Selective iliofemoral stent placement for complex pediatric cases: a decade of institutional experience.

BACKGROUND: Pediatric iliofemoral venous thromboembolism that is resistant to conventional treatments poses significant management challenges. Stent placement represents a potentially underutilized strategy in children when stenosis or thrombosis persists intraprocedurally or recurs postoperatively, despite treatments such as venoplasty, lysis, and thrombectomy. OBJECTIVE: This study aims to report our institutional experience with iliofemoral stenting in 17 pediatric patients with recurrent iliofemoral venous thromboembolism or stenosis. MATERIALS AND METHODS: We performed an IRB-approved retrospective review of pediatric patients (<18 years of age) who underwent iliofemoral venous stenting for recurrent stenosis or thrombosis between January 2012 and December 2022 at a single tertiary care institution. Patient demographics, risk factors for venous thromboembolism, presenting symptoms, and procedural characteristics were recorded. The primary outcome was stent patency rates at interval imaging follow-up. RESULTS: Seventeen patients with mean age of 14.6 years (range 7-17) and mean BMI of 27.7 were stented during the study period. Sixteen of 17 patients presented with evidence of May-Thurner anatomy. 14/17 patients presented with acute iliofemoral venous thromboembolism, 2/17 with chronic venous thromboembolism, and 1/17 with left lower extremity swelling without thrombosis. Seventy-three total angiographic procedures were performed, which included angioplasty, lysis, and thrombectomy, and 23 stent placements. Patients underwent an average of 3 procedures (range 1-9) over a mean of 2.8 months (range 0-17 months) prior to undergoing stent placement. Stents were deployed successfully in all patients. The median follow-up was 18 months (range, 1-77 months). Primary and secondary patency rates were 13/17 (76%) and 14/14 (100%) at 12 months and 12/17 (71%) and 14/14 (100%) at 24 months, respectively. CONCLUSION: In our experience of 17 patients, stent placement appears to be a durable option for children with iliofemoral venous thromboembolism following failure to establish vessel patency or development of recurrent thrombosis/stenosis postoperatively.

Appendix to the Society of Interventional Radiology Consensus Guidelines for the Periprocedural Management of Thrombotic and Bleeding Risk in Patients Undergoing Percutaneous Image-Guided Interventions: Pediatric Considerations.

PURPOSE: To provide guidance on the use of anticoagulant and antithrombotic agents in pediatric patients undergoing interventional radiology procedures. MATERIALS AND METHODS: A multidisciplinary writing group conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were developed for procedural risk and medication dosage and withholding. A modified Delphi technique was used to achieve consensus agreement on the recommendations. RESULTS: A total of 24 studies, including systematic reviews and meta-analyses, randomized controlled trials, and prospective and retrospective cohort studies, were identified as relevant. The expert writing group agreed on procedural risk categorization, laboratory testing thresholds, and medication dosage and withholding recommendations specific to pediatric practice. They additionally described the nuances of anticoagulation in clinical conditions specific to pediatrics. CONCLUSIONS: The Society of Interventional Radiology recommends following the guidance provided in the document when developing multidisciplinary management protocols for anticoagulation and antithrombotic treatment in pediatric patients undergoing interventional radiology procedures.

Response to Denosumab in 2 Children With Recurrent Giant Cell Tumor of the Bone With Pulmonary Metastasis.

Giant cell tumor of the bone (GCTB) is an uncommon bone tumor, usually localized, and rarely presents at <20 years of age. Denosumab, a fully human monoclonal antibody against RANKL (receptor activator of nuclear factor κB ligand), is approved for the treatment of unresectable GCTB in skeletally mature individuals. We present a case series of 2 pediatric patients with recurrent GCTB with pulmonary metastasis, with clinical response to denosumab therapy.

Diagnosis, Clinical Characteristics, and Treatment Modalities of Adolescent May-Thurner Syndrome-associated Deep Venous Thrombosis.

