Radiation Exposure During Endourologic Procedures Using Over-the-Table Fluoroscopy Sources

Reducing hand radiation during renal access for percutaneous nephrolithotomy: a comparison of radiation reduction techniques

Percutaneous nephrolithotomy confers the highest radiation to the urologist's hands compared to other urologic procedures. This study compares radiation exposure to the surgeon's hand and patient's body when utilizing three different techniques for needle insertion during renal access. Simulated percutaneous renal access was performed using a cadaveric patient and separate cadaveric forearm representing the surgeon's hand. Three different needle-holding techniques were compared: conventional glove (control), a radiation-attenuating glove, and a novel needle holder. Five 300-s fluoroscopy trials were performed per treatment arm. The primary outcome was radiation dose (mSv) to the surgeon's hand. The secondary outcome was radiation dose to the patient. One-way ANOVA and Tukey's B post-hoc tests were performed with p < 0.05 considered significant. Compared to the control (3.92 mSv), both the radiation-attenuating glove (2.48 mSv) and the needle holder (1.37 mSv) reduced hand radiation exposure (p < 0.001). The needle holder reduced hand radiation compared to the radiation-attenuating glove (p < 0.001). The radiation-attenuating glove resulted in greater radiation produced by the C-arm compared to the needle holder (83.49 vs 69.22 mGy; p = 0.019). Patient radiation exposure was significantly higher with the radiation-attenuating glove compared to the needle holder (8.43 vs 7.03 mSv; p = 0.027). Though radiation-attenuating gloves decreased hand radiation dose by 37%, this came at the price of a 3% increase in patient exposure. In contrast, the needle holder reduced exposure to both the surgeon's hand by 65% and the patient by 14%. Thus, a well-designed low-density needle holder could optimize radiation safety for both surgeon and patient.

[Radiation-induced cataract-an occult risk for urologists]

BACKGROUND

Radiation-induced cataracts represent a relevant risk to people occupationally exposed to radiation. The annual limit dose for the eye lens was reduced to 20 mSv per year by German legislation (radiation protect law StrlSchG 2017; 2013/59/Euratom) based on recommendation of International Commission on Radiation Protection (2011 ICRP) to avoid radiation-induced cataracts.

OBJECTIVES

Is there a risk of exceeding the annual limit dose for the eye lens in routine urological practice without special radiation protection for the head?

METHODS

As part of a prospective, monocentric dosimetry study, of 542 different urological, fluoroscopically guided interventions, the eye lens dose was determined using a forehead dosimeter (thermo-luminescence dosemeter TLD, Chipstrate) over a period of 5 months.

RESULTS

An average head dose of 0.05 mSv per intervention (max. 0.29 mSv) was found with an average dose area product of 485.33 Gy/cm². Significant influencing factors for a higher dose were a higher patient body mass index (BMI), a longer operation time, and a higher dose area product. The level of experience of the surgeon showed no significant influence.

DISCUSSION

With 400 procedures per year or an average of 2 procedures per working day, the critical annual limit value for the eye lenses or for the risk of radiation-induced cataract would be exceeded without special protective measures.

CONCLUSION

Consistently effective radiation protection of the eye lens is essential for daily work in uroradiological interventions. This may require further technical developments.

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.

Radiation exposure of patients during endourological procedures: IAEA-SEGUR study

Fluoroscopy is increasingly used to guide minimally invasive endourological procedures and optimised protocols are needed to minimise radiation exposure while achieving best treatment results. This multi-center study of radiation exposure of patients was conducted by the South-Eastern European Group for Urolithiasis Research (SEGUR), in cooperation with the International Atomic Energy Agency. Seven clinical centers from the SEGUR group collected data for 325 procedures performed within a three-months period, including standard percutaneous nephrolithotomy (PCNL), mini PCNL, retrograde intrarenal surgery (RIRS), semirigid ureterorenoscopy (URS) and flexible URS. Data included: air kerma area product (P_KA), air kerma at the patient entrance reference point (K_a,r), fluoroscopy time (FT), number of radiographic images (N) and fluoroscopy pulse rate, as well as total procedure duration, size and location of stones. Data were centrally analysed and statistically compared. MedianP_KAvalues per center varied 2-fold for RIRS (0.80-1.79 Gy cm²), 7.1 fold for mini-PCNL (1.39-9.90 Gy cm²), 7.3 fold for PCNL (2.40-17.50 Gy cm²), 19 fold (0.13-2.51 Gy cm²) for semi-rigid URS and 29-fold for flexible URS (0.10-2.90 Gy cm²). LowerP_KAandK_a,rwere associated with use of lower FT,Nand lower fluoroscopy pulse rate. FT varied from 0.1 to 14 min, a small fraction of the total procedure time, ranging from 10 to 225 min. HigherNwas associated with higherP_KAandK_a,r. Higher medianP_KAin PCNL was associated with the use of supine compared to prone position. No correlation was found between the concrement size and procedure duration, FT,P_KAorK_a,r. Dose values for RIRS were significantly lower compared to PCNL. The maximumK_a,rvalue of 377 mGy was under the threshold for radiation induced skin erythema. The study demonstrated a potential for patient dose reduction by lowering FT andN, using pulsed fluoroscopy and beam collimation.

