Establishing the European diagnostic reference levels for interventional cardiology

Ionizing radiation exposure in complex percutaneous coronary intervention: Defining local diagnostic reference levels in the catheterization laboratory

INTRODUCTION AND OBJECTIVES

Concerns regarding the consequences of ionizing radiation (IR) have been increasing in the field of interventional cardiology (IC). There is little information on reported national and local radiation diagnostic reference levels (DRLs) in catheterization laboratories in Portugal. This study was designed to assess the IR dose exposure during complex percutaneous coronary intervention (PCI), and to set the respective DRLs and future achievable doses (ADs).

METHODS

This was a retrospective cohort study which took place between 2019 and 2020, including patients who underwent complex PCI. Complex PCI was defined as all procedures that encompass treatment of chronic total occlusions (CTO) or left main coronary artery. DRLs were defined as the 75th percentile of the distribution of the median values of air kerma area product (PKA) and cumulative air kerma (Ka,r). ADs were set at the 50th percentile of the study dose distribution. Multivariate analysis was performed using linear regression to identify predictors significantly associated with radiation dose (Ka,r).

RESULTS

A total of 242 patients were included in the analysis. Most patients underwent a CTO procedure (146, 60.3%). Patients were aged 67.9±11.2 years and mostly male (81.4%). DRLs were set in Ka,r (3012 mGy) and PKA (162 Gy cm2) for complex PCI. ADs were also set in Ka,r (1917 mGy) and PKA (101 Gy cm2). Independent predictors of Ka,r with a positive correlation were PKA (0.893, p<0.001), fluoroscopy time (0.520, p<0.001) and PCI time (0.521, p<0.001).

CONCLUSIONS

This study reports the results of IR in complex PCI. DRLs were set for IR dose exposure measured in Ka,r (3012 mGy) and PKA (162 Gy cm2). ADs, values to be achieved in future assessment, were set to Ka,r (1917 mGy) and PKA (101 Gy cm2).

An audit of patient radiation doses during interventional cardiology procedures in Uttarakhand, India, and establishment of local diagnostic reference levels

The objective of this study was to investigate patient radiation doses by a dose audit of three common interventional cardiology (IC) procedures: coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA) and CA-PTCA procedures performed in IC centres in the Uttarakhand state of India, for the establishment of local diagnostic reference levels (DRLs) and the estimation of average effective dose (Eav) for these procedures. For each procedure, the values of kerma-area product (PKA), reference air kerma (Ka,r), fluoroscopy time (FT) and the number of cine images were recorded from 1233 CA, 458 PTCA and 736 CA-PTCA procedures performed over a 12-month period at 13 IC centres of the state. From the recorded dose data, 0.6%, 1.53% and 7.9% patients were identified to have exceeded the PKA trigger level of 500 Gy cm2 for possible skin injury for CA, PTCA and CA-PTCA procedures, respectively. The 3rd quartile of the distribution of the recorded PKA values for each type of procedure was calculated to estimate local DRL values. The estimated values of DRLs and Eav were 37, 153 and 224 Gy cm2, and 6.72, 23.97 and 34.79 mSv for CA, PTCA and CA-PTCA procedures, respectively. For about 77% of the surveyed centres, the recorded patient doses were in agreement with the international standards. The local DRLs proposed in this study may be used to achieve patient dose optimization during IC procedures and the obtained patient dose data may also be archived into national dose database for the establishment of national DRLs.

Estimating brain and eye lens dose for the cardiologist in interventional cardiology-are the dose levels of concern?

OBJECTIVES

To establish conversion coefficients (CCs), between mean absorbed dose to the brain and eye lens of the cardiologist and the air kerma-area product, PKA, for a set of projections in cardiac interventional procedures. Furthermore, by taking clinical data into account, a method to estimate the doses per procedure, or annual dose, is presented.

