Children are a distinct group of patients in terms of medical imaging. Their size, physiology and the location of their organs change as the child grows, and the fact that children have a longer life expectancy than adults must also be taken into account when the appropriate radiation dose is delivered. In addition, immobilization, sedation or anaesthesia may be required in young children to ensure the necessary clarity of imaging.
It is important to evaluate and optimize the radiation dose without reducing the quality of the image, and the evolution in imaging and detector technology and dose optimization techniques can help ensure that as low a dose as possible is delivered to each patient.
A recent IAEA Coordinated Research Project, Evaluation and Optimization of Paediatric Imaging, has shown that reduced amounts of radiation can be used in paediatric radiology and nuclear medicine exams, and highlighted the necessity of close coordination among medical physicists and radiology and nuclear medicine teams.
The overall objective of the research was to enhance the capabilities of IAEA Member States to improve the efficiency of existing modalities for paediatric medical imaging, and to optimize the radiation dose administered to paediatric patients, while maintaining the image quality needed to make a clear diagnosis.
Both nuclear medicine and diagnostic radiology examinations were included in the research, which had the following specific objectives:
- To quantify, in terms of dose and image quality, the practices involving paediatric patient in diagnostic radiology and nuclear medicine.
- To develop tools suitable for training or information for paediatric clinical practice.
- To provide guidelines and assist Member States on the evaluation of paediatric practices and optimization methodologies.
- To assess the impact of training on optimization with particular emphasis on typical delivered doses and administered activities, with respect to Diagnostic Reference Levels (the maximum dose level at which an investigation into the appropriateness of the dose should be initiated).
The CRP resulted in new guidance for radiology and nuclear medicine departments worldwide. It was found that a key element for a successful optimization strategy is medical physicists working closely with the radiation technologists and clinicians.
"Evaluating and improving practices is a clear benefit of this CRP,” said Harry Delis, Diagnostic Radiology Medical Physicist at the IAEA. “At the same time, putting the focus on children and creating an international network of scientists collaborating on paediatric imaging are equally important.”
The project looked at the process of optimization and the fact that it is an iterative process involving multiple consultations and reviews with the clinical teams over time. Each step of an optimization process is important and cannot be missed, so optimization may not be a rapid process, particularly for less frequently performed procedures. The greatest challenges were found to be in collecting reliable dose data, obtaining image quality data, and it was also difficult for clinical teams to make changes to long-established practices, which had been identified as suboptimal. In all participating centres, however, by the end of the project, if the imaging systems were not found to be optimized, imaging parameters or the amount of activity administered were changed to reduce paediatric patient exposure. Standard data collection forms were developed for this research and will be made available to Member States.
“The ultimate beneficiaries of this CRP are the large number of paediatric patients undergoing diagnostic procedures with ionizing radiation,” said Gian Luca Poli, IAEA Nuclear Medicine Medical Physicist. “The project has led to significant reductions in the amount of activity administered in nuclear medicine exams, which has resulted in important and appropriate reductions in the radiation doses for children.”
