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

Radiation dose during transarterial chemoembolization and associated factors

PURPOSE

To provide detailed reports on radiation doses during transarterial chemoembolization (TACE) in the cone-beam computed tomography (CBCT) era and to identify the associated factors.

METHODS

This retrospective study included 385 consecutive patients who underwent initial conventional TACE for hepatocellular carcinoma (HCC) between January 2016 and December 2017. In most cases, CBCT was performed at the common hepatic artery or celiac axis to confirm the location of the tumor and the three-dimensional hepatic artery anatomy. Superselective TACE was performed for all technically feasible cases. Information on total dose area product (DAP), total cumulative air kerma (CAK), fluoroscopy time, and DAP and CAK of each digital subtraction angiography (DSA) and CBCT scan was recorded. Multiple linear regression analysis was performed to identify the factors associated with increased DAP during TACE.

RESULTS

The mean values of total DAP and CAK were 165.2 ± 81.2 (Gy·cm²) and 837.1 ± 571.0 (mGy), respectively. The mean fluoroscopy time was 19.1 ± 10.3 min. The mean DAP caused by fluoroscopy, DSA, and CBCT was 51.8 ± 43.9, 28.0 ± 24.1, and 83.9 ± 42.1 Gy·cm², respectively. Male sex, a high body mass index, largest tumor size > 3 cm, presence of aberrant right and left hepatic arteries, and superselective TACE were identified as independent predictors of increased total DAP during TACE.

CONCLUSION

We were able to provide detailed reports on radiation doses during TACE and associated factors.

Clinical diagnostic reference levels in neuroradiology based on clinical indication

This study focuses on patient radiation exposure in interventional neuroradiology (INR) procedures, a field that has advanced significantly since its inception in the 1980s. INR employs minimally invasive techniques to treat complex cerebrovascular diseases in the head, neck, and spine. The study establishes diagnostic reference levels (DRLs) for three clinical indications (CIs): stroke (S), brain aneurysms (ANs), and brain arteriovenous malformation (AVM). Data from 209 adult patients were analyzed, and DRLs were determined in terms of various dosimetric and technical quantities. For stroke, the established DRLs median values were found to be 78 Gy cm2, 378 mGy, 118 mGy, 12 min, 442 images, and 15 runs. Similarly, DRLs for brain AN are 85 Gy cm2, 611 mGy, 95.5 mGy, 19.5, 717 images, and 26 runs. For brain AVM, the DRL's are 180 Gy cm2, 1144 mGy, 537 mGy, 36 min, 1375 images, and 31 runs. Notably, this study is unique in reporting DRLs for specific CIs within INR procedures, providing valuable insights for optimizing patient safety and radiation exposure management.

Metal-Halide Perovskite Submicrometer-Thick Films for Ultra-Stable Self-Powered Direct X-Ray Detectors

Metal-halide perovskites are revolutionizing the world of X-ray detectors, due to the development of sensitive, fast, and cost-effective devices. Self-powered operation, ensuring portability and low power consumption, has also been recently demonstrated in both bulk materials and thin films. However, the signal stability and repeatability under continuous X-ray exposure has only been tested up to a few hours, often reporting degradation of the detection performance. Here it is shown that self-powered direct X-ray detectors, fabricated starting from a FAPbBr3 submicrometer-thick film deposition onto a mesoporous TiO2 scaffold, can withstand a 26-day uninterrupted X-ray exposure with negligible signal loss, demonstrating ultra-high operational stability and excellent repeatability. No structural modification is observed after irradiation with a total ionizing dose of almost 200 Gy, revealing an unexpectedly high radiation hardness for a metal-halide perovskite thin film. In addition, trap-assisted photoconductive gain enabled the device to achieve a record bulk sensitivity of 7.28 C Gy-1 cm-3 at 0 V, an unprecedented value in the field of thin-film-based photoconductors and photodiodes for "hard" X-rays. Finally, prototypal validation under the X-ray beam produced by a medical linear accelerator for cancer treatment is also introduced.

National survey to update the diagnostic reference levels in interventional radiology procedures in Italy: working methodology

Interventional Radiology (IR) deals with the diagnosis and treatment of various diseases through medically guided imaging. It provides unquestionable benefits to patients, but requires, in many cases, the use of high doses of ionizing radiation with a high impact on radiation risks to patients and to overall dose to the population. The International Commission on Radiological Protection introduced Diagnostic reference levels (DRLs) as an effective tool to facilitate dose verification and optimize protection for patients undergoing radiological procedures. In addition, EURATOM Council Directive 2013/59 and its Italian transposition (Legislative Decree 101/2020) have reiterated that DRLs must be established for many common radiological diagnostic procedures to compare the radiation dose delivered for the same diagnostic examination. Within this framework, Istituto Superiore di Sanità-Italian National Institute of Health (ISS)-, in collaboration with relevant Italian Scientific Societies, has provided documents on DRLs in radiological practices such as diagnostic and IR and diagnostic nuclear medicine. These reference documents enable National Hospitals to comply national regulation. The implementation of DRLs in IR is a difficult task because of the wide distribution of doses to patients even within the same procedure. Some studies have revealed that the amount of radiation in IR procedures is influenced more by the complexity of the procedure than by the weight of the patient, so complexity should be included in the definition of DRLs. For this reason, ISS promoted a survey among a sample of Italian Centers update national DRL in IR procedures with related complexity factors than can be useful for other radiological centers and to standardize the DRLs values. In the present paper the procedural methodology developed by ISS and used for the survey will be illustrated.

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.

Cumulative Effective Dose During Fluoroscopically Guided Interventions (FGI): Analysis of More Than 5000 FGIs in a Single European Center

BACKGROUND

The number of fluoroscopically guided interventions (FGI) has increased significantly over time. However, little attention has been paid to possible stochastic radiation effects. The aim of this retrospective study was to investigate the number of patients who received cumulative effective doses over 100 mSv during FGI procedures.

MATERIAL AND METHODS

Five thousand five hundred and fifty four classified FGI procedures were included. Radiation dose data, retrieved from an in-house-dose-management system, was analysed. Effective doses and cumulative effective doses (CED) were calculated. Patients who received a CED > 100 mSv were identified. Radiology reports, patient age, imaging and clinical data of these patients were used to identify reasons for CED ≥ 100 mSv.

RESULTS

One Hundred and thirty two (41.1% female) of 3981 patients received a CED > 100 mSy, with a mean CED of 173.5 ± 84.5 mSv. Mean age at first intervention was 66.1 ± 11.7 years. 81 (61.4%) of 132 were older than 64 years, one patient was < 30 years. 110 patients received ≥ 100 mSv within one year (83.4%), through FGIs: EVAR, pelvic/mesenteric interventions (stent or embolization), hepatic interventions (chemoembolization, TIPSS), embolization of cerebral aneurysms or arterio-venous-malformations.

CONCLUSIONS

Substantial CED may occur in a small but not ignorable fraction of patients (~ 3%) undergoing FGIs. Approximately 2/3rd of patients may most likely not encounter radiation-related stochastic effects due to life-threatening diseases and age at first treatment > 65 years but 1/3rd may. Patients undergoing more than one FGI (77%) carry a higher risk of accumulating effective doses > 100 mSv. Remarkably, 23% received a mean CED 162.2 ± 72.3 mSv in a single procedure.

Fast dose calculation in x-ray guided interventions by using deep learning

Objective.Patient dose estimation in x-ray-guided interventions is essential to prevent radiation-induced biological side effects. Current dose monitoring systems estimate the skin dose based in dose metrics such as the reference air kerma. However, these approximations do not take into account the exact patient morphology and organs composition. Furthermore, accurate organ dose estimation has not been proposed for these procedures. Monte Carlo simulation can accurately estimate the dose by recreating the irradiation process generated during the x-ray imaging, but at a high computation time, limiting an intra-operative application. This work presents a fast deep convolutional neural network trained with MC simulations for patient dose estimation during x-ray-guided interventions.Approach.We introduced a modified 3D U-Net that utilizes a patient's CT scan and the numerical values of imaging settings as input to produce a Monte Carlo dose map. To create a dataset of dose maps, we simulated the x-ray irradiation process for the abdominal region using a publicly available dataset of 82 patient CT scans. The simulation involved varying the angulation, position, and tube voltage of the x-ray source for each scan. We additionally conducted a clinical study during endovascular abdominal aortic repairs to validate the reliability of our Monte Carlo simulation dose maps. Dose measurements were taken at four specific anatomical points on the skin and compared to the corresponding simulated doses. The proposed network was trained using a 4-fold cross-validation approach with 65 patients, and evaluating the performance on the remaining 17 patients during testing.Main results.The clinical validation demonstrated a average error within the anatomical points of 5.1%. The network yielded test errors of 11.5 ± 4.6% and 6.2 ± 1.5% for peak and average skin doses, respectively. Furthermore, the mean errors for the abdominal region and pancreas doses were 5.0 ± 1.4% and 13.1 ± 2.7%, respectively.Significance.Our network can accurately predict a personalized 3D dose map considering the current imaging settings. A short computation time was achieved, making our approach a potential solution for dose monitoring and reporting commercial systems.

