Strategies to Optimize Nephrolithiasis Emergency Care (STONE): Prospective Evaluation of an Emergency Department Clinical Pathway.

OBJECTIVE: To convene a multi-disciplinary panel to develop a pathway for Emergency Department (ED) patients with suspected nephrolithiasis and then prospectively evaluate its effect on patient care. MATERIALS AND METHODS: The STONE Pathway was developed and linked to order sets within our Electronic Health Record in April 2019. Records were prospectively reviewed for ED patients who underwent ultrasound or Computerized Tomography (CT) to evaluate suspected nephrolithiasis between January 2019 and August 2019 within our institution. The primary outcome measure was the proportion of patients whose ED CT was low dose (<4 mSv). Secondary outcome measures included receipt of pathway-concordant pain medications and urine strainers. Order set utilization was evaluated as a process measure. Balance measures assessed included repeat ED visits, imaging, hospitalizations, and a urologic clinic visit or surgery within 30 days of discharge. RESULTS: 441 patients underwent ED imaging, of whom 261 (59%) were evaluated for suspected nephrolithiasis. The STONE Pathway was used in 50 (30%) eligible patients. Patients treated with the Pathway were more likely to undergo low-dose CTs (49% vs 23%, P <.001), and receive guideline-concordant pain medications such as NSAIDs (90% vs 62%, P <.001), and were less likely to return to the ED within 30 days (13% vs 2%, P = .01). These measures demonstrated special cause variation following Pathway release. CONCLUSION: Clinical pathways increase compliance with evidence-based practices for pain control and imaging in nephrolithiasis emergency care and may improve the delivery of value-based care.

Findings of the AAPM Ad Hoc committee on magnetic resonance imaging in radiation therapy: Unmet needs, opportunities, and recommendations.

The past decade has seen the increasing integration of magnetic resonance (MR) imaging into radiation therapy (RT). This growth can be contributed to multiple factors, including hardware and software advances that have allowed the acquisition of high-resolution volumetric data of RT patients in their treatment position (also known as MR simulation) and the development of methods to image and quantify tissue function and response to therapy. More recently, the advent of MR-guided radiation therapy (MRgRT) - achieved through the integration of MR imaging systems and linear accelerators - has further accelerated this trend. As MR imaging in RT techniques and technologies, such as MRgRT, gain regulatory approval worldwide, these systems will begin to propagate beyond tertiary care academic medical centers and into more community-based health systems and hospitals, creating new opportunities to provide advanced treatment options to a broader patient population. Accompanying these opportunities are unique challenges related to their adaptation, adoption, and use including modification of hardware and software to meet the unique and distinct demands of MR imaging in RT, the need for standardization of imaging techniques and protocols, education of the broader RT community (particularly in regards to MR safety) as well as the need to continue and support research, and development in this space. In response to this, an ad hoc committee of the American Association of Physicists in Medicine (AAPM) was formed to identify the unmet needs, roadblocks, and opportunities within this space. The purpose of this document is to report on the major findings and recommendations identified. Importantly, the provided recommendations represent the consensus opinions of the committee's membership, which were submitted in the committee's report to the AAPM Board of Directors. In addition, AAPM ad hoc committee reports differ from AAPM task group reports in that ad hoc committee reports are neither reviewed nor ultimately approved by the committee's parent groups, including at the council and executive committee level. Thus, the recommendations given in this summary should not be construed as being endorsed by or official recommendations from the AAPM.

Fluoroscopically-guided interventions with radiation doses exceeding 5000 mGy reference point air kerma: a dosimetric analysis of 89,549 interventional radiology, neurointerventional radiology, vascular surgery, and neurosurgery encounters.

