Programme Implementation

On this page

1. Introduction to Nuclear Medicine Facilities
2. Site planning
3. Radiation protection of patients in nuclear medicine
4. Radiation protection of workers and the public in nuclear medicine
5. Prevention of incidents in nuclear medicine
6. Radiation protection – calibration
7. Radiation protection – general/quality practice
8. Radiation protection – PET/CT shielding
9. Radiation protection – waste
10. Department design
11. Equipment selection
12. Medical physics staffing

Introduction to Nuclear Medicine Facilities

Medical exposure is the largest human-made source of radiation exposure, accounting for more than 95% of radiation exposure. Furthermore, the use of radiation in medicine continues to increase worldwide. More machines are accessible to more people, the continual development of new technologies and new techniques adds to the range of procedures available in the practice of medicine and the role of imaging is becoming increasingly important in day to day clinical practice. Worldwide, the total number of nuclear medicine examinations is estimated to be about 35 million per year. Radiation can cause healthy cells to become malignant or bring about other detrimental functional changes. Therefore, a system of radiation protection and proper planning and design of the nuclear medicine facility is essential.

These considerations allow the many beneficial uses of radiation while simultaneously ensuring detrimental radiation effects are either prevented or minimized. This can be achieved by having the objectives of preventing the occurrence of deterministic effects (e.g. tissue reactions) and limiting the probability of the stochastic effects (e.g. cancer and heritable) to a level that is considered acceptable. In a nuclear medicine facility, consideration needs to be given to the patient, the staff involved in performing the nuclear medicine procedures, members of the public and other staff that may be in the nuclear medicine facility, carers and comforters of patients undergoing procedures and persons who may be undergoing a nuclear medicine procedure as part of a biomedical research project. Additionally, the location, general building requirements, radiation source security and storage as well as structural shielding of a nuclear medicine facility within a hospital or clinic need to be considered within a proper radiation protection system.

Site planning

In order to reduce or minimize the harmful effects of ionizing radiation while being able to utilize its beneficial effects, it is important to provide a proper radiation protection system. Such a system needs to guarantee that all personnel involved in protection and safety are qualified, appropriately trained, ?and knowledgeable so that they understand their responsibilities and perform their duties according to defined procedures. In addition, a nuclear medicine facility within a hospital or clinic needs to consider and fulfil certain criteria in order to provide proper radiation protection.

Important Principles?

The location of the nuclear medicine facility within the hospital or clinic should be readily accessible, especially for outpatients who constitute the majority of patients. The facility should also be located away from radiotherapy sources and other strong sources of ionizing radiation such as a cyclotron, which can interfere with the measuring equipment. Isolation wards for patients treated with radionuclides should be located outside of the nuclear medicine facility. Furthermore, it is essential to reduce uncontrolled spread of contamination. This will be achieved by locating rooms for preparation of radiopharmaceuticals as far away as possible from rooms for measurements and patient waiting areas. Another important factor is to reduce the transport of unsealed sources within the facility.

The design of the facility should take into consideration the type of work to be performed and the radionuclides (and their activity) intended to be used. Based on the ICRP’s (International Commission on Radiological Protection) concept of categorization of hazards, the different rooms in the facility will be categorized as low, medium or high hazard areas which helps to determine the special needs concerning ventilation and plumbing, and the materials used in walls, floors and workbenches. The floors and workbenches should generally be finished in an impermeable material which is washable and resistant to chemical change, with all joints sealed. The floor cover should be curved to the wall. The walls should also be easily cleaned. Chairs and beds used in high hazard areas should be easily decontaminated. Rooms in which unsealed sources, especially radioactive aerosols or gases, may be produced or handled should have an appropriate ventilation system and a separate bathroom for the exclusive use by injected patients is recommended.

Radiation protection of patients in nuclear medicine

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.?
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/CT.?Pregnant 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.

