The addition of a leaded arm sleeve to leaded aprons further decreases operator upper outer quadrant chest wall radiation dose during fluoroscopically guided interventions.

OBJECTIVE: Breast cancer most commonly occurs in the upper outer quadrant (UOQ) chest wall (CW). The effectiveness of routine leaded aprons to protect this region of the body in interventionalists during fluoroscopically guided interventions (FGIs) is unknown. Given the high lifetime attributable risks of prolonged occupational exposure to ionizing radiation and the increasing number of practicing female vascular surgeons and interventionalists, we sought to determine if the use of a leaded arm shield would offer additional protection to the lateral CW and axilla in operators compared with routine leaded aprons. METHODS: Effectiveness of leaded sleeves in attenuating radiation dose to the axilla and UOQ was evaluated in clinical practice and simulated scenarios. In the clinical setting, optically stimulated luminescence nanoDot detectors were placed at the UOQ lateral CW position, both over and under a standard leaded apron vest with and without the addition of an antimony/bismuth Enviro-Lite sleeve on two vascular surgeons performing FGIs. In the simulation, nanoDots were similarly placed on an anthropomorphic phantom positioned to represent a primary operator performing right femoral access. Fluorography was performed on 12-inch-thick acrylic scatter phantom at 80 kVp for an exposure of 3 Gy reference air kerma. Experiments were done with and without the sleeve. Paired Wilcoxon and χ2 tests were performed to identify the statistical significance of radiation attenuation. RESULTS: Operator UOQ CW dose was measured during 61 FGIs: 33 cases (54%) with and 28 cases (46%) without the sleeve. Median procedure reference air kerma and fluoroscopy time was 180 mGy (interquartile range [IQR], 85-447 mGy) and 21 minutes (IQR, 11-39 minutes) when the sleeve was worn vs 100 mGy (IQR, 67-270 mGy) and 11 minutes (IQR, 6.3-25 minutes) without the sleeve. Radiation dose to the operator's UOQ was reduced by 96% (IQR, 85%-96%) when the sleeve was present and by 62% (IQR, 44%-82%; P < .001) without the sleeve. In the simulated setting, the sleeve reduced the radiation dose to the UOQ compared with the apron alone (96% vs 67%; P < .001). CONCLUSIONS: Routine leaded aprons do attenuate the majority of UOQ chest wall radiation dose; however, the addition of a lead-equivalent sleeve further significantly reduces this dose. Because this area of the body has a high incidence of cancer formation, additional protection, especially to female interventionalists, seems prudent. Vascular surgeons should consider using a protective sleeve with their personal protective equipment when performing complex fluoroscopically guided procedures.

Operator Lower Leg Radiation Dose during Fluoroscopically Guided Interventions is Effectively Reduced by Wearing Lead-Equivalent Leg Wraps.

BACKGROUND: The intensity of radiation scatter that emanates from the X-ray beam during fluoroscopically guided interventions is greater below the fluoroscopy table than above. Yet interventionalists' lower legs are typically unshielded and table skirts are often positioned incorrectly. We sought to characterize the efficacy of the leg protector wraps (Leg Wraps, Burlington Medical Inc.) in reducing the radiation dose to the operator's lower leg during fenestrated and branched endovascular aneurysm repair (F-BEVAR). METHODS: A prospective cohort study was performed evaluating the lower leg radiation dose reduction of one vascular surgeon during F/BEVAR using antimony/bismuth Enviro-Lite leg wraps (0.35 mm lead equivalency, 99.7% attenuation at 50 kVp; Burlington Medical, Hampton Roads, Virginia). Optically Stimulated Luminescence nanoDot detectors (microSTARii System, LANDAUER, Inc., Glenwood, Illinois) were placed over and under the left leg wrap at the anterior tibial tuberosity position to compare operator leg dose with and without this additional protection. The table-mounted lead skirt was used consistently in all cases. The nanoDot detectors were cross-calibrated with a survey meter (RaySafe X2 survey sensor, Fluke Biomedical, Cleveland, Ohio) by measuring scattered radiation at a position equivalent to an operator's mid-tibia while performing digital acquisitions of a 25-cm thick, 30 cm × 30 cm acrylic phantom with a Philips FD20 fluoroscope (Philips Healthcare, Best, The Netherlands) with the table skirt removed. The measured radiation doses were converted to a Hp (0.07) skin dose, assuming an RQR6 beam spectrum (IEC-61267). Paired Wilcoxon test was performed to identify significant attenuation of radiation exposure. RESULTS: Leg dose measurements from 40 F-BEVARs were analyzed. The patients had a median (interquartile range) body mass index of 27 (24-32) kg/m2. Median procedure reference air kerma was 1,100 (728-1,601) mGy, kerma-area product was 127 (73-184) Gycm2, and fluoroscopy time was 69 (54-86) min. The median skin dose Hp (0.07) over the leg wraps (n = 40) was 54.2 (24-100) µSv and under the leg wraps (n = 40) was 2.7 µSv (1.0-5.8). The leg wraps attenuated the radiation dose by 95% (89-98%) (P < 0.001). The unprotected, Hp (0.07) per kerma-area product was determined to be 0.38 (0.30-0.55) µSv/Gycm2. CONCLUSIONS: The 0.35-mm lead-equivalent leg wraps significantly decreased scattered radiation to the lower leg during F-BEVAR. Protective leg wraps should be recommended to operators performing complex fluoroscopically guided procedures.

