Single Pulse-per-second Setting Reduces Fluoroscopy Time During Ureteroscopy

Radiation exposure of urologists during endourological procedures: a systematic review

INTRODUCTION

Ionizing radiation is used daily during endourological procedures. Despite the dangers of both deterministic and stochastic effects of radiation, there is a lack of knowledge and awareness among urologists. This study reviewed the literature to identify the radiation exposure (RE) of urologists during endourological procedures.

METHODS

A literature search of the Medline, Web of Science, and Google Scholar databases was conducted to collect articles related to the radiation dose to urologists during endourological procedures. A total of 1966 articles were screened. 21 publications met the inclusion criteria using the PRIMA standards.

RESULTS

Twenty-one studies were included, of which 14 were prospective. There was a large variation in the mean RE to the urologist between studies. PCNL had the highest RE to the urologist, especially in the prone position. RE to the eyes and hands was highest in prone PCNL, compared to supine PCNL. Wearing a thyroid shield and lead apron resulted in a reduction of RE ranging between 94.1 and 100%. Educational courses about the possible dangers of radiation decreased RE and increased awareness among endourologists.

CONCLUSIONS

This is the first systematic review in the literature analyzing RE to urologists over a time period of more than four decades. Wearing protective garments such as lead glasses, a thyroid shield, and a lead apron are essential to protect the urologist from radiation. Educational courses on radiation should be encouraged to further reduce RE and increase awareness on the harmful effects of radiation, as the awareness of endourologists is currently very low.

Do Flat Panel Detector C-Arms Decrease Radiation Exposure Compared to Conventional Image Intensifiers?

OBJECTIVE

To compare the radiation dose and image quality between flat panel detector (FPD) and traditional image intensifier (II) C-arms at their lowest radiation settings.

METHODS

In a ureteroscopy simulation using a cadaver model, the radiation exposure was compared between FPD and II at 4 pulses-per-second (pps) using both low dose and automatic exposure control (AEC) settings. Additionally, the lowest dose settings for each machine were compared (4 pps with low dose in the FPD and 1 pps with low dose in the II). Five trials of 5 minutes were conducted for each setting. Four new optically stimulated luminescent dosimeters were used in each trial to record radiation exposure. Ten blinded urologists completed a survey rating image quality for each setting.

RESULTS

When comparing the FPD and II at their lowest possible settings, the FPD produced significantly more radiation (P <.05). Using both machines at 4 pps in low dose mode resulted in no significant difference between C-arms (P >.05). Conversely, operating the C-arms at 4 pps and AEC resulted in significantly higher radiation exposure from the FPD compared to the II (P <.05). There was no significant difference in image quality at each setting.

CONCLUSION

FPDs produce significantly more radiation at the lowest settings compared to IIs. Surgeons should employ IIs when reducing radiation exposure as low as possible is imperative, such as when operating on pediatric and pregnant patients.

Linear relationship between absorbed radiation dose and pulse rate during fluoroscopy

PURPOSE

To identify the relationship between fluoroscopy pulse rate and absorbed radiation dose. We compared absorbed radiation dose with common proxy measurements such as fluoroscopy time and C-arm reported dose.

METHODS

Using a simulated patient model, 60 s fluoroscopy exposures were performed using pulse rates of 30, 8, 4, 2, and 1 pulse(s) per second. Each experiment was performed with both standard and low-dose settings using a GE OEC 9800 plus C-arm. Landauer nanoDot™ OSL dosimeters were used to measure the absorbed radiation dose.

RESULTS

Fluoroscopy pulse rate and absorbed radiation dose demonstrated a linear correlation for both standard (R² = 0.995, p < 0.001) and low-dose (R² = 0.998, p < 0.001) settings. For any given pulse rate, using the low-dose setting reduced absorbed radiation dose by 58 ± 2.8%. Fluoroscopy time demonstrated a linear relationship with absorbed radiation dose for both standard (R² = 0.996, p < 0.001) and low-dose (R² = 0.991, p < 0.001) settings, but did not change with use of the low-dose setting. C-arm reported radiation dose correlated linearly with absorbed dose (R² = 0.999) but consistently under-estimated measured values by an average of 49 ± 3.5%. Using a combination of 1 pulse-per-second and low-dose fluoroscopy, absorbed dose was reduced by 97.7 ± 0.1% compared to standard dose and 30 pulse-per-second settings.

CONCLUSION

Absorbed radiation dose decreases linearly with fluoroscopy pulse rate during equivalent exposure times. Adjusting fluoroscopy pulse rate and utilizing low-dose settings significantly reduces overall absorbed radiation exposure by up to 98%.