PURPOSE: To quantify and categorize fluoroscopically-guided procedures with radiation doses exceeding 5000 mGy reference point air kerma (Ka,r). Ka,r > 5000 mGy has been defined as a "significant radiation dose" by the Society of Interventional Radiology. Identification and analysis of interventions with high radiation doses has the potential to reduce radiation-induced injuries. MATERIALS AND METHODS: Radiation dose data from a dose monitoring system for 19 interventional suites and 89,549 consecutive patient encounters from January 1, 2013 to August 1, 2019 at a single academic institution were reviewed. All patient encounters with Ka,r > 5000 mGy were included. All other encounters were excluded (n = 89,289). Patient demographics, medical specialty, intervention type, fluoroscopy time (minutes), dose area product (mGy·cm2), and Ka,r (mGy) were evaluated. RESULTS: There were 260 (0.3%) fluoroscopically-guided procedures with Ka,r > 5000 mGy. Of the 260 procedures which exceeded 5000 mGy, neurosurgery performed 81 (30.5%) procedures, followed by interventional radiology (n = 75; 28.2%), neurointerventional radiology (n = 55; 20.7%), and vascular surgery (n = 49; 18.4%). The procedures associated with the highest Ka,r were venous stent reconstruction performed by interventional radiology, arteriovenous malformation embolization performed by neurointerventional radiology, spinal hardware fixation by neurosurgery, and arterial interventions performed by vascular surgery. Neurointerventional radiology had the highest mean Ka,r (7,799 mGy), followed by neurosurgery (7452 mGy), vascular surgery (6849 mGy), and interventional radiology (6109 mGy). The mean Ka,r for interventional radiology performed procedures exceeding 5000 mGy was significantly lower than that for neurointerventional radiology, neurosurgery, and vascular surgery. CONCLUSIONS: Fluoroscopically-guided procedures with radiation dose exceeding 5000 mGy reference point air kerma are uncommon. The results of this study demonstrate that a large proportion of cases exceeding 5000 mGy were performed by non-radiologists, who likely do not receive the same training in radiation physics, radiation biology, and dose reduction techniques as radiologists.

Radiation Dose for Multiregion CT Protocols: Challenges and Limitations.

OBJECTIVE. The purpose of this study was to devise a method for classification of individual chest and abdomen-pelvis CT doses for multiregion CT. MATERIALS AND METHODS. A retrospective analysis of volume CT dose index (CTDIvol) and dose-length product (DLP) associated with chest (150 adult patients), abdomen-pelvis (150 patients), and multiregion combined chest-abdomen-pelvis CT (210 patients; 60 single-run chest-abdomen-pelvis CT; 150 split-run with separate chest and abdomen-pelvis CT). All 510 CT examinations were performed with one of four MDCT scanners (64-, 64-, 128-, 256-MDCT). CTDIvol, DLP, and scan length were recorded. Scan lengths were obtained for these 510 CT examinations and for an additional 7745 examinations of patients at another institution. Data were analyzed by ANOVA and ROC analysis. RESULTS. The respective DLPs (chest, 258-381 mGy · cm; abdomen-pelvis, 360-433 mGy · cm; single-run chest-abdomen-pelvis, 595-636 mGy · cm) and scan lengths (chest, 31-33 cm; abdomen-pelvis, 45-46 cm; single-run chest-abdomen-pelvis, 63-65 cm) for chest, abdomen-pelvis, and multiregion combined chest-abdomen-pelvis CT were significantly different (p < 0.0001). For split-run, chest-abdomen-pelvis CT, scan lengths and dose indexes for individual body regions were not different from those of single-body-region CT (p > 0.05). ROC analysis of chest and abdomen examinations showed an ideal scan length threshold of 38 cm to differentiate abdomen-pelvis CT from chest CT with accuracy of 97.39% and an AUC of 0.9764. CONCLUSION. Despite interscanner variabilities in CT radiation doses, shorter scan length for chest than for abdomen-pelvis CT enables accurate binning of radiation doses for split-run combined chest-abdomen-pelvis CT.

Monitoring and Follow-Up of High Radiation Dose Cases in Interventional Radiology.