Radiation protection of workers and the public in nuclear medicine

Nuclear medicine involves handling of radioactive materials that can give rise to external and internal exposure of staff. The magnitude of exposure depends on radionuclide, its activity and type of work within a department in which the person is involved. Relatively newer imaging modality that involves use of positron-emitting radionuclides for PET scanning has lead to the increased exposure of staff. Within the field of therapeutic application in nuclear medicine, new agents with beta emitters of higher therapeutic effectiveness have been used. In line with increasing number of medical procedures involving beta emitting radionuclides, extremity doses and possible skin contamination of nuclear medicine staff is of special concern.

The public can be exposed to radiation from a patient as external radiation emitted from the patient, internal contamination from radioactive body fluids and through multiple environmental pathways.

Radiation protection in nuclear medicine is concerned with the control of both normal and potential exposure of workers in all situations that involve use of unsealed sources of radiation.

Important principles

The principles of the protection of workers from ionising radiation in all areas of medicine are directed at prevention of deterministic effects and minimization of risk for stochastic effects (cancer).? These principles include use of dose limits for workers and general public and “As Low As Reasonably Achievable” (ALARA) principle to keep doses well below the dose limits.

The control of occupational exposure in nuclear medicine is effectively utilised by numerous actions as: design of facilities, designation of workplaces in control and supervised areas, individual monitoring arrangement, area monitoring, monitoring for contamination, use of personal protective devices and? protective tools as appropriate, following the local rules and procedures for safe handling of radiopharmaceuticals and appropriate education and training. The principles apply to all situations that involve handling of unsealed sources of radiation and where in addition to external exposure, the contamination of staff and working environment may occur. ?

Public access to designated areas in hospitals and nuclear medicine departments is restricted and limited in terms of its duration. Radiation protection of the public will therefore be efficiently utilised by shielding of the radiation sources, proper design of a facility, access restriction and by safe working procedures followed by the staff members.

Dose limits are introduced to ensure that the occupational exposure of any worker is controlled and below a certain effective dose per time period, as outlined in the International BSS. In nuclear medicine, total dose includes both internal and external exposure to ionising radiation. The sources of exposure of the general public are primarily the same as for workers. However, based on the level of acceptable risk, different dose limits apply for members of the public than for workers.

In nuclear medicine it is common that family member(s) of the patient (attendants) need to look after the patient at home who has been administrated radioactivity. This is not restricted to children or seriously ill family members but may apply to any member of the family. Moreover proximity to radioactive patient during travel from hospital to home is also a source of radiation exposure to attendant. The attendant comes in category of individuals who voluntary support or comfort patients undergoing procedures that involve ionizing radiation exposure. ?Further details on radiation protection of general public are available at Radiation Protection of Patients (RPoP) website.

The?Radiation Protection of Patients (RPoP)?website contains information to help health professionals achieve?safer use of radiation in nuclear medicine, also from the viewpoint of occupational and public exposure. This website also contains training material on?radiation protection in nuclear medicine?and?radiation protection in PET/CT?including specifically radiation protection of workers and the public.

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.

Prevention of incidents in nuclear medicine

Incidents in nuclear medicine can vary from a mild spillage to something that can have devastating implication such as misadministration of therapy dose of radioiodine to a lactating mother. Most of incidents remain unreported and that creates all problems in analysing and bringing out lessons. Misadministration is the commonest incident. ?Misadministration means giving the radiopharmaceutical to the wrong patient, giving the wrong radiopharmaceutical or wrong activity to the patient, or unjustified examination of pregnant or lactating female patients. Another type of misadministration is to use the wrong route of administration, which includes complete extravascular injections that can result in very high absorbed exposure at the injection site especially if the volume is small, the activity is high, and the radiopharmaceutical has a long retention time.

Important principles

A patient undergoing diagnostic and therapeutic procedure will be exposed to many potential risks (probability of harm) besides exposure to ionizing radiation. Each risk deserves due consideration. The radiation risk is low in many instances and the consequences of that risk in most of the cases are not severe, but in some they are.?

