ESR@Work July 2017
MEDIRAD Work Package 2: Dose evaluation and optimisation in medical imaging
Prof. John Damilakis
(University of Crete/GR, MEDIRAD WP2 Leader, Member of the EuroSafe Imaging Steering Committee)
It is well known that there is a need to evaluate the health effects of ionizing radiation used in medicine, optimise practices to reduce doses and develop dose evaluation tools that can be used in clinical practice to ensure adequate and improved radiation protection of patients and medical personnel. The Horizon 2020 MEDIRAD (Implications of Medical Low Dose Radiation Dose) project was recently launched to address this need by enhancing the scientific bases and practice of radiation protection in the medical field and to understand and evaluate the health effects of low dose ionising radiation exposure from diagnostic and therapeutic imaging and from off-target effects in radiotherapy (RT). The 4-year MEDIRAD project is coordinated by the European Institute for Biomedical Imaging Research (EIBIR). Prof. Guy Frija, Chair of Eurosafe Imaging, acts as Clinical Coordinator and Prof. Elisabeth Cardis, radiation epidemiologist and Head of Radiation Programme at ISGlobal, as Scientific Coordinator of the project.
The aim of work package (WP) 2 is to develop novel methodologies to reduce patient and staff radiation dose and potential radiation-related risks of cancer and non-cancer outcomes from chest imaging while maintaining or improving diagnostic information from existing and emerging techniques. Work will focus on state-of-the-art CT, fluoroscopically-guided interventional procedures and hybrid systems. This aim is in line with EuroSafe Imaging Campaign’s mission to support and strengthen medical radiation protection and the EuroSafe Imaging Call for Action.
Parameters for quantifying image quality are usually measured using standardised phantoms. However, the optimisation of protocols in clinical routine and the prediction of diagnostic performance may not be adequately accomplished using phantoms containing standard test objects. Moreover, methods have mainly been described in the literature for the assessment of effective dose from examinations. Anthropomorphic phantoms, either physical or computational in nature, represent only standard size patients of standard ages. Monte Carlo approaches have been based on oversimplified geometrical phantoms. Methods are needed to estimate organ and tissue doses based on patient models or detailed voxelised phantoms characterised with different body statures or models of real patients representing as many as possible human body anatomies and sizes and taking into account all parameters influencing patient dose. MEDIRAD WP2 will develop a novel tool for patient dose and image information optimisation in chest CT based on image quality assessment and detailed spatial three-dimensional (3D) organ and tissue dose distributions from chest CT examinations.
Fluoroscopically-guided interventional procedures deliver high doses to the patients, particularly to the skin and during long procedures. Patient dose monitoring usually involves estimation of dose quantities such as kerma-area product and cumulative air kerma, which are poor indicators of skin dose. Thermoluminescence dosimeters and radiochromic films do not provide real time information and their use requires considerable expertise. A state-of-the-art method has been described for dose monitoring for interventional cardiology procedures based on the accelerated Monte Carlo (MC) code, MC-GPU. The programme has only been tested with some simple ideal simulated cardiac procedures, but has not been benchmarked against standard simulation codes, nor has it been tested in the clinical environment. There is thus a need to fully leverage the potential of this dose monitoring tool through clinical validation and potential improvement of detected shortcomings. MEDIRAD WP2 will provide detailed spatial 3D dose distributions from fluoroscopically-guided ablation procedures for dose optimisation, optimise a novel dose monitoring system for interventional cardiology procedures and test the efficacy and effectiveness of newly developed tools for staff brain and eye lens protection in fluoroscopically guided procedures.
Tremendous growth in the use of multi-modality examinations took place in the last decade, with increases in numbers of procedures and of installed SPECT/CT and PET/CT systems and the introduction of new radiopharmaceuticals. CT scan protocols for multi-modality imaging are often not optimised, delivering much higher doses than actually required. There is thus a strong need for standardisation and optimisation of CT protocols for multi-modality imaging. The establishment and use of Dose Reference Levels (DRLs) in hybrid imaging are required and have been recommended by the International Commission on Radiological Protection (ICRP) and by the European Commission tender project on the establishment of European DRLs for paediatric patients (PiDRL project). Finally, DRLs are also needed for other applications for attenuation correction and anatomic localization and to optimise multi-modality examinations through the development of a novel method for estimation of organ doses from both the radiopharmaceutical and the CT. MEDIRAD WP2 will perform a European study on the current use of multi-modality systems as a basis for establishing European DRLs for specific applications of CT in PET/CT and SPECT/CT, develop a method for estimation of patient organ doses and risks from chest PET/CT and SPECT/CT and optimise protocols for multi-modality imaging.
There is a need for a European image and dose repository for benchmarking and research. Further, coding is not harmonised in Europe, with 3,200 codes in the UK and around 300 in other countries. Developing a harmonised coding system for Europe, integrated in all HIS / RIS systems, and including radiology and nuclear medicine imaging procedures is not only crucial for developing European DRLs, but also for providing high quality data for any further research program. MEDIRAD WP2 will develop and operate an integrated imaging and dose biobank to address the needs of MEDIRAD researchers (WPs 2-5), develop a common catalogue for names of procedures, clinical symptoms, anatomical locations and findings, develop integrated structured reporting templates to collect clinical information, radiological findings and radiation dose, integrate coding schemes into these templates, provide a web-based solution for structured reporting and develop tools to evaluate data collections of structured reports for advanced analytics or data-mining.
The MEDIRAD project has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 755523.
More information about the project can be found at http://www.medirad-project.eu/.