May-Thurner syndrome (MTS) predisposes individuals to develop lower extremity deep venous thrombosis (DVT) because of compression of the left common iliac vein. Diagnosis of the anatomic obstruction is critical for effective therapy, as treatment by interventional radiology is often required in addition to anticoagulation to prevent thrombus progression and recurrence. The authors performed a retrospective review of adolescent patients who presented with MTS-associated DVT at a pediatric tertiary care center from 2009 to 2018 to assess for delays in MTS diagnosis after the presentation. Fourteen patients (median age 16.5 y, range, 13.8 to 17.9 y) were included, no DVTs were provoked by a central venous catheter. The median time from DVT to MTS diagnosis was 0.65 months (range, 0 to 21.5 mo). The initial imaging modalities used for DVT diagnosis were not able to diagnosis MTS. All patients were treated with anticoagulation and 13 underwent interventional therapy. Four patients had thrombus progression or recurrence, whereas 6 had complete thrombus resolution on follow-up imaging. Three patients who had a delayed MTS diagnosis had clinical worsening despite therapeutic anticoagulation requiring rehospitalization. Adolescent patients with "unprovoked" left lower extremity DVT should undergo appropriate imaging to diagnose MTS to allow for adequate medical and interventional therapy.

Transarterial Radioembolization Treatment as a Bridge to Surgical Resection in Pediatric Hepatocellular Carcinoma.

BACKGROUND: Children with unresectable hepatocellular carcinoma (HCC) have a poor prognosis and limited treatment options. Transarterial radioembolization (TARE) using Yttrium-90 (Y90) has emerged as a potential bridge therapy to hepatic resection or transplantation for HCC with very limited studies in children. OBSERVATIONS: Here we present the clinical course of 2 children successfully treated with TARE Y90 for initially unresectable fibrolamellar HCC (FL-HCC) and bridged to partial hemihepatectomy with >1-year overall survival post-TARE. CONCLUSION: Although there have been prior published reports of pediatric patients with HCC being treated with TARE Y90 and some being able to undergo subsequent orthotopic liver transplantation, this is the first report of pediatric HCC patients treated with TARE Y90 as a bridge to nontransplant resections and going on to have >1-year overall survival.

Diagnostic sensitivity and specificity of CT angiography for renal artery stenosis in children.

BACKGROUND: Children with suspected renal artery stenosis (RAS) are screened with renal Doppler ultrasonography or computed tomography (CT) angiography/magnetic resonance (MR) angiography depending on institutional preference. CT angiography produces images with superior resolution, allowing higher quality multiplanar two-dimensional reformats and three-dimensional reconstructions. However, there is a paucity of data in the literature regarding the utility and diagnostic performance of renal CT angiography in pediatric RAS. OBJECTIVE: The objective of this study is to retrospectively review our experience with renal CT angiography in the diagnosis of pediatric RAS relative to digital subtraction angiography (DSA) as the reference standard. MATERIALS AND METHODS: All patients 0-18 years of age who underwent CT angiography for evaluation of RAS as a cause of hypertension between January 2012 and May 2019 were identified for the study. A total of 131 patients were identified, 23 of whom had DSA correlation. RESULTS: Twenty-three patients (17 boys, 6 girls) with a mean age of 6 years 3 months (range: 3 months to 14 years 7 months) were included in this study. Of the 59 renal arteries studied by DSA, 22 were abnormal on CT angiography and 20 were abnormal on DSA. Of the 59 renal arteries, CT angiography was true positive in 18 and true negative in 35. The sensitivity and specificity of CT angiography for RAS diagnosis were 90.0% and 89.7%, respectively. CT angiography identified all cases of main RAS. CONCLUSION: Renal CT angiography has a high sensitivity and specificity for pediatric RAS diagnosis in patients referred for DSA.

Clinical characteristics and outcomes of combined thrombolysis and anticoagulation for pediatric and young adult lower extremity and inferior vena cava thrombosis.

Effective treatment for acute, extensive, symptomatic lower extremity (LE) thrombosis involves thrombolysis in addition to anticoagulation. There is limited available data on the outcomes and safety of thrombolysis to help guide its use in pediatrics and young adults. A retrospective study of children and young adults (<21 years of age) that received catheter directed thrombolysis (CDT) for LE and inferior vena cava (IVC) thrombosis was performed over a 5-year span at a pediatric tertiary care center. A total of 29 patients were identified for inclusion in the study, 76% (n = 22) received overnight CDT while 24% (n = 7) received tissue plasminogen activator as a bolus dose during a single interventional procedure. The median age of the cohort was 15.8 years (range 0-19.1). All patients were treated with a course of therapeutic anticoagulation. The thromboses represented were extensive, with 93% (n = 27) being occlusive and affecting multiple venous segments. Thrombus resolution occurred in 35% (n = 10) of patients. Rivaroxaban use (p < 0.01) during the course of anticoagulation and estrogen-containing hormonal therapy (p = 0.01) use prior to diagnosis were associated with thrombus resolution, while Hispanic ethnicity (p = 0.06) had a trend toward thrombus persistence. There were one major and 3 minor bleeding events that occurred as complications of thrombolysis and no treatment related deaths. This study provides baseline information that can be used to help guide clinicians treating similar patients and suggests the need to develop an improved, uniform treatment approach for superior resolution rates.