Middle meningeal artery embolization using cone-beam computed tomography augmented guidance in patients with cancer

PURPOSE

The purpose of this study was to evaluate the safety and efficacy of middle meningeal artery embolization (MMAE) performed under cone-beam computed tomography (CBCT) augmented guidance in patients with cancer.

MATERIALS AND METHODS

Eleven patients with cancer (seven women, four men; median age, 75 years; age range: 42-87 years) who underwent 17 MMAEs under CBCT with a combination of particles and coils for chronic subdural hematoma (SDH) (n = 6), postoperative SDH (n = 3), or preoperative embolization of meningeal tumor (n = 2) from 2022 to 2023 were included. Technical success, fluoroscopy time (FT), reference dose (RD), kerma area product (KAP) were analyzed. Adverse events and outcomes were recorded.

RESULTS

The technical success rate was 100% (17/17). Median MMAE procedure duration was 82 min (interquartile range [IQR]: 70, 95; range: 63-108 min). The median FT was 24 min (IQR: 15, 48; range: 21.5-37.5 min); the median RD was 364 mGy (IQR: 37, 684; range: 131.5-444.5 mGy); and the median KAP was 46.4 Gy.cm2 (9.6, 104.5; range: 30.2-56.6 Gy.cm2). No further interventions were needed. The adverse event rate was 9% (1/11), with one pseudoaneurysm at the puncture site in a patient with thrombocytopenia, which was treated by stenting. The median follow-up was 48 days (IQR; 14, 251; range: 18.5-91 days]. SDH reduced in 11 of 15 SDHs (73%) as evidenced by follow-up imaging, with a size reduction greater than 50% in 10/15 SDHs (67%) .

CONCLUSION

MMAE under CBCT is a highly effective treatment option, but appropriate patient selection and careful consideration of potential risks and benefits is important for optimal patient outcomes.

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.

Modified design of x-ray protective clothing to enhance radiation protection for interventional radiologists

BACKGROUND

In interventional radiology procedures, the operator typically stands on the right side of the patient's right thigh to manipulate devices through the femoral sheath. Because the standard x-ray protective clothing is designed as sleeveless and scatter radiations from the patient are mainly incident from the left-anterior direction to the operator, the arm hole of the clothing may be a significant unprotected area, contributing to an increase in the operator's organ doses and effective dose.

PURPOSE

This study aimed to compare the organ doses and effective dose received by the interventional radiologist when wearing the standard x-ray protective clothing and when wearing the modified clothing with an additional shoulder guard.

METHODS

The experimental setup aimed to simulate actual clinical practice in interventional radiology. The patient phantom was located at the beam center to generate scatter radiation. An adult female anthropomorphic phantom loaded with 126 nanoDots (Landauer Inc., Glenwood, IL) was used to measure organ and effective doses to the operator. The standard wrap-around type x-ray protective clothing offered 0.25-mm lead-equivalent protection, and the frontal overlap area offered 0.50-mm lead-equivalent protection. The shoulder guard was custom-made with a material providing x-ray protection equivalent to lead of 0.50 mm thickness. The organ and effective doses were compared between the operator wearing the standard protective clothing and the one wearing the modified clothing with a shoulder guard.

RESULTS

After adding the shoulder guard, doses to the lungs, bone marrow, and esophagus decreased by 81.9%, 58.6%, and 58.7%, respectively, and the effective dose to the operator decreased by 47.7%.

CONCLUSIONS

Widespread use of modified x-ray protective clothing with shoulder guards can significantly decrease the overall occupational radiation risk in interventional radiology.

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.

Preoperative Embolization of Metastatic Spinal Cord Compression with n-Butyl Cyanoacrylate: Safety and Effectiveness in Limiting Blood Loss

PURPOSE

To evaluate the safety and effectiveness of preoperative embolization with n-butyl cyanoacrylate (nBCA) performed for metastatic spinal cord compression (MSCC) in limiting blood loss (BL).

MATERIALS AND METHODS

In this institutional review board-approved retrospective study, clinical records from 2017 to 2022 were reviewed. Twenty consecutive patients (11 men and 9 women; mean age, 65.8 years ± 10.0; range, 45-82 years) underwent 21 preoperative spine tumor embolizations with nBCA. Angiograms were used to calculate the percentage reduction in tumor vascularity, and relevant clinical data (levels studied and embolized, fluoroscopy time [FT], reference dose [RD], and Kerma area product [KAP]) and operative data (BL and operative time [OT]) were analyzed. Adverse events and outcomes were recorded.

RESULTS

A median of 2 levels were embolized per procedure (range, 1-5) but 4.9 were studied (range, 1-10). After embolization, tumor blush was reduced by a median of 87.3% (range, 50%-90%). The mean FT was 41 minutes ± 15.4 (range, 16-67 minutes), the mean RD was 1,977.1 mGy ± 1,794.3 (range, 450.2-6,319 mGy), and the mean KAP was 180.5 Gy·cm² ± 166.2 (range, 30.4-504 Gy·cm²). The adverse event rate was 1 (4.7%) of the 21 embolizations because a weakness of lower extremities related to swelling was observed. Surgery was performed at a mean of 1.4 days ± 1 (range, 1-5 days) after embolization. The mean surgical estimated BL was 432.5 mL ± 328.5 (range, 25-1,100 mL), and the mean OT was 210.1 minutes ± 97.4 (range, 57-489 minutes).

CONCLUSIONS

Preoperative embolization of tumors resected for MSCC with nBCA is a safe procedure allowing for performance of surgery with acceptable BL.

Local reference and achievable dose levels for vascular and enterostomy access procedures in pediatric interventional radiology

BACKGROUND

Knowledge of radiation quantities delivered in routine practice is an essential responsibility of a pediatric interventional radiology department.

OBJECTIVE

To review radiation indices in frequently performed vascular and enterostomy access procedures at a quaternary pediatric hospital to formulate dosimetric reference levels and achievable levels.

MATERIALS AND METHODS

A retrospective review of patient demographics, procedure information and quantitative dose metrics over a 2-year period was performed. Dosimetric details for common procedures (central line insertions, gastrostomy/gastrojejunostomy insertions and maintenance) were evaluated, correlated with demographic data and stratified across five weight groups (0-5 kg, 5-15 kg, 15-30 kg, 30-50 kg, 50-80 kg). Achievable (50th percentile) and reference (75th percentile) levels with confidence intervals were established for each procedure.

RESULTS

Within the evaluation period, 3,165 studies satisfied the inclusion criteria. Five were classified as device insertions (peripherally inserted central catheter, n=1,145; port-a-catheter, n=321; central venous line, n=285; gastrostomy-tube [G-tube], n=262, and gastrojejunostomy-tube [GJ-tube], n=66), and two were classified as maintenance procedures (G-tube, n=358, and GJ-tube, n=728, checks, exchanges and reinsertions). Representative reference and achievable levels were calculated for each procedure category and weight group.

CONCLUSION

This work highlights the creation of local reference and achievable levels for common pediatric interventional procedures. These data establish a dosimetric reference to understand the quantity of radiation routinely applied, allowing for improved relative radiation risk assessment and enriched communication to interventionalists, health care providers, parents and patients.

Radiation metrics for vascular and interventional radiology procedures in a tertiary care institution: A retrospective cohort study over 5-years

OBJECTIVES

To evaluate the radiation metrics from frequently carried out vascular and interventional radiology (VIR) procedures at a tertiary care institution and compare them to international diagnostic reference levels (DRLs).

