The licensee and employer have the joint responsibility to ensure that appropriate personal monitoring is provided to staff. This normally means that the RPO would specify which workers need to be monitored routinely, the type of monitoring device to be used, and the body position where the monitor should be worn, bearing in mind that some countries may have specific regulatory requirements on these issues. Further, the regulatory body is likely to have specified the monitoring period and the time frame for reporting monitoring results.
Staff to be monitored in a nuclear medicine facility should include all those who work routinely with radionuclides or with the patients who have received administrations of radiopharmaceuticals. This will include nursing staff who either work routinely in nuclear medicine or nurse patients who have received radionuclide therapy and staff dealing with excreta from radionuclide therapy. Monitoring would not normally be extended to those that come into occasional contact with nuclear medicine patients.
There are several types of external personal dosimetry systems, and the system to use is dependent on national or local conditions. In many countries, the service is centralized to the regulatory body or provided through third-party personal dosimetry providers. Occasionally, some large hospitals have their own personal dosimetry service. In all cases, the dosimetry provider must be approved by the regulatory body.
Finger monitoring should be carried out occasionally on staff that regularly prepare and administer radioactive substances to patients, and also when setting up an operation which requires the routine handling of large quantities of radionuclides. After handling unsealed radionuclides, the hands should be monitored. It may, therefore, be convenient to mount a suitable contamination monitor near the sink where hands are washed. Care should be taken to ensure that the monitor itself does not become contaminated. In high background areas, it will be necessary to shield the detector, and it may be convenient to have a foot or elbow-operated switch to activate the monitor.
Monitoring for internal contamination is rarely necessary in nuclear medicine on radiation protection grounds but it may be useful in providing reassurance to staff. The circumstances in which internal monitoring becomes advisable are those where staff use significant quantities of 131I for thyroid therapy. They should be included in a programme of thyroid uptake measurements.
In other circumstances where it is necessary to assess the intake of γ emitting radionuclides (e.g. after a serious incident), the use of a whole-body counter may be appropriate. Such equipment should be available at national referral centres. The possible use of an uncollimated gamma camera should also be considered.
Sometimes, a more detailed monitoring survey may be indicated if staff doses have increased (or it is anticipated that they may do so in the future) as a result of either the introduction of new examinations or procedures, or a change in the nuclear medicine facility’s equipment. The RPO should decide who should be monitored and at which monitoring sites.
Individual monitoring results must be analysed and records must be kept. It is vital that the individual monitoring results are regularly assessed, and the cause of unusually high dosimeter readings should be investigated by the RPO, with ensuing corrective actions where appropriate. The administrative arrangements, the scope and nature of the individual monitoring records, and the length of time for which records have to be kept may differ among countries.