Radiation Exposure of Surgical Team During Endourological Procedures: International Atomic Energy Agency-South-Eastern European Group for Urolithiasis Research Study

Introduction: Fluoroscopy-guided endourology procedures require proper radiation protection to minimize radiation risk. This multicenter study aimed at investigating radiation protection practice and related radiation exposure of operating team members. Materials and Methods: Six endourology centers from the South-Eastern European Group for Urolithiasis Research answered questionnaires and collected data of 315 procedures performed within a 3-months period, with simultaneous measurement of dose to staff and dose area product (DAP) to patient. A pair of calibrated personal dosimeters, one for body and one for eye-lens dose, was worn by all key staff members. Dosimeters were centrally calibrated, measured, and analyzed. Results: The annual workload ranged from 173 to 865 procedures per center. Practice of personal dose monitoring and use of radiation protection shielding was found to be inconsistent. Lead aprons and thyroid collars were used by all, whereas protective eyewear was used in only half of centers. Due to the regular use of protective aprons, the whole-body dose of all 44 monitored staff members was safely below the regulatory dose limits. Eye-lens dose of 17 (14 urologists and 3 assisting staff) was above the dosimeter detection level, and dose per procedure varied from <10 to 63 μSv. The highest annual eye-lens dose of 13.5 mSv was found for the surgeon in the busiest department by using an over-the-couch X-ray tube without a ceiling suspended screen. Working closer to patient body with no protection resulted in a six-time higher eye-lens dose per DAP for a surgeon compared with others in the same center. Lower eye-dose per procedure was associated with lower DAP to patient and with the use of an under-the-couch tube, lower fluoroscopy pulse rate, collimation, fluoroscopy time, and acquired images. Conclusions: The study results call for the need to establish standard protocols about use of fluoroscopy during endourology procedures and to increase radiation protection knowledge and awareness of surgical staff.

[Effect of X-ray protective visors on the eye lens dose during ureteroscopy]

BACKGROUND AND OBJECTIVES

Eye lens radiation exposure during fluoroscopy-guided interventional procedures may result in occupational radiation-induced cataracts. We evaluated the eye lens radiation doses and the protective effect of X‑ray protective visors during ureteroscopic procedures.

MATERIALS AND METHODS

Eye lens doses were measured in front of and behind X‑ray protective visors using eye lens dosemeters during ureteroscopic procedures done by 4 different endourologic surgeons within a 12-week period. Background radiation dose, simultaneously measured with transport dosemeters, was subtracted. Measured eye lens doses below the detection limit of the eye lens dosemeters were adjusted to the detection limit of 0.028 mSv. Correlating the eye lens doses (ELD) to the dose-area-product (DAP) an ELD/DAP ratio was calculated. Applying this ELD/DAP ratio the potential reduction of the eye lens radiation dose was retrospectively calculated for all ureteroscopic procedures done within one year.

RESULTS

Within the 12-week period 76 ureteroscopies were done by the 4 endourologic surgeons. The accumulated eye lens radiation dose was 0.796 mSv in front of the X‑ray protective visors, and 0.338 mSv behind the X‑ray protective visors. Thus, the eye lens radiation exposure was reduced to at least 42% by using X‑ray protective visors. Considering the 215 documented ureteroscopies in our clinic in the year before starting the study, occupational radiation exposure to the eye lens would have been reduced by X‑ray protective visors from 4.090 to 1.737 mSv.

