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

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Journal of Pediatric Urology (2018) xx, 1.e1e1.e8

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

Children’s Hospital Los Angeles, Los Angeles, CA, USA

b

Boston Children’s Hospital, Boston, MA, USA

Paul J. Kokorowski a, Jeanne S. Chow b, Bartley G. Cilento Jr b, Don-Soo Kim b, Michael P. Kurtz b, Tanya Logvinenko b, Robert D. MacDougall b, Caleb P. Nelson b Summary

Correspondence to: Caleb P. Nelson, Harvard Medical School, Director of Quality and Safety, Department of Urology, Boston Children’s Hospital, 300 Longwood Ave, Boston, MA, 02115, USA, Tel.: þ1 617 355 7796; fax: þ1 617 730 0474. caleb.nelson@childrens. harvard.edu (C.P. Nelson) Keywords Ureteroscopy; Radiation exposure; Clinical trial

and exposure. Mixed linear models accounting for clustering by surgeon were developed.

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 Received 20 November 2017 Accepted 28 April 2018 Available online xxx

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 5e26 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 carm 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

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 2.0e20.0). Median FT in the surgeon control group was 0.5 min (range 0.01e6.10) versus 0.55 min (range 0.10e5.50) in the technologist-control group (p Z 0.284). Median ESAK in the surgeon control group was 46.02 mGy (range 5.44e3236.80) versus 46.99 mGy (range: 0.17e1039.31) in the technologist-control group (p Z 0.362). Other factors associated with lower FT on univariate analysis included female sex (p Z 0.015), no prior urologic surgeries (p Z 0.041), shorter surgery (p Z 0.011), and no access sheath (p Z 0.006). On multivariable analysis only female sex (p Z 0.017) and no access sheath (p Z 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.

Summary Table Fluoroscopy times and radiation exposure comparing surgeon-control vs. technologist control. Measure Total Fluoro Time (min) Median (IQR) Radiation ESAK (mGy) Median (IQR)

Tech Control (N Z 36)

Surgeon Control (N Z 37)

Overall (N Z 73)

0.55 (0.65)

0.50 (0.70)

0.50 (0.70)

46.99 (72.98)

46.02 (86.18)

46.50 (79.47)

P-value 0.2836 0.3616

https://doi.org/10.1016/j.jpurol.2018.04.035 1477-5131/ª 2018 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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Introduction As incidence of pediatric urolithiasis has increased, utilization of ureteroscopy for surgical management of stone disease has also increased in this population [1]. Fluoroscopy is commonly used during pediatric ureteroscopy (PURS) for urolithiasis, and the most important contributor to overall radiation exposure is fluoroscopy time (FT) [2]. However, fluoroscopy times during PURS vary significantly among institutions [2e4] One potential factor underlying this variation is the technique used to activate the X-ray beam during procedures. At some institutions, it is standard to use a radiation technologist to start and stop the X-ray beam on the verbal request of the surgeon; at other centers, activation is directly controlled by the surgeon using a foot pedal or other device. It is plausible that surgeon control of beam would result in lower total fluoroscopy times, but a case can be made that technologist control is actually preferable to surgeon control, given the multiple other issues vying for the surgeon’s attention. Few data are available regarding the impact of fluoroscope control on exposure. An information sheet from a company specializing in radiation barrier and safety equipment states that the best way to reduce fluoroscopy time “is for the physician, and not the x-ray technician, to use the C-Arm foot switch” [5]. No data were provided to support this assertion. One retrospective review compared FT before and after a change in fluoroscopy control practices at the authors’ institution, and did not detect any difference in overall exposure based on surgeon versus technologist control [6]. Given the recognition in recent years of the increasing exposure to medical radiation in the population, and in particular of possible long-term sequelae in pediatric patients due to increased radiosensitivity in younger people, as well as their longer lifespan, efforts have been made to reduce radiation exposure associated with both diagnostic and therapeutic procedures for pediatric urolithiasis [7,8]. However, no prospective studies have been conducted to investigate the impact of fluoroscopy control. In this study we sought to study the effect of control of fluoroscopic x-ray activation on fluoroscopy time and radiation exposure during pediatric ureteroscopy. We hypothesized that surgeon-control of fluoroscopy activation would result in a significant reduction in fluoroscopy time compared with technologist control.

