Diagnostic reference levels in angiography and interventional radiology: a Belgian multi-centre study

National UK Survey of Radiation Doses During Endovascular Aortic Interventions

PURPOSE

Endovascular aortic repair (EAR) interventions, endovascular abdominal aortic repair (EVAR) and thoracic endovascular aortic repair (TEVAR), are associated with significant radiation exposures. We aimed to investigate the radiation doses from real-world practice and propose diagnostic reference level (DRL) for the UK.

MATERIALS AND METHODS

Radiation data and essential demographics were retrospectively collected from 24 vascular and interventional radiology centres in the UK for all patients undergoing EAR-standard EVAR or complex, branched/fenestrated (BEVAR/FEVAR), and TEVAR-between 2018 and 2021. The data set was further categorised according to X-ray unit type, either fixed or mobile. The proposed national DRL is the 75th percentile of the collective medians for procedure KAP (kerma area product), cumulative air kerma (CAK), fluoroscopy KAP and CAK.

RESULTS

Data from 3712 endovascular aortic procedures were collected, including 2062 cases were standard EVAR, 906 cases of BEVAR/FEVAR and 509 cases of TEVAR. The majority of endovascular procedures (3477/3712) were performed on fixed X-ray units. The proposed DRL for KAP was 162 Gy cm2, 175 Gy cm2 and 266 Gy cm2 for standard EVAR, TEVAR and BEVAR/FEVAR, respectively.

CONCLUSION

The development of DRLs is pertinent to EAR procedures as the first step to optimise the radiation risks to patients and staff while maintaining the highest patient care and paving the way for steps to reduce radiation exposures.

Patient Radiation Doses in IR Procedures: The American College of Radiology Dose Index Registry-Fluoroscopy Pilot

PURPOSE

To update normative data on fluoroscopy dose indices in the United States for the first time since the Radiation Doses in Interventional Radiology study in the late 1990s.

MATERIALS AND METHODS

The Dose Index Registry-Fluoroscopy pilot study collected data from March 2018 through December 2019, with 50 fluoroscopes from 10 sites submitting data. Primary radiation dose indices including fluoroscopy time (FT), cumulative air kerma (Ka,r), and kerma area product (PKA) were collected for interventional radiology fluoroscopically guided interventional (FGI) procedures. Clinical facility procedure names were mapped to the American College of Radiology (ACR) common procedure lexicon. Distribution parameters including the 10th, 25th, 50th, 75th, 95th, and 99th percentiles were computed.

RESULTS

Dose indices were collected for 70,377 FGI procedures, with 50,501 ultimately eligible for analysis. Distribution parameters are reported for 100 ACR Common IDs. FT in minutes, Ka,r in mGy, and PKA in Gy-cm2 are reported in this study as (n; median) for select ACR Common IDs: inferior vena cava filter insertion (1,726; FT: 2.9; Ka,r: 55.8; PKA: 14.19); inferior vena cava filter removal (464; FT: 5.7; Ka,r: 178.6; PKA: 34.73); nephrostomy placement (2,037; FT: 4.1; Ka,r: 39.2; PKA: 6.61); percutaneous biliary drainage (952; FT: 12.4; Ka,r: 160.5; PKA: 21.32); gastrostomy placement (1,643; FT: 3.2; Ka,r: 29.1; PKA: 7.29); and transjugular intrahepatic portosystemic shunt placement (327; FT: 34.8; Ka,r: 813.0; PKA: 181.47).

CONCLUSIONS

The ACR DIR-Fluoro pilot has provided state-of-the-practice statistics for radiation dose indices from IR FGI procedures. These data can be used to prioritize procedures for radiation optimization, as demonstrated in this work.

DIAGNOSTIC REFERENCE LEVELS AND COMPLEXITY INDICES IN INTERVENTIONAL RADIOLOGY

The establishment of typical diagnostic reference levels (DRLs) values according to the complexity indices (CIs) for hepatic chemoembolisation (HC), iliac stent placement (ISP) and femoropopliteal revascularisation (FR) is reported in this study. To estimate patients' stochastic effects, effective dose was calculated through dose area product (DAP) values of this study and E/DAP conversion factors derived from the literature. Data for DAP, Reference Air Kerma (Ka,r) and fluoroscopy time (FT) were collected for 218 patients and CIs were assigned to each procedure to extract DRLs. To estimate effective dose, conversion factors and DAP values were used for seven IR procedures. DRL values for DAP were 141, 130 and 28 Gy*cm2 for HC, ISP, and FR, respectively. The corresponding DRL values for Ka,r were 634.6, 300.1 and 112.0 mGy, and for FT were 15.3, 12.4 and 17.9 min, respectively. CIs in interventional radiology are a useful tool for the optimisation of DRLs since they contribute to patient's doses.