New imaging technology system reduces patient radiation dose during peripheral arterial endovascular interventions.

BACKGROUND: Radiation exposure and imaging quality are among the main concerns in endovascular procedures. The Clear VD11 PURE platform technology system (Siemens Healthineers, Erlangen, Germany) has been reported to lower the radiation dose and improve image quality. In the present study, we evaluated whether the radiation dose during peripheral arterial endovascular procedures had decreased after implementation of this new imaging system. METHODS: The patient characteristics (age, gender, body mass index [BMI]), procedure type (diagnostic, balloon angioplasty, atherectomy, stenting), body location (aortoiliac, superficial femoral artery, tibial artery), reference air kerma (RAK), kerma area product (KAP), and fluoroscopy time (FT) were recorded during peripheral artery interventions performed 1 year before (group A) and 1 year after (group B) the CLEAR system upgrade. The procedures were performed in an Artis zeego hybrid room (Siemens Healthineers) with the same providers. A general linear model was used to estimate the average difference between groups adjusted by procedure type and patient age, gender, and BMI. Additionally, to control for variations in case complexity, groups A and B were matched by age, gender, BMI, lesion location, and intervention type. Propensity score matching and a paired t test were used to compare the KAP, RAK, and FT stratified by single intervention procedures. RESULTS: A total of 487 endovascular procedures were performed: 209 in group A and 278 in group B. A total of 111 single intervention procedures from each group were matched (1:1), with a mean age of 61 ± 8 years and a BMI of 26.5 ± 4 kg/m2. The median KAP, RAK, and FT for group A were 28.8 Gy · cm2 (interquartile range [IQR], 24-34 Gy · cm2), 146 mGy (IQR, 123-173 mGy), and 12 minutes (IQR, 10-14 minutes), respectively. The median KAP, RAK, and FT for group B were 18.3 Gy · cm2 (IQR, 16-22 Gy · cm2), 71.2 mGy (IQR, 60-85 mGy), and 10.4 minutes (IQR, 9-12 minutes), respectively. The KAP, RAK, and FT were significantly decreased in group B by 24% (P = .005), 41% (P < .001), and 22% (P = .002), respectively, compared with the values for group A. Stratified by single intervention procedures, the KAP and RAK had decreased significantly in group B (36% [P = .002] and 51% [P < .001], respectively) compared with group A. The FT decrease of 13% in group B was not statistically significant (P = .20). CONCLUSIONS: Use of the Clear VD11 PURE platform system (Siemens Healthineers) reduced the patient radiation dose by 51% during endovascular peripheral interventions. The similar FTs for the matched single intervention procedures before and after the upgrade indicated consistent case complexity and surgeon practice. This platform appears to be an effective system for lowering the radiation dose.

Use of a 2 Dimensional Vessel Navigator Roadmap Decreases Patient Radiation Dose Compared to Standard 3D Mapping for Fenestrated Endovascular Aneurysm Repair.

OBJECTIVE: For fenestrated endovascular aneurysm repair (FEVAR), the implementation of the VesselNavigator (Philips Healthcare, Best, The Netherlands) to provide a 3-dimensional vessel roadmap has been shown to reduce patient radiation exposure. Unfortunately, FEVAR radiation doses remain substantial despite utilization of this technology. Traditionally, registration of the live fluoroscopy with the pre-operative CTA is performed via the acquisition of a low-dose cone-beam CT scan. However, this registration can also be accomplished with the acquisition of 2D X-rays using the c-arm in 2 different projection angles. We hypothesized that the 2D image acquisition for vessel roadmap development would result in a significant reduction in patient radiation dose in comparison to the 3D CT registration without compromising image quality or increasing procedural length. METHODS: This single-center, retrospective study included FEVARs performed from January 2015 to May 2019. For patient data, the cumulative reference air kerma (RAK) was presented as geometric mean and standard deviation. A general linear model with log-normal distribution was used to test the difference in patient RAK between 2D X-ray and 3D CT VesselNavigator registration after adjusting for BMI and the number of vessel fenestrations (1 to 2 vs. 3 to 4). Fluoroscopy time was recorded and used as a surrogate for case complexity. All analyses were done in SAS 9.4 (SAS Institute, Inc., Cary, North Carolina). RESULTS: One hundred and sixty four FEVARs were performed on a Philips Allura Xper FD 20 fluoroscopy system equipped with clarity technology. The VesselNavigator registration was completed using 3D CT mapping in 99 cases and 2D X-rays in 65 procedures. On average, utilization of 2D mapping versus 3D mapping for the VesselNavigator resulted in a 20.4% reduction in patient RAK after controlling for BMI and number of vessel fenestrations, P = 0.0135. There was no significant difference in fluoroscopy time between the 2 study groups (P= 0.81) suggesting that image quality was not compromised by the use of 2D mapping leading to the need for additional fluoroscopy. CONCLUSION: Acquisition of 2D films rather than a 3D CT scan for VesselNavigator registration allows for a significant reduction in patient radiation dose during FEVAR without increasing the case complexity or compromising image quality.