METHODS

Thermoluminescence dosimeters were used together with anthropomorphic phantoms, simulating a cardiologist performing an interventional cardiac procedure, to estimate the CCs for the brain and eye lens dose for nine standard projections, and change in patient size and x-ray spectrum. Additionally, a single CC has been estimated, accounting for each projections fraction of use in the clinic and associated PKA using clinical data from the dose monitoring system in our hospital.

RESULTS

The maximum CCs for the eye lens and segment of the brain, is 5.47 μGy/Gycm2 (left eye lens) and 1.71 μGy/Gycm2 (left brain segment). The corresponding weighted CCs: are 3.39 μGy/Gycm2 and 0.89 μGy/Gycm2, respectively.

CONCLUSIONS

Conversion coefficients have been established under actual scatter conditions, showing higher doses on the left side of the operator. Using modern interventional x-ray equipment, interventional cardiac procedures will not cause high radiation dose levels to the operator when a ceiling mounted shield is used, otherwise there is a risk that the threshold dose values for cataract will be reached.

ADVANCE IN KNOWLEDGE

In addition to the CCs for the different projections, methods for deriving a single CC per cardiac interventional procedure and dose per year were introduced.

A report on a survey among Portuguese Association of Interventional Cardiology associates regarding ionizing radiation protection practices in national interventional cath-labs

INTRODUCTION AND OBJECTIVES

Concerns surrounding the consequences of ionizing radiation (IR) have increased in interventional cardiology (IC). Despite this, the ever-growing complexity of diseases as well as procedures can lead to greater exposure to radiation. The aim of this survey, led by Portuguese Association of Interventional Cardiology (APIC), was to evaluate the level of awareness and current practices on IR protection among its members.

METHODS

An online survey was emailed to all APIC members, between August and November 2021. The questionnaire consisted of 50 questions focusing on knowledge and measures of IR protection in the catheterization laboratory. Results were analyzed using descriptive statistics.

RESULTS

From a response rate of 46.9%, the study obtained a total sample of 159 responses (156 selected for analysis). Most survey respondents (66.0%) were unaware of the radiation exposure category, and only 60.4% reported systematically using a dosimeter. A large majority (90.4%) employed techniques to minimize exposure to radiation. All participants used personal protective equipment, despite eyewear protection only being used frequently by 49.2% of main operators. Ceiling suspended shields and table protectors were often used. Only two-thirds were familiar with the legally established limit on radiation doses for workers or the dose that should trigger patient follow-up. Most of the survey respondents had a non-certified training in IR procedures and only 32.0% had attended their yearly occupational health consultation.

CONCLUSIONS

Safety methods and protective equipment are largely adopted among interventional cardiologists, who have shown some IR awareness. Despite this, there is room for improvement, especially concerning the use of eyewear protection, monitoring, and certification.

Proposing national diagnostic reference levels for electrophysiology studies and catheter ablation procedures in Bulgaria

INTRODUCTION

The implementation of diagnostic reference levels (DRLs) is an essential tool for optimisation of the routine practice, better management of patient exposure while maintaining sufficient image quality. National DRLs for electrophysiology (EP) procedures are not available in our country.

PURPOSE

The main purpose of the study was to propose, for first time in Bulgaria, national DRLs (NDRLs) for EP studies and ablation procedures of two different levels of complexity. The proposed DRLs can be later used to establish NDRLs by the national authority with regulatory functions related to medical exposure.

METHOD

A retrospective study was done with the three highest volume Bulgarian EP centers, where over 95% of all cardiac ablations were performed. Data were extracted from the electronic registry for invasive electrophysiology BG-EPHY. Independently of the proposed NDRLs, we also compared the air kerma-area product (KAP) between the participating centers for procedures of the same level of complexity.

RESULTS

The proposed NDRL in terms of KAP were: 5.2 Gy.cm² for diagnostic EP studies, 25.5 Gy.cm² for simple ablations, and 52.1 Gy.cm² for complex ablations. There was a significant variation in KAP for procedures with the same degree of complexity within each center.

CONCLUSION

This study is the first to propose NDLRs for EP studies and ablation procedures of two levels of complexity in Bulgaria. The results identified EP procedures requiring further optimization of patient protection and provided a basis for future comparisons and standardization with further investigations on the topic. The proposed NDRLs are recommended to be used for better management of radiation exposure during EP procedures of different levels of complexity.

