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Recurrent imaging

Millions of patients globally benefit from diagnostic imaging and image guided interventional procedures every day. The increased awareness of radiation doses and risks associated with these medical  procedures led to actions improving implementation of two key radiation protection principles, justification and optimization of individual examinations.

The current international radiation protection standards require relevant information about the previous radiological procedures of a patient to be considered in the justification of every new imaging procedure. However, effective mechanisms to support this process are limited.

The IAEA initiated a Smart Card project in 2009 with the purpose to propose to  industry and users a methodology for tracking the radiation exposure history of individual patients. Currently, radiation dose tracking of individual patients is a routine in many hospitals and automatic dose monitoring and tracking systems are available commercially to facilitate this process. The wider availability of radiation exposure monitoring systems has allowed for improved information on the radiation history of patients.  

Publications in the scientific literature have shown that patients undergoing diagnostic and interventional radiological procedures can receive cumulative effective doses (CED) in the range of 50-500 mSv. It was however not known if this is a widespread phenomenon or it is restricted to isolated situations.

Following assessments carried out by the Massachusetts General Hospital (MGH), Boston, wherein several thousands of patients were found to have CED ≥100 mSv, a joint project was launched by IAEA and MGH to assess the situation in other parts of the world. This project covered 3.2 million patients who underwent recurrent CT imaging over periods between 1 to 5 years in different hospitals. It concluded that the number of patients who reach CED of 100 mSv is much larger than previously known— it might involve almost one million patients per year globally. The patients who receive such cumulative radiation doses typically need radiological imaging exams for multiple clinical indications, not only for follow-up of malignant disease or chronic conditions.

The reviews undertaken by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), International Commission on Radiological Protection (ICRP), and National Council on Radiation Protection and Measurements (NCRP) have demonstrated increase of radiation-related adverse effects (particularly cancer) at or above absorbed dose of around 100 mGy.

In March 2019, the IAEA held a Technical meeting on Radiation Exposure of Patients from Recurrent Radiological Imaging Procedures, with representatives of IAEA Member States, international organizations and professional bodies: ICRP, WHO, UNSCEAR, ISR, ISRRT, IOMP, ESR, Image Gently, and DITTA, representing a spectrum of specialties – radiologists, medical physicists, medical radiation technologists, radiation biologists, radiation epidemiologists, manufacturers, radiation protection specialists, and a patient champion from the WHO Patients for Patient Safety network. The meeting discussed results available to date on recurrent imaging and deliberated on interpretation and recommended actions as outlined in the publications and the report of the meeting.

Scientific publications from the data presented at the IAEA Technical meeting: