Pulsed versus continuous mode fluoroscopy during PCNL: safety and effectiveness comparison in a case series study

Radiation exposure during different percutaneous renal puncture techniques: A YAU endourology & urolithiasis study

PURPOSE

Radiation exposure is affected by C-arm fluoroscopy device positioning during percutaneous renal puncture. Our aim was to compare the exposure of surgeon's lens, hand and chest with a fluoroscopy protocol replicated in different C-arm positions.

MATERIALS AND METHODS

A standardized fluoroscopy protocol was created using water-equivalent solid phantoms to replicate a surgeon and patient. 111 mGy radiation (360 s) was applied in standard fluoroscopy mode (91 kVp, 2.7 mA/mAs). Dosimeters were placed on lens, chest and hand of surgeon and patient phantom models. 7 different C-arm positions were created: 0°, mediolateral (ML) +90°, ML -90°, ML +30°, ML -15°, craniocaudal (CC) +30°, CC +15°. Measurements were evaluated separately for different positions.

RESULTS

The highest radiation exposure was measured on patient dosimeter (2.97 mSv). The highest exposure on surgeon was recorded on finger dosimeter in all C-arm positions; highest dose was recorded in ML +90° position (2.88 mSv). In finger dosimeters, lowest exposure was recorded in 0° position (0.51 mSv). The lowest exposure of all positions was measured in chest dosimeter in ML -90° position (0.24 mSv).

CONCLUSIONS

In positions where X-ray generator of the C-arm was facing towards the surgeon, radiation exposure measured in all dosimeters was higher compared to positions where the generator was facing away. The hand radiation exposure in all positions was higher than chest and lens. Special care must be taken to avoid facing the X-ray generator tube and hands should be as well-protected as chest and eyes with special protective gear.

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%.

Low-dose fluoroscopy technique drastically decreases patient radiation exposure during percutaneous nephrolithotomy

Fluoroscopy is essential in percutaneous nephrolithotomy (PCNL) but exposes patients and operating room staff to radiation. We investigated whether a low-dose (LD) protocol could reduce radiation exposure during fluoroscopy-guided access without compromising clinical outcomes. Patients undergoing PCNL with fluoroscopy-guided access at a tertiary care stone center between January 2019 and July 2021 were identified. Prior to September 3, 2020, the Philips Veradius C-arm's default settings were used: standard per-frame dose, 15 pulses per second (PPS) frame rate. After this date, a low-dose protocol was used: reduced per-frame dose, reduced frame rate of 8 PPS for needle puncture and 4 PPS for all other steps. Clinical and radiographical data were retrospectively collected. The primary outcome was cumulative radiation dose. Secondary outcomes were stone-free status (SFS; defined as no fragments ≥ 2 mm) and complications. Multivariate regression analysis was performed. 100 patients were identified; 31 were in the LD group. The LD cohort was exposed to a significantly lower mean cumulative radiation dose of 11.68 mGy compared to 48.88 mGy (p < 0.0001). There were no differences in operative time, fluoroscopy time, stone burden, SFS, or complications. In a multivariable regression model adjusting for several variables, LD protocol was associated with lower radiation dose while skin-to-calyx-distance (STCD) was positively associated with cumulative radiation dose. Low-dose fluoroscopy and decreased frame rate during PCNL decreased radiation exposure fourfold without affecting SFS or complication rates.

Radiation protection measures during endourological therapies

Objective

The objective of this narrative review was to search the existing literature for studies reporting measures to minimize radiation use during endoscopic management of stone disease and present ways of reducing the exposure of both patients and operating room staff.

Methods

A literature review in PubMed was performed to identify studies describing protocols or measures to reduce radiation received during endourological procedures from January 1970 to August 2022. Eligible studies were those that reported outcomes for ureteroscopy or percutaneous nephrolithotripsy regarding measures to minimize radiation doses used intraoperatively, performed either in real-life theatres or using phantoms. Both comparative and non-comparative studies were deemed eligible.