METHODS

A retrospective study of the radiation metrics of VIR-procedures carried out from January 2015 to December 2019. The collected data included age, gender, height and weight, reference point air kerma (mGy), dose area product (DAP; Gy.cm2), and fluoroscopy time (min.) The body mass index (BMI) and peak skin dose were calculated. The study cohort included 8942 adult patients (54.4% male, 45.6% female) with a mean age of 56.96 years and mean BMI of 26.86.

RESULTS

Transjugular intrahepatic portosystemic shunt (TIPS) creation recorded the highest mean fluoroscopy time of 69.41 min., followed by central venous recanalization 39.67min. TIPS creation had the highest mean DAP (1161.16 Gy.cm2), followed by trans arterial chemoembolisation (TACE) (500.63Gy.cm2). TIPS creation was associated with the highest peak skin dose (2766.81mGy), followed by TACE (1588.29mGy). Compared to other studies, TIPS creation and TACE are associated with significantly higher DAP.

CONCLUSION

Majority of VIR-procedures demonstrate no significant institutional variations in dosimetry compared to other studies. Using these studied values as reference levels may help identifying procedures that need quality control to minimize unnecessary exposures.

Patient Radiation Doses in Interventional Radiology Procedures: Comparison of fluoroscopy dose indices from the American College of Radiology Dose Index Registry-Fluoroscopy (DIR-Fluoro) Pilot to the RAD-IR study

PURPOSE

To compare interventional radiology fluoroscopically-guided intervention (FGI) radiation dose index distributions from the American College of Radiology (ACR) Fluoroscopy Dose Index Registry (DIR-Fluoro) pilot to the Radiation Doses in Interventional Radiology (RAD-IR) study.

MATERIALS AND METHODS

Individual and grouped ACR Common IDs (procedure types) from the DIR-Fluoro pilot were matched to procedure types in the RAD-IR study. Fifteen comparisons were made. Distribution parameters including the 10^th, 25^th, 50^th, 75^th, and 95^th percentiles were compared for fluoroscopy time (FT), cumulative air kerma (K_a,r), and kerma area product (P_KA). Two derived indices were computed using median dose indices. The procedure-averaged reference air kerma rate (K_a,r¯) was computed as K_a,r / FT. The procedure-averaged X-ray field size at the reference point (A_r¯) was computed as P_KA / (K_a,r * 1,000).

RESULTS

Median FT was equally likely to be higher or lower in the DIR-Fluoro pilot compared to RAD-IR, while maximum FT was almost twice as likely to be higher in DIR-Fluoro than RAD-IR. Median K_a,r was lower in the DIR-Fluoro pilot for all procedures, as was median P_KA. The maximum K_a,r and P_KA were more often higher in the DIR-Fluoro pilot compared to RAD-IR. K_a,r¯ followed the same pattern as K_a,r, while A_r¯ was often greater in DIR-Fluoro.

CONCLUSIONS

Median dose indices have decreased since the RAD-IR study. Typical K_a,r rates are lower, a result of the use of lower default dose rates. However, opportunities for quality improvement exist, including a renewed focus on tight collimation of the imaging field of view.

THE EFFECTS OF CONE-BEAM COMPUTED TOMOGRAPHY IMAGING GUIDANCE ON PATIENT RADIATION EXPOSURES IN TRANS-ARTERIAL CHEMOEMBOLISATION FOR HEPATOCELLULAR CARCINOMA

This study investigated the effects of cone-beam computed tomography (CBCT) guidance in trans-arterial chemoembolisation (TACE) procedures on the number of digital subtraction angiography (DSA) runs acquired and total patient radiation exposure in patients with hepatocellular carcinoma (HCC). A retrospective, analytical cross-sectional, single institution, study was conducted. Dose data were compared across the control (DSA guidance alone) and study (DSA and CBCT guidance) groups. A total of 122 procedures were included within the study. There was a significant reduction in the number of DSA runs (3 vs 5, p < 0.001) and DSA air kerma-area product (PKA) (3077.3 vs 4276.6 μGym2, p = 0.042) for the study group when compared to the control group. Total procedural PKA and total procedural reference air kerma (Ka,r) were shown to be 50 and 73% higher, respectively, for the study group when compared to the control group. CBCT imaging guidance does reduce the number of DSA runs and DSA PKA required to complete the TACE procedure for patients diagnosed with HCC; however, a substantial increase in total procedural PKA is to be expected and it is thus important that this increased dose is carefully considered and justified.

Single Puncture TIPS—A 3D Fusion Image-Guided Transjugular Intrahepatic Portosystemic Shunt (TIPS): An Experimental Study

Background: The use of a transjugular intrahepatic portosystemic shunt (TIPS) has been established as an effective treatment for portal hypertension. Despite the rapid development of this use, serious peri-procedural complications have been reported in over 10% of cases. This has largely been attributed to the access to the portal vein, also referred to as a “blind puncture”, which often requires multiple attempts. The aim of this study was to demonstrate the safety, reproducibility and accuracy of the use of real-time 3D fusion image-guided (3DFIG) single puncture TIPS to minimize the complications that are related to the “blind puncture” of TIPS procedures. Methods: A 3DFIG TIPS approach was utilized on 22 pigs by combining pre-procedural cross-sectional imaging (CT, MR or CBCT) with intra-procedural cone beam CT or angiogram imaging, which allowed for the improved 3D visual spatial orientation of the portal vein and real-time tracking of the needle in 3D. Results: Thirty-five portosystemic shunts were successfully deployed in all 22 subjects without any peri-procedural complications. Overall, 91% (32/35) of the procedures were carried out using a single puncture. In addition, the mean fluoroscopy time in our study was more than 12 times lower than the proposed reference level that has previously been proposed for TIPS procedures. Conclusion: Multi-modality real-time 3DFIG TIPS can be performed safely using a single puncture, without complications, and can potentially be used in both emergency and non-emergency clinical situations.

Percutaneous nephrostomy for nondilated renal collecting system with ultrasound and fluoroscopic guidance: The results of a 10-year experience

PURPOSE This study aimed to evaluate the technical success rate, complications, and radiation doses of ultrasound- and fluoroscopy-guided percutaneous nephrostomy (PCN) in patients with a nondi- lated renal collecting system. METHODS Over a 10-year period, 50 patients were referred for PCN of 60 kidneys with a nondilated renal collecting system. The patients included 22 males and 28 females with a mean age of 63.2 years (range: 35-87 years). The most common reason for PCN in these patients was postoperative ure- teral leaks and/or fistula (21/50 patients). PCN was performed under ultrasound and fluoroscopic guidance. During PCN, intravenous contrast media or diuretics were not used. Technical success rate, complications, procedure time, and radiation exposure of the procedure were retrospec- tively evaluated. RESULTS Ultrasound- and fluoroscopy-guided PCN for nondilated renal collecting system showed a suc- cess rate of 83.3% (50/60 kidneys) in the initial attempt. Four PCNs were repeated and were suc- cessful after the initial PCN failure. There was 1 major complication of bleeding that required transfusion in 1.9% (1/54) PCNs and there were minor complications of transient gross hematuria through the PCN catheter in 31.5% (17/54) PCNs. Mean duration of the procedure was 15.97 ± 7.81 min and median fluoroscopy time was 4.2 min (range: 1.2-15.3 min). Median dose area product and cumulative dose were 345.37 μGy·m2 (range: 42.57-1659.76 μGy·m2) and 46.9 mGy (range: 7.7-267.8 mGy), respectively. CONCLUSION Ultrasound- and fluoroscopy-guided PCN for nondilated renal collecting system was feasible with acceptable technical success rate, complication rate, procedure time, and radiation exposure.

Impact of monoplane to biplane angiography upgrade on diagnostic angiography procedures: A retrospective cross-sectional study

The radiation dose during digital subtraction angiography (DSA) examination is determined on the basis of many factors. The aim of this study was to evaluate the dose-area product, air kerma, and fluoroscopy time on monoplane and biplane DSA of the cerebral arteries. Our results show that biplane angiography offered lower DAP, cumulative air kerma at the reference point and fluoroscopy time despite comparable procedure time.. Further research in this area and personnel training warrant the improvement of the radiosafety of angiographic interventional procedures and further development of angiographic technology.