Disposable, lightweight shield decreases operator eye and brain radiation dose when attached to safety eyewear during fluoroscopically guided interventions.

OBJECTIVE: Long-term radiation exposure from fluoroscopically guided interventions (FGIs) can cause cataracts and brain tumors in the operator. We have previously demonstrated that leaded eyewear does not decrease the operator eye radiation dose unless lead shielding has been added to the lateral and inferior portions. Therefore, we have developed a disposable, lightweight, lead-equivalent shield that can be attached to the operator's eyewear that conforms to the face and adheres to the surgical mask. In the present study, we evaluated the efficacy of our new prototype in lowering the operator brain and eye radiation dose when added to both leaded and nonleaded eyewear. METHODS: The attenuating efficacy of leaded eyewear alone, leaded eyewear plus the prototype, and nonleaded eyewear plus the prototype were compared with no eyewear protection in both a simulated setting and clinical practice. In the simulation, optically stimulated, luminescent nanoDot detectors (Landauer, Inc, Glenwood, Ill) were placed inside the ocular, temporal lobe, and midbrain spaces of a head phantom (ATOM model-701; CIRS, Norfolk, Va). The phantom was positioned to represent a primary operator performing right femoral access. Fluorography was performed on a plastic scatter phantom at 80 kVp for an exposure of 3 Gy reference air kerma. In the clinical setting, nanoDots were placed below the operator's eye both inside and outside the prototype during the FGIs. The median and interquartile ranges were calculated for the dose at each nanoDot location for the phantom and clinical studies. The average dose reduction was also recorded. RESULTS: Wearing standard leaded eyewear alone did not decrease the operator ocular or brain radiation dose. In the phantom experiment, the leaded glasses plus the prototype reduced the radiation dose to the lens, temporal lobe, and midbrain by 83% (P < .001), 78% (P < .001), and 75% (P < .001), respectively. The nonleaded glasses plus the prototype also reduced the dose to the lens, temporal lobe, and midbrain by 85% (P < .001), 81% (P < .001), and 71% (P < .001), respectively. A total of 15 FGIs were included in the clinical setting, with a median reference air kerma of 98.4 mGy. The use of our prototype led to an average operator eye dose reduction of 89% (P < .001). CONCLUSIONS: Attaching our prototype to both leaded and nonleaded glasses significantly decreased the eye and brain radiation dose to the operator. This face shield attachment provided meaningful radiation protection and should be considered as either a replacement or an adjunct to routine eyewear.

Dual fluoroscopy with live-image digital zooming significantly reduces patient and operating staff radiation during fenestrated-branched endovascular aortic aneurysm repair.

OBJECTIVE: Fenestrated-branched endovascular aneurysm repair (F/B-EVAR) is a complex procedure that generates high radiation doses. Magnification aids in vessel cannulation but increases radiation. The aim of the study was to compare radiation doses to patients and operating room staff from two fluoroscopy techniques, standard magnification vs dual fluoroscopy with live-image digital zooming during F/B-EVAR. METHODS: An observational, prospective, single-center study of F/B-EVAR procedures using Philips Allura XperFD20 equipment (Philips Healthcare, Amsterdam, The Netherlands) was performed during a 42-month period. Intravascular ultrasound, three-dimensional fusion, and extreme collimation were used in all procedures. Intraoperative live-image processing was performed with two imaging systems: standard magnification in 123 patients (81%) and dual fluoroscopy with live-image digital zooming in 28 patients (18%). In the latter, the live "processed" zoomed images are displayed on examination displays and live images are displayed on reference displays. The reference air kerma was collected for each case and represents patient dose. Operating staff personal dosimetry was collected using the DoseAware system (Philips Healthcare). Patient and staff radiation doses were compared using nonparametric tests. RESULTS: Mean age was 71.6 ± 11.4 years. The median body mass index was 27 kg/m2 (interquartile range [IQR], 24.4-30.6 kg/m2) and was the same for both groups. Procedures performed with dual fluoroscopy with digital zooming demonstrated significantly lower median patient (1382 mGy [IQR, 999-2045 mGy] vs 2458 mGy [IQR, 1706-3767 mGy]; P < .01) and primary operator radiation doses (101 µSv [IQR, 34-235 µSv] vs 266 µSv [IQR, 104-583 µSv]; P < .01) compared with standard magnification. Similar significantly reduced radiation doses were recorded for first assistant, scrub nurse, and anesthesia staff in procedures performed with dual fluoroscopy. According to device design, procedures performed with four-fenestration/branch devices generated higher operator radiation doses (262 µSv [IQR, 116.5-572 µSv] vs 171 µSv [IQR, 44-325 µSv]; P < .01) compared with procedures with three or fewer fenestration/branches. Among the most complex design (four-vessel), operator radiation dose was significantly lower with digital zooming compared with standard magnification (128.5 µSv [IQR, 70.5-296 µSv] vs 309 µSv [IQR, 150-611 µSv]; P = .01). CONCLUSIONS: Current radiation doses to patients and operating personnel are within acceptable limits; however, dual fluoroscopy with live-image digital zooming results in dramatically lower radiation doses compared with the standard image processing with dose-dependent magnification. Operator radiation doses were reduced in half during procedures performed with more complex device designs when digital zooming was used.

