Nuclear Medicine Resources Manual

Подождите немного. Документ загружается.

CHAPTER 8. RADIATION SAFETY PRACTICE IN NUCLEAR MEDICINE

520

(a) Pregnant staff.

(b) Radiopharmacy staff, for whom finger dose monitoring (special small

TLD badges that fit onto a finger) may be used. Finger doses will be very

much higher than body doses, especially with PET radiopharmaceuticals.

Finger badges must of course be worn underneath gloves.

then they should be regularly monitored, otherwise monitoring need only

be carried out for each case. This applies especially where the patient

needs a higher level of nursing care, such as in MIBG therapy. Here,

electronic direct reading dosimeters are advisable to allow continuous

knowledge of the total dose. Records must also be kept of these readings.

8.9.1.2. Routine and area monitoring

Routine and area monitoring covers regular surveys of the radiation

background in critical areas such as the radiopharmacy. These allow practices

and safety measures to be modified before staff doses increase, particularly

when new radiopharmaceuticals, radionuclides or increased activities are

involved.

The radiopharmacy should have a permanent area monitor (scintillation

counter or ionization chamber), with an audible signal for dose rate, to allow

staff to know when radioactive sources are exposed.

8.10. RADIATION SAFETY INFRASTRUCTURE

Each hospital or institute with a nuclear medicine facility should have

some form of radiation safety infrastructure body, established according to

local regulatory requirements. Typically this would be a radiation safety

committee with the responsibility for overseeing radiation safety practices in

the hospital, and advising the administration on radiation safety issues. Repre

sentation from the nuclear medicine section is very important and should be

mandatory. Often, the nuclear medicine physician or physicist is the only

person who can provide expert advice on internal radionuclide dosimetry, and

in investigation of radiation incidents where unsealed radionuclides are

involved.

The committee should have among its responsibilities the following:

—Review of staff radiation dose records, especially abnormally high doses;

—Review of radiation safety protocols;

—Approval of applications for licences under radiation legislation;

8.10. RADIATION SAFETY INFRASTRUCTURE

521

—Investigation of radiation incidents and accidents;

—Review of applications for research projects where radionuclides are

involved, especially where volunteers may receive a radiation exposure.

The hospital should also appoint an appropriately qualified and

experienced person as the radiation safety officer. Nuclear medicine physicists,

physicians or technologists are usually good candidates for this role.

523

Chapter 9

NUCLEAR MEDICINE: FUTURE TRENDS

Nuclear medicine is an evolving science. While this is common to all

medical specialties, it is particularly true for nuclear medicine because of its

relationship to, and dependence on, high technology advances. Rapidly

developing areas such as electronics, physics, computer sciences, radio

pharmacy and radiochemistry, as well as molecular biology, are closely related

to nuclear medicine so that this medical science not only follows developments

in such areas but also provides feedback to them. Some particular areas

regarding recently achieved advances or future potential ones in nuclear

medicine are worth highlighting.

9.1. ELECTRONIC DATA TRANSFER

The delivery of comprehensive nuclear medicine services to patients and

referring physicians is increasing around the world. The range and benefits of

these procedures, both diagnostic and therapeutic, are gaining in both

recognition and appreciation. Their role in medical decision making, as part of

standard patient care, helps fulfil an otherwise unmet need. The centralization

of nuclear medicine and radiopharmaceutical services is leading to a hub and

spoke concept. This means that patients may be studied in a peripheral hospital

according to the agreed protocols set out in this manual, and the data

transferred to a central point for analysis and reporting. This concept is parti

cularly appropriate in the case of advanced techniques. Just as in the past the

success of RIA depended on an efficient postal service, so the future successful

distribution of nuclear medicine services may depend on high speed image data

transfer.

Nuclear medicine is one of the areas to benefit most from advances in IT,

especially through the widespread use of personal computers and the Internet.