PATIENT AND STAFF DOSES FOR VARIOUS INTERVENTIONAL RADIOLOGY AND CARDIOLOGY EXAMINATIONS IN TURKEY

This study aims to determine the radiation doses of patients and staff during different interventional radiology and cardiology examinations. Dose measurements for interventional radiology examinations were performed in Ibn-i Sina Hospital of Ankara University using Siemens Artis-Zee medical imaging system. Patient dose measurement was carried out for interventional cardiology examinations in Cardiology Department of TOBB-ETU University, Medical Faculty Hospital using Philips Allura Centron interventional X-ray system. Patient doses were obtained in terms of kerma area product (KAP) and cumulative air kerma (CAK) from KAP meter attached to the angiography system. Performance tests of the angiography system were performed before patient dose measurements. Staff dose measurements were carried out with thermoluminescence dosimeters (TLD-100) placed in certain areas on the staff. Patient dose measurements were performed for 15 different interventional radiology examinations on a total of 431 patients and for four different cardiology examinations on a total of 299 patients. Monte Carlo based PCXMC 2.0 program was used to calculate patient effective doses. Lower extremity arteriography was the most common examination with a mean KAP value of 30 Gy cm2 and mean effective dose value of 1.2 mSv for total number of 194 patients. Mean KAP values calculated for coronary angiography, percutaneous coronary intervention, electrophysiological procedures and radiofrequency cardiac ablation examinations were 62.8, 162.8, 16.7 and 70.6 Gy cm2, respectively. Radiologist, nurse and technician effective dose normalised to the unit KAP of patient dose were 0.15, 0.11 and 0.14 μSv Gy-1 cm-2. Similarly, cardiologist, nurse and technician effective dose normalised to the unit KAP of patient dose were 0.22, 0.15 and 0.09 μSv Gy-1 cm-2. Measured KAP and CAK values vary depending on the type and complexity of the examination. The measured staff doses during cardiac examinations were higher when compared with that measured for interventional radiology as expected.

Typical doses and typical values for fluoroscopic diagnostic and interventional procedures

To implement typical doses (TD) and typical values (TV) for fluoroscopic diagnostic and interventional procedures. A total of 3811 fluoroscopic procedures performed within 34 months on three devices were included in this retrospective study. Dose-, patient- and procedure-related information were extracted using the institutional dose management system (DMS). TD/TV were defined as median dose and calculated for the five most frequent procedures per device for dose area product (DAP), cumulative air kerma (CAK) and fluoroscopy time (FT). National diagnostic reference levels and other single facility studies were compared to our results. Additionally, the five procedures with the highest doses of each device were analysed. To evaluate the data coverage of the DMS compared to the picture archiving and communication system (PACS), procedure lists were extracted from the PACS and compared to the procedure information extracted from the DMS. TD/TV for 15 procedures were implemented. Among all devices, TD for DAP ranged between 0.6 Gycm²for port catheter control (n= 64) and 145.9 Gycm²for transarterial chemoembolisation (n= 84). TD for CAK ranged between 5 mGy for port catheter control and 1397 mGy for aneurysm treatment (n= 129) and TV for FT ranged between 0.3 min for upper cavography (n= 67) and 51.4 min for aneurysm treatment. TD for DAP and CAK were lower or within the range of other single facility studies. The five procedures with the highest median DAP per device were identified, 6 of 15 procedures were also found to be among the most frequent procedures. Data coverage of the DMS compared to the PACS ranged between 71% (device 2, stroke treatment) and 78% (device 1, lower limb angiography) for the most common procedure per device. Thus, in 22%-29% of cases dose data of the performed procedure was not transferred into the DMS. We implemented TD/TV for fluoroscopic diagnostic and interventional procedures which enable a comprehensive dose analysis and comparison with previously published values.

Radiation exposure in the endovascular therapy of cranial and spinal dural arteriovenous fistula in the last decade: a retrospective, single-center observational study

PURPOSE

This study aims to determine local diagnostic reference levels (DRLs) in the endovascular therapy (EVT) of patients with cranial and spinal dural arteriovenous fistula (dAVF).

METHODS

In a retrospective study design, DRLs and achievable dose (AD) were assessed for all patients with cranial and spinal dAVF undergoing EVT (I) or diagnostic angiography (II). All procedures were performed at the flat-panel angiography-system Allura Xper (Philips Healthcare). Interventional procedures were differentiated according to the region of fistula and the type of procedure.

RESULTS

In total, 264 neurointerventional procedures of 131 patients with dAVF (94 cranial, 37 spinal) were executed between 02/2010 and 12/2020. The following DRLs, AD, and mean values could be determined: for cranial dAVF (I) DRL 507.33 Gy cm2, AD 369.79 Gy cm2, mean 396.51 Gy cm2; (II) DRL 256.65 Gy cm2, AD 214.19 Gy cm2, mean 211.80 Gy cm2; for spinal dAVF (I) DRL 482.72 Gy cm2, AD 275.98 Gy cm2, mean 347.12 Gy cm2; (II) DRL 396.39 Gy cm2, AD 210.57 Gy cm2, mean 299.55 Gy cm2. Dose levels of EVT were significantly higher compared to diagnostic angiographies (p < 0.001). No statistical difference in dose levels regarding the localization of dAVF was found.

CONCLUSION

Our results could be used for establishing DRLs in the EVT of cranial and spinal dAVF. Because radiation exposure to comparably complex interventions such as AVM embolization is similar, it may be useful to determine general DRLs for both entities together.

Radiation Dose and Fluoroscopy Time of Endovascular Coil Embolization in Patients with Carotid Cavernous Fistulas

Carotid cavernous fistulas (CCFs) are abnormal connections between the cavernous sinus and the internal and/or external carotid artery. Endovascular therapy is the gold standard treatment. In the current retrospective single-center study we report detailed dosimetrics of all patients with CCFs treated by endovascular coil embolization between January 2012 and August 2021. Procedural and dosimetric data were compared between direct and indirect fistulas according to Barrow et al., and different DSA protocol groups. The local diagnostic reference level (DRL) was defined as the 3rd quartile of the dose distribution. In total, thirty patients met the study criteria. The local DRL was 376.2 Gy cm². The procedural dose area product (DAP) (p = 0.03) and the number of implanted coils (p = 0.02) were significantly lower in direct fistulas. The median values for fluoroscopy time (FT) (p = 0.08) and number of DSA acquisitions (p = 0.84) were not significantly different between groups. There was a significantly positive correlation between DAP and FT (p = 0.003). The application of a dedicated low-dose protocol yielded a 32.6% DAP reduction. In conclusion, this study provides novel DRLs for endovascular CCF treatment using detachable coils. The data presented in this work might be used to establish new specific DRLs.

Patient radiation dose during angiography and embolization for abdominal hemorrhage: the influence of CT angiography, fluoroscopy system, patient and procedural variables

Background

Angiography and embolization (AE) is a lifesaving, high radiation dose procedure for treatment of abdominal arterial hemorrhage (AAH). Interventional radiologists have utilized pre-procedure CT angiography (CTA) and newer fluoroscopic systems in an attempt to reduce radiation dose and procedure time.

Purpose

To study the factors contributing to the radiation dose of AE for AAH and to compare to the reference standard.

Materials and methods

This retrospective single-centre observational cohort study identified 154 consecutive AE procedures in 138 patients (median age 65 years; interquartile range 54–77; 103 men) performed with a C-arm fluoroscopic system (Axiom Artis DTA or Axiom Artis Q (Siemens Healthineers)), between January 2010 and December 2017. Parameters analysed included: demographics, fluoroscopy system, bleeding location, body mass index (BMI), preprocedural CT, air kerma-area product (PKA), reference air kerma (K_a,r), fluoroscopy time (FT) and the number of digital subtraction angiography (DSA) runs. Factors affecting dose were assessed using Mann–Whitney U, Kruskal–Wallis one-way ANOVA and linear regression.