The Effects of Gender on Radiation Dose during Fenestrated Endovascular Aneurysm Repair.

BACKGROUND: Female gender is considered a risk factor for worse perioperative outcomes after fenestrated endovascular aneurysm repair (FEVAR). We hypothesized that women would have more unfavorable anatomy, increasing case complexity and leading to higher radiation doses. Our aim was to evaluate the effect of gender on radiation dose during FEVARs. METHODS: This single-center retrospective study was performed from 1/2015 to 2/2018. For patient data, linear model and stepwise variable selection algorithm were used. All dose measurements were log transformed before analysis. Significance level for parameter estimates and corresponding 95% confidence intervals were all transformed back using an exponential function. P-value of <0.05 was considered statistically significant. All analyses were performed in SAS 9.4 (SAS Institute Inc., Cary, NC). RESULTS: A total of 169 FEVARs (45 women) were performed on a Philips Allura Xper FD 20 fluoroscopy system equipped with clarity technology. There was no difference in body mass index (BMI) or operative time between genders, P = 0.9. The median reference air kerma for women was significantly lower than that for men (1,672 mGy vs. 2,496 mGy), P < 0.001. Women had on average a 28% total dose reduction after controlling for BMI, number of vessels fenestrated, operative time, and type of device, P < 0.001. The median fluorography and fluoroscopy doses for women were significantly lower than those for men (973 mGy vs. 1,401 mGy and 659 mGy vs. 1,008 mGy), resulting in a 24% fluorography dose reduction and a 38% fluoroscopy dose reduction for women, P < 0.001. CONCLUSIONS: FEVARs can be performed successfully in women with comparatively lower radiation doses.

A Comprehensive CT Radiation Dose Reduction and Protocol Standardization Program in a Complex, Tertiary Hospital System.

PURPOSE: To present our experience in reducing CT radiation doses in a complex tertiary health system through CT protocol standardization and optimization. METHODS: A CT radiation task force was created to reduce CT protocol heterogeneity and radiation doses. Redundant protocols were eliminated. By an iterative process, protocols with least radiation dose were identified. Radiation dose tracking software was used to store and analyze radiation doses. CT protocols were published in an intranet site after training of technologists. SOPs were established for maintaining and changing protocols. The radiation doses for each CT protocol before and after optimization were compared using geometric means. RESULTS: A total of 222 CT protocols were reviewed, with elimination of 86 protocols. One-year follow-up showed homogeneous protocols with lower radiation doses. The improvement in radiation doses ranged from 23% to 58% (P< 0.001). CONCLUSION: CT radiation dose reduction of up to 58% can be achieved by homogenizing and optimizing CT protocols through a comprehensive CT operations program.

Novel modification to leaded eyewear results in significant operator eye radiation dose reduction.

OBJECTIVE: Ocular radiation exposure from fluoroscopically guided interventions (FGIs) can cause cataracts. Standard lead eyewear may not significantly reduce eye radiation dose as the majority of scattered radiation penetrates the operator's eye obliquely. Our aim was to evaluate the efficacy of standard leaded eyewear and a customized eyewear design in lowering eye radiation dose to vascular surgeons. METHODS: The attenuating efficacy of three forms of leaded eyewear (standard eyewear, eyewear with built-in leaded side shields, and our modified eyewear) was tested in both a simulated setting and clinical practice. The modified design consisted of safety eyewear with 0.75 mm of added lead shielding attached to the lateral and inferior borders of the eyewear frame to attenuate oblique radiation. We performed simulated experiments using an anthropomorphic head phantom (ATOM model 701; CIRS, Norfolk, Va) positioned to represent a primary operator performing right femoral access. Optically stimulated, luminescent nanoDot detectors (Landauer, Glenwood, Ill) were placed inside the phantom's ocular spaces and at the surface of the left eye within and outside the leaded glasses to measure the eye radiation dose reduction provided by each eyewear type. All three eyewear types were also tested during clinical FGIs by placing nanoDots below the operator's left eye, inside and outside of the eyewear coverage. Means and standard errors were calculated using a pooled linear mixed model with repeated measurements. RESULTS: This prospective, single-center study included 60 FGIs, 30 with traditional eyewear and 30 with our modified design. There was no significant eye radiation dose reduction (P > .05) with the standard eyewear or leaded side shield eyewear in both the simulated and clinical settings. In the simulated environment, our modified design resulted in an 86% radiation dose reduction to the surface of the left eye and an 80% reduction in left lens radiation dose (P < .0001). In the clinical FGIs, the modified eyewear led to a 62% left ocular radiation dose reduction (P < .0001). CONCLUSIONS: Standard lead-equivalent glasses are ineffective at reducing ocular radiation dose during FGIs. Eyewear modification with lateral and inferior lead shielding molded to the operator's face significantly decreases radiation exposure to the eye closest to the X-ray source.