Safely repositioning dual-lumen ECMO cannulas with a transfemoral lasso snare.

INTRODUCTION: Dual-lumen cannulas were designed to provide venovenous extracorporeal membrane oxygenation (VV ECMO) with single-vessel access. Anatomic and size considerations may make appropriate placement challenging in children. Dual-lumen cannulas are repositioned in 20-69% of pediatric patients, which can be difficult without transient discontinuation of ECMO support. METHODS: We repositioned three dual-lumen ECMO cannulas introduced via the right internal jugular vein using a transfemoral snare technique under real-time ultrasound and fluoroscopy. RESULTS: Two of three patients were supported on VV ECMO and one on veno-veno-arterial (VV-A) ECMO. Two of the three patients had their dual-lumen cannula repositioned under ultrasound and fluoroscopy guidance and one was repositioned just with ultrasound. No patient experienced a complication from the transfemoral snare technique such as femoral hematoma, hemorrhage or limb ischemia. CONCLUSION: We describe three patients who successfully had dual-lumen cannulas repositioned without cessation of ECMO using a transfemoral "lasso" technique.

Transarterial radioembolization with yttrium-90 of unresectable primary hepatic malignancy in children.

BACKGROUND: Primary malignant liver tumors are rare, accounting for 1% to 2% of all childhood cancers. When chemotherapy fails, transarterial radioembolization with yttrium-90 (TARE-Y90) may offer an alternative therapy as a bridge to surgical resection or liver transplant or for palliation. METHODS: We conducted a retrospective review of 10 pediatric patients with histologically confirmed primary liver malignancy who received treatment with TARE-Y90. RESULTS: The median age at treatment was 5.5 years (range, 2-18 years). Median patient survival from initial diagnosis was 12.5 months (range, 10-28 months), and median patient survival after TARE-Y90 was 4 months (range, 2-20 months). Retreatment was well tolerated in three of 10 patients, with these patients demonstrating the longest survival times (range, 17-20 months). One patient was transplanted 6 weeks after TARE-Y90. By RECIST 1.1 criteria of all target lesions, eight of nine patients had stable disease, and one of nine had progressive disease. By mRECIST criteria (requiring postcontrast arterial phase imaging), two of seven patients had a partial response, four of seven had stable disease, and one of seven had progressive disease. CONCLUSION: TARE-Y90 of unresectable primary liver malignancy is both technically feasible and demonstrates an anticancer effect, and retreatment is well tolerated. TARE-Y90 could be considered as adjunctive therapy in pediatric patients with unresectable hepatic malignancies and could be used as a bridge to surgical resection or liver transplant. More research is required to determine the efficacy of this treatment in children and to define the clinical scenarios where benefit is likely to be optimized.

Ultrasound-guided cervical puncture for nusinersen administration in adolescents.

BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal-recessive disease affecting motor neurons and is the most common genetic cause of death in infants. Intrathecal nusinersen is the only therapy approved by the U.S. Food and Drug Administration for SMA. Deformities and spinal instrumentation from orthopedic surgeries are common in children with SMA, complicating traditional intrathecal access for nusinersen delivery. Cervical punctures are routinely performed in adults for cervical myelograms and should be considered for children with SMA as a viable form of intrathecal access. OBJECTIVE: This retrospective study assessed technical feasibility and complications of ultrasound-guided cervical puncture for nusinersen administration. MATERIALS AND METHODS: We reviewed 14 consecutive ultrasound-guided cervical punctures for nusinersen administration with local anesthesia. We reviewed technical success and complications. RESULTS: All procedures were technically successful. There were no major complications. Two minor complications included headaches that resolved by observation within 24 h after the procedure. CONCLUSION: Our series describes a successful novel method of ultrasound-guided cervical spine access for intrathecal administration of nusinersen, adding to the armamentarium of procedures for delivering nusinersen to adolescents with challenging lumbar spine access caused by scoliosis and spinal instrumentation. This technique has the advantages of real-time ultrasound guidance and potential avoidance of general anesthesia in children.

