Radiation dosing in the investigation and follow-up of urolithiasis: Comparison between historical and contemporary practices

This article compared the amount and frequency of radiation exposure of patients between the year 1990 and 2013 during diagnostic procedures due to the change in imaging equipment. Considering the rise in interest of the safety issues concerning over-exposure of radiation, this paper merits further consideration. Though it is difficult to draw a definitive conclusion due to the small case numbers, the authors were unable to show that there was a clear disparity in radiation exposure between the 2 groups. Simple comparison may show that patients undergoing computed tomography (CT) scans are exposed to higher amounts of radiation than intravenous urography (IVU). However CT scans allow faster diagnosis and requires less concurrent studies and thus the overall exposure is not very different. I believe this the message that the authors wish to present to the readers. If possible, remarks on the composition of stones that were examined are advised. The authors mention in their manuscript that the radiation exposure during CT scans were approximately 3.5 mSV, which is probably a protocol for low dose CT scans. The amount of radiation exposure for traditional renal stone protocol is approximately 9–16 mSV which is considerably higher [1]. Many patients will likely have recurrences and will need additional scans, adding to radiation exposure. A study on the frequency of CT scans reports that patients with acute stone episodes will require an average of 1.7 CT scans within the following year [2]. The diagnostic imaging method the authors used for comparison in 1990 was in fact an IVU. The IVU is a relatively invasive procedure with risks concerning complication due to contrast. The IVU is also slow in diagnosis and is currently no longer used in practice. No studies have yet reported the effects of continuous low dose radiation exposure, but due to advancement of diagnostic imaging tools, the amount of radiation exposure is increasing. It has been reported in the United States there has been a 600% (from 0.54 to 3.0) increase in radiation exposure from medical sources per capita from the year 1982 to 2006 [3]. This concern is augmented in ureter stone patients where radiation is frequently used during diagnosis, treatment and follow-up. Considering the high rate of recurrence in ureter stones, urologists should always be concerned of the risk of overexposure in their patients and try to minimize the amount of radiation during procedures. Recent studies on low dose (3 mSv), and ultra-low dose (1–2 mSv) CT scans show that even with low amounts of radiation, stones larger than 3 mm in patients with body mass index less than 30 can be detected with comparable sensitivity and specificity to standard CT scans [4,5,6]. Fluoroscopy used during percutaneous nephrolithotomy, ureteroscopy or extracorporeal shock-wave lithotripsy is also a major source of medical radiation and should follow the "as low as reasonably achievable" principle whenever possible during procedures to lessen the chance of radiation exposure.