Radiation doses and image quality of abdominal CT scans at different patient sizes using spectral detector CT scanner: a phantom and clinical study.

PURPOSE: To compare radiation dose and image quality for abdominal CTs performed on a spectral detector CT (SDCT) and a comparable single-energy conventional CT scanner for patients of different sizes. METHODS: Four semi-anthropomorphic phantoms were scanned on an SDCT (IQon, Philips Healthcare) and a comparable single-energy CT (iCT 256, Philips Healthcare) under matched scan parameters. Image noise and radiation dose were compared. For the HIPAA-compliant, IRB-approved retrospective cohort patient study, radiation dose was compared after adjusting for patient water equivalent diameter. Difference in subjective and objective image quality was assessed on a subset of 50 patients scanned on both scanners by two readers. RESULTS: CTDIvol and noise from SDCT were higher than conventional CT for all phantoms, with a relative difference of 7.8% (range 5.3-14%) for radiation dose and average difference of 9.0% (range 5.5-11%) for noise. 718 SDCT and 937 conventional CT patients were included in the patient study. CTDIvol for SDCT patients tends to be lower for smaller patients (- 2%, 95% confidence interval (- 5%, - 0.2%) for 200 mm water equivalent diameter) and higher for larger patients compared to conventional CT (8%, (6%, 11%) for 400 mm). No difference was seen for subjective image quality, SNR, CNR, or image noise between the two scanners, except for higher image noise in the portal vein and higher signal in the aorta on SDCT. CONCLUSION: Radiation dose for abdominal CT performed on SDCT is similar to the dose on a conventional CT for average size patients, lower for smaller patients, and slightly higher for larger patients. Image quality is similar between the two scanners.

Radiation dose reduction for musculoskeletal computed tomography of the pelvis with preserved image quality.

OBJECTIVE: To analyze the impact of pelvic computed tomography (CT) technique optimization on estimated dose and subjective and objective image quality. MATERIALS AND METHODS: An institutional review board (IRB)-approved retrospective records review was performed with waived informed consent. Five CT scanners (various manufacturers/models) were standardized to match the lowest dose profile on campus via subjective assessment of clinical images by experienced musculoskeletal radiologists. The lowest dose profile had previously been established through image assessment by experienced musculoskeletal radiologists after a department-wide radiation dose reduction initiative. A consecutive series of 60 pre- and 59 post-optimization bony pelvis CTs were analyzed by two residents, who obtained signal-to-noise ratio for femoral cortex and marrow, gluteus medius muscle, and subcutaneous and visceral fat in a standardized fashion. Two blinded attending radiologists ranked image quality from poor to excellent. RESULTS: Pre- and post-optimization subjects exhibited no difference in gender, age, or BMI (p > 0.2). Mean CT dose index (CTDIvol) and dose-length product (DLP) decreased by approximately 45%, from 39± 14 to 18± 12 mGy (p < 0.0001) and 1,227± 469 to 546± 384 mGy-cm (p < 0.0001). Lower body mass index (BMI) was associated with a larger dose reduction and higher BMI with higher DLP regardless of pre- or post-optimization examination. Inter-observer agreement was 0.64-0.92 for SNR measurements. Cortex SNR increased significantly for both observers (p < 0.02). Although qualitative image quality significantly decreased for one observer (p < 0.01), adequate mean quality (3.3 out of 5) was maintained for both observers. CONCLUSION: Subjective and objective image quality for pelvic CT examination remains adequate, despite a substantially reduced radiation dose.

Patient and operating room staff radiation dose during fenestrated/branched endovascular aneurysm repair using premanufactured devices.