An audit of patient radiation doses in interventional radiology at a South African hospital

Background

Interventional radiology (IR) is becoming more relevant in patient care and is associated with increased patient radiation exposure and radiation-induced adverse effects. Diagnostic reference levels (DRLs) are crucial for radiation control. There is a paucity of published DRLs for IR in South Africa and sub-Saharan Africa.

Objectives

This study aimed to determine local DRLs for fluoroscopically-guided IR procedures and compare the achieved DRLs with published local and international DRLs.

Method

Retrospective, descriptive, single-centre study. Kerma air product (KAP), reference point air kerma (K_a,r) and fluoroscopy time (FT) were collected for patients (12 years and older) who underwent IR procedures at a university hospital from 01 January 2019 to 31 December 2019. The 75th percentile of the distribution of each dose parameter (KAP, K_a,r and FT) per procedure was calculated and taken as the local diagnostic reference levels (LDRL). The established LDRLs were compared to published DRLs.

Results

A total of 564 cases were evaluated. The 13 most frequent procedures (with 15 or more cases) represented 86.1% (487/564). Percutaneous transhepatic biliary drainage was the most common procedure (n = 146, 25.9%). Diagnostic cerebral angiogram DRLs exceeded the published DRL data ranges for all parameters (DRL 209.3), and interventional cerebral angiogram exceeded published ranges (DRL 275). Uterine artery embolisation (UAE) exceeded these ranges for KAP and K_a,r. (KAP-954.9 Gy/cm², K_a,r-2640.8 mGy).

Conclusion

The LDRLs for diagnostic cerebral angiogram, interventional cerebral angiogram and UAE exceeded published international DRL ranges. These procedures require radiation optimisation as recommended by the International Commission on Radiological Protection (ICRP).

Contribution

In addition to informing radiation protection practices at the level of the institution, the established LDRLs contribute towards Regional and National DRLs.

Institutional Diagnostic Reference Levels and Peak Skin Doses in selected diagnostic and therapeutic interventional radiology procedures

PURPOSE

Institutional (local) Diagnostic Reference Levels for Cerebral Angiography (CA), Percutaneous Transhepatic Cholangiography (PTC), Transarterial Chemoembolization (TACE) and Percutaneous Transhepatic Biliary Drainage (PTBD) are reported in this study.

MATERIALS AND METHODS

Data for air kerma-area product (P_KA), air kerma at the patient entrance reference point (K_a,r), fluoroscopy time (FT) and number of images (NI) as well as estimates of Peak Skin Dose (PSD) were collected for 142 patients. Therapeutic procedure complexity was also evaluated, in an attempt to incorporate it into the DRL analysis.

RESULTS

Local P_KA DRL values were 70, 34, 189 and 54 Gy.cm² for CA, PTC, TACE and PTBD respectively. The corresponding DRL values for K_a,r were 494, 194, 1186 and 400 mGy, for FT they were 9.2, 14.2, 27.5 and 22.9 min, for the NI they were 844, 32, 602 and 13 and for PSD they were 254, 256, 1598 and 540 mGy respectively. P_KA for medium complexity PTBD procedures was 2.5 times higher than for simple procedures. For TACE, the corresponding ratio was 1.6. PSD was estimated to be roughly 50% of recorded K_a,r for procedures in the head/neck region and 10% higher than recorded K_a,r for procedures in the body region. In only 5 cases the 2 Gy dose alarm threshold for skin deterministic effects was exceeded.

CONCLUSION

Procedure complexity can differentiate DRLs in Interventional Radiology procedures. PSD could be deduced with reasonable accuracy from values of K_a,r that are reported in every angiography system.

Diagnostic reference levels for fluoroscopically guided procedures in a South African tertiary hospital

BACKGROUND

The burgeoning usage and complexity of fluoroscopically guided procedures (FGPs) contribute to extended examination times and increased risk of adverse radiation effects. Diagnostic reference levels (DRLs) play a pivotal role in dose optimization. There are limited DRL data for FGPs in low- and middle-income countries (LMICs).

PURPOSE

To determine local DRLs (LDRLs) for common FGPs in the South African (SA) context and compare these with published international data.