How should radiation exposure be handled in fluoroscopy-guided endoscopic procedures in the field of gastroenterology?

Fluoroscopy-guided endoscopic procedures (FGEPs) are rapidly gaining popularity in the field of gastroenterology. Radiation is a well-known health hazard. Gastroenterologists who perform FGEPs are required to protect themselves, patients, as well as nurses and radiologists engaged in examinations from radiation exposure. To achieve this, all gastroenterologists must first understand and adhere to the International Commission on Radiological Protection Publication. In particular, it is necessary to understand the three principles of radiation protection (Justification, Optimization, and Dose Limits), the As Low As Reasonably Achievable principle, and the Diagnostic Reference Levels (DRLs) according to them. This review will mainly explain the three principles of radiation exposure protection, DRLs, and occupational radiological protection in interventional procedures while introducing related findings. Gastroenterologists must gain knowledge of radiation exposure protection and keep it updated.

Safety During Ureteroscopy: Radiation, Eyes, and Ergonomics

It is known that urologic surgeons are at risk of work-place injury due to the physical requirements of operating and exposure to hazards. These hazards include radiation, exposure to body fluids, use of laser energy, and orthopedic injury due to the physical nature of operating. The risks that these hazards present can be mitigated by implementing several evidence-based safety measures. The methods to protect against radiation exposure include keeping radiation usage in the operating room as low as reasonably achievable, donning lead aprons, and wearing protective glasses. Additionally, protective glasses decrease the risk of eye injury from laser injury and exposure to body fluids. Finally, practicing sound surgical ergonomics is essential to minimize the risk of orthopedic injury and promote career longevity. The interventions discussed herein are simple and easy to implement in one's daily practice of urology.

Reducing Radiation Exposure to Patients and Staff During Routine Ureteroscopic Stone Surgery: Adopting a Fluoroless Technique

Purpose

Urologists have an obligation to limit radiation exposure during routine stone surgery. We therefore sought to evaluate the impact of our technique for fluoroless ureteroscopy on perioperative outcomes.

Methods

Medical records of 44 patients who underwent ureteroscopy with laser lithotripsy without the use of fluoroscopy between October 2017 and December 2018 were examined. Multiple variables were collected, including age, body mass index (BMI), mean stone volume and density, operative times, complications, and stone-free rates. These patients were then compared to a cohort of 44 patients who underwent stone surgery with a conventional technique prior to the adoption of a fluoroless technique by the same surgeons. The primary study outcome was reduction of intraoperative fluoroscopy. Secondary outcomes included complications, operative time, and stone-free rates.

Results

Of the 44 patients undergoing a fluoroless technique, 38 (86.4%) were able to receive ureteroscopy without the use of fluoroscopy. A significant difference was observed in mean fluoroscopy times for the fluoroless group (2.8 seconds) and the conventional group (33.7 seconds). No complications were observed in either group. Operative length was 38.9 minutes in the fluoroless group versus 42.2 minutes in the conventional group. Age, BMI, stone characteristics, and stone-free rates were similar in both.

Conclusions

The use of a fluoroless technique for the treatment of uncomplicated stones is not only safe but also effective and efficient. This technique eliminates extraneous radiation doses to the patient and operative staff in most cases.

Flat Panel Detector c-Arms Are Associated with Dramatically Reduced Radiation Exposure During Ureteroscopy and Produce Superior Images

Background: We wished to determine whether newly available flat panel detector (FPD) c-arms were (1) associated with lower radiation dose during ureteroscopy (URS) than conventional image intensifier (CII) c-arms and (2) to compare fluoroscopic image quality between the units. Materials and Methods: We retrospectively reviewed 44 consecutive patients undergoing URS at a pediatric hospital, with c-arms assigned by availability in the operating room. We performed dosimetry experiments using the same c-arms on standard phantoms. Results: Patient and case characteristics did not differ significantly between the two groups of patients. The median dose in the FPD group was less than a quarter of the dose in the CII group, 0.48 [0.42, 0.97] mGy vs 2.2 [1.1, 3.8] mGy, p < 0.0001. The FPD dose remained at less than one-third of the CII dose accounting for any difference in fluoroscopy time, and remained significant in a multivariate model including fluoroscopy time and patient weight (β = 2.4, p = 0.007). Phantom studies showed higher image quality for FPDs at all simulated patient sizes, even at lower radiation doses. Conclusions: This is the first report comparing radiation dose from c-arms of image intensifiers and FPDs in adults or children. Use of an FPD during URS was associated with a substantially decreased absorbed dose for patients while simultaneously improving image quality.

