. There were 72 males and 32 females with a mean age of 49 years (range 21-78). Patients underwent an average 1.8 (range 0-5) and 0.7 (range 0-2) plain radiographs, 0.82 (range 0-4) and 0.15 (range 0-2) CTs, 0.09 (range 0-1) and 0.03 (range 0-1) intravenous urograms, and 0.3 (range 0-1) and 0.6 (range 0-2) ultrasounds (US) during the first and second years, respectively (all P<.05). The average calculated ERE dose per CT scan was 23.16 mSv (range 4.94-72.77). The calculated mean ERE dose per patient significantly decreased from 29.29 mSv (range 1.7-77.27) in the first year to 8.04 mSv (range 1.4-24.72) in the second year (P<.01). This was because of significantly fewer CT scans and significantly more US imaging during the second year (P<.05). Although 18 (17.3%) patients exceeded 50 mSv during the first year, none exceeded this threshold during the second year. The mean ERE dose did not correlate with stone location, patient age, and sex. The calculated mean ERE dose significantly decreased during the second year of follow-up in patients with urolithiasis because of significantly higher use of US.