RATIONALE AND OBJECTIVES: To assess the implementation of radiation dose monitoring software, create a process for clinical follow-up and documentation of high-dose cases, and quantify the number of patient reported radiation-induced tissue reactions in fluoroscopically guided interventional radiology (IR) and neuro-interventional radiology (NIR) procedures. MATERIALS AND METHODS: Web-based radiation dose monitoring software was installed at our institution and a process to flag all procedures with reference point air kerma (Ka,r) > 5000 mGy was implemented. The entrance skin dose was estimated and formal reports generated, allowing for physician-initiated clinical follow-up. To evaluate our process, we reviewed all IR and NIR procedures performed at our hospital over a 1-year period. For all procedures with Ka,r > 5000 mGy, retrospective medical chart review was performed to evaluate for patient reported tissue reactions. RESULTS: Three thousand five hundred eighty-two procedures were performed over the 1-year period. The software successfully transferred dose data on 3363 (93.9%) procedures. One thousand three hundred ninety-three (368 IR and 1025 NIR) procedures were further analyzed after excluding 2189 IR procedures with Ka,r < 2000 mGy. Ten of 368 (2.7%) IR and 52 of 1025 (5.1%) NIR procedures exceeded estimated skin doses of 5000 mGy. All 10 IR cases were abdominal/pelvic trauma angiograms with/without embolization; there were no reported tissue reactions. Of 52 NIR cases, 49 were interventions and 3 were diagnostic angiograms. Five of 49 (10.2%) NIR patients reported skin/hair injuries, all of which were temporary. CONCLUSION: Software monitoring and documentation of radiation dose in interventional procedures can be successfully implemented. Radiation-induced tissue reactions are relatively uncommon.

Pediatric Percutaneous Osteoid Osteoma Ablation: Cone-Beam CT with Fluoroscopic Overlay Versus Conventional CT Guidance.

PURPOSE: To compare technical success, clinical success, complications, radiation dose, and total room utilization time for osteoid osteoma thermal (radiofrequency or microwave) ablation using cone-beam computed tomography (CBCT) with two-axis fluoroscopic navigational overlay versus conventional computed tomography (CT) guidance. MATERIALS AND METHODS: A retrospective review was performed to identify all osteoid osteoma ablations performed over a 5.5-year period at a single tertiary care pediatric hospital. Twenty-five ablations (15 radiofrequency and 10 microwave) in 23 patients undergoing fluoroscopic CBCT-guided osteoid osteoma ablation were compared to 35 ablations (35 radiofrequency) in 32 patients undergoing ablation via conventional CT guidance. Dose area product and dose length product were recorded for CBCT and conventional CT, respectively, and converted to effective doses. Technical success, clinical success (cessation of pain and medication use 1 month after ablation), complications, radiation dose, and total room utilization time were compared. RESULTS: All procedures were technically successful. Twenty-two of 25 (88.0%) CBCT and 31 of 35 (88.6%) conventional CT-guided ablations achieved immediate clinical success. There were two minor complications in each group and no major complications. Mean effective radiation dose was significantly lower for CBCT compared to CT guidance (0.12 vs. 0.39 mSv, p = 0.02). Mean total room utilization time for CBCT was longer (133.5 vs. 97.5 min, p = 0.0001). CONCLUSIONS: Fluoroscopic CBCT guidance for percutaneous osteoid osteoma ablation yields similar technical and clinical success, reduced radiation dose, and increased total room utilization time compared to conventional CT guidance.

Wide-detector axial CT versus 4 cm detector helical CT for transcatheter aortic valve replacement: iodine dose, radiation, and image quality.

PURPOSE: This study aims to compare transcatheter aortic valve replacement (TAVR) planning on 16 cm wide-detector computed tomography (CT) to TAVR planning on 4 cm detector CT. MATERIALS AND METHODS: A total of 36 patients who had TAVR planning axial CT on a wide-detector scanner (protocol 1) were compared to 36 patients who had helical 4 cm detector CT (protocol 2). RESULTS: Vascular attenuation was greater for protocol 1, but image noise, contrast-to-noise ratio, and signal-to-noise ratio were the same. Radiation dose was lower and iodine dose was less for protocol 1. CONCLUSION: Protocol 1 had greater vascular attenuation and similar image quality but lower radiation and less iodine compared to protocol 2.

Variation in Pediatric Cervical Spine Computed Tomography Radiation Dose Index.

OBJECTIVES: The objective was to evaluate variation in the current estimated radiation dose index for pediatric cervical spine (c-spine) computed tomography (CT) examinations. METHODS: This was a retrospective analysis of pediatric (age younger than 19 years) c-spine CT examinations from the American College of Radiology Dose Index Registry, July 2011 through December 2014. We used the volume CT dose index (CTDIvol) as the radiation dose estimate and used summary statistics to describe patient and hospital characteristics. RESULTS: There were 12,218 pediatric CT c-spine examinations performed across 296 participating hospitals. Fifty-six percent were in male patients, and 79% were in children older than 10 years. Most hospitals (55%) were community hospitals without trauma designations, and the largest proportion of examinations (41%) were performed at these hospitals. The median CTDIvol was 15 mGy (interquartile range = 9 to 23 mGy) representing a more than 2.5-fold difference between the 25th and 75th percentiles. Pediatric hospitals (both trauma and nontrauma centers) delivered the lowest CTDIvol across all age groups and showed the least amount of variability in dose. CONCLUSIONS: There is significant variation in the radiation dose index for pediatric c-spine CT examinations. Pediatric hospitals practice at lower CT dose estimates than other hospitals. Individual hospitals should examine their practices in an effort to ensure standardization and optimization of CT parameters to minimize radiation exposures to pediatric patients.