Results

Patients treated with the new angiographic system (NS) had a median PKA, median K_a,r, Q3 PKA and Q3 K_a,r that were 74% (p < 0.0005), 66%(p < 0.0005), 55% and 52% lower respectively than those treated with the old system (OS). This dose reduction was consistent for each bleeding location (upper GI, Lower GI and extraluminal). There was no difference in PKA (p = 0.452), K_a,r (p = 0.974) or FT (p = 0.179), between those who did (n = 137) or did not (n = 17) undergo pre-procedure CTA. Other factors significantly influencing radiation dose were: patient BMI and number of DSA runs. A multivariate model containing these variables accounts for 15.2% of the variance in K_a,r (p < 0.005) and 45.9% of the variance of PKA (p < 0.005).

Conclusion

Radiation dose for AE in AAH is significantly reduced by new fluoroscopic technology. Higher patient body mass index is an independent key parameter affecting patient dose. Radiation dose was not influenced by haemorrhage site or performance of pre-procedure CTA.

Percutaneous Transsplenic Balloon-Assisted Transjugular Intrahepatic Portosystemic Shunt Placement in Patients with Portal Vein Obliteration for Portal Vein Recanalization: Feasibility, Safety and Effectiveness

Purpose

To assess the feasibility, safety and effectiveness of portal vein recanalization (PVR)–transjugular portosystemic shunt (TIPS) placement via splenic access using a balloon puncture technique.

Materials and Methods

In a single-center retrospective study from March 2017 to February 2021, 14 consecutive patients with portal hypertension, chronic liver disease and portal vein occlusion or near-complete (> 95%) occlusion were referred for PVR–TIPS placement. Feasibility, safety and effectiveness including procedural characteristics such as technical success, complication profile and splenic access time (SAT), balloon positioning time (BPT), conventional portal vein entry time (CPVET), overall procedure time (OPT), fluoroscopy time (FT), dose–area product (DAP) and air kerma (AK) were evaluated.

Results

Transsplenic PVR–TIPS using balloon puncture technique was technically feasible in 12 of 14 patients (8 men, 49 ± 13 years). In two patients without detectable intrahepatic portal vein branches, TIPS placement was not feasible and both patients were referred for further treatment with nonselective beta blockers and endoscopic variceal ligation. No complications grade > 3 of the Cardiovascular and Interventional Radiological Society of Europe classification system occurred. The SAT was 25 ± 21 min, CPVET was 33 ± 26 min, the OPT was 158 ± 54 min, the FT was 42 ± 22 min, the DAP was 167.84 ± 129.23 Gy*cm² and the AK was 1150.70 ± 910.73 mGy.

Conclusions

Transsplenic PVR–TIPS using a balloon puncture technique is feasible and appears to be safe in our series of patients with obliteration of the portal vein. It expands the interventional options in patients with chronic PVT.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-021-03054-2.

Radiation Dose and Fluoroscopy Time of Diagnostic Angiography in Patients with Spinal Dural Arteriovenous Fistula

PURPOSE

Spinal dural arteriovenous fistulas (SDAVFs) represent the most common indication for a spinal angiography. The diagnostic reference level (DRL) for this specific endovascular procedure is still to be determined. This single-center study provides detailed dosimetrics of diagnostic spinal angiography performed in patients with SDAVFs.

METHODS

Retrospective analysis of all diagnostic spinal angiographies between December 2011 and January 2021. Only patients with an SDAVF who had baseline magnetic resonance angiography (MRA), diagnostic digital subtraction angiography (DSA), treatment and follow-up at this institution were included. Dose area product (DAP, Gy cm²) and fluoroscopy time were compared between preoperative and postoperative angiographies, according to SDAVF locations (common versus uncommon), MRA results at baseline (positive versus negative) and DSA protocols (low-dose, mixed-dose, normal-dose). The 75th percentile of the DAP distribution was used to define the local DRL.

RESULTS

A total of 62 spinal angiographies were performed in 25 patients with SDAVF. Preoperative angiographies (30/62, 48%) yielded a significantly higher DAP and longer fluoroscopy time when compared to postoperative angiographies (32/62, 53%) (p < 0.01). The local DRL was 329.41 Gy cm² for a nonspecific (n = 62), 395.59 Gy cm² for a preoperative and 138.6 Gy cm² for a postoperative spinal angiography. Preoperative angiography of uncommonly located SDAVFs yielded a significantly longer fluoroscopy time (p = 0.02). The MRA-based fistula detection had no significant impact on dosimetrics (p > 0.05). A low-dose protocol yielded a 61% reduction of DAP.

CONCLUSION

The results of the present study suggest novel DRLs for spinal angiography in patients with SDAVF. Dedicated low-dose protocols enable radiation dose optimization in these procedures.

Expandable Intravertebral Implant in Cancer-Related Vertebral Compression Fractures: A Retrospective Review of 36 Implantations

The purpose of this retrospective review was to evaluate SpineJack implantation in cancer-related vertebral compression fractures in 13 consecutive patients (mean age, 62.8 years ± 18.8). A total of 36 devices were inserted at 20 levels (13 [65%] lumbar and 7 [35%] thoracic vertebrae), with a mean Spinal Instability Neoplastic Score of 9.1 ± 2.1. Vertebral height restoration was observed in 10 levels (50%), with a mean height restoration of 5.6 mm ± 2.2 (interquartile range [IQR], 4-7.5). A total of 6 cement leakages were observed in 3 (23%) patients without clinical consequences. No severe adverse events were observed. One adjacent fracture occurred. Average pain scores on the visual analog scale significantly improved from 5.5 ± 1.8 (IQR, 4-7) preoperatively to 1.5 ± 2.2 (IQR, 0-3.3) at 1 month (P < .01) and to 1.5 ± 1.3 (IQR, 0.3-2.8) at 6 months (P < .01). In this small cohort, SpineJack offered pain relief in cancer-related fractures without an observed increase in adverse events.

Transjugular intrahepatic portosystemic shunt with transhepatic portal vein puncture guided by ultrasound: a technical alternative

OBJECTIVE

Evaluation of an alternative technique to perform transjugular intrahepatic portosystemic shunt (TIPS), using abdominal ultrasound to guide portal puncture.

METHODS

Retrospective analysis of TIPS performed from January 2014 to December 2018 in an interventional radiology service. TIPS were performed according to the classic technique, except at the moment of portal branch puncture, when abdominal ultrasound was used to guide it, visualized its path within the parenchyma in real-time. Qualitative and quantitative variables were analyzed considering a 95% confidence interval and application of the Student's t-test with a significance level of P < 0.05.

RESULTS

Forty-one TIPS were performed. The technical success rate of ultrasound guidance in portal puncture was 100.0%. After its performance, a reduction in the portosystemic pressure gradient was observed, with an initial gradient average of 18.8 mmHg (12-25 ± 3.6 mmHg) and a final gradient of 9.2 mmHg (5-14 ± 2.4 mmHg). The mean values for the TIPS execution time, fluoroscopy time and the radiation dose, verified through the dose area product, were 65.2 ± 46.7 min, 25 ± 14.1 min and 85.6 ± 70 Gy cm2, respectively. There were no complications related to the inadvertent puncture of nontarget structures or deaths due to complications resulting from TIPS.

CONCLUSION

The results demonstrate that the portal transhepatic puncture guided by the abdominal ultrasound is an effective and safe procedure and results in time of execution, time of fluoroscopy and radiation dose below the current reference values of the conventional procedure.

Radiation Exposure During Diagnostic and Therapeutic Angiography of Carotid-cavernous Fistula : A Retrospective Single Center Observational Study

Purpose

The aim of this study was to determine local diagnostic reference levels (DRLs) during endovascular diagnostics and therapy of carotid-cavernous fistulas (CCF).

Methods

In a retrospective study design, DRLs, achievable dose (AD) and mean values were assessed for all patients with CCF undergoing diagnostic angiography (I) or embolization (II). All procedures were performed with the flat-panel angiography system Allura Xper (Philips Healthcare). Interventional procedures were differentiated according to the type of CCF and the type of procedure.

Results

In total, 86 neurointerventional procedures of 48 patients with CCF were executed between February 2010 and July 2021. The following DRLs, AD and mean values could be determined: (I) DRL 215 Gy ∙ cm², AD 169 Gy ∙ cm², mean 165 Gy ∙ cm²; (II) DRL 350 Gy ∙ cm², AD 226 Gy ∙ cm², mean 266 Gy ∙ cm². Dose levels of embolization were significantly higher compared to diagnostic angiography (p < 0.001). No significant dose difference was observed with respect to the type of fistula or the embolization method.