Patient radiation dose during diagnostic and interventional cardiology procedures: A study in a tertiary hospital

BACKGROUND

Fluoroscopy-guided diagnostic and interventional cardiology (IC) procedures help to identify and treat several problems associated with the heart. However, these procedures expose patients, cardiologists, radiographers, and nurses to radiation doses. Due to the risk that ionizing radiation poses, concerns have been raised and studies are continually being done to ensure that optimization is achieved during such procedures. This study assessed patient radiation dose during diagnostic and interventional cardiology procedures as well as right heart studies at a tertiary hospital in Ghana to formulate the facility's diagnostic reference levels (DRLs) for optimization purposes. As this study was the first of its kind in Ghana, it was a vital step towards dose optimization within the local department, as well as contributing to future DRLs in Ghana.

METHODS

The study collected dose (air kerma, and kerma area product (KAP) and procedural data, and assessed any correlation between parameters such as fluoroscopy time and KAP, and between body mass index (BMI) and KAP. The DRL values were determined as the 75th percentile level for the dose distribution for the various IC procedures including percutaneous coronary interventions (PCI), coronary angiography (CA), and right heart catheterization (RHC). Data were analyzed using SPSS version 23.

RESULTS

CA was the most frequently performed IC procedure (77.3%), while RHC was the least recorded (3.3%). The highest mean KAP was observed during the PCI procedure. The proposed diagnostic reference levels (DRLs) were 162.0 Gy.cm² (PCI), 69.4 Gy.cm² (CA), 39.8 Gy.cm² (RHC) and 159.9 Gy.cm² (CA+PCI). Patients who presented for the CA+PCI and RHC procedures received the highest and lowest mean KAP of 159.9 Gy.cm² and 39.8 Gy.cm² of radiation respectively.

CONCLUSION

This study, therefore, concludes that there is a need for dose optimization of radiation exposures for IC procedures at the cardiothoracic center in Ghana.

Current status of diagnostic reference levels in interventional cardiology

Interventional cardiology provides indisputable benefits for patients but uses a substantial amount of ionising radiation. The diagnostic reference level (DRL) is the tool recommended by the International Commission on Radiological Protection to optimise imaging procedures. In this work, a review of studies dealing with radiation dose or recommending DRL values for interventional cardiology since 2010 is presented, providing quantitative and qualitative results. There are many published papers on coronary angiography (CA) and percutaneous coronary intervention. The DRL values compiled for different continental regions are different: the DRL for CA is about 35 Gy cm²for Europe and 83 Gy cm²for North America. These differences emphasise the need to establish national DRLs considering different social and/or economic factors and the harmonisation of the survey methodology. Surveys with a large amount of data collected with the help of dose management systems provide more reliable information with less chance of statistical bias than those with a small amount of data. The complexity of procedures and improvements in technology are important factors that affect the radiation dose delivered to patients. There is a need for additional data on structural and electrophysiological procedures. The analysis of paediatric procedures is especially difficult because some studies present results split into age bands and others into weight bands. Diagnostic procedures are better described, but there is a great variety of therapeutic procedures with different DRL values (up to a factor of nine) and these require a dedicated review.

Local diagnostic reference levels and effective doses: single institution levels for interventional cardiology procedures for adult patients

Introduction: The current regulations in Poland in the field of interventional radiology only include diagnostic reference levels (DRL) for five procedures, containing only two for cardiological (hemodynamic) procedures, and only for adults. Given the insufficient number of DRLs, the need to introduce local levels based on the intervention procedures performed was identified. The purpose of this research was the evaluation of radiation doses (DRL, effective dose) received by patients in cardiological interventional procedures.

Material and methods: The DRL level was defined as the 75th percentile of the distribution of dosimetric parameters KAP and Kair,ref for each type of cardiological procedure. Data include three different X-ray units and 27 interventional cardiologists, derived from February 2019 to June 2019 and from August 2021 to December 2021. In order to estimate the effective dose, the appropriate conversion factors for cardiological procedures were used. The total number of analyzed procedures was 3818.