INTRODUCTION: Fenestrated endovascular aneurysm repair (FEVAR) is the highest radiation dose procedure performed by vascular surgeons. We sought to characterize the radiation dose to patients and staff during FEVAR procedures with different premanufactured devices. METHODS: A single-center prospective study of FEVARs was performed over 24 months. Three FEVAR devices were included: off-the-shelf (OTS; t-Branch, p-Branch), Zenith Fenestrated (ZFen), and investigational custom-made devices (CMDs). Radiation doses to the surgeon, trainee, anesthesiologist, and scrub/circulating nurses were measured using a personal dosimetry system (DoseAware, Philips Healthcare, Amsterdam, The Netherlands). Procedure type, patient body mass index (BMI), reference air kerma (RAK), and kerma area product (KAP) were recorded. RAK and KAP were corrected for BMI based on an exponential fit of fluoroscopy dose rate and the dose per radiographic frame. Operator dose was corrected for BMI by the ratio of corrected to actual KAP. A one-sided Wilcox rank-sum test was used to compare personnel radiation doses, RAKs, and KAPs between procedure types. Statistical significance was set at P ≤ .05. RESULTS: There were 80 FEVARs performed by a single surgeon on a Philips Allura XperFD20 fluoroscopy system equipped with Clarity technology. Average BMI was 27 kg/m2. Sixty CMDs (36 four-, 21 three-, and 3 two-vessel fenestrations), 11 ZFens (8 three- and 3 two-vessel fenestrations), and 9 OTS devices (4 p-Branch, 5 t-Branch) were included. ZFens had significantly lower patient (1800 mGy vs 2950 mGy; P = .004), operator (120 µSv vs 370 µSv; P = .004), assistant (60 µSv vs 210 µSv; P = .003), circulator (10 µSv vs 30 µSv; P = .049), and scrub nurse dose (10 µSv vs 40 µSv; P = .02) compared with CMDs. OTS devices had significantly lower operator (220 µSv vs 370 µSv; P = .04), assistant (110 µSv vs 210 µSv; P = .02), and circulator doses (4 µSv vs 30 µSv; P = .001) compared with CMDs. Four-vessel fenestrated devices had significantly higher patient dose (3020 mGy) compared with three-vessel FEVARs (2670 mGy; P = .03) and two-vessel FEVARs (1600 mGy; P = .0007), and significantly higher operator dose (440 µSv) compared with three-vessel FEVARs (170 µSv; P = .0005). Patient dose was lowest with ZFens. Operating room personnel dose was lower with ZFens and OTS devices compared with CMDs. Four-vessel fenestrations required significantly more radiation compared with those involving three-vessel fenestrations; however, the dose increase was only 12% and should not preclude operators from extending coverage, if anatomically required. CONCLUSIONS: Overall, patient and personnel radiation doses during FEVAR with all devices were within acceptable limits and lower in our series than previously reported.

Radiation brain dose to vascular surgeons during fluoroscopically guided interventions is not effectively reduced by wearing lead equivalent surgical caps.

OBJECTIVE: Radiation to the interventionalist's brain during fluoroscopically guided interventions (FGIs) may increase the incidence of cerebral neoplasms. Lead equivalent surgical caps claim to reduce radiation brain doses by 50% to 95%. We sought to determine the efficacy of the RADPAD (Worldwide Innovations & Technologies, Lenexa, Kan) No Brainer surgical cap (0.06 mm lead equivalent at 90 kVp) in reducing radiation dose to the surgeon's and trainee's head during FGIs and to a phantom to determine relative brain dose reductions. METHODS: Optically stimulated, luminescent nanoDot detectors (Landauer, Glenwood, Ill) inside and outside of the cap at the left temporal position were used to measure cap attenuation during FGIs. To check relative brain doses, nanoDot detectors were placed in 15 positions within an anthropomorphic head phantom (ATOM model 701; CIRS, Norfolk, Va). The phantom was positioned to represent a primary operator performing femoral access. Fluorography was performed on a plastic scatter phantom at 80 kVp for an exposure of 5 Gy reference air kerma with or without the hat. For each brain location, the percentage dose reduction with the hat was calculated. Means and standard errors were calculated using a pooled linear mixed model with repeated measurements. Anatomically similar locations were combined into five groups: upper brain, upper skull, midbrain, eyes, and left temporal position. RESULTS: This was a prospective, single-center study that included 29 endovascular aortic aneurysm procedures. The average procedure reference air kerma was 2.6 Gy. The hat attenuation at the temporal position for the attending physician and fellow was 60% ± 20% and 33% ± 36%, respectively. The equivalent phantom measurements demonstrated an attenuation of 71% ± 2.0% (P < .0001). In the interior phantom locations, attenuation was statistically significant for the skull (6% ± 1.4%) and upper brain (7.2% ± 1.0%; P < .0001) but not for the middle brain (1.4% ± 1.0%; P = .15) or the eyes (-1.5% ± 1.4%; P = .28). CONCLUSIONS: The No Brainer surgical cap attenuates direct X rays at the superficial temporal location; however, the majority of radiation to an interventionalist's brain originates from scatter radiation from angles not shadowed by the cap as demonstrated by the trivial percentage brain dose reductions measured in the phantom. Radiation protective caps have minimal clinical relevance.

Technical Note: Quantitative accuracy evaluation for spectral images from a detector-based spectral CT scanner using an iodine phantom.