Conclusion

This article reports on diagnostic and therapeutic DRLs in the management of CCF that could serve as a benchmark for the national radiation protection authorities. Differentiation by fistula type or embolization method does not seem to be useful.

Monitoring Radiation Doses during Diagnostic and Therapeutic Neurointerventional Procedures: Multicenter Study for Establishment of Reference Levels

PURPOSE

To assess patient radiation doses during diagnostic and therapeutic neurointerventional procedures from multiple centers and propose dose reference level (RL).

MATERIALS AND METHODS

Consecutive neurointerventional procedures, performed in 22 hospitals from December 2020 to June 2021, were retrospectively studied. We collected data from a sample of 429 diagnostic and 731 therapeutic procedures. Parameters including dose-area product (DAP), cumulative air kerma (CAK), fluoroscopic time (FT), and total number of image frames (NI) were obtained. RL were calculated as the 3rd quartiles of the distribution.

RESULTS

Analysis of 1160 procedures from 22 hospitals confirmed the large variability in patient dose for similar procedures. RLs in terms of DAP, CAK, FT, and NI were 101.6 Gy·cm2, 711.3 mGy, 13.3 minutes, and 637 frames for cerebral angiography, 199.9 Gy·cm2, 3,458.7 mGy, 57.3 minutes, and 1,000 frames for aneurysm coiling, 225.1 Gy·cm2, 1,590 mGy, 44.7 minutes, and 800 frames for stroke thrombolysis, 412.3 Gy·cm2, 4,447.8 mGy, 99.3 minutes, and 1,621.3 frames for arteriovenous malformation (AVM) embolization, respectively. For all procedures, the results were comparable to most of those already published. Statistical analysis showed male and presence of procedural complications were significant factors in aneurysmal coiling. Male, number of passages, and procedural combined technique were significant factors in stroke thrombolysis. In AVM embolization, a significantly higher radiation dose was found in the definitive endovascular cure group.

CONCLUSION

Various RLs introduced in this study promote the optimization of patient doses in diagnostic and therapeutic interventional neuroradiology procedures. Proposed 3rd quartile DAP (Gy·cm2) values were 101.6 for diagnostic cerebral angiography, 199.9 for aneurysm coiling, 225.1 for stroke thrombolysis, and 412.3 for AVM embolization. Continual evolution of practices and technologies requires regular updates of RLs.

Comparative analysis of physical doses and biomarker changes in subjects underwent Computed Tomography, Positron Emission Tomography-Computed Tomography, and interventional procedures

Even though the medical uses of ionizing radiation are well-acknowledged globally as vital tools for the improvement of human health, they also symbolize the major man-made sources of radiation exposure to the population. Estimation of absorbed dose and biological changes after radiation-based imaging might help to better understand the effects of low dose radiation. Because of this, we measured the Entrance Surface Dose (ESD) at different anatomical locations using Lithium tetraborate doped with manganese (Li₂B₄O₇: Mn), recorded Dose Length Product (DLP) and Dose Area Product (DAP), analyzed Chromosomal Aberration (CA), Micronucleus (MN), gamma-H2AX (γ-H2AX), and p53^ser15 proteins in the blood lymphocytes of patients (n = 267) underwent Computed Tomography (CT), Positron Emission Tomography-CT (PET/CT), and interventional procedures and healthy volunteers (n = 19). The DLP and effective doses obtained from PET/CT procedures were significantly higher (p < 0.05) when compared to CT. Fluoroscopic time and DAP were significantly higher (p < 0.05) in therapeutic compared to diagnostic interventional procedures. All the anatomical locations registered a significant amount of ESD, the ESD obtained from CT and interventional procedures were significantly (p < 0.05) higher when compared to PET/CT. Fluoroscopic time did not correlate with the ESD (eye, head, thyroid, and shoulder; R² = 0.03). CA frequency after PET/CT was significantly higher (p < 0.001) when compared to CT and interventional procedures. MN frequency was significantly higher in 24-hs (p < 0.001) post-interventional procedure compared to 2-hs. The mean ± SD of mean fluorescence intensity of γ-H2AX and p53^ser15 obtained from all subjects underwent PET/CT and interventional procedures did not show a significant difference (p > 0.05) between pre- and post-procedure. However, the relative fluorescence intensity of γ-H2AX and p53^ser15 was >1 in 58.5 % and 65.8 % of subjects respectively. Large inter-individual variation and lack of correlation between physical dose and biomarkers suggest the need for robust dosimetry with a large sample size to understand the health effects of low dose radiation.

Analysis of Factors Affecting Air Kerma Area Product Obtained during Uterine Artery Embolization Procedures Using Logistic Regression

Purpose Uterine artery embolization (UAE) is a common interventional radiology procedure used in medicine; the procedure is safe but there is always a concern regarding radiation dose received by the patient. The aim of this study was to use multivariable logistic regression analysis (MLRA) to study a certain number of independent prognostic variables believed to provide an estimate of the likelihood of obtaining a high kerma area product ( P_KA ) at the end of the procedure.

Method Radiation dose indices registered by the angiographic system structured dose report, the total fluoroscopy time (FT), the patient’ body mass index (BMI), the number of images taken during the procedures (IMGS), and the performing physician experience (EXPER) were used to drive a logistic regression model (LRM).

Results The LRM found was: Logit ( P_KA ) = −6.1525 + 0.0416 (FT) + 0.1028 (IMGS) + 0.1675 (BMI) – 0.1012 (EXPER). The prediction accuracy of the LRM was assessed using receiver operating characteristic (ROC) curve; by calculating the area under the curve (AUC), we found AUC = 0.7896, with optimal ROC point of 0.3261, 0.8036.

Conclusion The suggested LRM seems to indicate that patients with higher BMI, have taken longer FT, acquired higher IMGS and the procedure done by a less experienced performing physician is more susceptible to receive a higher P_KA at the end. The proposed LRM is useful in predicting the occurrence of higher radiation exposure interventions and can be used in patients’ radiation dose optimization strategies during UAE procedures.

Percutaneous Image-Guided Vertebral Fixation in Cancer-Related Vertebral Compression Fractures: A Case Series Study

Background and objectives: Cancer-related vertebral compression fractures (VCF) may cause debilitating back pain and instability, affecting the quality of life of cancer patients. To further drive cement deposition during vertebroplasty, the aims of this restrospective case series study were to report the feasibility, safety and short term efficacy (≤6 months) of percutaneous vertebral fixation in cancer-related vertebral compression fractures using various intravertebral implants. Methods: All consecutive cancer patients treated with percutaneous vertebral fixation for VCF were retrospectively included. Various devices were inserted percutaneously under image guidance and filled by cement. Descriptive statistics were used and a matched paired analysis of pain scores was performed to assess for changes following interventions. Results: A total of 18 consecutive patients (12 women (66.6%) and 6 men (33.3%); mean age 59.7 ± 15.5 years) were included. A total of 42 devices were inserted in 8 thoracic and 16 lumbar vertebrae. Visual analogue scale measurement significantly improved from 5.6 ± 1.8 preoperatively to 1.5 ± 1.7 at 1 week (p < 0.01) and to 1.5 ± 1.3 at 6 months (p < 0.01). No severe adverse events were observed, but three adjacent fractures occurred between 1 week and 5 months after implantation. Conclusions: Percutaneous vertebral fixation of cancer-related VCF is feasible and safe and allows pain relief.

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.

Ultrasound-guided portal vein puncture during Transjugular Intrahepatic Portosystemic Shunt: Technique and experience of a quaternary liver transplant hospital

INTRODUCTION

Portal hypertension (PH) is associated with complications including refractory ascites and variceal haemorrhage and can be treated endovascularly with a Transjugular Intrahepatic Portosystemic Shunt (TIPS). Portal vein puncture during TIPS using real-time transabdominal ultrasound guidance is one of many portal vein puncture techniques and is seldom used compared with other methods. The purpose of this manuscript is to describe this technique and its associated procedural outcomes at a quaternary liver transplant hospital.