Results: The proposed local DRL levels were found to be mostly lower than data found in literature and in the current Polish national requirements (60%-70% lower for coronary angiography (CA) and percutaneous coronary angioplasty (PCI) procedures). Median equivalent doses for cardiological procedures were estimated at 2.66 mSv, 6.11 mSv and 7.22 mSv for CA, PCI and combined PCI with CA procedure, respectively.

Conclusions: The proposed local/institutional DRLs seem to be suitable for use and could be utilized by other centers for comparison purposes.

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.

NATIONWIDE SURVEY OF RADIATION EXPOSURE FOR RADIOFREQUENCY CATHETER ABLATION FOR PULMONARY VEIN ISOLATION AND NONPULMONARY VEIN ISOLATION IN JAPAN

To propose typical values for the arrhythmia region between pulmonary vein isolation (PVI) and nonpulmonary vein isolation (non-PVI) in Japan. A nationwide questionnaire was posted to 343 facilities, to which 125 facilities (36.4%) responded. Results is the median for PVI and non-PVI were in terms of Ka,r (317 and 196 mGy), PKA (40.8 and 26.3 Gy.cm2), FT (43.0 and 27.3 min), and CI (326 and 102 images). When comparing PVI and non-PVI procedures, there were significant differences in Ka, r, PKA, FT, and CI (p < 0.05). In other words, by classifying into two types, PVI and non-PVI, we contributed to the establishment of typical values in Japan's RFCA.

First local diagnostic reference levels for fluoroscopically guided cardiac procedures in adult patients in Chile

The goal of this study was to generate the first values of local diagnostic reference levels for a range of fluoroscopically guided cardiac diagnostic and therapeutic procedures in adult patients in Chile and to compare radiation dose levels with others presented in the literature. The dosimetric data collection period was conducted over the whole of 2020. The local diagnostic reference levels were calculated as the 75th percentile of patient dose data distributions for kerma area-product values. The sample of collected clinical procedures (480) was divided into diagnostic and therapeutic procedures. The kerma area-product differences found between diagnostic and therapeutic procedures were statistically significant. The local diagnostic reference levels were 81.6 Gy cm2 and 166.9 Gycm2 for fluoroscopically guided cardiac diagnostic and therapeutic procedures, respectively. A comparison of our results with results found in the literature for the last 10 years, showed that there are no published papers for hospitals in Latin America and the Caribbean. It becomes urgent to be able to carry out more research of this type, given that the health reality between countries on different continents is very different. While in some the establishment of diagnostic reference levels is a legal obligation, in others it is a matter of good or bad will.

TYPICAL VALUES OF DOSIMETRIC DATA FOR CARDIAC FLUOROSCOPY-GUIDED PROCEDURES IN A SOUTH AFRICAN TEACHING HOSPITAL

Currently there are limited diagnostic reference level (DRL) data for South African (SA) public sector cardiac fluoroscopy-guided procedures (FGPs). A 4-y retrospective study of dosimetric data on 6265 patients determined typical values (50th percentile) of dosimetric data for the seven most frequent cardiac FGPs at a SA teaching hospital. Kerma-area-product (KAP), reference point air Kerma (Ka,r) and fluoroscopy time (FT) were, respectively, calculated for coronary angiography (CA) (n = 1935; 61Gy.cm2, 624 mGy, 5 min); CA with left ventriculography (n = 1687; 85Gy.cm2, 840 mGy, 3.9 min), valve screening (n = 129; 6Gy.cm2, 164 mGy, 2.3 min), percutaneous coronary intervention (n = 1922; 145Gy.cm2, 1569 mGy, 11.9 min), pacemaker implantation (n = 432; 9Gy.cm2, 100 mGy, 6.5 min), pericardial tap (n = 115; 1.9Gy.cm2, 18 mGy, 1.5 min) and transcatheter aortic valve implantation (n = 45; 65Gy.cm2, 658 mGy, 14.1 min). This work presents the largest SA public sector cardiac FGP dosimetric data to date and provides a key resource for future work in this domain.