Equivalent success and complication rates of tunneled common femoral venous catheter placed in the interventional suite vs. at patient bedside.

BACKGROUND: Femoral tunneled central line placement in the pediatric population offers an alternative means for intravenous (IV) access, but there is concern for higher complication and infection rates when placed at bedside. OBJECTIVE: To describe the complications and infection outcomes of primary femoral tunneled central venous catheter placement in the interventional radiology suite compared to the portable bedside location at a single tertiary pediatric institution. MATERIALS AND METHODS: We conducted a retrospective review comparing interventional radiology suites vs. bedside primary tunneled common femoral vein central line placement (January 2014 to December 2015). We identified 244 primary femoral placements in pediatric patients, ages 1 day to 18 years, using our electronic medical record and collected into a Research Electronic Data Capture. We compared categorical variables using the Fisher exact test. We compared continuous variables using the Wilcoxon rank test. RESULTS: In total, 2,375 pediatric patients received peripherally inserted and central lines; 244 of these were primary femoral tunneled central venous catheters (in 140 boys and 104 girls). In 140 children (mean age: 206 days), lines were inserted in the interventional radiology (IR) suite (technical success of 100%), with 14 (10.0%) complications including infection (n=7), malposition (n=2), bleeding (n=0), thrombosis (n=1) and line occlusion (n=4). The infection rate was 2.1 per 1,000 line days. In 104 children (mean age: 231 days), lines were placed at bedside (technical success 100%) with 14 (13.3%) complications including infection (n=3), malposition (n=5), bleeding (n=0), thrombosis (n=2) and line occlusion (n=4). The infection rate was 0.78 per 1,000 line days. The total line days were 7,109, of which 3,258 were in the IR suite and 3,851 in the bedside group. There was no statistical significance for complication rate (P=0.55) or infection rate (P=0.57) between bedside and interventional suite placements. CONCLUSION: In a cohort of children receiving primary femoral tunneled central venous catheters, the complication and infection rates in a bedside setting are not significantly increased compared to the lines placed in an IR suite. The perception of increased infection and complications from bedside-placed tunneled central venous catheters appears to be hyperbolized.

CT-guided localization of pulmonary nodules in children prior to video-assisted thoracoscopic surgical resection utilizing a combination of two previously described techniques.

BACKGROUND: Pulmonary nodules in pediatric oncology patients can present a diagnostic and treatment dilemma. Imaging findings are often nonspecific and tissue diagnosis may be required for appropriate treatment. The smaller subpleural nodules may not be visualized and cannot be palpated during video-assisted thoracoscopic surgical (VATS) resection. Preoperative localization has been beneficial in obtaining an adequate pathological specimen. OBJECTIVE: This study presents experience in a large pediatric hospital using CT-guided preoperative localization of pulmonary nodules combining two previously utilized techniques, hook wire and methylene blue blood patch localization. MATERIALS AND METHODS: A search of the electronic medical record utilizing a medical record search application was performed to identify all patients who underwent preoperative lung nodule localization during a 12.5-year period (July 1999 through January 2012). A retrospective chart review of these patients was then performed. Pre- and postoperative imaging, interventional radiology procedural images and reports, surgical reports, and pathology reports were obtained and evaluated. RESULTS: Thirty-five patients, with 40 nodules, who underwent preoperative CT-guided lung nodule localization were identified. Patients ranged in age from 8 months to 21 years. The pulmonary nodules ranged in size from 1.4 mm to 18 mm. Twelve nodules were localized using a Kopans breast lesion localization needle with hook wire, 4 were localized using a methylene blue blood patch, and 24 were localized using the combination of these two techniques. The technical success rate of all procedures was 100%. A pathological diagnosis was determined in 39 patients (97.5%). There were 6 (15.0%) minor complications and no major complications. CONCLUSION: CT-guided lung nodule localization using the combined techniques of methylene blue blood patch and hook wire is safe, technically feasible and successful in children. Using this combination of techniques will consistently yield a pathological diagnosis, is currently the preferred technique at our tertiary pediatric hospital and could be considered the new best practice.