Methods Between January 2013 and December 2016, all patients aged 5e30 years undergoing ureteroscopy for suspected urolithiasis at our institution were approached to participate, and informed consent obtained. Institutional Review Board approval was sought and obtained for this study. See Fig. 1 for the CONSORT flow diagram describing enrollment. Subjects were included in the analysis if ureteroscopy was performed, whether or not a stone was identified or treated intraoperatively. In those cases where ureteroscopic access could not be obtained, and a stent was placed for passive dilation and delayed ureteroscopy at a later date, the subject was re-enrolled at the time of the delayed procedure. Each case was randomized to surgeon -control or

P.J. Kokorowski et al. technologist-control of activation of the x-ray source, using a four-case block randomization technique and sealed light-impermeable envelopes, which were handled and opened by the research staff only, after study consent was obtained. Randomization was stratified by surgeon to limit bias associated with individual surgeon practices. For subjects assigned to technologist control, the surgeon directed the technologist to activate and cease exposure during the procedure using previously developed standard terminology (e.g., “live fluoro” to activate live fluoroscope imaging). For those assigned to surgeon control, activation of the fluoroscope was controlled by the surgeon using a foot pedal. In both groups, positioning and movement of the fluoroscope unit was performed by the technologist at the surgeon’s direction. For all cases, fluoroscope settings were pre-defined according to institutional guidelines to minimize exposure (toddler default settings, pulsed digital mode, correct position) and verified via use of a previously developed pre-fluoroscopy checklist. At the time of surgery, data were collected regarding the clinical and patient parameters as well as fluoroscope parameters (positioning and unit settings including potential in kilovolts and current in milliamperes). Source to skin distance and the patient’s anterior to posterior diameter were directly measured using tape measure and calipers. Surgical time was measured as time from the termination of the “time out” to the surgeon announcing termination of the procedure. Relative participation of trainees was assessed based on whether the attending staff was the primary operator in greater than 50%, less than 50%, or approximately 50% of the case (based on the assessment of the attending). BMI percentile was calculated using CDC BMI calculator for children. Patients 20 years older or over were considered 20 years of age for BMI percentile calculations. The primary outcome in this study was total fluoroscopy time for the procedure. Fluoroscopy time was assessed from the readout on the fluoroscopy unit. A secondary outcome was radiation exposure measured as entrance surface air kerma (ESAK, mGy). (Kerma is an acronym for Kinetic Energy Released in Material [9].) ESAK was calculated based on the following equation: ESAK Z CRE  [D/ 30]2, where CRE Z cumulative radiation exposure in mGy, from the readout on the fluoro unit, and D Z distance from the top of table pad to the surface of image intensifier. In addition to analyzing the association of the intervention with primary and secondary outcomes, we analyzed the association of other patient and procedure factors with both fluoroscopy time and ESAK. Data were collected and stored in a REDCAP database. Descriptive statistics were used to characterize the patient cohort. Fisher’s exact and Wilcoxon tests were used to compare categorical and continuous patient and procedure characteristics between the two randomized arms, respectively. Mixed linear models accounting for clustering by surgeon were used to assess associations between primary and secondary outcomes FT and radiation exposure (ESAK) and patient and procedure characteristics. Variables that had significant univariate associations (<0.1) and/or clinical relevance were included in the final multivariate model. Both FT and ESAK were log-transformed prior to analyses to ensure normality of residual distributions. SAS v. 9.4 (SAS Institute Inc., Cary, NC, USA) was used for

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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Effect of surgeon versus technologist on radiation

Figure 1

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CONSORT flow diagram describing screening, enrollment, and loss of study subjects.

analyses. A p value < 0.05 was considered to be statistically significant; however, we considered p  0.10 to be significant for purposes of inclusion in the multivariate models.

Trial termination The original power calculation for this trial projected 75 subjects per arm (150 total). When we reached 65 subjects enrolled, an interim analysis showed no statistical difference between treatment arms (8.9 s absolute difference). We extrapolated the interim findings to a projected enrollment of 150 subjects, showing even with the larger sample, there would still be no significant difference between groups (projected p Z 0.598). We concluded that it was highly unlikely that continued enrollment in the trial would permit us to demonstrate any meaningful effect, and so therefore we elected to terminate the trial. (The trial reached the final enrollment of 73 subjects during the analysis period.)