Percutaneous closure of ventricular septal defects in children: key parameters affecting patient radiation exposure

BACKGROUND

Ventricular septal defect (VSD) transcatheter closure is gaining worldwide popularity despite its complexity. Reports on key factors affecting radiation exposure in children are scarce.

AIMS

This clinical study is the first to comprehensively analyze the impact of all relevant parameters on children's radiation exposure during VSD interventional closures.

METHODS

Between March 2016 and August 2019, all pediatric VSD cases percutaneously treated at a reference center for interventional congenital cardiology and equipped with a single-plane Innova 2100 X-ray unit were retrospectively reviewed. Multiple linear regression was performed to investigate the impact of clinical, technical, and procedural parameters on patients' radiation exposure assessed using total air kerma area product (PKA,T).

RESULTS

A total of 85 patients were included in this study and 82.4% had perimembranous defects. Device implantation was successful in 96.5% of cases. The procedure lasted for a median of 60 min with a median PKA,T of 19.6 Gy.cm2 (range, 1.1 to 244.8 Gy.cm2). Patients' weight (B = 1.679, P = 0.01), number of operators (B = 1.561, P = 0.02), device positioning complexity (B = 2.381, P = 0.002), and procedural incidents (B = 2.096, P = 0.008) significantly increased PKA,T. Patients' age (B = 1.053, P = 0.784), device design (B = -1.216, P = 0.780) and approach of delivery (B = -1.119, P = 0.511) did not significantly affect PKA,T.

CONCLUSIONS

Radiation exposure in children undergoing VSD percutaneous closure was highly variable. A higher patient's weight, numbers of operators, complexity in device positioning, and procedural incidents, were identified as key factors increasing patient dose for this kind of intervention.

AN INTERVENTIONAL CARDIOLOGY INVESTIGATION: PATIENT EXPOSURE TO RADIATION AND INTER-OPERATOR VARIABILITY IN AN IRISH SETTING

AIM

To evaluate patient radiation exposure for Diagnostic Coronary Angiography (DCA) and Percutaneous Cardiac Intervention (PCI) performed by different operators.

METHODS AND RESULTS

Retrospective (n = 160) and prospective (n = 62) data for DCA (n = 179) and PCI (n = 43) examinations performed by interventional cardiologists (n = 3) using the same imaging equipment were reviewed. The operator with consistently low diagnostic reference levels (DRLs) was interviewed for their personal perceptions upon operator training. Retrospective Median [IQR] DAP was 18.8 [11.8-31.6] and 50.7 [35.3-85.6] Gy.cm2 for DCA and PCI, respectively. Prospective Median [IQR] DAP for DCA and PCI was 7.9 [5.2-10.6] and 15.9 [10.0-17.7] Gy.cm2, respectively. DRLs were within Irish and European DRLs; however, significant inter-operator variability (p < .001) was identified.

CONCLUSION

Radiation exposure in Interventional cardiology is highly operator dependent; further research is warranted in standardization of operator training with evolving technologies.

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.

Radiation Dose of Patients in Fluoroscopically Guided Interventions: an Update

The benefits of fluoroscopically guided interventional procedures are significant and have established new standards in the clinical management of many diseases. Despite the benefits, it is known that they come with known risks, such as the exposure to ionizing radiation. To minimize such risks, it is crucial that the health professionals involved in the procedures have a common understanding of the concepts related to radiation protection, such as dose descriptors, diagnostic reference levels and typical dose values. An update about these concepts will be presented with the objective to raise awareness amongst health professionals and contribute to the increase in knowledge, skills and competences in radiation protection in fluoroscopically guided interventional procedures.

