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

Implementing Patient Protection Radiation Dose Alerts for Pediatric Cardiac Catheterization Examinations

Background

Advancements in cardiac catheterization have improved survival for pediatric congenital heart disease patients, but the associated ionizing radiation risks necessitate ethical consideration.

Methods

This study presents an empirical model, developed from 3131 unique pediatric procedures, to establish alert levels based on a patient's lateral thickness of the thorax for various procedural categories during diagnostic or interventional cardiac catheterization. The model uses linear regression of logarithmic reference air kinetic energy released per unit mass (KERMA) and air KERMA area product, also referred to as dose area product, to set alert levels at the top 95% and 99% of patient data.

Results

Coefficients of the regression fits are provided for diagnostic and interventional procedural groups and fluoroscopic plane allowing any facility to scale the results of this study's single facility data to model their practice's unique procedural dose levels.

Conclusions

The proposed method allows institutions to tailor dose alert levels to their specific pediatric populations to reduce overexposure events.

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.

Anthropometric parameters and radiation doses during percutaneous coronary procedures

PURPOSE

Body size is a major determinant of patient's dose during percutaneous coronary interventions (PCI). Body mass index, body surface area (BSA), lean body mass and weight are commonly used estimates for body size. We aim to identify which of these measures and which procedural/clinical characteristics can better predict received dose.

METHODS

Dose area product (DAP, Gycm²), fluoroscopy DAP rate (Gycm²/min), fluoroscopy DAP (Gycm²), cine-angiography DAP (Gycm²), Air Kerma (mGy) were selected as indices of patient radiation dose. Different clinical/procedural variables were analysed in multiple linear regression models with previously mentioned patient radiation dose parameters as end points. The best model for each of them was identified.

RESULTS

Overall 6623 PCI were analysed, median fluoroscopy DAP rate was 35 [IQR 2.7,4.4] Gycm², median total DAP was 62.7 [IQR 38.1,107] Gycm². Among all anthropometric variables, BSA showed the best correlation with all radiation dose parameters considered. Every 1 m² increment in BSA added 4.861 Gycm²/min (95% CI [4.656, 5.067]) to fluoroscopy DAP rate and 164 Gycm² (95% CI [145.3, 182.8]) to total DAP. Height and female sex were significantly associated to a reduction in fluoroscopy DAP rate and total DAP. Coronary angioplasty, diabetes, basal creatinine and the number of treated vessels were associated to higher values.

CONCLUSIONS

Main determinants of patient radiation dose are: BSA, female sex, height and number of treated vessels. In an era of increasing PCI complexity and obesity prevalence, these results can help clinicians tailoring X-ray administration to patient's size.

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.