Variation in CT pediatric head examination radiation dose: results from a national survey.

OBJECTIVE. The purpose of this article is to examine the variation in radiation dose, CT dose index volume (CTDIvol), and dose-length product (DLP) for pediatric head CT examinations as a function of hospital characteristics across the United States. MATERIALS AND METHODS. A survey inquiring about hospital information, CT scanners, pediatric head examination protocol, CTDIvol, and DLP was mailed to a representative sample of U.S. hospitals. Follow-up mailings were sent to nonrespondents. Descriptive characteristics of respondents and nonrespondents were compared using design-based Pearson chi-square tests. Dose estimates were compared across hospital characteristics using Bonferroni-adjusted Wald test. Hospital-level factors associated with dose estimates were evaluated using multiple linear regressions and modified Poisson regression models. RESULTS. Surveys were sent out to 751 hospitals; 292 responded to the survey, of which 253 were eligible (35.5% response rate, calculated as number of hospitals who completed surveys [n = 253] divided by sum of number who were eligible and initially consented [n = 712] plus estimated number who were eligible among those who refused [n = 1]). Most respondents reported using MDCT scanners (99.2%) and having a dedicated pediatric head CT protocol (93%). Estimated mean reported CTDIvol values were 27.3 mGy (95% CI, 24.4-30.1 mGy), and DLP values were 390.9 mGy × cm (95% CI, 346.6-435.1 mGy × cm). These values did not vary significantly by region, trauma level, teaching status, CT accreditation, number of CT scanners, or report of a dedicated pediatric CT protocol. However, estimated CTDIvol reported by children's hospitals was 19% lower than that reported by general hospitals (p < 0.01). CONCLUSION. Most hospitals (82%) report doses that meet American College of Radiology accreditation levels. However, [corrected] the mean CTDI(vol) at children's hospitals was approximately 7 mGy (21%, adjusted for covariates), lower than that at nonchildren's hospitals.

Transjugular Intrahepatic Portosystemic Shunt Placement During Pregnancy: A Case Series of Five Patients.

BACKGROUND AND AIMS: Complications of portal hypertension, such as variceal hemorrhage and ascites, are associated with significant increases in both mortality and complications during pregnancy. Transjugular intrahepatic portosystemic shunt (TIPS) is a well-established procedure for treating portal hypertension, but the safety of TIPS during pregnancy is largely unknown. In this series, we review five patients who underwent TIPS placement while pregnant and describe their clinical outcomes. METHODS: Five pregnant patients with cirrhosis and portal hypertension underwent elective TIPS for complications of portal hypertension (four for secondary prevention of variceal bleeding and one for refractory ascites). Outcomes measured were recurrent bleeding episodes or need for further paracenteses during pregnancy, estimated radiation dose to the fetus and gestational age at delivery. All patients were followed after delivery to evaluate technical and clinical success of the procedure. RESULTS: All five patients survived pregnancy and went on to deliver successfully. When TIPS was performed for secondary prevention of variceal bleeding (n = 4), no patients demonstrated variceal bleeding after TIPS placement. When TIPS was performed for refractory ascites (n = 1), no further paracenteses were required. All patients delivered successfully, albeit prematurely. Average radiation dose estimated to the fetus was 16.3 mGy. CONCLUSIONS: This series suggests that TIPS can be performed in selective pregnant patients with portal hypertension, with little added risk to the mother or fetus.

Dual-energy liver CT: effect of monochromatic imaging on lesion detection, conspicuity, and contrast-to-noise ratio of hypervascular lesions on late arterial phase.

