Factors influencing radiation exposure during the extracorporeal shock wave lithotripsy

Radiation exposure of patients during endourological procedures

PURPOSE

Considering the existing gaps in the literature regarding patient radiation dose (RD) and its associated risks, a systematic review of the literature on RD was conducted, focusing on percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL), and ureteroscopy (URS).

METHODS

Two authors conducted a literature search on PubMed, Web of Science, and Google Scholar to identify studies on RD during endourological procedures. Two thousand two hundred sixty-six articles were screened. Sixty-five publications met the inclusion criteria using the PRISMA standards.

RESULTS

RD was generally highest for PCNL, reaching levels up to 33 mSv, 28,700 mGycm2, and 430.8 mGy. This was followed by SWL, with RD reaching up to 7.32 mSv, 13,082 mGycm2, and 142 mGy. URS demonstrated lower RD, reaching up to 6.07 mSv, 8920 mGycm2, and 46.99 mGy. Surgeon experience and case load were inversely associated with RD. Strategies such as optimizing fluoroscopy settings, implementing ultrasound (US), and following the ALARA (As Low As Reasonably Achievable) principle minimized RD.

CONCLUSIONS

This is the first systematic review analyzing RD, which was generally highest during PCNL, followed by SWL and URS. There is no specific RD limit for these procedures. Implementation of strategies such as optimizing fluoroscopy settings, utilizing US, and adhering to the ALARA principle proved effective in reducing RD. However, further research is needed to explore the factors influencing RD, assess their impact on patient outcomes, and establish procedure-specific reference levels for RD.

Office-based stone management

As hospital resources are becoming strained, ambulatory surgical centers and day hospitals are being increasingly utilized. For the urologist, a working knowledge of local anesthetics and conscious sedation protocols are important, as many surgical kidney-stone procedures can be performed without general anesthetic. With any anesthesia, the key goal is to maximize patient comfort while minimizing respiratory depression and avoiding prolonged sedation. When using these medications, a working knowledge of emergency reversal, ventilation (bag mask/laryngeal mask airway/intubation), and cardiopulmonary resuscitation is recommended.

ICRP Publication 117. Radiological protection in fluoroscopically guided procedures performed outside the imaging department

An increasing number of medical specialists are using fluoroscopy outside imaging departments, but there has been general neglect of radiological protection coverage of fluoroscopy machines used outside imaging departments. Lack of radiological protection training of those working with fluoroscopy outside imaging departments can increase the radiation risk to workers and patients. Procedures such as endovascular aneurysm repair, renal angioplasty, iliac angioplasty, ureteric stent placement, therapeutic endoscopic retrograde cholangio-pancreatography,and bile duct stenting and drainage have the potential to impart skin doses exceeding Gy. Although tissue reactions among patients and workers from fluoroscopy procedures have, to date, only been reported in interventional radiology and cardiology,the level of fluoroscopy use outside imaging departments creates potential for such injuries.A brief account of the health effects of ionising radiation and protection principles is presented in Section 2. Section 3 deals with general aspects of the protection of workers and patients that are common to all, whereas specific aspects are covered in Section 4 for vascular surgery, urology, orthopaedic surgery, obstetrics and gynaecology,gastroenterology and hepatobiliary system, and anaesthetics and pain management.Although sentinel lymph node biopsy involves the use of radio-isotopic methods rather than fluoroscopy, performance of this procedure in operating theatres is covered in this report as it is unlikely that this topic will be addressed in another ICRP publication in coming years. Information on radiation dose levels to patients and workers, and dose management is presented for each speciality.

Impact of radiological technologists on the outcome of shock wave lithotripsy

OBJECTIVE

To evaluate the correlation of radiological technologists (RTs) and the outcome of shock wave lithotripsy (SWL) in terms of fluoroscopy time, fragmentation rate, and stone-free rate.

MATERIAL AND METHODS

A retrospective review of a prospectively collected database of 601 SWL treatments between June 2009 and March 2010 was performed. Patients with radiolucent stones were excluded. SWL was done by 6 RTs with different levels of experience. Follow up was available for 534 treatments. Multivariate analysis was performed.