Results Table 1 shows the characteristics of the cohort. A total of 73 procedures were included, performed by five different

surgeons. Number of procedures performed by each surgeon ranged from seven to 36. Pre-stenting had been performed in 43% of cases. Thirty-one procedures were leftside, 35 were right-side, and seven were bilateral. Stones were treated in 71% of procedures (21% laser, 13% basket, and 65% laser and basket). Stone locations were distal ureter in 12%, proximal/mid ureter in 8%, renal in 69%, and ureteral/renal in 12%. An access sheath was used in 77%. Median stone size was 8.0 mm (range 2.0e20.0). There was no significant difference between treatment groups in fluoroscopy time (Table 2). Median fluoroscopy time in the surgeon control group was 0.5 min (range 0.01e6.10) versus 0.55 min (range 0.10e5.50) in the technologist control group (p Z 0.284). There was also no significant difference in exposure between treatment groups (Table 2). Median ESAK in the surgeon control group was 46.02 mGy (range 5.44e3236.80) versus 46.99 mGy (range 0.17e1039.31) in the technologist control group (p Z 0.362). Factors associated with FT (Table 3) on univariate analysis included female sex (average 39.6% decrease compared with males, p Z 0.015), no prior urologic surgeries (average 36.3% decrease compared with patients with prior urologic surgeries, p Z 0.041), shorter surgery

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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1.e4 Table 1

P.J. Kokorowski et al. Characteristics of the study cohort, stratified by randomization group.

Characteristic

Technologist control (N Z 36)

Surgeon control (N Z 37)

Overall (N Z 73)

pa

Age, months, median (range) Sex Male Female BMI percentile, median (range) Anatomic abnormalities Yes No Prior urologic procedure Yes No Pre-existing stent No Yes Postoperative stent placement No Yes Retrograde pyelogram No Yes Ureteral access sheath No Yes Trainee role < 50% > 50% w50/50% Surgery length, min, median (range) Stone removal method None Laser Basket extraction Laser þ basket Number of stones treated None 1 2 3 4 5 or more Total linear stone burden, mm, median (range) (n Z 44) Stones location None seen Distal Proximal Renal Ureteral þ renal Laterality Unilateral Bilateral

195.7 (61.8e311)

219.9 (79.1e309.3)

197.1 (61.8e311)

0.3153 0.8163

18 (50.0%) 18 (50.0%) 47.2 (0.3e99.2)

20 (54.1%) 17 (45.9%) 55.2 (0e99.6)

38 (52.1%) 35 (47.9%) 48.6 (0e99.6)

8 (22.2%) 28 (77.8%)

8 (21.6%) 29 (78.4%)

16 (21.9%) 57 (78.1%)

17 (47.2%) 19 (52.8%)

24 (64.9%) 13 (35.1%)

41 (56.2%) 32 (43.8%)

23 (63.9%) 13 (36.1%)

19 (51.4%) 18 (48.6%)

42 (57.5%) 31 (42.5%)

1 (2.8%) 35 (97.2%)

3 (8.1%) 34 (91.9%)

4 (5.5%) 69 (94.5%)

36 (100.0%)

1 (2.7%) 36 (97.3%)

1 (1.4%) 72 (98.6%)

9 (25.0%) 27 (75.0%)

8 (21.6%) 29 (78.4%)

17 (23.3%) 56 (76.7%)

3 (8.3%) 22 (61.1%) 11 (30.6%) 99 (37e239)

5 (13.5%) 23 (62.2%) 9 (24.3%) 94 (46e204)

8 (11.0%) 45 (61.6%) 20 (27.4%) 96 (37e239)

10 (27.8%) 7 (19.4%) 2 (5.6%) 17 (47.2%)

11 (29.7%) 4 (10.8%) 5 (13.5%) 17 (45.9%)

21 (28.8%) 11 (15.1%) 7 (9.6%) 34 (46.6%)

10 (27.8%) 16 (44.4%) 6 (16.7%) 2 (5.6%) 1 (2.8%) 1 (2.8%) 9 (2e30)

11 (29.7%) 19 (51.4%) 4 (10.8%) 2 (5.4%) 0 (0.0%) 1 (2.7%) 8.5 (4e56)

21 (28.8%) 35 (47.9%) 10 (13.7%) 4 (5.5%) 1 (1.4%) 2 (2.7%) 9 (2e56)

10 (27.8%) 2 (5.6%) 21 (58.3%) 3 (8.3%)

11 (29.7%) 6 (16.2%) 2 (5.4%) 15 (40.5%) 3 (8.1%)

21 (28.8%) 6 (8.2%) 4 (5.5%) 36 (49.3%) 6 (8.2%)

31 (86.1%) 5 (13.9%)

35 (94.6%) 2 (5.4%)

66 (90.4%) 7 (9.6%)

a

0.9282 1

0.1601

0.3461

0.6145

1

0.787

0.7393

0.4301 0.5719

0.9553

0.85 0.1132

0.2611

p value obtained from Fisher’s exact test for categorical and Wilcoxon test for continuous variables.