CONCLUSION

X‑ray protective visors can effectively reduce the radiation exposure to the eye lens during fluoroscopy-guided endourologic procedures and should be used especially by high-volume endourologic surgeons.

Risk of Radiation-Induced Cataracts: Investigation of Radiation Exposure to the Eye Lens During Endourologic Procedures

BACKGROUND

Due to new radiobiologic data, the International Commission on Radiological Protection recommends a dose limit of 20 mSv per year to the eye lens. Therefore, the IAEA International Basic Safety Standard and the European council directive 2013/59/EURATOM require a reduction of the annual dose limit from 150 to 20 mSv. Urologists are exposed to an elevated radiation exposure in the head region during fluoroscopic interventions, due to the commonly used overtable X-ray tubes and the rarely used radiation protection for the head. Aim of the study was to analyze real radiation exposure to the eye lens of the urologist during various interventions, during which the patient is in the lithotomy position.

MATERIALS AND METHODS

The partial body doses (forehead and apron collar) of the urologists and surgical staff were measured over a period of 2 months. 95 interventions were performed on Uroskop Omnia Max workplaces (Siemens Healthineers, Erlangen, Germany). Interventions were class-divided in less (stage I) and more complex (stage II) interventions. Two dosimeter-types were applied, well-calibrated electronic personal dosimeter Mk2 and self-calibrated thermoluminescent dosimeter-100H (both Thermo Fisher Scientific, Waltham, MA). The radiation exposure parameters were documented using the dose area product (DAP) and the fluoroscopy time.

RESULTS

The correlation between DAP and the apron dose of the urologist was in average 0.07 μSv per 1 μGym². The more experienced urologists yielded a mean DAP of 166 μGym² for stage I and 415 μGym² for stage II procedures. The interventionist was exposed with 10 μSv in mean outside the lead apron collar. The mean dose value of the eye lenses per intervention was ascertained to 20 μSv (mean DAP: 233 μGym²).

CONCLUSIONS

The study setup allows a differentiated and time-resolved measurement of the radiation exposure, which was found heterogeneous depending on intervention and surgeon. In this setting, ∼1000 interventions can be performed until the annual eye lens dose limit is achieved.

Retrograde intrarenal surgery using the single - use flexible ureteroscope Uscope 3022 (Pusen™): evaluation of clinical results

Introduction

Reusable endoscopes have some limitations regarding their continued use. To sort out these problems, several disposable devices have appeared on the market. Our objective is to show our clinical results with a new digital flexible single-use ureteroscope.

Materials and methods

This study presents a prospective series of patients who underwent endoscopic surgery as treatment for renal stones using the digital disposable endoscope Uscope 3022™. Demographic, procedure and stone information were registered including surgery time, stone-free rate, need of ureteral catheterization and complications, among others. The behavior of the ureteroscope in terms of image quality and problems associated with flexibility and the working channel were also registered.

Results

A total of 71 procedures were included in the analysis. The mean age was 49.9 years old, with 70.4% of male patients. Mean stone size was 11.4 mm (4 to 40 mm). The most frequent stone location was in the lower calyces (28.2%). The stone burden was high (>2 cm) in 8.4% of patients. The mean surgical time was 56.6 minutes (15–180 min). In 94.4% of the cases, a laser was used with dusting parameters. The global stone-free rate (SFR) was 95.2%, but in the subgroups analysis SFR were significantly superior in stones less than 10 mm (97.9%) versus stones between 10 and 20 mm (94.5%) and greater than 20 mm (78.3%) (p <0.01). The postoperative placement of double-J stents was required in 66.2% of patients. Two minor complications were recorded and they were related to the ureteral access sheath used. There were no problems regarding the performance of the ureteroscope.

Conclusions

The clinical data observed in this series does not differ from the results traditionally obtained with other reusable devices. To our knowledge, this series is the first worldwide report evaluating the clinical behavior and results in humans of the Uscope 3022.