A review of lessons learned from misadministrations in the past, indicate that many of these have occurred under certain conditions, as: communication problems, busy environment, distraction, not following local rules, lack of training in emergency situations, undefined responsibilities or inefficient or missing quality assurance (including audits to reveal deficiencies and procedures to deal with emergency situations). If such events occur, the primary actions to be taken include the following: immediate use all available means to minimize any adverse effects, informing responsible nuclear medicine physician, patient and referring physician, dose calculation,?? implementation of corrective measures, and informing all staff of the incident and the corrective measures.

The?Radiation Protection of Patients (RPoP)?website contains information on?misadministrations,?incidents and accident?and?pregnancy and nuclear medicine, all to help health professionals? prevent incidents in nuclear medicine. This website also contains training material on?radiation protection in nuclear medicine?and?radiation protection in PET/CT.

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.

Radiation protection – calibration

The primary objectives of calibration are:

1. To ensure that an instrument is working properly and hence will be suitable for its intended monitoring purpose.
2. To determine, under a controlled set of standard conditions, the indication of an instrument as a function of the value of the measure and (the quantity intended to be measured). This should be done over the complete range of indication of the instrument.
3. To adjust the instrument calibration, if possible, so that the overall measurement accuracy of the instrument is optimized.

The IAEA has put together a?report?intended to serve those who are establishing or operating calibration facilities for radiation monitoring instruments, and a comprehensive range of calibration equipment and techniques. ?In addition to presenting a description of calibration facilities and procedures, this Safety Report includes appropriate definitions and describes appropriate methods for the statement of uncertainties in measurements.

Additional information can be found here

Radiation protection – general/quality practice

The?International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources?(the 'Standards' or the 'BSS') were published by the IAEA in 2014 and jointly sponsored by EC, FAO, ILO, OECD/NEA, PAHO, UNEP, WHO. This publication was the culmination of efforts towards harmonization of radiation protection and safety standards internationally.

The purpose of the Standards is to establish basic requirements for protection against the risks associated with exposure to ionizing radiation and for the safety of radiation sources that may deliver such exposure.

The IAEA has also published?Applying Radiation Safety Standards in Nuclear Medicine, Safety Reports Series No. 40, which provides guidance on how regulatory requirements are to be fulfilled with respect to Nuclear Medicine practice. The objective of this safety report is to assist regulatory bodies in preparing regulatory guidance on the proper and consistent application of basic requirements of the BSS, by the legal persons responsible for the nuclear medicine practice. The report is applicable to all the established uses of ionizing radiation sources employed in the practice of nuclear medicine, to the facilities where the sources are located and used, and to the individuals involved. The guidance covers occupational, public, medical, and potential and emergency exposure situations.

Radiation protection – PET/CT shielding

Shielding considerations for PET/CT systems must take into account the photon radiation in both the diagnostic imaging energies presented by the CT (<200 keV), as well as the energies resulting from the PET imaging (511 keV). Shielding also needs to be designed to take into account high flux radiation from the CT, as well as the radiation that comes from a patient's taking into account the entire time the patient is present after they are administered with a radiopharmaceutical (because they become a radiation source).?

Two useful documents are available for guidance on PET/CT?sheilding.

The IAEA has produced a?document?which outlines shielding and other considerations in PET/CT. This report is directed primarily at facilities adopting PET/CT technology, and focuses on radiation protection issues. The main topics discussed in this document includes:

• Current PET/CT technology
• Clinical methodology
• Radiation exposure of patients undergoing PET/CT examinations
• Patient dose management
• Radiation protection of the staff in a PET/CT facility
• Training
• Summary of guidance

The AAPM?has also produced a guidance?document, which?outlines many issues relative to PET/CT shielding, including:

• Positron-emitting radionuclides
• Factors affecting radiation protection
• Rb-82 myocardial perfusion PET studies.
• How F-18 FDG PET studies are performed.
• Transmission sources
• Radioactivity administration
• Factors affecting dose rates from Radioactive patients
• Uptake room calculation
• Imaging room calculation
• Calculation for rooms above and below the PET facility
• Dose levels in controlled areas
• Adjacent rooms on the same level in controlled areas
• Design considerations
• PET/CT installations
• Shielding of the PET tomography from ambient radiation
• PET facilities located in Nuclear Medicine departments

Radiation protection – waste

Radioactive materials have been found to be very effective when used in a variety of medical applications for diagnostic, therapeutic and research purposes. As a consequence of handling these materials, a wide range of radioactive waste is produced. The amount and types of these wastes varies depending on the scale of the medical application and the radionuclides involved. The waste that is generated during the different applications of radioisotopes in medicine or biological research is considered as biomedical radioactive waste.

