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Right Dose for Accurate Diagnosis: Track Radiation Dose to Patients and Use Diagnostic Reference Levels

Participants at the meeting on 'Patient Dose Monitoring and the Use of Diagnostic Reference Levels for Optimization of Protection in Medical Imaging' held at the IAEA headquarters. (Photo: C. Villarreal/IAEA)

Evaluation of radiation dose levels during diagnostic radiological procedures, and the use of this data to improve quality of diagnostic exams and patient safety were among the topics discussed at a recent IAEA meeting on patient dose monitoring.

According to the last available data,  over 4 billion diagnostic radiological procedures are performed around the world. Use of ionizing radiation for medical purposes provides many benefits, but it also increases the risk of cancer later in life. In situations where more radiation is used than necessary to provide a clinical diagnosis, increased risk is incurred but has no benefit to the patient. Ideally, only well justified medical imaging procedures should be performed and the lowest amount of radiation should be used to provide an image quality sufficient for diagnosing disease or injury.

"With the patient being the focus for any medical diagnosis, dose evaluation and diagnostic reference levels for patients are recognized as important tools for optimization of patient radiation protection," said Ehsan Samei, a Professor of Radiology and Medical Physics at Duke Health in Duke University Hospital, United States, who was the meeting's Chair.

In some cases, the patient may receive an incorrect dose which can jeopardize the quality of diagnosis. Therefore, the doses in radiation procedures need to be regularly evaluated to ensure the patients' safety and quality of medical images, he added.

What are diagnostic reference levels?

Diagnostic reference levels serve as a practical tool for health professionals to compare diagnostic imaging procedures across a country. They apply for a specific patient group (e.g. adults or children of different age or weight) and relate to specific types of medical examinations such as X-rays, computed tomography, image guided interventional procedures, or nuclear medicine procedures.

To ensure the clarity of effective and accurate imaging, each hospital should compare local doses to the nationally or regionally set diagnostic reference levels. "We need to have purpose-specific diagnostic reference levels to achieve this goal," said Samei. Diagnostic reference levels should relate to the purpose of the imaging, for example cancer and cardiovascular imaging may have different diagnostic reference levels, he said, adding that "clinical tests differ from country to country, capacity levels are not the same." The aim should be to have a universally agreed methodology for setting and using diagnostic reference levels.

The practical implementation of diagnostic reference levels is a complex task, requiring good knowledge of the medical technology and technical skills to perform patient dosimetry and to analyze image quality. It requires effective coordination between the health authority, relevant professional bodies, the regulatory body, and medical facilities motivated to participate in data collection, said Peter Johnston, Director of the IAEA Division of Radiation, Transport and Waste Safety.

Further, having comprehensive regulatory and legislative mechanisms, a sustained awareness building programme, effective evaluation tools to implement internationally agreed safety standards on radiation protection for patients are also vital, he added.

Why track radiation dose data?

Accurate and regular recording, reporting and analyzing of patient radiation doses in medical centers can help improve practice and reduce doses without loss of diagnostic quality. This information can be used to establish diagnostic reference levels at the national or regional level. The tracked information for a patient can also contribute to preventing unnecessary exposures.

Patients sometimes go from one imaging facility to another, new tests are done, involving duplication of radiation examinations, said Simone Kodlulovich, President of the Latin American Medical Physics Association (ALFIM). "What is lacking in many countries is a data system that tracks doses. We need to be more consistent and follow established guidelines consistently."

Another area that needs special attention among health professionals performing exams is imaging of children, for whom sensitivity to radiation is higher. Monitoring of doses to children in medical facilities helps improve clinical outcome and reduce risks. Without proper and specialized guidance, this advanced technology has the potential to significantly increase patients' exposure to ionizing radiation, said Kodlulovich.

Cooperate, coordinate to prevent overuse

Fast moving technological developments in medical imaging are providing new opportunities to automatically track and benchmark patient doses. Early evidence in some countries with more advanced electronic systems is very promising, said Samei. Further, the closer involvement of medical equipment manufacturers and developers of specialised dose tracking software is needed to establish proper standards as well as to coordinate further improvements.

During the weeklong discussion, good practices and successful approaches for optimization in medical imaging by establishing diagnostic reference levels and using dose monitoring was covered.

Representatives from more than 30 Member States participated in 'Patient Dose Monitoring and the Use of Diagnostic Reference Levels for Optimization of Protection in Medical Imaging' meeting, which took place from 30 May to 3 June at the IAEA headquarters.