OBJECTIVE: The purpose of this study was to evaluate the effect of use of dual-energy CT monochromatic imaging in the late hepatic arterial phase on hyperenhancing focal lesion detection and lesion conspicuity. SUBJECTS AND METHODS: This prospective study included 72 patients imaged with a single-source dual-energy CT scanner. Late arterial phase imaging was performed with dual energies of 140 and 80 kVp, and the portal venous and delayed phases were performed with a single energy of 120 kVp. Two deidentified image sets were created: set A consisted of 77-keV images only, and set B consisted of 40-, 50-, 70-, and 77-keV images and iodine-based contrast material decomposition images. Two independent reviewers identified hypervascular lesions and subjectively scored lesion conspicuity. Contrast-to-noise ratios were calculated, and radiation dose (volume CT dose index) was recorded. RESULTS: The 128 lesions identified had a mean size of 1.7 ± 1.4 cm. There was no difference in lesion detection between the two reviewers or the two image sets. The contrast-to-noise ratio at 50 keV was 72% greater than that at 77 keV (p < 0.0001). Subjective conspicuity was statistically greatest at 50 keV (p < 0.0001). There was no statistical difference in mean volume CT dose index between the dual-energy (12.8 mGy) and the two single-energy (14.4 and 14.2 mGy) phases. CONCLUSION: Viewing dual-energy CT images may result in the greatest subjective lesion conspicuity and measured contrast-to-noise ratio at 50 keV with equal detection of hyperenhancing liver lesions compared with viewing 77-keV images alone. In addition, the radiation doses of dual-energy CT may be similar to those of single-energy CT.

Impact of incremental increase in CT image noise on detection of low-contrast hypodense liver lesions.

RATIONALE AND OBJECTIVES: To determine the impact of incremental increases in computed tomography (CT) image noise on detection of low-contrast hypodense liver lesions. MATERIAL AND METHODS: We studied 50 CT examinations acquired at image noise index (NI) of 15 and hypodense liver lesions and 50 examinations with no lesions. Validation of a noise addition tool to be used in the evaluation of the CT examinations was performed with a liver phantom. Using this tool, three 100-image sets were assembled: an NI of 17.4 (simulating 75% of the original patient radiation dose), 21.2 (simulating 50% dose), and 29.7 (simulating 25%). Three readers scored certainty of lesion presence using a five-point Likert scale. RESULTS: For original images (NI 15) plus images with NI of 17.4 and 21.2, sensitivity was >90% threshold (range, 95%-98%). For images with NI of 29.7, sensitivity was just below the threshold (89%). Reader Az values for receiver operating characteristic curves were good for original, NI 17.4, and NI 21.2 images (0.976, 0.973, and 0.96, respectively). For NI of 29.7, the Az decreased to 0.913. Detection sensitivity was <90% for both lesion size < 10 mm (85%) and lesion-to-liver contrast <60 Hounsfield units (85%) only at NI 29.7. CONCLUSIONS: For low-contrast lesion detection in liver CT, image noise can be increased up to NI 21.2 (a 50% patient radiation dose reduction) without substantial reduction in sensitivity.

Standard and reduced radiation dose liver CT images: adaptive statistical iterative reconstruction versus model-based iterative reconstruction-comparison of findings and image quality.