Many nuclear medicine centres are now fully digitized and electronically

connected to permit clinical study file exchanges, teleconsultations, remote

reporting, collaborative research and tele-education through PACSs of

increasing efficiency. This in turn enables nuclear medicine physicians to assist

colleagues who work in new centres or in remote areas. Telenuclear medicine

practices have proved to be cost effective and to have a very bright future in

promoting the development of the specialty, particularly in developing

CHAPTER 9. NUCLEAR MEDICINE: FUTURE TRENDS

524

countries. The core part of telenuclear medicine is image transfer over the

Internet. Simple telenuclear medicine practice requires an image acquisition

site coupled with an image interpretation site. In order to provide additional

information, a digital film scanner is needed at the acquisition site so that X ray

films, CT or MRI images may be used for comparison. In advanced telenuclear

medicine networks, different sites should have the same system configurations

to ensure basic compatibility and interoperability, enabling image acquisition,

data analysis and data interpretation. It is important, however, to ensure the

confidentiality of patient data at all times.

The Internet has provided many new opportunities for education in

nuclear medicine through distance learning. Universities, scientific societies

and international organizations can place a range of teaching resources — slide

shows, multimedia teaching packages, relevant textbooks and documents, and

digital case study files — on the Internet, for easy access and downloading.

Teaching materials on the Internet can be used for both education and on-the-

job training in nuclear medicine. Staff members can tailor these materials and

design their own purpose made teaching packages. Teaching resources can also

be stored on CD-ROM or other universal mass-storage devices so that these

resources can be accessed from any conventional computer system. This is

particularly useful when there is no Internet connection available or telephone

links are too slow for image file transfer.

Advances in telecommunications have opened a new horizon for the

promotion of nuclear medicine around the world. Telenuclear medicine will

continue to develop quickly once some of the problems, such as the issue of

licensing, standards, reimbursement, patient confidentiality, telecommuni

cation infrastructure and costs, have been solved. Ultimately, its cost effec-

tiveness and far reaching impact will make telenuclear medicine an extremely

useful tool, particularly for developing countries.

9.2. RADIOIMMUNOASSAY AND MOLECULAR BIOLOGY

The future of RIA will depend on the overall economic development of a

country as well as the degree to which the country embraces biotechnology and

information technology. In most developing countries, socioeconomic

conditions are likely to remain poor. After careful consideration of the local

infrastructure, robustness and cost of nuclear and non-nuclear assays, it is likely

that bulk reagent methodology will still be the main workhorse of routine

diagnostic services. Quality control will remain a key ongoing continuous

activity to assure the quality of results.

9.2. RADIOIMMUNOASSAY AND MOLECULAR BIOLOGY

525

In economically stronger countries, RIA will be carried out in national

reference laboratories and used as the reference method to solve problems

generated by non-isotopic immunoassay. With the use of modular robotic

systems and improved antibody design for short incubation assays, RIA may be

modularly automated to reduce further operating costs. It is well suited to

nationwide targeted screening of congenital diseases and other disorders. This

can also be implemented in countries with low gross national products.

In more developed countries, the establishment of indigenous immuno-

diagnostics will become one of the essential components of a comprehensive

biotechnological strategic plan. Here RIA will play an important role in early

screening of hybridoma clones in the monoclonal antibody production process.

It will also be used to set up the first workable immunoassay methodology for

new analytes before they are thoroughly evaluated and marketed or

transformed into other commercial assay formats.

In the field of research, RIA will continue to be used as the gold standard

in the search for novel solid phase, cost effective methods of protein immobili

zation and cheaper high affinity binders to improve the overall minimal

detection limit of immunoassay. Being a reliable methodology, it is an ideal tool

for the development of consensus investigative protocols in evidence based

diagnostic medicine. The wealth of the knowledge base in RIA should be

systematically documented in the format of an interactive multimedia learning

resource for self-directed learning, thus further reducing the cost of training.

In the near future, the exact role of thousands of genes will be charac-

terized by the human genome project. Other bacterial, protozoan, helminthic,

viral and fungal genomes have already been, or will be, elucidated very soon.

The most important application of this variety of sequences will be in

diagnostics. Current diagnostic methods can be slow and relatively insensitive,

lack specificity, require invasive clinical samples and, moreover, fail to provide

quantitative information about the disease. Molecular methods, based on

published sequences, will overcome these constraints to a significant extent.

Other applications of molecular methods will be as prognostic markers for

cancer, drug resistance indicators, predictive markers for malignant and degen

erative disorders, models for molecular modelling for drug design, gene

therapy, pathogenicity evaluation, detection of minimal residual disease,

molecular epidemiological information and control measures, and the

detection of new emerging diseases.

Technical trends that will be used in the above applications are quanti-

tative, multiple and in situ PCR, multiple DNA sequencing and diagnosis by

hybridization with enriched stable isotope labels using mass spectrometry,

peptide nucleic acid probes that provide faster results than traditional DNA

probes, DNA biochip technology, where distinct probes can be linked to an

CHAPTER 9. NUCLEAR MEDICINE: FUTURE TRENDS

526

inert support and hybridized with the test DNA from clinical samples,

phosphor imagers that detect beta and gamma radiations, as well as X ray

techniques with improved sensitivities compared with those of autoradio

graphy, protein tests and functional genomics.

9.3. IMAGING AND THERAPY

9.3.1. Instrumentation and image processing

Magnification scintigraphy enhances the spatial resolution of nuclear

medicine images to a level comparable to those of radiography, CT scanning

and MRI, and considerably raises the diagnostic accuracy. The dual head mode

generates a pair of high resolution images at one time. Pinhole SPECT, a hybrid

of the pinhole magnification technique and SPECT, can portray parts of small

bones and joints and can detect a subtle increase in bone metabolism at the

insertions of tendons and ligaments. Future development of gamma camera

systems dedicated to magnification scintigraphy will open new opportunities in

nuclear medicine imaging.

The use of multifunctional and hybrid SPECT–PET cameras, as well as

dedicated PET cameras and PET–CT systems, will increase and become

available to more institutions. More interaction with other imaging modalities

is expected in order to use the X ray CT information for rigorous attenuation

correction and image registration.

New semiconductor detectors are being developed that allow for the

manufacturing of specially dedicated cameras with versatile detector sizes and

shapes, exhibiting outstanding sensitivity and resolution never achieved before

by a nuclear medicine instrument. These new detectors will also be more

portable and will permit bedside examinations, as well as coupling with other

non-nuclear devices such as mammographs to obtain high resolution functional

imaging with full co-registration to facilitate comparison with structural data

and improve interpretation.

Iterative SPECT reconstruction algorithms are now increasingly

available in view of the powerful processing capabilities of modern computer

systems. These algorithms yield more accurate trans-sectional data, improving

tomographic resolution and avoiding some common image artefacts.

Attenuation correction with line source devices or transmission–emission

hybrid CT–SPECT instruments can significantly improve diagnostic specificity.

Gated SPECT will continue to represent a valuable clinical tool for the simulta

neous assessment of myocardial perfusion and function.

9.3. IMAGING AND THERAPY

527

9.3.2. Clinical applications

The use of sentinel node scintigraphy and other intraoperative applica-

tions of probes will increase in their clinical application to a more compre-

hensive approach to surgical oncology and other non-oncological indications.

Imaging probes are also being developed with the use of semiconductor

technology, which will aid in intraoperative localization of the target organ or

tissue.

PET imaging using

F-FDG will expand, especially in oncology, and will

find new applications even in benign diseases. With the use of special PET

tracers it will be possible to image hypoxic cells and apoptotic cell death.