Staff lens doses in interventional urology. A comparison with interventional radiology, cardiology and vascular surgery values

The purpose of this work is to evaluate radiation doses to the lens of urologists during interventional procedures and to compare them with values measured during interventional radiology, cardiology and vascular surgery. The measurements were carried out in a surgical theatre using a mobile C-arm system and electronic occupational dosimeters (worn over the lead apron). Patient and staff dose measurements were collected in a sample of 34 urology interventions (nephrolithotomies). The same dosimetry system was used in other medical specialties for comparison purposes. Median and 3rd quartile values for urology procedures were: patient doses 30 and 40 Gy cm(2); personal dose equivalent Hp(10) over the apron (μSv/procedure): 393 and 848 (for urologists); 21 and 39 (for nurses). Median values of over apron dose per procedure for urologists resulted 18.7 times higher than those measured for radiologists and cardiologists working with proper protection (using ceiling suspended screens) in catheterisation laboratories, and 4.2 times higher than the values measured for vascular surgeons at the same hospital. Comparison with passive dosimeters worn near the eyes suggests that dosimeters worn over the apron could be a reasonable conservative estimate for ocular doses for interventional urology. Authors recommend that at least the main surgeon uses protective eyewear during interventional urology procedures.

The Knowledge of Radiation and the Attitude Towards Radio-Protection among Urology Residents in India

INTRODUCTION

Exposure to radiation is a hazard and precautions are necessary to limit it. This study was done to assess the knowledge of radiation and the attitude towards radio-protection among urology residents in India.

MATERIALS AND METHODS

A questionnaire was administered to assess the knowledge and attitude of urology residents who came from all over the country to attend a clinical meeting at Apollo Gleneagles Hospital, Kolkata, India.

RESULTS

All the respondents agreed to being exposed to radiation, with 78.2% using radiation in more than five cases a week. Only 65.2% always took some steps for radio-protection. Lead aprons and thyroid shields were the most common radiation protection devices used. None of the residents ever used lead gloves or protective eye glasses or dosimeters. An 82.6% felt that they did not have adequate knowledge, 85.4% of residents did not receive any formal classes regarding the risk of radiation, 21.7% either rarely or never moved out of the operating room when the radiation was being used, 42.4% did not know that the SI unit of the equivalent absorbed dose of radiation & 52.1% did not know about the amount of radiation delivered to an adult during a contrast enhanced CT scan of the abdomen.

CONCLUSION

Results of the present study reveal that the urology residents of India lack knowledge about the risks of radiation exposure. Majority of them did not take necessary precautions to limit their exposure to radiation.

[Eye lens radiation exposure during ureteroscopy with and without a face protection shield: Investigations on a phantom model]

BACKGROUND AND OBJECTIVES

Eye lens radiation exposure during radiologically-guided endoscopic procedures may result in radiation-induced cataracts; therefore, we investigated the ocular radiation exposure during ureteroscopy on a phantom model.

MATERIALS AND METHODS

Using an Alderson phantom model and eye lens dosimeters, we measured the ocular radiation exposure depending on the number of X-ray images and on the duration of fluoroscopic imaging. The measurements were done with and without using a face protection shield.

RESULTS

We could demonstrate that a significant ocular radiation exposure can occur, depending on the number of X-ray images and on the duration time of fluoroscopy. Eye lens doses up to 0.025 mSv were recorded even using modern digital X-ray systems. Using face protection shields this ocular radiation exposure can be reduced to a minimum.

CONCLUSION

The International Commission on Radiological Protection (ICRP) recommendations of a mean eye lens dosage of 20 mSv/year may be exceeded during repeated ureteroscopy by a high volume surgeon. Using a face protection shield, the eye lens dose during ureteroscopy could be reduced to a minimum in a phantom model. Further investigations will show whether these results can be transferred to real life ureteroscopic procedures.

Ultrasonographic versus Fluoroscopic Access for Percutaneous Nephrolithotomy: A Meta-Analysis