PURPOSE: To investigate whether reduced radiation dose liver computed tomography (CT) images reconstructed with model-based iterative reconstruction ( MBIR model-based iterative reconstruction ) might compromise depiction of clinically relevant findings or might have decreased image quality when compared with clinical standard radiation dose CT images reconstructed with adaptive statistical iterative reconstruction ( ASIR adaptive statistical iterative reconstruction ). MATERIALS AND METHODS: With institutional review board approval, informed consent, and HIPAA compliance, 50 patients (39 men, 11 women) were prospectively included who underwent liver CT. After a portal venous pass with ASIR adaptive statistical iterative reconstruction images, a 60% reduced radiation dose pass was added with MBIR model-based iterative reconstruction images. One reviewer scored ASIR adaptive statistical iterative reconstruction image quality and marked findings. Two additional independent reviewers noted whether marked findings were present on MBIR model-based iterative reconstruction images and assigned scores for relative conspicuity, spatial resolution, image noise, and image quality. Liver and aorta Hounsfield units and image noise were measured. Volume CT dose index and size-specific dose estimate ( SSDE size-specific dose estimate ) were recorded. Qualitative reviewer scores were summarized. Formal statistical inference for signal-to-noise ratio ( SNR signal-to-noise ratio ), contrast-to-noise ratio ( CNR contrast-to-noise ratio ), volume CT dose index, and SSDE size-specific dose estimate was made (paired t tests), with Bonferroni adjustment. RESULTS: Two independent reviewers identified all 136 ASIR adaptive statistical iterative reconstruction image findings (n = 272) on MBIR model-based iterative reconstruction images, scoring them as equal or better for conspicuity, spatial resolution, and image noise in 94.1% (256 of 272), 96.7% (263 of 272), and 99.3% (270 of 272), respectively. In 50 image sets, two reviewers (n = 100) scored overall image quality as sufficient or good with MBIR model-based iterative reconstruction in 99% (99 of 100). Liver SNR signal-to-noise ratio was significantly greater for MBIR model-based iterative reconstruction (10.8 ± 2.5 [standard deviation] vs 7.7 ± 1.4, P < .001); there was no difference for CNR contrast-to-noise ratio (2.5 ± 1.4 vs 2.4 ± 1.4, P = .45). For ASIR adaptive statistical iterative reconstruction and MBIR model-based iterative reconstruction , respectively, volume CT dose index was 15.2 mGy ± 7.6 versus 6.2 mGy ± 3.6; SSDE size-specific dose estimate was 16.4 mGy ± 6.6 versus 6.7 mGy ± 3.1 (P < .001). CONCLUSION: Liver CT images reconstructed with MBIR model-based iterative reconstruction may allow up to 59% radiation dose reduction compared with the dose with ASIR adaptive statistical iterative reconstruction , without compromising depiction of findings or image quality.

Hospital-level factors associated with use of pediatric radiation dose-reduction protocols for head CT: results from a national survey.

OBJECTIVES: To examine hospital-level factors associated with the use of a dedicated pediatric dose-reduction protocol and protective shielding for head CT in a national sample of hospitals. METHODS: A mixed-mode (online and paper) survey was administered to a stratified random sample of US community hospitals (N = 751). Respondents provided information on pediatric head CT scanning practices, including use of a dose-reduction protocol. Modified Poisson regression analyses describe the relative risk (RR) of not reporting the use of a pediatric dose-reduction protocol or protective shielding; multivariable analyses adjust for census region, trauma level, children's hospital status, and bed size. RESULTS: Of hospitals that were contacted, 38 were ineligible (no CT scanner, hospital closed, do not scan infants), 1 refused, and 253 responded (35.5% response rate). Across all hospitals, 92.6% reported using a pediatric dose-reduction protocol. Modified Poisson regression showed that small hospitals (0-50 beds) were 20% less likely to report using a protocol than large hospitals (>150 beds) (RR: 0.80, 95% confidence interval [CI]: 0.65-0.99; adjusted for covariates). Teaching hospitals were more likely to report using a protocol (RR: 1.10, 95% CI: 1.02-1.19; adjusted for covariates). After adjusting for covariates, children's hospitals were significantly less likely to report using protective shielding than nonchildren's hospitals (RR: 0.64, 95% CI: 0.56-0.73), though this may be due to more advanced scanner type. CONCLUSION: Results from this study provide guidance for tailored educational campaigns and quality improvement interventions to increase the adoption of pediatric dose-reduction efforts.

Severe obesity is associated with 3-fold higher radiation dose rate during ureteroscopy.