METHODS

Clinical data of all patients who underwent ultrasound-guided TIPS at our institution between 1 January 2009 and 1 January 2019 were retrospectively obtained from electronic medical records and reviewed. Patient demographics, indications, procedural outcomes and complications were recorded.

RESULTS

Forty-four ultrasound-guided TIPS procedures were performed during the study period. The most common indication for TIPS was refractory ascites (n = 26; 57%) and variceal haemorrhage (n = 12; 26%). Technical success rate was 100%. No intraprocedural complications occurred. Periprocedural complication rate was 35% (n = 16) with encephalopathy (n = 8; 17%) and sepsis (n = 5; 11%) the most common. One patient with sepsis died. No other TIPS-related deaths occurred. Median fluoroscopy time, contrast volume, air kerma and dose area product values for all procedures were 35 minutes (IQR 24-51), 100 ml (IQR 70-160), 0.95 Gy (IQR 0.50-1.53) and 127 Gycm² (IQR 68.75-206), respectively.

CONCLUSION

Transabdominal ultrasound-guided portal vein puncture during TIPS is safe and technically feasible. When compared to fluoroscopically guided methods, it is associated with lower intraprocedural complication rates, fluoroscopy times, contrast volumes and radiation doses in our experience. Radiation doses, FTs and contrast volumes were also considerably lower than recommended limits.

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.

Diagnostic reference levels during fluoroscopically guided interventions using mobile C-arms in operating rooms: A national multicentric survey

PURPOSE

To establish diagnostic reference levels (DRLs) and achievable levels (ALs) for the most common fluoroscopically guided interventions (FGIs) performed in operating rooms using mobile C-arm equipment.

METHODS

A national survey was performed in 57 centers in France. Anonymous data from 6817 patients undergoing FGIs were prospectively collected over a period of 7 months. DRLs (third quartile of the distribution) and ALs (median of the distribution) were determined for each type of intervention in terms of kerma area product (KAP) and fluoroscopy time (FT).

RESULTS

DRLs and ALs were proposed for 31 procedure types related to seven surgical specialties: orthopedics (n = 9), urology (n = 3), vascular (n = 6), cardiology (n = 5), neurosurgery (n = 3), gastrointestinal (n = 3), and multi-specialty (n = 2). DRLs in terms of KAP ranged from 0.1 Gy·cm² for hallux valgus to 78 Gy·cm² for abdominal aortic aneurysm endovascular repair. A factor of 155 was obtained between the FTs for a herniated lumbar disk (0.2 min) and an abdominal aortic aneurysm endovascular repair (31 min). The highest variations were obtained within orthopedic procedures in terms of KAP (ratio 122) and within gastrointestinal procedures in terms of FT (ratio 9). Overall, the FGIs associated with the highest radiation exposure (KAP > 10 Gy·cm²) were found in the cardiology, vascular, and gastrointestinal specialties.

CONCLUSIONS

DRLs and ALs are suggested for a wide range of FGIs performed in operating rooms using a mobile C-arm. We aim at providing a practical optimization tool for medical physicists and surgeons.

Radiation dose and diagnostic reference levels for four interventional radiology procedures: results of the prospective European multicenter survey EUCLID

OBJECTIVES

To assess information reflecting radiation dose and define diagnostic reference levels (DRL) on a European basis for four interventional radiology (IR) procedures considering clinical indication, anatomical region, and procedure.

METHODS

A prospective European study was performed to provide data on the IR procedures percutaneous recanalization of iliac arteries, percutaneous recanalization of femoropopliteal arteries, transarterial chemoembolization of hepatocellular carcinoma, and percutaneous transhepatic biliary drainage. Hospitals were asked to complete a questionnaire giving information on procedure, equipment, and protocol. Patient size and weight, experience of the operator graded in number of procedures performed, and complexity level of each procedure were reported. Sixteen hospitals from 13 countries could be surveyed. The percentiles of the kerma-area product, fluoroscopy time, cumulative air kerma at the interventional reference point, and number of images were determined. The impact of equipment, year of installation, and complexity level of the procedure on dose were analyzed.

RESULTS

DRLs based on clinical indication were defined. Dose values varied considerably within hospitals, between them, and within each subgroup of complexity level. The use of state-of-the-art equipment reduced dose significantly by 52%. Although dose also varied within each subgroup of complexity level, for transarterial chemoembolization of hepatocellular carcinoma and percutaneous transhepatic biliary drainage, dose significantly correlated with complexity.

CONCLUSIONS

This was the first study reporting exposure practice and defining DRLs based on clinical indication for four IR procedures on a European basis. These DRLs can serve as a baseline for comparison with local practice, the study as a guideline for future surveys.

KEY POINTS

• The use of state-of-the-art angiographic equipment reduces dose significantly. • A significant correlation between radiation dose and complexity level is found. • Dose values vary considerably, both within and between individual hospitals, and within each complexity level of interventional radiology procedure.

Interventional pain training using phantom model during COVID-19 pandemic

Background

Fluoroscopic‐guided lumbar procedures have increased in daily pain practice because the lumbar spine is one of the most common sources of pain. Interventional pain fellows must develop a minimum number of skills during their training in order to achieve the competences without neglecting radiological safety. However, medical training in fluoroscopic‐guided interventions is being affected by the current coronavirus disease 2019 (COVID‐19) situation.

Methods

The objective of this study was to evaluate the use of a phantom model for lumbar injection as a training strategy during the COVID‐19 pandemic in fellows of interventional pain. The study was divided into theoretical and practical modules. The hands‐on practice was performed in a lumbar model phantom where fellows were evaluated in four fluoroscopically guided approaches: intra‐articular facet block (IAFB), medial branch block (MBB), transforaminal block (TFB), and interlaminar block (ILB) divided in 5 sessions. The aim was to make as many punctures as possible in every session. We measured total procedural performance (TPP), total needle hand time (TNH), and total radiation dose generated by the fluoroscopic machine (TRD) during each procedure. Additionally, a survey was applied to evaluate confidence and satisfaction before and after training.

Results

A total of 320 lumbar punctures were completed. The results were statistically significant in all approaches attempted (p < 0.01). The fellow’s survey for satisfaction and confidence demonstrated a significant difference between pre and post‐test (p < 0.01).

Conclusions

The results of this study highlight the importance of adaptations and adoption of new educational models. The use of the phantom model for simulation could be a strategy for other emerging situations, like the COVID‐19 pandemic. Including this practice in the interventional pain programs could lead to better results for the patient and operator radiology safety.

Uterine Myomas: Endovascular Treatment

Uterine fibroids embolization is a safe and effective organ sparing treatment for fibroid-related symptoms based on a broad range of published evidence including randomized-controlled trials. Indication to treatment is usually the presence of symptomatic uterine fibroids. In this review, a systematic search of journal articles relevant to the treatment of symptomatic uterine fibroids was conducted, with a special focus on the indication to treatment, technique, procedural outcomes and pain control. All clinical trials published in English language, representing original research, and reporting clinical outcomes associated with interventions for the management of symptomatic uterine fibroids were considered.

ESTABLISHING LOCAL AND NATIONAL DIAGNOSTIC AND INTERVENTIONAL CARDIOLOGY AND RADIOLOGY REFERENCE LEVELS IN A SMALL EUROPEAN STATE: THE CASE OF MALTA

European Directive 2013/59/EURATOM requires the establishment and use of diagnostic reference levels (DRLs) for diagnostic and interventional procedures. The purpose of this study was to establish local DRLs for a major tertiary public hospital. As the hospital is the only such hospital in Malta, the same data collected for setting local DRLs can also be used for setting national DRLs, making local DRLs de facto national DRLs. A retrospective survey of cumulative kerma-area product (KAP) and fluoroscopy time data from the cardiac catheterisation laboratory and interventional radiology suites was carried out. The effect of system upgrades on cumulative KAP was also assessed. Local DRLs were set for common cardiology and interventional radiology procedures. All DRLs compare favourably with those in European literature. A Philips Allura Clarity upgrade to the cardiac catheterisation laboratories led to significant reductions in cumulative KAP (p ≪  0.05) for most procedures.