Minimizing radiation dose in management of stone disease: how to achieve 'ALARA'

PURPOSE OF REVIEW

Exposure to radiation is known to have adverse effects such as secondary malignancies. Patients with nephrolithiasis are exposed to radiation in the workup and treatment of their condition. Furthermore, exposure to radiation is often repeated due to the high recurrence rate of nephrolithiasis.

RECENT FINDINGS

We discuss practices inside and outside of the operating room to strive to keep radiation exposure as low as reasonably achievable (ALARA) for patients being treated for nephrolithiasis. These efforts include reduced dose computed tomography scans, fluoroless surgical techniques and new alternative technologies.

SUMMARY

Maintaining radiation exposure ALARA for our patients is increasingly practical. The urologist must make every effort to adhere to ALARA principles to protect patients from the stochastic effects of radiation.

Factors Influencing Fluoroscopy Use During Ureteroscopy at a Residency Training Program

Introduction: Ionizing radiation is used throughout urologic surgery and is known to cause a greater cancer risk with increasing exposure. The International Commission on Radiological Protection states that "it is the control of radiation dose that is important, no matter the source." However, there are few reports on the amount of radiation used by urology residents during ureteroscopy (URS). We present the largest database evaluating fluoroscopy (fluoro) use during URS at a resident training program. Our objective is to assess the amount of fluoro use at varying levels of experience and to identify factors that lead to increased fluoro use. Methods: Retrospective data from 242 URSs performed at two resident training sites were collected. In total, 105 surgeries were done by two attending physicians without and 137 surgeries with residents (Uro1-Uro3). Patient data were collected from the electronic medical record. Statistical analyses included analysis of variance, Spearman correlations, and multiple linear regression (MLR). Results: Comparisons between years 1 and 2 revealed significantly (p < 0.05) decreased fluoro time (20.0 seconds) and operative time (OT) (12.2 minutes) for the year 2 resident. Total OT was significantly (p < 0.05) decreased (11.1 minutes) for attending physicians operating on their own compared with a year 1 resident. Significant (p < 0.05) correlations with fluoro time were demonstrated for OT, stone size, ureteral dilation, ureteral access sheath use, presence of a preoperative stent, resident year, and resident month. OT, ureteral dilation, and a preoperative stent placement were significant predictors of fluoro time on MLR (p < 0.05). Conclusion: Fluoro time during retrograde URS was significantly reduced as residents gained more experience in the operating room. An increase in fluoro time was also associated with ureteral dilation, access sheath use, increasing stone size, and lack of prestenting. With knowledge of these factors, emphasis can be placed on using and teaching techniques that limit radiation exposure.

Is fluoroscopy necessary during flexible ureteroscopy for the treatment of renal stones?

Objective

To investigate the feasibility and effectiveness of flexible ureteroscopy (fURS) without fluoroscopy during the treatment of renal stones.

Patients and methods

Between April 2013 and August 2018, 744 patients’ data were evaluated retrospectively. Of these, 576 patients were included in the study. All fURS were performed by experienced surgeons. All procedures were planned with zero-dose fluoroscopy. But, if fluoroscopy was necessary for any reasons, these patients were excluded from the study. Demographic data, perioperative parameters, stone-free rate (SFR), and complication rates were recorded.

Results

Of the patients planned for fluoroless fURS (ffURS), the procedure was successfully achieved in 96.7% (557/576 patients), as 19 patients required fluoroscopy during the procedure for various reasons. In the patients included in the study, the mean (SD) stone size was 11.6 (5.2) mm and the mean (SD) operating time was 39.4 (8.2) min. After the first session of ffURS, the SFR was 83.3% (achieved in 464 patients). Second and third sessions of ffURS were performed in 32 (5.7%) and seven (1.2%) patients, respectively. Overall, the complication rate was 11.8% and all complications were minor (Clavien–Dindo Grade I or II).

Conclusions

The ffURS technique seems to be a safe and effective treatment compared to conventional fURS in patients with renal stones. This procedure should be performed in experienced centers, where fluoroscopy can be considered not to be mandatory during fURS.