The IAEA has put together material highlighting and discussing important issues relating to radioactive waste in nuclear medicine, including:

• Basic requirements
• Legal framework
• Waste collection, segregation, and storage
• Waste treatment and disposal

Department design

The design of a nuclear medicine department needs to consider certain criteria in order to guarantee efficiency, safety and security standards. Every nuclear medicine facility is unique and there is no one design that can be applied to all situations. The requirements of a single camera practice using only ^99mTc radiopharmaceuticals will be very different from a large teaching hospital with PET facilities and in-patient radionuclide therapy rooms. Nevertheless, there are simple criteria that can be applied in almost all facilities to assure quality and safety standards are met.

Important Principles

A typical nuclear medical physics department consists of its own radiopharmacy and certain imaging devices, such as a PET/CT (Positron Emission Tomography/Computed Tomography) scanner. The following criteria can help guarantee a certain standard within a nuclear medicine department:

Radiopharmacies

• The radiopharmacy should be located in an area that is not accessible to members of the public, however there should be easy access to the injection and imaging rooms to minimize the transportation distances.
• There should be an area within the radiopharmacy designated as a non-active area used for record keeping and computer entry.
• A dedicated dispensing area with a body shield and lead glass viewing window is required (the thickness of the shield and window will depend on the radionuclides in use).
• The radiopharmacy needs to contain facilities for radioactive waste disposal that normally include separate shielded storage bins for short lived radionuclides, such as ^99mTc, and for radionuclides with longer half-lives, such as ¹³¹I. In addition, there must be a shielded container for sharp waste items, such as syringes with needles.
• Wall, floor and ceiling surfaces should be smooth, impervious and durable in order to facilitate any radioactive decontamination.
• Hand and eye washing facilities must be available which can be operated without the use of the operator’s hands to prevent the spread of any contamination.
• A contamination monitor must be available in a readily accessible location.
• Radioactive materials are at most risk of being stolen or lost when they are being transported to and from the facility. Therefore, all deliveries must be signed for by a designated stuff member and the material needs to be safely unpacked and stored within the department.

Imaging devices

• The location of nuclear medicine imaging devices need to be considered with all the occurring advantages and disadvantages as it affects the flow of patients, materials and radiation protection.
• Different functions and activities should be allocated to areas with either low risk of significant radiation exposure (“cold” areas) or with high risk of radiation exposure (“hot” areas).
• The reception (arrival of patients), waiting room, consulting room, storage of cleaning utilities and offices should be located at low risk areas.
• The preparation room, injection and uptake room, patient toilets, control and scanning room, post-examination waiting room, reporting room and waste disposal room should be allocated in high risk areas

Equipment selection

The quality and reliability of imaging instrumentation is critical to the practice of nuclear medicine and adds to the complexity of making decisions on equipment purchases. Selection criteria should include flexibility in use, reliability and backup, and features determined by the desired function. It is important to ensure equipment is specified to meet full requirements and, where possible, contractual conditions are in place to ensure the performance of the delivered system. The instrumentation in nuclear medicine falls logically into three main sections: single photon imaging instruments (including SPECT), dual photon imaging instruments (combining the various approaches to PET) and various other non-imaging instruments.

Important principles

The reason for buying a new imaging system should be considered carefully. An appropriate configuration should be selected to best match the desired end-application, bearing in mind that the system may need to be used for other functions in the future. ?In considering the overall cost of a system, maintenance contract costs should be included and considered essential. In some circumstances, the system purchased should be compatible with existing systems in the department. Advantages include the familiarity of staff with operation, sharing of accessories and proven availability of support.