(average 0.7% decrease for 1 min shorter surgery time, p Z 0.011), and no access sheath (average 51.4% decrease compared with procedures with access sheath, p Z 0.006), although on multivariate analysis (controlling for surgeon

clustering) only female sex (average 37.5% decrease compared with males, p Z 0.017) and no access sheath (average 41.4% decrease compared with procedures with access sheath, p Z 0.049) remained significantly associated

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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Effect of surgeon versus technologist on radiation Table 2

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Fluoroscopy times and radiation exposure comparing surgeon-control vs. technologist control.

Measure

Technician control (N Z 36)

Surgeon control (N Z 37)

Overall (N Z 73)

p

Total fluoro time, min, median (IQR) Radiation ESAK, mGy, median (IQR)

0.55 (0.65) 46.99 (72.98)

0.50 (0.70) 46.02 (86.18)

0.50 (0.70) 46.50 (79.47)

0.2836 0.3616

with FT (all factors included in the final model shown in Table 3). Factors associated with higher ESAK (Table 4) in univariate analysis included age (average increase of 0.5% for 1 extra month of age, p Z 0.0320), male sex (average increase of 73.8% compared to females, p Z 0.0591), higher BMI percentile (0.6% increase for a 1 percentage point higher BMI, p Z 0.0910), prior urologic surgeries (average 68.5% increase compared with patients with no prior urologic surgeries, p Z 0.0899), and longer surgery (average 0.6% increase for 1 min longer surgery time, p Z 0.0921). In multivariate analysis (controlling for surgeon clustering) only younger age (average increase of 0.5% for 1 extra month of age, p Z 0.0716), and male sex (average 65.1% increase compared to females, p Z 0.0811) remained marginally associated with ESAK (all factors included in the final model shown in Table 4). Trainee participation was not a significant factor: compared with the reference category of <50% trainee

participation, FT decreased by 42% (p Z 0.24) in cases with >50% trainee, and FT decreased by 14% (p Z 0.72) for cases with w50% trainee participation. However, there was significant variation among surgeons (p < 0.0001); individual surgeon median FT ranged from 0.40 min to 2.95 min. We did note that bilateral cases were skewed to the technologist control group (5/7), while cases for stones in the distal ureter were skewed to the surgeon-control group (6/6). The differences were not statistically significant, but both of these allocation trends would be expected to lead to increase fluoroscopy and radiation in the technologist group and less in the surgeon group, which could potentially neutralize any exposure-reducing effect of technologist control, if such an effect existed. Therefore, we performed a sensitivity analysis to control for laterality and distal stone location. We excluded cases that were either bilateral or distal ureteral location (n Z 13), and repeated the primary analysis of treatment arm vs. outcomes control on the remaining subjects. We found that in this subset

Table 3 Association of patient and procedure factors with fluoroscopy time in minutes (mixed linear model accounting for clustering by surgeon). Characteristic

Age, months Female sex (vs. male) BMI percentile Anatomic abnormalities (vs. none) No prior urologic procedure (vs. prior procedure) Pre-existing stent (vs. none) Postoperative stent placement (vs. none) Retrograde pyelogram (vs. none) No access sheath (vs. access sheath used) Trainee role <50% (reference) > 50% 50/50% Surgery length, min Stone removal None (reference) Laser Basket extraction Laser and basket Number of stones Linear stone burden Stones location None (reference) Distal Proximal Renal Ureteral þ renal Bilateral case (vs. unilateral)

Univariate analysis

Multivariate analysis

Percentage Change

p

0.02 39.62 0.08 12.29 36.28 8.90 52.10 32.70 51.36

0.9343 0.0151 0.7859 0.6187 0.0409 0.7036 0.1598 0.7569 0.0059

e 42.38 14.40 0.67

e 0.2457 0.7240 0.0107

e 8.24 0.99 5.41 0.96 0.27 e

e 0.8335 0.9814 0.8480 0.9256 0.8507 e

43.94 7.18 20.28 5.17 71.28

0.1814 0.8859 0.4968 0.9066 0.1425

Percentage Change

p

37.50

0.0171

15.69

0.4376

41.44

0.0487

0.34

0.2272

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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P.J. Kokorowski et al.