MATERIAL AND METHODS

A three-year, retrospective study of the 15 most frequently performed FGPs at a SA institution. For each procedure, the 50th and 75th percentiles of kerma area product (KAP), reference point air kerma (K_a,r), and fluoroscopy time data were derived. Published international FGP DRL data were collated and compared with the 75th percentiles of local institutional dosage parameters.

RESULTS

The commonest FGPs were aorto-bifemoral diagnostic angiography (n = 590), aorto-bifemoral interventional angiography (n = 287), nephrostomy (n = 265), and bronchial arterial embolization (BAE) (n = 208). Selective abdominal vessel interventional angiography (KAP = 170 Gy . cm²; K_a,r = 877 mGy) recorded the highest LDRL dosages; BAE was the longest procedure (LDRL = 38 min). Nephrostomies achieved the lowest LDRLs across all parameters (KAP = 10 Gy . cm²; K_a,r = 63 mGy, fluoroscopy time = 4.3 min). All Tygerberg Hospital LDRLs with comprehensive comparable data were within or below published ranges.

CONCLUSION

This study advances international radiation protection initiatives, addresses the paucity of LMIC DRL data, demonstrates broad alignment of Tygerberg Hospital FGP practice with international norms and highlights areas for optimization of institutional practice.

A MULTICENTRE SURVEY OF LOCAL DIAGNOSTIC REFERENCE LEVELS AND ACHIEVABLE DOSE FOR CORONARY ANGIOGRAPHY AND PERCUTANEOUS TRANSLUMINAL CORONARY INTERVENTION PROCEDURES IN KOREA

Interventional cardiology procedures can involve relatively high radiation doses compared to general radiography. During coronary angiography (CAG) and percutaneous transluminal coronary intervention (PCI), the same area is exposed to radiation for a long period. In this study, radiation exposure data of 1071 examinations in Korean hospitals were collected, and the achievable dose (AD) and diagnostic reference levels (DRLs) in actual medical practice for two types of interventional cardiology procedures in Korea were established. In CAG, 75th percentile DRLs and AD of the total kerma-area product were 47.0 and 33.1 Gy·cm 2, respectively. In PCI, those values were 171.3 and 102.6 Gy·cm2, respectively. This is the first study to introduce the DRLs for cardiovascular interventional procedures in Korea. These results will help optimise the interventional cardiology procedures for Korean cardiac centres.

Radiation Protection for Interventional Fluoroscopy: Results of a Survey Among Dutch Hospitals

A survey was conducted among 20 Dutch hospitals about radiation protection for interventional fluoroscopy. This was a follow-up of a previous study in 2007 that led to several recommendations for radiation protection for interventional fluoroscopy. The results indicate that most recommendations have been followed. However, radiation-induced complications from interventional procedures are still often not recorded in the appropriate register. Furthermore, even though professionals with appropriate training in radiation protection are usually involved in interventional procedures, this often is not the case when these procedures are carried out outside the radiology department. Although this involvement is not required by Dutch law, it is recommended to have radiation protection professionals present more often at interventional procedures. Further improvements in radiation protection for interventional fluoroscopy may come from a comparison of dose-reducing practices among hospitals, the introduction of diagnostic reference levels for interventional procedures, and a more thorough form of screening and follow-up of patients.

Patient Radiation Doses in Therapeutic Endoscopic Retrograde Cholangiopancreatography in Patras and the Key Role of the Operator

The patient radiation doses, in conjunction with the operator experience, in therapeutic endoscopic retrograde cholangiopancreatography (ERCP) procedures, performed in our hospital, were obtained. Ninety-six patients participated in the study and were divided into 3 groups, based on the operator experience. The dosemetric indices, fluoroscopy time (FT), cumulative dose (Ka,r) and air kerma-area product (PKA), were collected. For the total and weight banding group the third quartile values of the distribution of FT, Ka,r and PKA were 2.90 and 2.92 min, 6.89 and 6.93 mGy and 1.84 and 1.85 Gycm2, respectively, and were comparative or significantly lower than the corresponding values previously reported. Taking as a criterion the operator, the differences in the patient radiation doses were statistically significant, with the highest dose recorded for the operator of the lowest experience degree. The values obtained could contribute in establishing local and national diagnostic reference levels and in optimising ERCP procedure.