National survey to set diagnostic reference levels in nuclear medicine single photon emission imaging in Croatia

PURPOSE

In order to introduce the concept of diagnostic reference levels (DRLs) in the national nuclear medicine practice a survey was proposed and completed through all nuclear medicine departments in Croatia. An additional aim was to increase the awareness of importance and full implementation of a comprehensive quality program that includes devices used in the nuclear medicine chain.

METHODS

Data were collected for more than 30 nuclear medicine single photon emission procedures. National DRLs (NDRLs) as administered activity and also as administered activity per unit mass were calculated in accordance to International Commission on Radiological Protection (ICRP) recommendations. Additionally, effective doses were estimated using conversion factors published by the ICRP.

RESULTS

NDRLs for nuclear medicine single photon emission procedures were proposed. For procedures performed in only one department typical values were presented as reference. Effective doses related to applied radiopharmaceuticals were calculated to estimate radiation risk related to respective nuclear medicine procedure in more detail.

CONCLUSION

This work presents results of the first national survey on DRLs of nuclear medicine single photon emission procedures and proposes reliable NDRLs that represent an actual status of nuclear medicine practice in Croatia. Results have motivated departments to introduce and set their own typical values to be used, as one of the tools, for further optimization process. One of the drawbacks of the DRL concept in nuclear medicine is the lack of the image quality parameters involved. For this reason, a quantity that considers both radiation protection and image quality should be introduced.

[Multicenter Survey on Radiation Dose of Cardiac Intervention]

We conducted a nationwide survey of multiple institutions and collected data of various interventional procedures in the field of cardiology. Included in the analysis were 126 institutions, 381 X-ray systems, and 805 protocols. The dose values were compared with the Japanese diagnostic reference levels (DRLs) 2015. Fluoroscopy time, air kerma at the patient entrance reference point (K_{a, r}), and air kerma-area product (P_KA ) were analyzed for various interventional procedures in 5,734 cardiology patients. The fluoroscopic dose rate (FDR) for pulmonary vein isolation (PVI) was less than half that of the 75th percentile of the Japanese DRLs 2015. The 75th percentiles of fluoroscopy time, K_{a, r}, and P_KA for the respective interventional procedures were as follows: 11.0 min, 735 mGy, and 64 Gy･cm² for diagnostic coronary angiography (CA); 13.2 min, 839 mGy, and 75 Gy･cm² for CA + left ventriculography; 34.4 min, 1,810 mGy, and 148 Gy･cm² for percutaneous coronary intervention (PCI) excluding chronic total occlusion; 80.1 min, 4,338 mGy, and 312 Gy･cm² for PCI for chronic total occlusion; 74.4 min, 833 mGy, and 90 Gy･cm² for PVI; and 34.0 min, 795 mGy, and 94 Gy･cm² for transcatheter aortic valve implantation, respectively. In assessing dose values in interventional radiology, the difficulty of the technique needs to be considered, and the DRL values for FDR, fluoroscopic time, K_{a, r}, and P_KA for each interventional procedure are considered necessary when reassessing or updating DRLs.

Combining Optimized Image Processing With Dual Axis Rotational Angiography: Toward Low-Dose Invasive Coronary Angiography

Background

Dual axis rotational coronary angiography (DARCA) reduces radiation exposure during coronary angiography on older x‐ray systems. The purpose of the current study is to quantify patient and staff radiation exposure using DARCA on a modality already equipped with dose‐reducing technology. Additionally, we assessed applicability of 1 dose area product to effective dose conversion factor for both DARCA and conventional coronary angiography (CCA) procedures.

Methods and Results

Twenty patients were examined using DARCA and were compared with 20 age‐, sex‐, and body mass index–matched patients selected from a prior study using CCA on the same x‐ray modality. All irradiation events are simulated using PCXMC (STUK, Finland) to determine organ and effective doses. Moreover, for DARCA each frame is simulated. Staff dose is measured using active personal dosimeters (DoseAware, Philips Healthcare, The Netherlands). With DARCA, median cumulative dose area product is reduced by 57% (ie, 7.41 versus 17.19 Gy·cm²). Effective dose conversion factors of CCA and DARCA are slightly different, yet this difference is not statistically significant. The occupational dose at physician's chest, leg, and collar level are reduced by 60%, 56%, and 16%, respectively, of which the first 2 reached statistical significance. Median effective dose is reduced from 4.75 mSv in CCA to 2.22 mSv in DARCA procedures, where the latter is further reduced to 1.79 mSv when excluding ventriculography.