Endovascular Thrombolysis in the Management of Iliofemoral Thrombosis in Children: A Multi-Institutional Experience.

PURPOSE: To evaluate technical feasibility, complications, and clinical outcomes of endovascular thrombolysis for iliofemoral thrombosis at two tertiary-care children's hospitals. MATERIALS AND METHODS: Institutional review board-approved retrospective review from March 2003 through June 2013 showed that venous thrombolysis for iliofemoral thrombosis was performed in 57 children (64 limbs) with a median age of 16.1 years (mean age, 14.5 y; range, 1.0-17.8 y). Techniques included catheter-directed thrombolysis (CDT), percutaneous mechanical thrombectomy (PMT), and pharmacomechanical catheter-directed thrombolysis (PCDT) with adjunctive angioplasty and/or stent placement. Villalta and modified Villalta scales were applied retrospectively to follow-up data to assess postthrombotic syndrome (PTS). RESULTS: Technical success (≥ 50% thrombolysis) rate was 93.7%: grade III (100%) in 19 limbs, grade II (50%-99%) in 41 limbs, and grade I (< 50%) in four limbs. Techniques included CDT with PCDT (32.8%) or PMT (35.9%), CDT alone (26.6%), PCDT alone (4.7%) or with adjunctive angioplasty (54.7%), and stent placement (6.3%). Mean duration of CDT was 36.5 hours (range, 2.9-89.6 h). There was one major complication (1.8%) of bleeding requiring transfusion. Minor complications (ie, bleeding) occurred in seven patients (12.2%). Median follow-up was 1.5 years (range, 30 d to 7 y). Seven patients underwent repeat thrombolysis for recurrent thrombosis. The PTS rate was 59.3% per modified Villalta scale but only 2.1% per Villalta scale. CONCLUSIONS: Endovascular thrombolysis is technically feasible and safe for iliofemoral thrombosis in children. Variable results were seen with two scales to assess PTS, suggesting an acute need for standardization of outcome measurement in children.

Use of cone-beam CT and live 3-D needle guidance to facilitate percutaneous nephrostomy and nephrolithotripsy access in children and adolescents.

BACKGROUND: Gaining access into non-dilated renal collecting systems for percutaneous nephrolithotripsy, particularly in patients with prohibitive body habitus and/or scoliosis, is often challenging using conventional techniques. OBJECTIVE: To evaluate the feasibility of cone-beam CT for percutaneous nephrostomy placement for subsequent percutaneous nephrolithotripsy in children and adolescents. MATERIALS AND METHODS: A retrospective review of percutaneous nephrostomy revealed use of cone-beam CT and 3-D guidance in 12 percutaneous nephrostomy procedures for 9 patients between 2006 and 2015. All cone-beam CT-guided percutaneous nephrostomies were for pre-lithotripsy access and all 12 were placed in non-dilated collecting systems. RESULTS: Technical success was 100%. There were no complications. CONCLUSION: Cone-beam CT with 3-D guidance is a technically feasible technique for percutaneous nephrostomy in children and adolescents, specifically for nephrolithotripsy access in non-dilated collecting systems.

Endovascular thrombolysis to salvage central venous access in children with catheter-associated upper extremity deep vein thrombosis: technique and initial results.

Nine patients (average age 8.3 years, range 20 days to 17 years; average weight 31 kg, range 2.7-79 kg) with catheter-associated UE-DVT underwent upper extremity venous thrombolysis with the goal of access salvage. Catheter directed therapy with alteplase (tPA), balloon angioplasty, and mechanical thrombectomy was used in all cases. The mean total dose of TPA was 15 mg (range 1-40 mg). Venous access was ultimately preserved in all patients. No stents or superior vena cava filters were used. There was one episode of symptomatic clinically suspected pulmonary embolism managed by systemic tPA and heparin without long term sequaele. Mean imaging and clinical follow-up was 351 ± 208 and 613 ± 498 days respectively. Endovenous thrombolysis for catheter-associated upper-extremity DVT in children may be safe and effective and could be considered particularly in patients in whom long-term venous access is needed.

Outcomes in children with deep vein thrombosis managed with percutaneous endovascular thrombolysis.