Table 4 Association of patient and procedure factors with radiation exposure, calculated as entrance surface air kerma (ESAK) in mGy (mixed linear model accounting for clustering by surgeon). Characteristic

Univariate Percentage Change

p

Percentage change

p

Age, months Male sex (vs. female) BMI percentile Anatomic abnormalities (vs. none) Prior urologic procedure (vs. none) Preexisting stent (vs. none) Postoperative stent placement (vs. none) Retrograde pyelogram Ureteral access sheath (vs. none) Trainee role <50% (ref) > 50% w50/50% Surgery length, min Stone removal None (ref) Laser Basket extraction Laser þ basket Number of stones Linear stone burden Stones location None (ref) Distal Proximal Renal Ureteral þ renal Bilateral case (vs. unilateral)

0.58 73.78 0.71 19.49 68.47 30.07 27.15 12.56 36.14

0.0320 0.0591 0.0910 0.6283 0.0899 0.2501 0.6685 0.9258 0.4060

0.49 65.08 0.64

0.0716 0.0811 0.1183

21.54

0.5496

0.79

0.9837

e 63.05 25.89 0.64

e 0.1221 0.6165 0.0921

0.38

0.3700

e 35.44 26.16 3.69 2.72 3.49

e 0.5594 0.6075 0.9220 0.8479 0.1483

e 28.19 3.18 12.86 44.09 81.73

e 0.5839 0.9657 0.7529 0.3379 0.2723

(unilateral procedure, stone location other than distal ureter only), fluoroscopy control was NOT significantly associated with FT (surgeon control 13.2% lower vs. technologist control [95% CI e54.0% to 63.9%], p Z 0.6745) or ESAK (surgeon control 28.0% higher vs. technologist control [95% CI e34.6% to 150.5%], p Z 0.4924). Additionally, we developed a mixed linear multivariate model to assess the association of treatment arm with FT and ESAK, while controlling for laterality and distal ureter stone location. In these models, fluoro control was NOT significantly associated with FT (surgeon control 9.2% lower vs. technologistcontrol [95% CI e40.9% to 39.3%], p Z 0.6687) or ESAK (surgeon control 31.9% higher vs. technologist-control [95% CI e28.2% to 142.2%], p Z 0.3983).

Discussion In this study we compared surgeon versus technologist control of X-ray activation during ureteroscopy for urolithiasis. There was no significant difference in exposure or FT between the two groups. We did observe fairly dramatic differences in fluoroscopy use among surgeons. There have been increasing efforts in recent years to reduce radiation exposure to patients during evaluation and treatment of urolithiasis. Much of these efforts, particularly

Multivariate

in the pediatric sphere, have been driven by concerns about the increased sensitivity of children to the long-term deleterious effects of radiation. Children have been estimated to be significantly more radiation-sensitive than adults [10e12], and it has been postulated that the radiation from a single CT scan may have a measurable impact on long-term cancer risk in this population [13]. Publications and conferences focused on the ALARA (“as low as reasonably achievable”) principle [14], and the related Image Gently Campaign, have sought to bring attention to these concerns and reduce overall levels of exposure [15]. With the increasing incidence of pediatric urolithiasis [16], both imaging and surgical intervention have similarly been increasing. At many centers, ureteroscopy is the firstline surgical treatment for pediatric stone disease [17,18]. Conventionally, fluoroscopy is used throughout these procedures to gain access to the upper tracts, localize stones, define renal anatomy, and place stents and other devices. A number of investigators in recent years have sought techniques for reducing the fluoroscopy requirement during ureteroscopy. Protocols, checklists and similar interventions to reduce variability in technique seem to be useful in reducing exposure [7,19,20]. Other investigators have sought technical changes in fluoroscopy settings or equipment to limit radiation [21,22]. Lastly, a number of centers have sought to eliminate fluoroscopy entirely from

Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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Effect of surgeon versus technologist on radiation ureteroscopy, using ultrasound alone for imaging guidance [23e26], but experience with this approach in the pediatric population remains very limited. In this study we addressed yet another factor in radiation exposure, that of fluoroscope control during the procedure. There are plausible reasons to imagine that either technologist or surgeon control of fluoroscope on/off might favorably impact exposure. The surgeon is the individual performing the procedure, so it makes sense that it might be the surgeon who best knows when to activate the fluoroscope, when to turn it off, and how much or little exposure time is needed. Surgeons have many other things on their plate during ureteroscopy, however, including handling the scope and other equipment, keeping the relevant anatomy in view, and so forth. One might expect that the surgeon would be easily distracted, and thus more inclined to have a “lead foot” on the fluoro control pedal. Alternatively, the technologist is often unfamiliar with the details of the procedure being performed, and may not know how much or little imaging is needed or desired by the surgeon. It is easy to imagine overuse of fluoroscopy during these procedures due to suboptimal communication between surgeon and technologist. The technologist on the other hand has only the fluoroscope to worry about, and may be able to serve as a check on overuse of fluoroscopy due to their focus on this without diversion. In the event, however, we found that exposure measures were similar regardless of which fluoroscopy control approach was used. Our findings demonstrate that individual surgeon was a significant predictor of fluoroscopy use during ureteroscopy. This suggests that at least some of the radiation exposure during these cases may be avoidable via standardization of techniques and training. A number of investigators have looked at this and confirmed that training and experience with these procedures may reduce exposure during cases. Sfoungaristos et al. [27] found that more experienced surgeons may utilize fluoroscopy less than lessexperienced peers. Similarly, Weld et al. [28] found that fluoroscopy use among residents diminished with increased operative experience. We additionally found that surgeons varied in use of access sheaths (p Z 0.036), postoperative stent placement (p Z 0.002), trainee role (p < 0.001), and patient factors such as age (p Z 0.011) and stone location (p Z 0.005). This variability lends further evidence to the argument that efforts to standardize these procedures may be warranted. The results of this study should be interpreted in light of its limitations. One inherent limitation is the potential for the Hawthorne effect. This was necessarily an un-blinded study and we could not prevent the surgeon, radiation technologist, or operating room staff from altering their behavior, knowing that they were being observed. We limited this by using a discrete, measurable outcome (total fluoroscopy time), and by stratifying the randomization within surgeon. The study took place over a number of years, and unmeasured changes in techniques or equipment could have impacted the results. Other limitations include a relatively limited number of participating surgeons, and the fact that all cases were performed at a single center. Thus, while the randomized trial design eliminates much of the potential unmeasured confounding, it is still possible that these findings are not generalizable to other centers or

1.e7 surgeons. There were also a number of factors that were skewed into one group or the other, most notably bilateral cases and distal stone-only cases. These factors clearly might influence the amount of fluoroscopy used, but in our sensitivity analysis we found that even accounting for (or excluding) these outlier cases, control of fluoroscopy activation still did not impact total exposure. We did not have dedicated endourology technologists, and the technologist assigned by OR staffing could be relieved by others during the procedure; these factors might have impacted FT, although likely reflect “real-world” staffing processes at most institutions. Lastly, this study had a relatively small sample size. Our initial target enrollment was 150 subjects, but after an interim analysis showed no clinically or statistically significant differences between groups, and extrapolation furthermore showed that continued enrollment would be very unlikely to result in the observed differences becoming significant, we elected to terminate the trial. However, it is possible (albeit highly unlikely) that a larger sample size would have demonstrated a meaningful effect of one fluoroscope control strategy over the other.

Conclusions Fluoroscopy time and radiation exposure during ureteroscopy for suspected urolithiasis are similar whether the surgeon or technologist controls activation of the fluoroscope. Other strategies to reduce exposure might focus on surgeon-specific factors, given the significant variation between surgeons in fluoroscopy use.

Funding This work was supported in part by a K23 Career Development Award from NIDDK (K23DK088943).

Conflicts of interest None.

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Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035

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Please cite this article in press as: Kokorowski PJ, et al., The effect of surgeon versus technologist control of fluoroscopy on radiation exposure during pediatric ureteroscopy: A randomized trial, Journal of Pediatric Urology (2018), https://doi.org/10.1016/ j.jpurol.2018.04.035