OBJECTIVE: To investigate and characterize the association between fluoroscopy radiation dose rate and various patient size metrics during ureteroscopy. MATERIALS AND METHODS: Fluoroscopy data were collected from 100 patients undergoing ureteroscopy for stone disease. Radiation dose rates were determined from fluoroscopy dose and time. Estimated entrance skin dose was calculated from air kerma (AK) by applying correction factors. Effective dose (ED) was estimated with Monte Carlo-based simulation software. Patient size metrics included body mass index (BMI), anterior-posterior (AP) midline distance, AP transrenal thickness, and region of interest (ROI) pixel value magnitude on computed tomography scout. Univariate and multivariate regression analyses were performed to determine the association between AK dose rate and patient size metrics, adjusting for laterality and stone location. RESULTS: Obese patients (>30 kg/m(2)) comprised 46% of the cohort. Mean fluoroscopy time, displayed AK, entrance skin dose, and ED were 4.2 ± 6.0 second, 1.2 ± 2.1 mGy, 1.2 ± 2.2 mGy, and 0.08 ± 0.15 mSv, respectively. Mean AK dose rate and ED dose rates were 0.30 ± 0.23 mGy/second and 0.021 ± 0.016 mSv/second, respectively. Compared with the nonobese category, the highest BMI category (≥35 kg/m(2)) had over a 3-fold higher mean AK rate (0.50 vs 0.16 mGy/second). On univariate and multivariate analysis, BMI, AP midline distance, AP transrenal thickness, and computed tomography scout region of interest pixel value magnitude were each significantly associated with dose rate. CONCLUSION: Larger patients experience higher radiation dose rates under fluoroscopy. Severely obese patients receive 3-fold higher dose rates compared with nonobese patients. Given the higher incidence of stone disease in obese patients, all attempts should be made to minimize radiation exposure during ureteroscopy.

Effective and organ specific radiation doses from videourodynamics in children.

PURPOSE: Effective and organ specific doses of ionizing radiation during videourodynamics are unknown. We estimated radiation exposure in children undergoing videourodynamics, and identified patient and examination factors that contribute to higher dosing. MATERIALS AND METHODS: Fluoroscopy data were collected from consecutive patients undergoing videourodynamics. Documented dose metrics were used to calculate entrance skin dose after applying a series of correction factors. Effective doses and organ specific doses (ovaries/testes) were estimated from entrance skin dose using Monte Carlo methods on a mathematical anthropomorphic phantom (ages 0, 1, 5, 10 and 15 years). Regression analysis was performed to determine patient and procedural factors associated with higher dosing. RESULTS: A total of 100 children (45% male, mean ± SD age 9.3 ± 5.7 years) were studied. Diagnoses included neurogenic bladder (73%), anatomical abnormality (14%) and functional/nonneurogenic disorder (13%). Mean fluoroscopy time was 0.17 ± 0.12 minutes. Mean age adjusted entrance skin dose, effective dose, and testis and ovary doses were 2.18 ± 2.00 mGy, 0.07 ± 0.05 mSv, 0.09 ± 0.10 mGy and 0.20 ± 0.13 mGy, respectively. On univariate analysis age, height, weight, body mass index, bladder capacity and fluoroscopy time were associated with effective dose. On multivariate adjusted analysis, body mass index, bladder capacity and fluoroscopy time were independently associated with effective dose. CONCLUSIONS: The average effective dose of ionizing radiation from videourodynamics was less compared to voiding cystourethrogram dose reported in the literature. Greater fluoroscopy time, body mass index and bladder capacity are independently associated with higher dosing.

Radiation-induced complications in endovascular neurosurgery: incidence of skin effects and the feasibility of estimating risk of future tumor formation.

BACKGROUND: The incidence of radiation-induced complications is increasingly part of the informed consent process for patients undergoing neuroendovascular procedures. Data guiding these discussions in the era of modern radiation-minimizing equipment is lacking. OBJECTIVE: To quantify the rates of skin and hair effects at a modern high-volume neurovascular center, and to assess the feasibility of accurately quantifying the risk of future central nervous system (CNS) tumor formation. METHODS: We reviewed a prospectively collected database of endovascular procedures performed at our institution in 2008. The entrance skin dose and brain dose were calculated. Patients receiving skin doses >2 Gy were contacted to inquire about skin and hair changes. We reviewed several recent publications from leading radiation physics bodies to evaluate the feasibility of accurately predicting future cancer risk from neurointerventional procedures. RESULTS: Seven hundred two procedures were included in the study. Of the patients receiving >2 Gy, 39.6% reported subacute skin or hair changes following their procedure, of which 30% were permanent. Increasing skin dose was significantly associated with permanent hair loss. We found substantial methodological difficulties in attempting to model the risk of future CNS tumor formation given the gaps in our current understanding of the brain's susceptibility to low-dose ionizing radiation. CONCLUSION: Radiation exposures exceeding 2 Gy are common in interventional neuroradiology despite modern radiation-minimizing technology. The incidence of side effects approaches 40%, although the majority is self-limiting. Gaps in current models of brain tumor formation after exposure to radiation preclude accurately quantifying the risk of future CNS tumor formation.