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Radiation protection of patients in nuclear medicine

Introduction 

As with many other imaging modalities, the utilisation of nuclear medicine has increased in last decades. As per United Nations Scientific Committee on Effects of Atomic Radiation (UNSCEAR), a total of 33 million nuclear medicine examinations are performed worldwide, in which among the most frequent are bone scans and cardiovascular studies. There are significant advantages in combining PET - CT images and SPECT-CT imaging systems that also require special radiation protection concerns, mainly du to CT part of the examination.

Important Principles

Justification and optimization are two of the cornerstones of radiation protection in medical exposures, as dose limits do not apply to exposure of patients. As other modalities that involve exposure to ionizing radiation, nuclear medicine studies must be rigorously justified in a way that benefit from the study unambiguously overweighs the risk associated with exposure to ionizing radiation. Once study is justified, it shall be optimized to prevent any unnecessary radiation exposure of patients. For any given procedure, the optimum activity will depend on the body weight of the individual patient, the patient's metabolic characteristics and clinical condition, the type of equipment used the type of study and the examination time. For a given type of imaging equipment, the diagnostic value of the information obtained from a test will vary with the amount of administered activity. Once an acceptable quality of the image has been reached, any further increase of the administered activity will increase only the absorbed dose and organ doses and not the value of the diagnostic information

Above mentioned principles are even more impotent in high dose studies in nuclear medicine, as cardiovascular and PET/CT studies and in special population groups as children and female patients of reproductive capacity. 

Important references

The Radiation Protection of Patients (RPoP) website contains information to help health professionals achieve safer use of radiation in medicine for the benefit of patients. Radiation protection of patients in nuclear medicine covering diagnostic nuclear medicine, therapeutic nuclear medicine and biomedical research is included as topics on the RPoP website. This website also contains training materials on radiation protection in nuclear medicine and radiation protection in PET/CTPregnant women form specific group for radiation protection purpose and they are dealt with separately.

The key standards in this area are the International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, also known as the International BSS. These standards mark the culmination of efforts that have continued over the past several decades towards the harmonization of radiation protection and safety standards internationally. Safety reports to guide users in applying safety standards in different areas of medical application of ionising radiation are available for free download.