Procedure reimbursement will extend to other applications as evidence

accumulates in favour of its utilization. Single photon oncological applications

of non-specific tumour seeking agents such as

Ga,

201

Tl and

99m

Tc-MIBI will

be replaced to a great extent by

F-FDG imaging and by SPECT studies using

more specific

99m

Tc labelled peptides and genetically engineered monoclonal

antibodies. Infection remains a major challenge, although the development of a

radiolabelled antibiotic for imaging bacterial infection including tuberculosis

through an IAEA Coordinated Research Programme may not only identify the

presence and site of infection but also indicate the efficacy of treatment.

The primary basis of nuclear medicine is the tracer technique. Nuclear

imaging will become a reference procedure for absolute measurement of

physiological and pathophysiological processes for both clinical and research

purposes. Receptor tracers are being developed that allow for quantitative and

qualitative evaluation of organ functions. Receptor imaging with SPECT and

PET will permit advances in the understanding of the complex functions of the

brain, aiding in the management of various neurological and neuropsychiatric

disorders. Cardiac receptor imaging will be used for more accurate prognosis

and management of heart diseases, while other receptor techniques will be

employed in oncology for tumour detection and characterization, as well as for

selection of the most appropriate therapeutic approach.

Nuclear cardiac testing will consolidate as the non-invasive gold standard

procedure for ischaemic heart disease. Furthermore, its applications may

expand in view of the possible use of electron beam computed tomography as a

screening procedure for the detection of coronary artery calcifications in high

risk patients.

9.3.3. Therapy

Radionuclide internal targeted therapy will expand generally. Radio-

labelled peptides emitting beta particles and radiolabelled monoclonal

CHAPTER 9. NUCLEAR MEDICINE: FUTURE TRENDS

528

antibody derivatives will be increasingly employed in specialized centres, as

well as alpha emitting radionuclides for both palliative and curative purposes in

oncology. Other transarterial radioconjugates are being evaluated for liver

cancer. These agents will be used in conjunction with tracer doses to evaluate

the progress of the treatment, and will constitute a method complementary to

other conventional procedures or even become the treatment of choice for

some malignant and non-malignant diseases. The radiobiological basis of low

dose, long lived radionuclide therapy will be investigated and will probably

lead to new therapeutic strategies.

9.4. COMPETENCE AND EDUCATION

The range and quality of services should continue to improve.

Departments of nuclear medicine will be expected to meet internationally

recognized ISO quality standards for service as well as for the environment.

These will in turn lead to accreditation procedures not only for the continuing

competence of staff but also for the quality of the facilities and the documen

tation of patient protocols and procedures. With evolving and more complex

techniques available, the challenge is evident for all members of the nuclear

medicine team, from physicians to technologists and from physicists to radio

pharmacists. Hence, more intensive and extensive training and better

continuing education programmes and activities are needed if reliable results

are to be obtained and a sustainable growth of the specialty is to be achieved.

Nuclear medicine is underutilized in most countries. As Dr. H.N. Wagner,

Jr., likes to say, “Nuclear medicine is the best kept secret in medicine”. That

means that nuclear medicine specialists and scientists have to work harder to

spread the large amount of information available that favours the use of

nuclear techniques for a vast range of clinical applications. Evidence based

medicine practice is already becoming standard worldwide, so both individual

practitioners and institutions will increasingly include nuclear medicine

procedures in their diagnostic and treatment algorithms. Emphasis must be

placed, however, on cost effectiveness in order to abolish the argument that

procedures are too expensive and to demonstrate the innocuousness of the low

dose radiation used in most procedures.

Universities, nuclear medicine societies and associations, commercial

companies as well as international institutions like the IAEA are expected to

play a major role regarding all the above mentioned aspects. Linking the key

professional bodies of nuclear medicine with the IAEA and the use of

electronic journals should improve the communication between practitioners

of nuclear medicine, especially in developing countries.

9.4. COMPETENCE AND EDUCATION

529

For nuclear medicine, the future is bright. It only depends on us to make

the future prospects become reality.