EURADOS Report 2023-02 published: "Individual Exposure and Monitoring in Interventional Radiology and Cardiology"
EURADOS Report 2023-02 is published: "Individual Exposure and Monitoring in Interventional Radiology and Cardiology"
Eleftheria Carinou, Isabelle Clairand, Jérémie Dabin, Paolo Ferrari, Mercè Ginjaume, Oliver Hupe, María Gracia Ochoa, Una O’Connor, Filip Vanhavere
Abstract: The aim of this report is to summarise the technical and legal aspects of individual monitoring requirements in interventional radiology and cardiology (IR/IC) workplaces, incorporating some of the most recent research in this area. The report is aimed at all those working in dose monitoring in the interventional field such as radiation protection experts, radiation protection officers, medical physicists, dosimetry services and other relevant stakeholders.
This report provides information on dose limits, operational quantities used in radiation protection, and classification of workers in IR/IC. The establishment of dose constraints as an optimization tool is discussed. Typical occupational dose levels from various international projects are detailed for information and guidance.
Radiation protection equipment available to staff during IR/IC procedures is presented. Figures of the general level of effectiveness and practical attention points are given. Details of the effectiveness of equipment, along with advice on storage and maintenance are presented.
The importance of individual dose monitoring for staff working in IR/IC to demonstrate compliance with regulatory dose limits is detailed in the report. A variety of personal monitoring devices are available from different manufacturers and a summary of the most commonly used devices for monitoring occupational radiation doses is shown. Passive dosemeters remain as the dosemeter of choice in most countries for demonstrating compliance with the dose limits. However, the use of active personal dosemeters (APDs) for real-time monitoring is increasing. Hybrid solutions allowing for frequent local readouts of staff doses are also becoming widely used.
One of the major challenges in setting up an individual monitoring programme in interventional workplaces is the wearing position of the dosemeters (either for the whole body, eye lens or extremities). Due to the inhomogeneity of the field, the assessment of the respective dose is strongly dependent on the dosemeter position and other important parameters such as the energy and angular distribution of the X-ray beam, the beam projections or the distance between the operator and the patient.
In terms of assessment of the effective dose, there are generally two methods in use: (i) the “double-dosimetry” approach, which consists of using two dosemeters at the level of the trunk, one worn under the apron, and the other worn over the apron (the effective dose is estimated by the use of various algorithms based mainly on the radiation protection garments); and (ii) the single dosimetry, i.e. to wear the dosemeter over the apron or under the apron, preferably at the central position to minimise the dependence on the beam projection. When the dosemeter is worn under the apron, the effective dose is assumed to be the dosemeter reading itself. When the dosemeter is worn above, the effective dose is estimated by dividing the dosemeter reading by a factor (typical range from 10 to 20) which depends on the type of practice, the thickness of protection, the position of dosemeters, etc. The use of two dosemeters is particularly relevant in fluoroscopically guided interventional procedures, when it is possible to reach or exceed the effective dose limit of 20 mSv per year.
For the assessment of the dose to the lens of the eye, the use of a specific eye-lens dosemeter located close to the most exposed eye and measuring Hp(3) is generally the preferred option. Another common option is the use of an unprotected whole body dosemeter situated at the chest or collar level and the use of a multiplication factor (the most common value being 0.75) to convert the reading of the whole body dosemeter to dose to the lens of the eye.
To estimate extremity doses, a dosemeter capable of measuring Hp(0.07) is used, ideally placed as close as possible to the most exposed area of the skin and oriented towards the radiation beam. For the majority of interventional procedures, the most exposed area appears to be from the little finger to the middle finger. Ring dosemeters worn on the little finger are proposed as the most appropriate monitoring method. Lower extremities might also need to be considered when table shielding is not used or is not long enough. Wrist dosemeters can be used at the ankles to provide assessment of the lower leg exposure if required.