PURPOSE: The purpose of this study was to evaluate the quantitative accuracy of spectral images from a detector-based spectral CT scanner using a phantom with iodine-loaded inserts. METHODS: A 40-cm long-body phantom with seven iodine inserts (2-20 mg/ml of iodine) was used in the study. The inserts could be placed at 5.5 or 10.5 cm from the phantom axis. The phantom was scanned five times for each insert configuration using 120 kVp tube voltage. A set of iodine, virtual noncontrast, effective atomic number, and virtual monoenergetic spectral CT images were generated and measurements were made for all the iodine rods. Measured values were compared with reference values calculated from the chemical composition information provided by the phantom manufacturer. Radiation dose from the spectral CT was compared to a conventional CT using a CTDI (32 cm) phantom. RESULTS: Good agreement between measurements and reference values was achieved for all types of spectral images. The differences ranged from -0.46 to 0.1 mg/ml for iodine concentration, -9.95 to 6.41 HU for virtual noncontrast images, 0.12 to 0.35 for effective Z images, and -17.7 to 55.7 HU for virtual monoenergetic images. For a similar CTDIvol, image noise from the conventional CT was 10% lower than the spectral CT. CONCLUSIONS: The detector-based spectral CT can achieve accurate spectral measurements on iodine concentration, virtual non-contrast images, effective atomic numbers, and virtual monoenergetic images.

New image-processing and noise-reduction software reduces radiation dose during complex endovascular procedures.

BACKGROUND: A new proprietary image-processing system known as AlluraClarity, developed by Philips Healthcare (Best, The Netherlands) for radiation-based interventional procedures, claims to lower radiation dose while preserving image quality using noise-reduction algorithms. This study determined whether the surgeon and patient radiation dose during complex endovascular procedures (CEPs) is decreased after the implementation of this new operating system. METHODS: Radiation dose to operators, procedure type, reference air kerma, kerma area product, and patient body mass index were recorded during CEPs on two Philips Allura FD 20 fluoroscopy systems with and without Clarity. Operator dose during CEPs was measured using optically stimulable, luminescent nanoDot (Landauer Inc, Glenwood, Ill) detectors placed outside the lead apron at the left upper chest position. nanoDots were read using a microStar ii (Landauer Inc) medical dosimetry system. For the CEPs in the Clarity group, the radiation dose to surgeons was also measured by the DoseAware (Philips Healthcare) personal dosimetry system. Side-by-side measurements of DoseAware and nanoDots allowed for cross-calibration between systems. Operator effective dose was determined using a modified Niklason algorithm. To control for patient size and case complexity, the average fluoroscopy dose rate and the dose per radiographic frame were adjusted for body mass index differences and then compared between the groups with and without Clarity by procedure. Additional factors, for example, physician practice patterns, that may have affected operator dose were inferred by comparing the ratio of the operator dose to procedural kerma area product with and without Clarity. A one-sided Wilcoxon rank sum test was used to compare groups for radiation doses, reference air kermas, and operating practices for each procedure type. RESULTS: The analysis included 234 CEPs; 95 performed without Clarity and 139 with Clarity. Practice patterns of operators during procedures with and without Clarity were not significantly different. For all cases, procedure radiation dose to the patient and the primary and assistant operators were significantly decreased in the Clarity group by 60% compared with the non-Clarity group. By procedure type, fluorography dose rates decreased from 44% for fenestrated endovascular repair and up to 70% with lower extremity interventions. Fluoroscopy dose rates also significantly decreased, from about 37% to 47%, depending on procedure type. CONCLUSIONS: The AlluraClarity system reduces the patient and primary operator's radiation dose by more than half during CEPs. This feature appears to be an effective tool in lowering the radiation dose while maintaining image quality.

An iterative deconvolution algorithm for image recovery in clinical CT: A phantom study.

PURPOSE: To study the feasibility of using an iterative reconstruction algorithm to improve previously reconstructed CT images which are judged to be non-diagnostic on clinical review. A novel rapidly converging, iterative algorithm (RSEMD) to reduce noise as compared with standard filtered back-projection algorithm has been developed. MATERIALS AND METHODS: The RSEMD method was tested on in-silico, Catphan(®)500, and anthropomorphic 4D XCAT phantoms. The method was applied to noisy CT images previously reconstructed with FBP to determine improvements in SNR and CNR. To test the potential improvement in clinically relevant CT images, 4D XCAT phantom images were used to simulate a small, low contrast lesion placed in the liver. RESULTS: In all of the phantom studies the images proved to have higher resolution and lower noise as compared with images reconstructed by conventional FBP. In general, the values of SNR and CNR reached a plateau at around 20 iterations with an improvement factor of about 1.5 for in noisy CT images. Improvements in lesion conspicuity after the application of RSEMD have also been demonstrated. The results obtained with the RSEMD method are in agreement with other iterative algorithms employed either in image space or with hybrid reconstruction algorithms. CONCLUSIONS: In this proof of concept work, a rapidly converging, iterative deconvolution algorithm with a novel resolution subsets-based approach that operates on DICOM CT images has been demonstrated. The RSEMD method can be applied to sub-optimal routine-dose clinical CT images to improve image quality to potentially diagnostically acceptable levels.

Surgeon radiation dose during complex endovascular procedures.