Objective: To assess the safety and efficacy of ultrasonographic vs. fluoroscopic access for percutaneous nephrolithotomy (PCNL). Methods: Medline (PubMed), Embase, Ovid, Cochrane, and the Chinese Biomedical Literature databases were searched to identify clinically controlled trials (CCTs) and randomized controlled trials (RCTs) that compared ultrasonographic access with fluoroscopic access for PCNL. RevMan 5.1 software and Stat Manager V4.1 software were used for the meta-analysis. Results: Five RCTs and nine CCTs were included in our study, which contained a total of 3,019 patients. Of these, 1,574 (52%) had undergone ultrasonographic access, and 1,445 (48%) had undergone fluoroscopic access. The pooled results revealed that the ultrasonographic access patients had shorter duration of access (min) by 2.56 min (weighted mean difference (WMD) = −2.56, 95% confidence interval (CI): −4.40 to −0.72, p = 0.006). There was a higher stone-free rate in the ultrasonographic access group (odds ratio (OR) = 1.26, 95% CI: 1.02-1.55, p = 0.03), as well as a lower rate of operative complications (OR = 0.72, 95% CI: 0.56-0.93, p = 0.01), reduced intraoperative blood loss (ml) (WMD = −14.55 ml, 95% CI: −27.65 to −1.46, p = 0.03), and a lower rate of blood transfusion requirement (OR = 0.39, 95% CI: 0.24-0.63, p = 0.0001). Sensitivity and subgroup analyses were also performed. Conclusion: Except for no radiation exposure, our meta-analysis revealed that ultrasonographic access had many advantages, such as a shorter access time, reduced intraoperative blood loss, a lower rate of operative complications, a lower rate of blood transfusion, and a higher stone-free rate. Because of these significant advantages, we recommend the use of ultrasonographic access for PCNL.

Limiting radiation exposure during percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

An increase in the prevalence of urologic stone disease and the refinement of endourologic techniques has seen a concomitant rise in the use of fluoroscopy during surgery. As such, there has been increasing concern in regard to the intraoperative radiation exposure to both clinicians and patients. The objective of the study was to audit contemporary data on radiation exposure during percutaneous nephrolithotomy (PCNL), in comparison with published series, and demonstrate that relatively low levels are achievable with clinical vigilance and attention to technique Methods: A retrospective analysis was performed of all PCNLs undertaken between July 2005 and December 2011. The primary outcome measure was fluoroscopy times and associated radiation exposure, measured as dose area product (DAP). No statistical analysis was undertaken.

RESULTS

Between July 2005 and October 2011, 376 PCNLs were performed. Data were available on 348 patients including 16 pediatric patients. Mean DAP and screening time (ST) over the whole study period were 45 cGy/cm(2) and 96s, respectively. On a year by year basis, the ST and DAP reduced from 917 to 375 and from 180 to 65, respectively. We acknowledge the limitation of this being a retrospective case series.

CONCLUSIONS

This study represents the largest series to date on radiation exposure during PCNL and compares favorably with other published series, including those purporting novel techniques. Subtle changes in surgical technique and experience over time can lead to low screening times and can be potentially achieved by all operators performing PCNL within a high throughput center. It is now recognized that surgical outcome in stone surgery is related to caseload. The radiation dose the patient receives during PCNL is increasingly recognized to be an important factor and can be reduced by careful technique and experience.

Occupational hazard: radiation exposure for the urologist--developing a reference standard

INTRODUCTION

To date, there is a paucity of literature offering practicing urologists a reference for the amount of radiation exposure received while surgically managing urolithiasis. This study examines the cumulative radiation exposure of an urologist over 9 months.

MATERIALS AND METHODS

We present a case series of fluoroscopic exposures of an experienced stone surgeon operating at an academic comprehensive stone center between April and December 2011. Radiation exposure measurements were determined by a thermoluminescent dosimeter worn on the outside of the surgeon's thyroid shield. Estimations of radiation exposure (mrem) per month were charted with fluoroscopy times, using scatter plots to estimate Spearman's rank correlation coefficients.

RESULTS

The total 9-month radiation exposure was 87 mrems for deep dose equivalent (DDE), 293 mrem for lens dose equivalent (LDE), and 282 mrem for shallow dose equivalent (SDE). Total fluoroscopy time was 252.44 minutes for 64 ureteroscopies (URSs), 29 percutaneous nephrolithtomies (PNLs), 20 cystoscopies with ureteral stent placements, 9 shock wave lithotripsies (SWLs), 9 retrograde pyelograms (RPGs), 2 endoureterotomies, and 1 ureteral balloon dilation. Spearman's rank correlation coefficients examining the association between fluoroscopy time and radiation exposure were not significant for DDE (p = 0.6, Spearman's rho = 0.2), LDE (p = 0.6, Spearman's rho = 0.2), or SDE (p = 0.6, Spearman's rho = 0.2).

CONCLUSIONS

Over a 9-month period, total radiation exposures were well below annual accepted limits (DDE 5000 mrem, LDE 15,000 mrem and SDE 50,000 mrem). Although fluoroscopy time did not correlate with radiation exposure, future prospective studies can account for co-variates such as patient obesity and urologist distance from radiation source.