Results

Protection can be achieved initially at the level of diagnosis and follow-up of patients, which should be done following an algorithm and choice of more conservative imaging methods. Certain protocols, which follow principles for minimized fluoroscopy use should be implemented and urologists as well as operating room staff should be continuously trained regarding radiation damage and protection measures. Wearing protective lead equipment remains a cornerstone for personnel protection, while configuration of the operating room and adjusting X-ray machine settings can also significantly reduce radiation energy.

Conclusion

There are specific measures, which can be implemented to reduce radiation exposure. These include avoiding excessive use of computed tomography scans and X-rays during diagnosis and follow-up of urolithiasis patients. Intraoperative protocols with minimal fluoroscopy use can be employed. Staff training regarding dangers of radiation plays also a major role. Use and maintenance of protective equipment and setting up the operating room properly also serve towards this goal. Machine settings can be customized appropriately and finally continuously monitoring of exposure with dosimeters can be adopted.

3D Imaging Segmentation and 3D Rendering Process for a Precise Puncture Strategy During PCNL – a Pilot Study

Percutaneous nephrolithotomy (PCNL) is frequently used as the first-line treatment of large and complex stones. The key point for successful complex stone removal with minimal risk of complications is to establish the most appropriate access route. Understanding the three-dimensional (3D) relationship of kidney stones and renal collecting systems is crucial for planning and creating an optimal access route. By using a 3D volume segmentation tool a more accurate approach to the renal collecting system and stone treatment could be planned. The objective of this study was assessing the impact of 3D software in getting the desired access.

Simplified biplanar (0-90°) fluoroscopic puncture technique for percutaneous nephrolithotomy: the learning curve

PURPOSE

To evaluate the learning curve of the simplified fluoroscopic biplanar (0-90º) puncture technique for percutaneous nephrolithotomy.

METHODS

We prospectively evaluated patients with renal stones treated with percutaneous nephrolithotomy by a single institution's fellows employing the simplified bi-planar (0-90º) fluoroscopic puncture technique for renal access. The learning curve was assessed with the fluoroscopic screening time and the percutaneous renal puncture time. Data obtained were compared to a subset of patients operated by a senior surgeon.

RESULTS

Eighty-nine patients were included in the study. Forty patients were operated by fellow-1, 39 by fellow-2, and 10 patients by the senior surgeon. Demographic data of all patients between groups were homogeneous, with no difference in gender (p = 0.432), age (p = 0.92), stone volume (p = 0.78), puncture laterality (p = 0.755), and body mass index (p = 0.365). The mean puncture time was 7.5, 4, and 3.1 min for fellow-1, fellow-2, and expert, respectively. The mean fluoroscopic screening time for the puncture was 10, 11, and 5.1 s for fellow-1, fellow-2, and the expert, respectively. Stone cases, both fellows needed to complete 10 procedures to match the senior surgeon in the mean puncture time (p = 0.046); meanwhile, the fluoroscopic screening time was equal even before to complete 10 procedures.

CONCLUSION

This study suggests that with the simplified biplanar (0-90º) puncture technique, the fluoroscopic screening time used in the learning process is brief. A novice fellow could require to complete ten cases to flatten the learning curve treating complex stone cases, and a flat learning curve is seen since the beginning when treating simple renal stones.

European Association of Urology Section of Urolithiasis and International Alliance of Urolithiasis Joint Consensus on Percutaneous Nephrolithotomy

CONTEXT

Although percutaneous nephrolithotomy (PCNL) has been performed for decades and has gone through many refinements, there are still concerns regarding its more widespread utilization because of the long learning curve and the potential risk of severe complications. Many technical details are not included in the guidelines because of their nature and research protocol.

OBJECTIVE

To achieve an expert consensus viewpoint on PCNL indications, preoperative patient preparation, surgical strategy, management and prevention of severe complications, postoperative management, and follow-up.

EVIDENCE ACQUISITION

An international panel of experts from the Urolithiasis Section of the European Association of Urology, International Alliance of Urolithiasis, and other urology associations was enrolled, and a prospectively conducted study, incorporating literature review, discussion on research gaps (RGs), and questionnaires and following data analysis, was performed to reach a consensus on PCNL.