BACKGROUND: Surgeon radiation dose during complex fluoroscopically guided interventions (FGIs) has not been well studied. We sought to characterize radiation exposure to surgeons during FGIs based on procedure type, operator position, level of operator training, upper vs lower body exposure, and addition of protective shielding. METHODS: Optically stimulable, luminescent nanoDot (Landauer, Inc, Glenwood, Ill) detectors were used to measure radiation dose prospectively to surgeons during FGIs. The nanoDot dosimeters were placed outside the lead apron of the primary and assistant operators at the left upper chest and left lower pelvis positions. For each case, the procedure type, the reference air kerma, the kerma-area product, the relative position of the operator, the level of training of the fellow, and the presence or absence of external additional shielding devices were recorded. Three positions were assigned on the right-hand side of the patient in decreasing relative proximity to the flat panel detector (A, B, and C, respectively). Position A (main operator) was closest to the flat panel detector. Position D was on the left side of the patient at the brachial access site. The nanoDots were read using a microSTARii medical dosimetry system (Landauer, Inc) after every procedure. The nanoDot dosimetry system was calibrated for scattered radiation in an endovascular suite with a National Institute of Standards and Technology traceable solid-state radiation detector (Piranha T20; RTI Electronics, Fairfield, NJ). Comparative statistical analysis of nanoDot dose levels between categories was performed by analysis of variance with Tukey pairwise comparisons. Bonferroni correction was used for multiple comparisons. RESULTS: There were 415 nanoDot measurements with the following case distribution: 16 thoracic endovascular aortic repairs/endovascular aneurysm repairs, 18 fenestrated endovascular aneurysm repairs (FEVARs), 13 embolizations, 41 lower extremity interventions, 10 fistulograms, 13 visceral interventions, and 3 cerebrovascular procedures. The mean operator effective dose for FEVARs was higher than for other case types (P < .03), 20 µSv at position A and 9 µSv at position B. For all case types, position A (9.0 µSv) and position D (20 µSv) received statistically higher effective doses than position B (4 µSv) or position C (0.4 µSv) (P < .001). However, the mean operator effective dose for position D was not statistically different from that for position A. The addition of the lead skirt significantly decreased the lower body dose (33 ± 3.4 µSv to 6.3 ± 3.3 µSv) but not the upper body dose (6.5 ± 3.3 µSv to 5.7 ± 2.2 µSv). Neither ceiling-mounted shielding nor level of fellow training affected operator dose. CONCLUSIONS: Surgeon radiation dose during FGIs depends on case type, operator position, and table skirt use but not on the level of fellow training. On the basis of these data, the primary operator could perform approximately 12 FEVARs/wk and have an annual dose <10 mSv, which would not exceed lifetime occupational dose limits during a 35-year career. With practical case loads, operator doses are relatively low and unlikely to exceed occupational limits.

Deterministic effects after fenestrated endovascular aortic aneurysm repair.

BACKGROUND: Endovascular aortic aneurysm repairs (EVARs) with fenestrated (FEVAR) stent grafts are high radiation dose cases, yet no skin injuries were found retrospectively in our 61 cases with a mean peak skin dose (PSD) of 6.8 Gy. We hypothesize that skin injury is under-reported. This study examined deterministic effects in FEVARs after procedural changes implemented to detect skin injury. METHODS: All FEVARs during a 6-month period with a radiation dose of 5 Gy reference air kerma (RAK; National Council on Radiation Protection and Measurements threshold for substantial radiation dose level [SRDL]) were included. Patients were questioned about skin erythema, epilation, and necrosis, with a physical examination of the back completed daily until discharge and then at 2 and 4 weeks and at 3 and 6 months. PSD distributions were calculated with custom software using input data from fluoroscopic machine logs. These calculations have been validated against Gafchromic (Ashland Inc, Covington, Ky) film measurements. Dose was summed for the subset of patients with multiple procedures ≤6 months of the SRDL event, consistent with the joint commission recommendations. RESULTS: Twenty-two patients, 21 FEVARs and one embolization, reached an RAK of 5 Gy. The embolization procedure was excluded from review. The average RAK was 7.6 ± 2.0 Gy (range, 5.1-11.4 Gy), with a mean PSD of 4.8 ± 2.0 Gy (range, 2.3-10.4 Gy). Fifty-two percent of patients had multiple endovascular procedures ≤6 months of the SRDL event. The mean RAK for this subset was 10.0 ± 2.9 Gy (range, 5.5-15.1 Gy), with a mean PSD of 6.6 ± 1.9 Gy (range, 3.4-9.4 Gy). One patient died before the first postoperative visit. No radiation skin injuries were found. Putative risk factors for skin injury were evaluated and included smoking (32%), diabetes (14%), cytotoxic drugs (9%), and fair skin type (91%). No other risk factors were present (hyperthyroidism, collagen vascular disorders). CONCLUSIONS: Deterministic skin injuries are uncommon after FEVAR, even at high RAK levels, regardless of cumulative dose effects. This study addresses the concern of missed injuries based on the retrospective clinical examination findings that were published in our previous work. Even with more comprehensive postoperative skin examinations and patient questioning, the fact that no skin injuries were found suggests that radiation-induced skin injuries are multifactorial and not solely dose dependent.