THE ESTABLISHMENT OF LOCAL DIAGNOSTIC REFERENCE LEVELS IN ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY: A PRACTICAL TOOL FOR THE OPTIMISATION AND FOR QUALITY ASSURANCE MANAGEMENT

Fluoroscopic procedures are an area of special concern in relation to radiation protection. The aim of this study was to describe the current level of patient radiation doses in endoscopic retrograde cholangiopancreatography (ERCP) collected from a single centre, as well as to establish and review local diagnostic reference levels (DRLs) in ERCP. A total of 100 patients' radiation doses in ERCP were recorded, and the third-quartile method was adopted to establish local DRLs for ERCP. The mean dose area product (DAP) was 2.05 Gy cm2, fluoroscopy time (FT) 1.7 min and the number of images was 3. The proposed local DRLs for ERCP were 3.00 Gy cm2 and 3.0 min. Local DRLs were reviewed in a sample of 25 patients 5 y after they had been established. In reviewing data, the averages of DAP and FT were below the local DRLs. Local DRLs help in the optimisation process of fluoroscopic procedures and guides to a good clinical practice.

Patient radiation doses and reference levels in pediatric interventional radiology

OBJECTIVES

To describe, in a multicentric paediatric population, reference levels (RLs) for three interventional radiological procedures.

METHODS

From January 2012 to March 2015, children scheduled for an interventional radiological procedure in two French tertiary centres were retrospectively included and divided into four groups according to age: children younger than 2 years (A1), aged 2-7 years (A5), 8-12 years (A10) and 13-18 years (A15). Three procedures were identified: cerebral digital subtraction angiography (DSA), brain arteriovenous malformation (bAVM) embolization, and head and neck superficial vascular malformation (SVM) percutaneous sclerotherapy. Demographic and dosimetric data, including dose area product (DAP), were collected.

RESULTS

550 procedures were included. For DSA (162 procedures), the proposed RL values in DAP were 4, 18, 12 and 32 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For bAVM embolization (258 procedures), values were 33, 70, 105 and 88 Gy∙cm² in groups A1, A5, A10 and A15, respectively. For SVM sclerotherapy (130 procedures), values were 350, 790, 490 and 248 mGy∙cm² in groups A1, A5, A10 and A15, respectively.

CONCLUSION

Consecutive data were available to permit a proposal of reference levels for three major paediatric interventional radiology procedures.

KEY POINTS

• We determined reference levels (RLs) for bAVM embolization, DSA and SVM sclerotherapy. • The proposed RLs will permit benchmarking practice with an external standard. • The proposed RLs by age may help to develop paediatric dose guidelines.

Radiation Exposure during Neurointerventional Procedures in Modern Biplane Angiographic Systems: A Single-Site Experience

Background and Purpose

Per the ALARA principle, reducing the dose delivered to both patients and staff must be a priority for endovascular therapists, who should monitor their own practice. We evaluated patient exposure to radiation during common neurointerventions performed with a recent flat-panel detector angiographic system and compared our results with those of recently published studies.

Methods

All consecutive patients who underwent a diagnostic cerebral angiography or intervention on 2 modern flat-panel detector angiographic biplane systems (Innova IGS 630, GE Healthcare, Chalfont St Giles, UK) from February to November 2015 were retrospectively analyzed. Dose-area product (DAP), cumulative air kerma (CAK) per plane, fluoroscopy time (FT), and total number of digital subtraction angiography (DSA) frames were collected, reported as median (interquartile range), and compared with the previously published literature.

Results

A total of 755 consecutive cases were assessed in our institution during the study period, including 398 diagnostic cerebral angiographies and 357 interventions. The DAP (Gy × cm²), fontal and lateral CAK (Gy), FT (min), and total number of DSA frames were as follows: 43 (33-60), 0.26 (0.19-0.33), 0.09 (0.07-0.13), 5.6 (4.2-7.5), and 245 (193-314) for diagnostic cerebral angiographies, and 66 (41-110), 0.46 (0.25-0.80), 0.18 (0.10-0.30), 18.3 (9.1-30.2), and 281 (184-427) for interventions.

Conclusion

Our diagnostic cerebral angiography group had a lower median and was in the 75th percentile of DAP and FT when compared with the published literature. For interventions, both DAP and number of DSA frames were significantly lower than the values reported in the literature, despite a higher FT. Subgroup analysis by procedure type also revealed a lower or comparable DAP.

Radiation dose in coronary angiography and intervention: initial results from the establishment of a multi-centre diagnostic reference level in Queensland public hospitals

Introduction

Radiation dose to patients undergoing invasive coronary angiography (ICA) is relatively high. Guidelines suggest that a local benchmark or diagnostic reference level (DRL) be established for these procedures. This study sought to create a DRL for ICA procedures in Queensland public hospitals.