Potential application of γ-H2AX as a biodosimetry tool for radiation triage

Radiation triage and biological dosimetry are two initial steps in the medical management of exposed individuals following radiological accidents. Well established biodosimetry methods such as the dicentric (DC) assay, micronucleus (MN) assay, and fluorescence in-situ hybridization (FISH) translocation assay (for residual damage) have been used for this purpose for several decades. Recent advances in scoring methodology and networking among established laboratories have increased triage capacity; however, these methods still have limitations in analysing large sample numbers, particularly because of the ∼ 48 h minimum culture time required prior to analysis. Hence, there is a need for simple, and high throughput markers to identify exposed individuals in case of radiological/nuclear emergencies. In recent years, a few markers were identified, one being phosphorylated histone 2AX (γ-H2AX), which measured a nuclear foci or nuclear staining intensity that was found to be suitable for triage. Measurement of γ-H2AX foci formed at and around the sites of DNA double-strand breaks is a rapid and sensitive biodosimetry method which does not require culturing and is thus promising for the analysis of a large number of samples. In this review, we have summarized the recent developments of γ-H2AX assay in radiation triage and biodosimetry, focusing chiefly on: i) the importance of baseline frequency and reported values among different laboratories, ii) the influence of known and unknown variables on dose estimation, iii) quality assurance such as inter-laboratory comparison between scorers and scoring methods, and iv) current limitations and potential for future development.

Transjugular intrahepatic portosystemic shunt placement: portal vein puncture guided by 3D/2D image registration of contrast-enhanced multi-detector computed tomography and fluoroscopy

Background

To assess the technical feasibility, success rate, puncture complications and procedural characteristics of transjugular intrahepatic portosystemic shunt (TIPS) placement using a three-dimensional vascular map (3D-VM) overlay based on image registration of pre-procedural contrast-enhanced (CE) multi-detector computed tomography (MDCT) for portal vein puncture guidance.

Materials and methods

Overall, 27 consecutive patients (59 ± 9 years, 18male) with portal hypertension undergoing elective TIPS procedure were included. TIPS was guided by CE-MDCT overlay after image registration based on fluoroscopic images. A 3D-VM of the hepatic veins and the portal vein was created based on the pre-procedural CE-MDCT and superimposed on fluoroscopy in real-time. Procedural characteristics as well as hepatic vein catheterization time (HVCT), puncture time (PT), overall procedural time (OPT), fluoroscopy time (FT) and the dose area product (DAP) were evaluated. Thereafter, HVCT, PT, OPT and FT using 3D-VM (61 ± 9 years, 14male) were compared to a previous using classical fluoroscopic guidance (53 ± 9 years, 21male) for two interventional radiologist with less than 3 years of experience in TIPS placement.

Results

All TIPS procedure using of 3D/2D image registered 3D-VM were successful with a significant reduction of the PSG (p < 0.0001). No clinical significant complication occurred. HVCT was 14 ± 11 min, PT was 14 ± 6 min, OPT was 64 ± 29 min, FT was 21 ± 12 min and DAP was 107.48 ± 93.84 Gy cm². HVCT, OPT and FT of the interventionalist with less TIPS experience using 3D/2D image registered 3D-VM were statistically different to an interventionalist with similar experience using fluoroscopic guidance (p_HVCT = 0.0022; p_OPT = 0.0097; p_FT = 0.0009). PT between these interventionalists was not significantly different (p_PT = 0.2905).

Conclusion

TIPS placement applying registration-based CE-MDCT vessel information for puncture guidance is feasible and safe. It has the potential to improve hepatic vein catherization, portal vein puncture and radiation exposure.

Typical values related to the complexity of interventional treatment of acute ischemic stroke

BACKGROUND AND PURPOSE

Interventional Neuroradiology (INR) procedures are often complex, requiring prolonged high-dose exposures. This leads to increased radiation exposure to both patient and operating staff. The purpose of this study is to identify parameters related to the complexity of acute ischemic stroke (AIS) procedures that increase patient exposure and derive DRLs according to ICRP 135.

METHODS

Data from 145 patients treated for AIS between 2017 and 2019 in a Hub Stroke center were retrospectively analyzed. Dosimetric parameters, demographic and clinical data were collected for each patient. The INR operator and the fluoroscopy system used were included.

RESULTS

A multivariable analysis was performed to identify which parameters significantly influence the dosimetric data. Thrombus location and the use of stent retriever were noted as the most likely parameters of complex INR procedures. Male sex is an indicator of complex procedure only with regards to the Kerma area product and the air kerma. Patient age significantly affects the exposure time alone. Senior or more experienced operator's data demonstrated reduced patient's exposure time and therefore the KAP and Kar values. The type of X-ray equipment influenced the outcome of the procedure in terms of number of images acquired. Typical values obtained are 168 Gycm², 0.68 Gy, 19 min and 181 images.

CONCLUSION

Typical values derived in this study promote patient dose optimization, when considering the complexity of INR procedures. The clinical variables related to the complexity of procedure that mainly affect the dosimetric data in our experience are thrombus location and use of stent retrievers.

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

Purpose

To quantify and categorize fluoroscopically-guided procedures with radiation doses exceeding 5000 mGy reference point air kerma (K_a,r). K_a,r > 5000 mGy has been defined as a “significant radiation dose” by the Society of Interventional Radiology. Identification and analysis of interventions with high radiation doses has the potential to reduce radiation-induced injuries.

Materials and methods

Radiation dose data from a dose monitoring system for 19 interventional suites and 89,549 consecutive patient encounters from January 1, 2013 to August 1, 2019 at a single academic institution were reviewed. All patient encounters with K_a,r > 5000 mGy were included. All other encounters were excluded (n = 89,289). Patient demographics, medical specialty, intervention type, fluoroscopy time (minutes), dose area product (mGy·cm²), and K_a,r (mGy) were evaluated.

Results

There were 260 (0.3%) fluoroscopically-guided procedures with K_a,r > 5000 mGy. Of the 260 procedures which exceeded 5000 mGy, neurosurgery performed 81 (30.5%) procedures, followed by interventional radiology (n = 75; 28.2%), neurointerventional radiology (n = 55; 20.7%), and vascular surgery (n = 49; 18.4%). The procedures associated with the highest K_a,r were venous stent reconstruction performed by interventional radiology, arteriovenous malformation embolization performed by neurointerventional radiology, spinal hardware fixation by neurosurgery, and arterial interventions performed by vascular surgery. Neurointerventional radiology had the highest mean K_a,r (7,799 mGy), followed by neurosurgery (7452 mGy), vascular surgery (6849 mGy), and interventional radiology (6109 mGy). The mean K_a,r for interventional radiology performed procedures exceeding 5000 mGy was significantly lower than that for neurointerventional radiology, neurosurgery, and vascular surgery.

Conclusions

Fluoroscopically-guided procedures with radiation dose exceeding 5000 mGy reference point air kerma are uncommon. The results of this study demonstrate that a large proportion of cases exceeding 5000 mGy were performed by non-radiologists, who likely do not receive the same training in radiation physics, radiation biology, and dose reduction techniques as radiologists.

Exposure of patients to low doses of X-radiation during neuro-interventional imaging and procedures: Dose estimation and analysis of γ-H2AX foci and gene expression in blood lymphocytes

Radiation has widespread applications in medicine. However, despite the benefits of medical radiation exposures, adverse long-term health effects are cause for concern. Protein and gene biomarkers are early indicators of cellular response after low-dose exposure. We examined DNA damage by quantifying γ-H2AX foci and expression of twelve candidate genes in the blood lymphocytes of patients exposed to low doses of X-radiation during neuro-interventional procedures. Entrance surface dose (ESD; 10.92-1062.55 mGy) was measured by thermoluminescence dosimetry (TLD). Absorbed dose was estimated using γ-H2AX focus frequency and gene expression, with in vitro dose-response curves generated for the same biomarkers. γ-H2AX foci in post-exposure samples were significantly higher than in pre-exposure samples. Among the genes analysed, FDXR, ATM, BCL2, MDM2, TNFSF9, and PCNA showed increased expression; CDKN1A, DDB2, SESN1, BAX, and TNFRSF10B showed unchanged or decreased expression. Absorbed dose, estimated based on γ-H2AX focus frequency and gene expression changes, did not show any correlation with measured ESD. Patients undergoing interventional procedures receive considerable radiation doses, resulting in DNA damage and altered gene expression. Medical procedures should be carried out using the lowest radiation doses possible without compromising treatment.