RESULTS

RTs (A-F) performed 144, 109, 118, 58, 57, and 48 SWL sessions, respectively. There was no statistical difference among RTs in terms of mean stone size or stone location. Compared with other RTs, RT A had a significantly lower mean fluoroscopy time of 129 seconds (95% CI 120.8-137.3) (P <.001), higher stone-free rate (75.7%; P = .035), and stone fragmentation rate after a single SWL session (82.6%; P = .004). After correcting for stone size and location, fluoroscopy time (P <.001), fragmentation rate (P = .002), and stone-free rate (P = .04) maintained their significance. When comparing the top 3 RTs performing >100 SWL sessions, RTs B and C had significantly higher fluoroscopy time compared with RT A (OR [95% CI] 1.84 [1.38-2.45]; P <.001 and 2.67 [2.00-3.57]; P <.001), respectively. After correcting for stone size and location, RT B had significantly lower fragmentation rate when compared with RT A (OR [95% CI] 0.21 [0.05-0.86], P = .03]. However, there were no significant differences among the top 3 RTs in terms of stone-free rates.

CONCLUSION

RTs significantly differ in fluoroscopy usage in addition to stone fragmentation and stone-free rates.

Assessment of patient effective radiation dose and associated radiogenic risk from extracorporeal shock-wave lithotripsy

The aim of the present study was to calculate patient effective dose and associated radiogenic risk from fluoroscopy guided extracorporeal shock-wave lithotripsy procedures. Fluoroscopy required during extracorporeal shock-wave lithotripsy was classified in two types identified by beam orientation: antero-posterior and 30 degrees anterior-oblique projected exposures. Duration of each exposure was monitored in 124 patients undergoing extracorporeal shock-wave lithotripsy treatment for ureteral stones. The dose from a kidney-ureter-bladder radiograph and the dose per min of fluoroscopy along antero-posterior and anterior-oblique projections were measured at 13 organs/tissues using an anthropomorphic phantom and thermoluminescence dosimetry. A radio-opaque object was placed in the phantom to simulate an ureteral stone at the proximal and distal ureter. The total effective dose in male and female patients with proximal ureteral stones was 1.71 mSv and 1.82 mSv, respectively. The corresponding values for male and female patients with distal ureteral stones was 0.76 mSv and 1.62 mSv, respectively. In the United States, the theoretical sex-averaged radiogenic excess of fatal cancers was estimated to be 140 per million and 85 per million of patients treated for proximal and distal ureteral stone, respectively. The average radiogenic risk for genetic defect associated to treatments of proximal and distal ureteral stones was found to be 2.5 and 24.4 per million of births, respectively. The radiation risk from a typical fluoroscopy guided extracorporeal shock-wave lithotripsy treatment of ureteral stones is low. Presented data may be used to determine patient effective dose from extracorporeal shock-wave lithotripsy procedures performed in any laboratory.

Reduction of radiation exposure to patients in the follow-up of shockwave lithotripsy

OBJECTIVES

To assess, in patients undergoing extracorporeal shock wave lithotripsy (ESWL), if a policy of using unilateral X-rays of the kidney, ureter and bladder (hemi-KUB) whenever possible and appropriate during diagnosis and follow-up, was successful in reducing the radiation exposure associated with ESWL.

PATIENTS AND METHODS

Two groups of patients of statistically comparable size and demography were assessed retrospectively before and after the implementation of the policy. All had undergone ESWL for radio-opaque upper urinary tract stones and all were finally rendered stone-free. The number and type of all radiological procedures from initial diagnosis of the stone to documented stone-free status were recorded and the dose calculated.

RESULTS

The appropriate use of hemi-KUB X-rays resulted in a significant mean reduction of radiation exposure after treatment of 2.28 mSv per patient (P<0.05). Furthermore, as expected, the radiation dose was clearly but not closely correlated with stone size (r = 0.419).

CONCLUSIONS

The appropriate use of hemi-KUB X-rays during the follow-up after ESWL is a simple and effective way of significantly reducing the radiation exposure of such patients.

Patient radiation dose during lithotripsy

Measurements were made of the radiation dose to patients undergoing lithotripsy. Two groups were studied; patients undergoing ultrasound localization of calculi, and patients undergoing fluoroscopic localization. Dose area product (DAP) measurements were obtained using a Diamentor ionization chamber. Ultrasound localization produced a mean DAP of 137 cGy cm2 equivalent to a mean effective dose of 0.24 mSv. Fluoroscopy localization produced a mean DAP of 552 cGy cm2 equivalent to a mean effective dose of 1.2 mSv. There was no correlation between stone size and fluoroscopy time. We recommend the use of ultrasound localization as a first option whilst restricting the use of fluoroscopy (preferably pulsed) for ureteric and difficult renal calculi.