Ocular radiation exposure in modern urological practice

PURPOSE

The human eye is a highly radiosensitive portion of the body and repeat radiation exposure can lead to cataract. The minimum fractionated long-term dose to initiate cataract formation is about 2,500 mSv. We determined whether further radiation related precautions are necessary to protect the eyes of the surgeon.

MATERIALS AND METHODS

Radiation doses received near the right eye of the operating surgeon were measured with a thermoluminescent dosimeter badge worn near the eye of 6 urologists for a single endourological procedure at an academic center. Procedures included stent insertion, ureteroscopic lithotripsy and percutaneous nephrolithotomy. The mean radiation dose was calculated. Extrapolated doses required to potentiate cataract formation were also calculated.

RESULTS

We assessed 28 urological procedures for radiation exposure, of which 13 were ureteroscopy done for calculus disease (range 0.05 to 0.66 mSv) and 7 were ureteral stent insertion (range 0.13 to 0.32 mSv). The mean radiation dose received during these cases was 0.208 mSv. Based on the mean dose and an average of 20 such cases per month, it would take about 50 years to reach the minimum threshold for progressive cataract formation. Eight percutaneous renal operations were performed and the mean dose received was 0.125 mSv (range 0.04 to 0.22). Based on 10 cases per month, this would require more than 160 years of exposure to reach the minimal threshold.

CONCLUSIONS

Long-term radiation can lead to cataract formation. However, the accumulated lifetime exposure of the typical urologist may not necessitate further safety precautions, such as lead-lined glasses.

[The urological Dyna-CT. Urological cross-sectional imaging on a newly developed urological intervention table]

BACKGROUND

The development of a new urological intervention table now enables the application of an Artis zee ceiling Dyna-CT (Siemens, Erlangen, Germany) for interventional cross-sectional imaging and 3-D reconstruction of the urinary tract in the prone and supine positions (urological Dyna-CT).

MATERIALS AND METHODS

We tested the feasibility of the urological Dyna-CT with the newly developed urological intervention table. The system was moved five times to enable 3-D reconstruction of the urinary tract of a test person in the prone and in supine positions.

RESULTS

Handling of the free floating table is easily possible during the intervention. We found no limitation of imaging system movement in any position of the test person.

CONCLUSION

Apart from standard urological imaging such as fluoroscopy, intravenous pyelography or plain abdominal X-ray the urological Dyna-CT enables further imaging of the urinary tract. Fluoroscopy sequences can be stored as videos, and 3-D reconstructions of the urinary tract are possible with permanent patient access for any intervention. Extensive tests led to the technical approval of the system in urology.

Laser-guided percutaneous kidney access with the Uro Dyna-CT: first experience of three-dimensional puncture planning with an ex vivo model

BACKGROUND AND PURPOSE

Safe and successful puncture of the kidney's collecting system is essential for acute therapy of hydronephrosis or as part of percutaneous nephrolithotomy. The procedure is technically challenging and might lead to major complications. We describe the feasibility of a laser guidance system and three-dimensional puncture planning in the endourological operation room.

MATERIALS AND METHODS

An Uro Dyna-CT of the biological model was performed with the Artis Zee(®) Ceiling (Siemens Medical Solutions, Erlangen, Germany) to gain multiplanar reconstructions. 10 punctures were performed with the syngo iGuide(®) laser guidance system. Puncture success was depicted with antegrade contrast filling of the collecting system and fluoroscopic control. Puncture time, tract length, and fluoroscopy time was documented.

RESULTS

Data acquisition (8 s) and 3D rendering (48 s) was possible in approximately 1 min. Median time for planning the punctures was 7 [5-15] min. Median puncture time was 4.6 [2-10.2] min. Median tract length was 4.96 [4.33-6.5] cm. Median fluoroscopy time was 0.4 [0.2-1] min. 9 of 10 punctures were successful. A second puncture was needed to gain access to the collecting system in one case, and one puncture was broken up.

CONCLUSION

The tested laser guidance system was feasible to perform successful percutaneous punctures of the kidney in this ex vivo study. Handling was intuitive and time within acceptable limits. Due to the requirement of multiplanar reconstructions with higher radiation exposure to the patient than with standard fluoroscopy, this technique should be limited to complex cases.