Conclusions

During invasive coronary angiography, DARCA reduces radiation exposure even further toward low‐dose values on a system already equipped with advanced image processing and noise reduction algorithms. For both DARCA and CCA procedures, using 1 effective dose conversion factor of 0.30 mSv·Gy⁻¹·cm⁻² is feasible.

CONTEMPORARY RADIATION DOSES IN INTERVENTIONAL CARDIOLOGY: A NATIONWIDE STUDY OF PATIENT SKIN DOSES IN FINLAND

In contemporary interventional cardiology, for typical elderly patients, the most severe radiation-related harm to patients can be considered to come from skin exposures. In this paper, maximum local skin doses in cardiological procedures are explored with Gafchromic film dosimetry. Film and reader calibrations and reading were performed at the Secondary Standards Dosimetry Laboratory of the Radiation and Nuclear Safety Authority (STUK), and data were gathered from seven hospitals in Finland. As alert levels for early transient erythema, 200 Gycm2 kerma area product (KAP) and 2000 mGy air kerma levels for transcatheter aortic valve implantations (TAVI) procedures are proposed. The largest doses were measured in TAVI (4158.8 mGy) and percutaneous coronary interventions (PCI) (941.68 mGy). Accuracies of the GE DoseWatch and Siemens CareMonitor skin dose estimates were reasonable, but more results are needed to reliably assess and validate the tools' capabilities and reliabilities. Uncertainty of the Gafchromic dosimetry was estimated as 9.1% for a calibration with seven data points and 19.3% for a calibration with five data points.

The role of a commercial radiation dose index monitoring system in establishing local dose reference levels for fluoroscopically guided invasive cardiac procedures

PURPOSE

The primary goal was to evaluate local dose level for fluoroscopically guided invasive cardiac procedures in a high-volume activity catheterization laboratory, using automatic data registration with minimal impact on operator workload. The secondary goal was to highlight the relationship between dose indices and acquisition parameters, in order to establish an effective strategy for protocols optimization.

METHODS

From September 2016 to December 2018, a dosimetric survey was conducted in the 2 rooms of the catheterization laboratory of our institution. Data collection burden was minimized using a commercial Radiation Dose Index Monitoring System (RDIMs) that analyzes dicom files automatically sent by the x-ray equipment. Data were combined with clinical information extracted from the HIS records reported by the interventional cardiologist. Local dose levels were established for different invasive cardiac procedures.

RESULTS

A total of 3029 procedures performed for 2615 patients were analyzed. Median KAP were 21 Gycm² for invasive coronary angiography (ICA) procedures, 61 Gycm² for percutaneous coronary intervention (PCI) procedures, 59 Gycm² for combined (ICA+PCI) procedures, 87 Gycm² for structural heart intervention (TAVI) procedures. A significant dose reduction (51% for ICA procedures and 58% for PCI procedures) was observed when noise reduction acquisition techniques were applied.

CONCLUSIONS

RDIMs are effective tools in the establishment of local dose level in interventional cardiology, as they mitigate the burden to collect and register extensive dosimetric data and exposure parameters. Systematic review of data support the multi-disciplinary team in the definition of an effective strategy for protocol management and dose optimization.