BACKGROUND: Our center has developed a multidisciplinary approach to percutaneous endovascular thrombolysis with the goal of improving outcomes in children with thrombosis. There is little data describing the safety and efficacy of endovascular thrombolysis and the frequency of post-thrombotic syndrome after thrombolysis in children. OBJECTIVE: Retrospective analysis of children undergoing percutaneous endovascular thrombolysis to determine (1) the safety and efficacy of this procedure and (2) the frequency of the diagnosis of post-thrombotic syndrome after thrombolysis. MATERIALS AND METHODS: We reviewed the medical and imaging databases for children who underwent percutaneous endovascular thrombolysis for deep venous thrombosis (DVT) between November 2008 and June 2013 at our institution. Demographic data were reviewed for the technical success and complications of thrombolysis and the last assigned post-thrombotic syndrome score using standardized scoring tools. RESULTS: Forty-one children ages 3 months to 21 years (median age: 15 years; 44% male) underwent percutaneous endovascular thrombolysis between November 2008 and June 2013. Upper extremity DVT occurred in 13 patients (32%); lower extremity DVT occurred in 28 patients (68%). All 41 patients received thrombolysis grading; 90% of those patients achieved greater than 50% thrombus lysis. Twenty-eight patients received formal post-thrombotic syndrome scoring and 4 (14%) met diagnostic criteria for post-thrombotic syndrome. One major bleeding episode and one pulmonary embolism occurred with no long-term sequelae. CONCLUSION: Endovascular thrombolysis for DVT in children is safe, effective at thrombus removal and may reduce the incidence of post-thrombotic syndrome. Randomized or larger clinical trials would be needed to determine the long-term benefits of endovascular thrombolysis.

Comparison of pediatric radiation dose and vessel visibility on angiographic systems using piglets as a surrogate: antiscatter grid removal vs. lower detector air kerma settings with a grid - a preclinical investigation.

The purpose of this study was to reduce pediatric doses while maintaining or improv-ing image quality scores without removing the grid from X-ray beam. This study was approved by the Institutional Animal Care and Use Committee. Three piglets (5, 14, and 20 kg) were imaged using six different selectable detector air kerma (Kair) per frame values (100%, 70%, 50%, 35%, 25%, 17.5%) with and without the grid. Number of distal branches visualized with diagnostic confidence relative to the injected vessel defined image quality score. Five pediatric interventional radiologists evaluated all images. Image quality score and piglet Kair were statistically compared using analysis of variance and receiver operating curve analysis to define the preferred dose setting and use of grid for a visibility of 2nd and 3rd order vessel branches. Grid removal reduced both dose to subject and imaging quality by 26%. Third order branches could only be visualized with the grid present; 100% detector Kair was required for smallest pig, while 70% detector Kair was adequate for the two larger pigs. Second order branches could be visualized with grid at 17.5% detector Kair for all three pig sizes. Without the grid, 50%, 35%, and 35% detector Kair were required for smallest to largest pig, respectively. Grid removal reduces both dose and image quality score. Image quality scores can be maintained with less dose to subject with the grid in the beam as opposed to removed. Smaller anatomy requires more dose to the detector to achieve the same image quality score.

Effect of real-time radiation dose feedback on pediatric interventional radiology staff radiation exposure.

PURPOSE: To measure and compare individual staff radiation dose levels during interventional radiologic (IR) procedures with and without real-time feedback to evaluate whether it has any impact on staff radiation dose. MATERIALS AND METHODS: A prospective trial was performed in which individuals filling five different staff roles wore radiation dosimeters during all IR procedures during two phases: a 12-week "closed" phase (measurements recorded but display was off, so no feedback was provided) and a 17-week "open" phase (display was on and provided real-time feedback). Radiation dose rates were recorded and compared by Mann-Whitney U test. RESULTS: There was no significant difference in median procedure time, fluoroscopy time, or patient dose (dose-area product normalized to fluoroscopy time) between the two phases. Overall, the median staff dose was lower in the open phase (0.56 µSv/min of fluoroscopy time) than in the closed phase (3.01 µSv/min; P < .05). The IR attending physician dose decreased significantly for procedures for which the physicians were close to the patient, but not for ones for which they were far away. CONCLUSIONS: A radiation dose monitoring system that provides real-time feedback to the interventional staff can significantly reduce radiation exposure to the primary operator, most likely by increasing staff compliance with use of radiation protection equipment and dose reduction techniques.