Abbreviations CIRF

clinically insignificant residual fragment; CT: computed tomography; EAU: European Association of Urology; (f)fURS: (fluoroless) flexible ureteroscopy; FT: fluoroscopy time; KUB: plain abdominal radiograph of the kidneys, ureters and bladder; mSv: millisievert; PCNL: percutaneous nephrolithotomy; pps: pulse-per-second; rem: roentgen equivalent man; PUJ: pelvi-ureteric junction; SFR: stone-free rate

Outcomes of Endourologic Interventions in Patients with Preoperative Funguria

Introduction: Funguria is encountered in 1% to 5% of cultured urine specimens and may be a result of specimen contamination, colonization, or invasive infection. The characteristics and outcomes of patients with funguria undergoing endourologic intervention have not been evaluated. Materials and Methods: Patients with preoperative funguria undergoing endourologic intervention were retrospectively identified. Preoperative funguria was defined as a urine culture containing >10,000 colony forming units of fungus within 30 days of the operative intervention. Univariable and multivariable regression was performed to identify predictors of postoperative systemic inflammatory response syndrome (SIRS). Results: A total of 65 patients with preoperative funguria were identified, of whom 49 (75.4%) underwent ureteroscopy and 16 (24.6%) underwent percutaneous nephrolithotomy. Average patient age was 55.1 ± 18.3 years, body mass index was 31.8 ± 11.0, and Charlson comorbidity index was 2.52 ± 2.0. Twenty-three patients (35.4%) carried a diagnosis of neurogenic bladder, of whom 18 (27.7%) required indwelling or intermittent catheterization. In total 57 patients (87.7%) had been exposed to antibiotics in the 3 months before intervention. Eighteen (27.7%) patients met SIRS criteria postoperatively, of whom 11 (16.9%) required intensive care unit (ICU) admission. Three (4.6%) and two (3.1%) patients developed postoperative fungemia and bacteremia, respectively. All cases of fungemia were caused by Candida glabrata. On univariable analysis, presence of an indwelling catheter (p = 0.009), presence of a known neurological diagnosis (p = 0.02), presence of C. glabrata on preoperative culture (p = 0.04), and longer operative time (p = 0.04) were predictive of development of postoperative SIRS. No significant predictors were identified on multivariable analysis. Conclusions: Patients with preoperative funguria have high rates of comorbid illness, urinary catheterization, and recent exposure to antibiotics. This patient population is at high risk of perioperative infectious complications after endourologic intervention.

The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial

BACKGROUND

Fluoroscopy is commonly used during pediatric ureteroscopy (PURS) for urolithiasis, and the most important contributor to overall radiation exposure is fluoroscopy time (FT). One factor that may impact FT is who controls activation of the fluoroscope: the urologist (with a foot pedal) or the radiation technologist (as directed by the urologist). While there are plausible reasons to believe that either approach may lead to reduced FT, there are no systematic investigations of this question. We sought to compare FT with surgeon-control versus technologist control during PURS for urolithiasis.

METHODS

We conducted a randomized controlled trial (Clinicaltrials.gov ID number: NCT02224287). Institutional Review Board approval was sought and obtained for this study. All subjects (or their legal guardians) provided informed consent. Each patient (age 5-26 years) was randomized to surgeon- or technologist-controlled fluoroscope activation. Block randomization was stratified by the surgeon. For technologist control, the surgeon verbally directed the technologist to activate the fluoroscope. For surgeon control, a foot pedal was used by the surgeon. The technologist controlled c-arm positioning, settings, and movement. The primary outcome was total FT for the procedure. Secondary outcomes included radiation exposure (entrance surface air kerma [ESAK] mGy). We also analyzed clinical and procedural predictors of FT and exposure. Mixed linear models accounting for clustering by surgeon were developed.

RESULTS

Seventy-three procedures (5 surgeons) were included. The number of procedures per surgeon ranged from seven to 36. Forty-three percent were pre-stented. Thirty-one procedures were left side, 35 were right side, and seven were bilateral. Stones were treated in 71% of procedures (21% laser, 14% basket, and 65% laser/basket). Stone locations were distal ureter (11.5%), proximal/mid-ureter (8%), renal (69%), and ureteral/renal (11.5%). An access sheath was used in 77%. Median stone size was 8.0 mm (range 2.0-20.0). Median FT in the surgeon control group was 0.5 min (range 0.01-6.10) versus 0.55 min (range 0.10-5.50) in the technologist-control group (p = 0.284). Median ESAK in the surgeon control group was 46.02 mGy (range 5.44-3236.80) versus 46.99 mGy (range: 0.17-1039.31) in the technologist-control group (p = 0.362). Other factors associated with lower FT on univariate analysis included female sex (p = 0.015), no prior urologic surgeries (p = 0.041), shorter surgery (p = 0.011), and no access sheath (p = 0.006). On multivariable analysis only female sex (p = 0.017) and no access sheath (p = 0.049) remained significant. There was significant variation among surgeons (p < 0.0001); individual surgeon median FT ranged from 0.40 to 2.95 min.

CONCLUSIONS

Fluoroscopy time and radiation exposure are similar whether the surgeon or technologist controls fluoroscope activation. Other strategies to reduce exposure might focus on surgeon-specific factors, given the significant variation between surgeons.