Chen TT et al, 2015: Radiation Exposure during the Evaluation and Management of Nephrolithiasis.
Chen TT, Wang C, Ferrandino MN, Scales CD, Yoshizumi TT, Preminger GM, Lipkin ME.
School of Medicine, Duke University Medical Center, Durham, North Carolina.
Division of Radiation Safety, Duke University Medical Center, Durham, North Carolina.
Division of Urology, Department of Surgery, Duke University Medical Center, Durham, North Carolina.
Department of Radiology, Duke University Medical Center, Durham, North Carolina.
Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina.
Abstract
PURPOSE: There is rising concern over the increasing amount of patient radiation exposure from diagnostic imaging and medical procedures. Patients with nephrolithiasis are at potentially significant risk for radiation exposure due to the need for imaging to manage recurrent stone disease. We reviewed the literature in an attempt to better characterize actual risks and discussed methods to reduce radiation exposure for adult patients with nephrolithiasis.
MATERIALS AND METHODS: A PubMed® search was performed using the key words nephrolithiasis, stones, radiation, fluoroscopy, ureteroscopy, percutaneous nephrolithotomy, computerized tomography and shock wave lithotripsy. Additional citations were identified by reviewing reference lists of pertinent articles.
RESULTS: A total of 50 relevant articles were included in this review. Patients with a first time acute stone event are exposed to a significant amount of radiation. Most radiation is from computerized tomography. Patients undergoing percutaneous nephrolithotomy are exposed to an equal or greater amount of radiation than they received from computerized tomography. Risk factors for increased exposure during percutaneous nephrolithotomy include obesity, multiple tracts and a larger stone burden. Ureteroscopy exposes patients to approximately the same amount of radiation as plain x-ray of the kidneys, ureters and bladder. Risk factors for increased exposure during ureteroscopy include obesity and ureteral dilation. During shock wave lithotripsy the amount of radiation exposure is not well characterized. Interventions to reduce exposure to patients include using ultrasound when possible and implementing low dose computerized tomography protocols. The as low as reasonably achievable principle of radiation exposure should always be followed when fluoroscopy is performed. The use of an air retrograde pyelogram may also reduce exposure during percutaneous nephrolithotomy. Fluoroscopy time during ureteroscopy may be decreased by a laser guided C-arm, a dedicated C-arm technician, stent placement under direct vision and tactile feedback to help guide wire placement.
CONCLUSIONS: Patients with nephrolithiasis are at significant risk for increased radiation exposure from the imaging and fluoroscopy used during treatment. The true risks of low radiation exposure remain uncertain. It is important to be aware of these risks to provide better counseling for patients. Urologists must also be familiar with techniques to decrease radiation exposure for patients with nephrolithiasis.
J Urol. 2015 Jun 6. pii: S0022-5347(15)04108-7. doi: 10.1016/j.juro.2015.04.118.[Epub ahead of print]
Comments 1
I think that this article is very useful reading for urologists, because overuse as well as less careful use of modern radiological modalities will expose the patient to unnecessary and dangerous radiation doses.
There are some lessons that should be learnt when stone removal with SWL is applied. The first point is that diagnostic imaging in most patients adequately can be carried out with low-dose CT (LDCT) or ultralow-dose CT (ULDCT). Moreover, in the follow-up, CT examinations should be avoided as far as possible, and in this regard KUB usually gives sufficient information.
The AUA recommendations are cited here:
During SWL it is extremely important to collimate the image as much as possible to reduce the fluoroscopic radiation. This is a step that very often is ignored. US is recommended when appropriate, but this modality is often associated with restrictions in stone identification. The application of pulsed fluoroscopy also is recommended, but it is my personal experience that with a too low pulse rate it might be difficult to appropriately adjust for respiratory movements of the target.