Elsevier

Urology

Volume 79, Issue 1, January 2012, Pages 43-47
Urology

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

https://doi.org/10.1016/j.urology.2011.07.1387Get rights and content

Objective

To quantify the effective radiation dose associated with the evaluation and follow-up of patients with urolithiasis.

Methods

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.

Results

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.

Conclusion

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.

Section snippets

Material and Methods

A retrospective review was performed for consecutive patients presenting to a tertiary stone clinic with an acute stone episode between November 2007 and December 2008, and who had at least 2 years of follow-up. Patients who had imaging studies at outside institutions were excluded. Also, patients with CTs and fluoroscopy procedures that did not report an effective radiation dose and/or fluoroscopy time were excluded. The tertiary stone clinic is composed of 2 urologists, 2 nephrologists, a

Results

One-hundred-four patients (72 males and 32 females) with documented stones were included in this study with a mean age of 49.0 years (range 21-78) and a mean stone burden of 5.3 mm (range 1-21 mm). Stones were located in the kidney in 60 (57.7%) patients, the ureter in 30 (28.8%) patients, and multiple locations in 14 (14.5%) patients. The 30 ureteral stones were located at the ureteropelvic junction, proximal ureter, distal ureter, and ureterovesical junction in 2, 6, 14, and 8 patients,

Comment

In the present study, the total number and the average number of IVUs, fluoroscopic studies, plain radiographs, and CT scans significantly decreased during the second year, whereas the total number and the average number of US studies significantly increased during the second year (P <.05) (Table 1). In particular, the average number of CT scans per patient during the first year of follow-up was 0.82 scans. This is lower than the mean of 1.7 CT scans per patient in the study by Ferrandino and

Conclusions

It is important to calculate the effective radiation exposure when DLP values are available for CT scans because there are wide variations in doses among patients. Furthermore, the effective radiation exposure doses caused by CT scans are above previous estimates. Although a significant portion of patients were exposed to MERE doses above the 50 mSv threshold during the first year of follow-up, none exceeded this threshold in the second year because of significantly fewer CT scans and

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Funding Support: This work was supported in part by the Northeastern AUA Young Investigator Award and Montreal General Hospital Foundation Award to Sero Andonian.

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