Methods

Data were collected for all Cardiac Catheter Laboratories in Queensland public hospitals. Data were collected for diagnostic coronary angiography (CA) and single-vessel percutaneous intervention (PCI) procedures. Dose area product (P_KA), skin surface entrance dose (K_AR), fluoroscopy time (FT), and patient height and weight were collected for 3 months. The DRL was set from the 75th percentile of the P_KA.

Results

2590 patients were included in the CA group where the median FT was 3.5 min (inter-quartile range = 2.3–6.1). Median K_AR = 581 mGy (374–876). Median P_KA = 3908 uGym² (2489–5865) DRL = 5865 uGym². 947 patients were included in the PCI group where median FT was 11.2 min (7.7–17.4). Median K_AR = 1501 mGy (928–2224). Median P_KA = 8736 uGym² (5449–12,900) DRL = 12,900 uGym².

Conclusion

This study established a benchmark for radiation dose for diagnostic and interventional coronary angiography in Queensland public facilities.

Patient radiation doses in interventional cardiology in the U.S.: advisory data sets and possible initial values for U.S. reference levels

PURPOSE

To determine patient radiation doses from interventional cardiology procedures in the U.S and to suggest possible initial values for U.S. benchmarks for patient radiation dose from selected interventional cardiology procedures [fluoroscopically guided diagnostic cardiac catheterization and percutaneous coronary intervention (PCI)].

METHODS

Patient radiation dose metrics were derived from analysis of data from the 2008 to 2009 Nationwide Evaluation of X-ray Trends (NEXT) survey of cardiac catheterization. This analysis used identified data and did not require review by an IRB. Data from 171 facilities in 30 states were analyzed. The distributions (percentiles) of radiation dose metrics were determined for diagnostic cardiac catheterizations, PCI, and combined diagnostic and PCI procedures. Confidence intervals for these dose distributions were determined using bootstrap resampling.

RESULTS

Percentile distributions (advisory data sets) and possible preliminary U.S. reference levels (based on the 75th percentile of the dose distributions) are provided for cumulative air kerma at the reference point (K(a,r)), cumulative air kerma-area product (P(KA)), fluoroscopy time, and number of cine runs. Dose distributions are sufficiently detailed to permit dose audits as described in National Council on Radiation Protection and Measurements Report No. 168. Fluoroscopy times are consistent with those observed in European studies, but P(KA) is higher in the U.S.

CONCLUSIONS

Sufficient data exist to suggest possible initial benchmarks for patient radiation dose for certain interventional cardiology procedures in the U.S. Our data suggest that patient radiation dose in these procedures is not optimized in U.S. practice.

Radiation exposure in vascular angiographic procedures

PURPOSE

To evaluate dose reduction in vascular angiographic procedures by using fluoroscopy capture instead of digital subtraction angiography frames for documentation.

MATERIALS AND METHODS

A total of 764 consecutive vascular interventional procedures performed over a period of 1 year were retrospectively analyzed with respect to the fluoroscopy time and the resulting dose-area product (DAP), the DAP of the radiographic frames, and the overall DAP.

RESULTS

A total of 70% of the total DAP was a result of the acquisition of radiographic frames, leaving only 30% being applied by fluoroscopy.

CONCLUSIONS

Fluoroscopy capture should be used for documentation whenever possible. A registry of radiation exposure should not only comprise a sufficiently large number of interventions but also different intervention types to allow the development of interventional reference levels.

Reference levels for patient radiation doses in interventional radiology: proposed initial values for U.S. practice

PURPOSE

To propose initial values for patient reference levels for fluoroscopically guided procedures in the United States.

MATERIALS AND METHODS

This secondary analysis of data from the Radiation Doses in Interventional Radiology Procedures (RAD-IR) study was conducted under a protocol approved by the institutional review board and was HIPAA compliant. Dose distributions (percentiles) were calculated for each type of procedure in the RAD-IR study where there were data from at least 30 cases. Confidence intervals for the dose distributions were determined by using bootstrap resampling. Weight banding and size correction methods for normalizing dose to patient body habitus were tested.

RESULTS

The different methods for normalizing patient radiation dose according to patient weight gave results that were not significantly different (P > .05). The 75th percentile patient radiation doses normalized with weight banding were not significantly different from those that were uncorrected for body habitus. Proposed initial reference levels for various interventional procedures are provided for reference air kerma, kerma-area product, fluoroscopy time, and number of images.

CONCLUSION

Sufficient data exist to permit an initial proposal of values for reference levels for interventional radiologic procedures in the United States. For ease of use, reference levels without correction for body habitus are recommended. A national registry of radiation-dose data for interventional radiologic procedures is a necessary next step to refine these reference levels.