EVIDENCE SYNTHESIS

The expert panel consisted of 36 specialists in PCNL from 20 countries all around the world. A consensus on PCNL was developed. The expert panel was not as large as expected, and the discussion on RGs did not bring in more supportive evidence in the present consensus.

CONCLUSIONS

Adequate preoperative preparation, especially elimination of urinary tract infection prior to PCNL, accurate puncture with guidance of fluoroscopy and/or ultrasonography or a combination, keeping a low intrarenal pressure, and shortening of operation time during PCNL are important technical requirements to ensure safety and efficiency in PCNL.

PATIENT SUMMARY

Percutaneous nephrolithotomy (PCNL) has been a well-established procedure for the management of upper urinary tract stones. However, according to an expert panel consensus, core technical aspects, as well as the urologist's experience, are critical to the safety and effectiveness of PCNL.

Percutaneous kidney stone surgery and radiation exposure: A review

During the past 3 decades, radiation exposure (RE) has increased drastically among patients undergoing percutaneous nephrolithotomy (PCNL), thus potentially causing new cases of cancer each year. The effective dose received by patients comes from pre- and post-operative computed tomography (CT) and intraoperative fluoroscopy (FL). We reviewed literature to find novel techniques and approaches that help to decrease RE of patients and personnel. We performed PubMed search using keywords percutaneous nephrolithotomy, intraoperative fluoroscopy, radiation exposure, imaging, percutaneous access, ultrasound, computed tomography, endoscopy, reconstruction, innovations, and augmented reality. Forty-four relevant articles were included in this review. As much as 20% of patients with first diagnosed urolithiasis exceed background RE level almost 17-fold. For diagnosing purposes using low-dose and ultra-low-dose CT, as well as low-dose dual energy scan protocols can be efficient ways to decrease RE while maintaining decent accuracy. Patients with urinary stones can be effectively monitored with digital tomosynthesis, ultrasound alone or ultrasound combined with plain film of the abdomen. Percutaneous access (PCA) into the kidney can be performed with reduced or even no RE, using novel PCA methods. REs from conventional imaging techniques during diagnosis and treatment increase probability of non-stochastic radiation effects. Urologists should be aware of protocols that decrease RE from CT and FL in diagnosis and management of urinary stones. Consideration of recently developed imaging modalities and PCA techniques will also aid in adherence to the “as low as reasonably achievable” principle.

Radiation exposure during TACE procedures using additional cone-beam CT (CBCT) for guidance: safety and precautions

Background During transarterial chemoembolization (TACE), cone-beam computed tomography (CBCT) can be used for tumor and feeding vessel detection as well as postembolization CT imaging. However, there will be additional radiation exposure from CBCT. Purpose To evaluate the additional dose raised through CBCT-assisted guidance in comparison to TACE procedures guided with pulsed digital subtraction angiography (DSA) alone. Material and Methods In 70 of 140 consecutive patients undergoing TACE for liver cancer, CBCT was used to facilitate the TACE. Cumulative dose area product (DAP), cumulative kerma(air), DAP values of DSA, total and cine specific fluoroscopy times (FT) of 1375 DSA runs, and DAP of 91 CBCTs were recorded and analyzed using Spearman's correlation, Mann-Whitney U-test, and Kruskal-Wallis test. P values < 0.05 were considered significant. Results Additional CBCT increased DAP by 2% ( P = 0.737), kerma(air) by 24.6% ( P = 0.206), and FT by 0.02% ( P = 0.453). Subgroup analysis revealed that postembolization CBCT for detection of ethiodized oil deposits added more DAP to the procedure. Performing CBCT-assisted TACE, DSA until first CBCT contributed about 38% to the total DAP. Guidance CBCT acquisitions conduced to 6% of the procedure's DAP. Additional DSA for guidance after CBCT acquisition required approximately 46% of the mean DAP. The last DSA run for documentation purposes contributed about 10% of the DAP. Conclusion CBCT adds radiation exposure in TACE. However, the capability of CBCT to detect vessels and overlay in real-time during fluoroscopy facilitates TACE with resultant reduction of DAPs up to 46%.