It is recommended that a single-head gamma camera with computer and SPECT capability is considered the minimum level of equipment for a new nuclear medicine department, although a dual-head camera may be considered more cost effective. The conventional gamma camera forms the basis of systems used for solely planar imaging. Mounting a single head on a rotating gantry enables the system to be used for tomographic imaging. To a large extent the versatility of the conventional gamma camera is a strength and the design of gamma cameras has improved dramatically over time. Although there have been various attempts to design specialized gamma camera systems for specific applications, in general the more successful designs are those that provide flexibility. In many centres, the camera is required for various applications, however at the time of purchase, it is often difficult to know all uses in advance. A system that permits efficient SPECT acquisition without compromising the utility for planar imaging is particularly attractive. Provided this flexibility is maintained, a dual head system has the advantage of improved throughput, and the low likelihood of both heads having problems means that a single-head can be available for continued operation, even when the second head is non-functioning. A dual head system also offers the possibility for dual photon imaging. It is this flexibility that has resulted in the dual head camera being the most popular system. Although more expensive than a single-head system, the dual head system is cost effective in terms of both throughput and flexibility.

The addition of a nuclear medicine facility must include equipment for handling, storage and disposal of radioactive material in gaseous, liquid, and solid form. In order to monitor radiation levels in the working environment personnel dosimeters, contamination monitoring instruments and radiation field monitoring instruments need to be provided.

The IAEA manual Nuclear Medicine Resources provides detailed information about considerations that need to be kept in mind during the selection of the equipment for a nuclear medicine facility. In addition, the manual takes account to the planning of a nuclear medicine facility and the demands to human resources. The IAEA reference book Nuclear Medicine Physics gives a comprehensive overview to the topic of nuclear medicine in general.

Medical physics staffing

The aim of medical physics services in diagnostic imaging and radionuclide therapy is to improve patient care through better safety, effectiveness and efficiency in diagnosis and treatment. In order to plan and initiate new services, as well as expand or upgrade existing services, there is a need to provide guidelines that recommend appropriate staffing levels of medical physics services. The medical physicist is a member of the multidisciplinary team involved in diagnosing and treating patients with ionizing and non-ionizing radiation and contributes to ensuring a high standard of quality of service in hospitals and clinics.

Important principles

The number of medical physicists needed in a hospital or medical physics department in order to fulfill the required services and guarantee a certain quality standard depends on several factors. These include the equipment, types of treatments, radiation protection regulations and additional academic teaching or research duties. Equipment associated duties of a medical physicist involve periodic equipment performance tests , tests after major maintenance procedures and evaluation and documentation of routine quality controls. Therefore, the equipment related need for a medical physicist strongly depends on the amount and complexity of the available equipment. Patient or treatment associated duties involve patient specific dosimetry in radionuclide therapy, radiation safety for patient management and patient dosimetry and risk assessment for individual patients (i.e. pregnant woman). Development of radiation management plans, general protection aspects for radiation and risk assessment, administration related to radiation licensing, waste management and dose monitoring of staff cover the radiation protection duties of a medical physicist. In addition, medical physicists play a role in the academic education of health professionals and students, and in research and development. The medical physicist evaluate new technologies and investigate the adoption of new procedures, assisting in the training of clinical staff for their implementation. They support the physical and technical aspects of clinical research and often have a leading role in the medical research team, particularly in centres of high technological complexity.

References

The reference book Nuclear Medicine Physics (IAEA) represents a detailed and comprehensive source of information in nuclear medicine physics in general and also provides guidelines for more specific topics as for example radiation protection. Further information is also provided in the IAEA Human Health Series No. 11: Planning a Clinical PET Centre, the IAEA Human Health Series No. 14: Planning National Radiotherapy Services: A Practical Tool?and the IAEA manual on Nuclear Medicine Resources.