Radiological Protection of Patients in Nuclear Medicine

Full text: This lecture aims at presenting the state of the art of radiological protection of patients in nuclear medicine focusing on three aspects of interest where to achieve improvement. The hierarchy of the justification principle of the radiation protection is one of them. There seems for a change to be presented in the paradigm of the radiological protection of patients. The role of the physician who prescribes the medical practice becomes more relevant, together with the nuclear medicine specialist who should be co-responsible for the application of this justification principle. Regarding the doses optimization and the implementation of Dose Reference Level the involvement extends far beyond the physician and radioprotection officer. It is clear that the Medical Physicist is to play a very relevant role in the coordination of actions, as the nuclear medicine technician is to execute them. Another aspect to consider is patient specific dosimetry. It should become a routine practice through calculation of the absorbed dose based on biodistribution data. It should be assessed for each individual patient, as it depends on a number of patient-specific parameters, such as gender, size and the amount of fatty tissue in the body, as well as the extent and nature of the disease. In most cases, dosimetry calculations are not carried out and patients are administered standard levels of activity. There may be situations with a lack of knowledge on internal dosimetry as in many centers either none or only one or two medical physics experts are available. It shows that a formal training for experts in internal dosimetry at national level is required. However up to now, there has been no satisfactory correlation between absorbed dose estimates and patient response. Moreover, the radiation protection for the patient is not assured, as the dose values given are often numbers without connection to radiobiological and/or hematological findings. Pending tasks related to knowing the therapy successful rates, to comparing the dose values with radiobiological findings and to determine late radiation effects to the patient should be a goal for radiological protection of patients in nuclear medicine. Finally, regarding regulations, it is interesting to discuss regulations, a balance should be achieved between: too many or not enough. The challenge for the regulator is to establish a regulatory structure that helps to minimize these unintended risks, while avoiding undue interference in medical judgments. Too many regulations can result in medical or technological needless delay of while too few regulations can lead to an increase in misadministrations and increase the likelihood for patients, medical staff, and the public to receive involuntary exposures. A careful balance must be attained in establishing an appropriate regulatory regime. Regulation should provide the appropriate vehicle for reducing radiation risks, while also minimizing interference with the beneficial uses of medicine. (authors)