Conversion factors to estimate effective doses from kerma area product in interventional cardiology. Impact of added filtration

There is a large variation in the factors used to estimate effective doses from kerma area product (KAP) for interventional cardiology. These factors are required to estimate population doses. This paper presents the results for this conversion factor for cardiac procedures using tissue weighting factors of ICRP-103 and the impact of the added copper filtration in the X-ray beam. The data from 925 cardiac procedures and 75,347 radiation events were collected from two angiography laboratories using the DICOM Radiation Dose Structured Reports (RDSR). Effective doses were calculated with Monte Carlo software and the dosimetric, technical and geometrical information included in the RDSR. In one laboratory, with an X-ray system without Cu filtration for the cine runs, a factor of 0.21 ± 0.05 mSv/(Gy·cm²) was obtained. In other laboratory, incorporating a patient dose reduction technique, and 0.4 mm of Cu filtration for cine runs, the conversion factor was 0.29 ± 0.05 mSv/(Gy·cm²). The analysis of the radiation events for the different Cu filtrations (0.0; 0.1; 0.4 and 0.9 mm) resulted in conversion factors of: 0.16; 0.27; 0.34 and 0.40 mSv/(Gy·cm²) respectively. The estimation of effective and population doses from KAP should take into account the Cu filtration in the X-ray beam. For the X-ray system with patient dose reduction technique, using 0.4 mm Cu for cine runs, the global conversion factor increased by 38%, from 0.21 to 0.29 mSv/(Gy·cm²) in comparison to the standard X-ray system with a protocol that did not include copper filtration for cine acquisitions.

Organ and effective doses detriment to paediatric patients undergoing multiple interventional cardiology procedures

The aims of the present study were to present the frequency of multiple interventional cardiac procedures for a certain group of patients obtained at one of the largest paediatric hospitals in Chile. In addition it has been analysed cumulative kerma area product (KAP) and cumulative air kerma (CAK), and calculated organ doses for the patient groups undergoing 2, 3 and ≥ 4 procedures, using Monte Carlo software. Effective doses were also estimated for epidemiological purposes and to permit comparison with other imaging procedures. The sample used corresponds to the last 9 years and refers to a total of 1521 paediatric patients and 1824 interventional cardiac procedures. The results for frequency were: 13.7% of patients underwent 2 procedures, 4.1% underwent 3 procedures and 1.4% underwent 4 or more procedures. The median KAP and CAK values measured for the cumulative procedures in these three groups of patients were 3.7, 5.4 and 10.8 Gy·cm² and 59.9, 83.2 and 147.6 mGy, respectively. In terms of the most irradiated organs during interventional cardiac procedures, the highest median values (for the group of ≥4 procedures) were: active bone marrow 5.0 mGy, lungs 23.5 mGy, oesophagus 15.2 mGy, thyroid 7.8 mGy and breast 11.0 mGy. Median dose value to the heart (for the group of ≥4 procedures) was 12.7 mGy. Median values in terms of calculated effective dose for the three patient groups (with 2, 3 and ≥4 procedures) were 3.4, 5.9 and 8.7 mSv, respectively.

Surgeon eye lens dose monitoring in catheterization lab: A multi-center survey: Invited for ECMP 2018 Focus Issue

PURPOSE

To perform a multi-centre survey on the eye lens equivalent dose absorbed by primary interventionalist during catheterization procedures, using a personal dosimeter placed close to the eye lens.

METHODS

15 different cardiologists working in 3 different centers, for a total of 5 operating rooms were enrolled. All of them were provided with a single thermoluminescent dosimeter positioned on the inner side of the temples of eyeglasses. The dose monitoring, performed on a two-months basis, started in 2016 and is still running. All dose measurements were performed by a ISO 17025 standard accredited dosimetry service thus providing certified uncertainties as well. Correlation of eye lens and wrist dose with KAP was also investigated.

RESULTS

A total number of 101 eye lens measurements were performed. Annual eye lens dose estimation was obtained for all 15 surgeons (mean, mode, range, standard deviation: 10.8, 8, 4.9-27.3, 5.6  mSv, respectively). Uncertainties on annual eye lens dose estimations ranged between 10% and 20%. No significant correlation was found between eye lens dose and KAP.

CONCLUSIONS

Cardiologists involved in catheterization procedures may receive annual eye lens doses close to the ICRP 118 dose limit and thus individual monitoring with a dedicated dosimeter should be carried out. Uncertainty assessment play a relevant role in eye lens equivalent dose estimation to ensure not to exceed dose limit.