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State radiation regulators have a broad scope of regulatory authority. They are responsible for regulating both man-made and naturally occurring radioactive material, radiation-producing machines, and nonionizing sources of radiation. This broad-scope authority presents challenges to state radiation regulatory agencies that must implement and maintain a regulatory framework that incorporates radiation safety principles for all types of uses, without unduly hindering effective use of sources of radiation. The challenges include resource allocation, prioritization of risk in order to appropriately allocate resources, and the ability to effectively predict and respond to changing risk-informed priorities. Changes in radiation protection principles and policies must be accomplished through a partnership of stakeholders to be most effective and to meet these challenges.
It has been shown that unithiol diminishes toxic action of cysteamine, AET, and disulfide of WR-1065 on mice. This permits to enhance protection of animals against X-rays by increasing of protector doses. The effect of unithiol on cysteamine action in rats was the same. Antitoxic effect of unithiol on cysteamine was shown both at i.p. and p.o. protector administration. The effect was also revealed in Chinese hamster V-79 cell culture. Combined disulfide of cysteamine and unithiol was synthetized, which ensures effective prolonged protection against ionizing radiation.
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Funding for radiation protection science and policy has been in decline for more than a decade. Agencies that set policies and standards for radiation protection depend on external expert groups for advice, and unless the funding situation is stabilized, the ability of these advisory organizations to provide timely advice will be compromised. This paper examines the history of radiation protection policy in the United States, reviews the funding patterns of international and national radiation protection advisory bodies, and suggests recommendations for assuring that radiological and radiation protection science remains an important part of the nation's public health policy agenda. Five major advisory organizations are the focus of this paper--ICRP, ICRU, NCRP, National Research Council BEIR Committees, and UNSCEAR. The recommendations developed in this paper address the following issues: (1) the need to coordinate activities among national and international advisory bodies in order to minimize overlap of work scope and ensure comprehensive coverage of major radiation protection issues; (2) the need to reevaluate activities and operations of advisory groups in the context of an ever-changing radiation protection landscape; and (3) the need to establish the NCRP as the major federal advisory organization for radiation protection in the United States and to stabilize funding through Congressional appropriations.
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Radiation-induced acute and late injuries often represent a limit to the optimal delivery of radiotherapy in cancer patients. Chung et al. reported that histone deacetylase (HDAC) inhibitors, a novel class compound of gene modulators, might have a role in controlling different adverse effects from radiotherapy in preclinical models. They also showed how protection of normal tissues and inhibition of tumor growth might be possible at the same time.
Not all operational radiation protection situations lend themselves to simple solutions. Often a Radiation Protection Program must be developed and implemented for difficult situations. A defense in depth approach to radiation protection was developed for 125I production activities. Defense in depth relies on key radiation protection elements that tend to be mutually supportive and in combination provide reasonable assurance that the overall desired level of protection has been provided. For difficult situations, defense in depth can provide both a reasonable and appropriate approach to radiation protection.
It appears that AB-132 potentiates radiation effects, and the local application of AET (MEG) protects the intestinal tract, the bladder and the skin against radiation toxicity. Combined use of selective radiation sensitizing and protecting agents may be considered for clinical studies.
The current status of radiation protection in Canada has been summarized in the present paper, the first of a three-part series. Particular emphasis has been placed on the role of the Radiation Protection Division of the Department of National Health and Welfare. Somatic and hereditary effects of radiation exposure are briefly discussed as a basis for an understanding of the radiation protection standards which have been developed at national and international levels. The rapid increase in use of radioactive materials and x-ray apparatus in medicine, industry and research, and the extensive atmosphere testing of nuclear weapons have led to the development of comprehensive radiation protection activities in Canada, especially in the Department of National Health and Welfare. Well-established lines of communication and liaison exist among the various agencies responsible for these activities.
One usually thinks of radiation safety as keeping patient and personnel exposure as low as reasonably achievable; however, radiation protection activities play an important role in quality assurance for both the clinical and physical aspects. Radiation protection has several aspects: The first step is the design of the irradiation device and its shielding. While this step is out of the hands of the user, the location and level of leakage radiation must be verified by the user. Periodic leak testing of sealed sources is required. Room shielding design is based on the leakage levels specified by the manufacturer and on levels of scatter and primary radiation impinging on the radiation barriers. The addition of shielding for photoneutrons should be planned for accelerators producing photons above 10 MeV. Integrity and adequacy of shielding should be verified by survey after unit installation. Installation and periodic testing of interlocks are necessary to assure that nonirradiation conditions can be restored as soon as necessary. Personnel monitoring serves two purposes; to provide a record of personnel exposures and to alert one to unsuspected changes that may have taken place in procedure, shielding integrity, or source location. Area monitoring and survey on a periodic basis also provides knowledge of unsuspected changes in procedure, shielding integrity, or source location. Brachytherapy and the transport of small radiation sources require additional precautionary actions. Protection of patient anatomy not being treated reduces the chance of normal tissue damage and the possibility of carcinogenic effects.
A scattered dose and a surface dose from phantom measurements during interventional procedures with computed tomography (IVR-CT) were evaluated. To reduce the personnel exposure in IVR-CT, the new protective devices were developed and its effect evaluated. Two radiation protection devices were experimentally made using a lead vinyl sheet with lead equivalent 0.125mmPb. The first device is a lead curtain which shields the space of CT-gantry and phantom for the CT examination. The second device is a lead drape which shields on the phantom surface adjacent to the scanning plane for the CT-fluoroscopy. Scattered dose and phantom surface dose were measured with an abdominal phantom during Cine-CT (130 kV, 150 mA, 5 seconds, 10 mm section thickness). They were measured by using ionization chamber dosimeter. They were measured with and without a lead curtain and a lead drape. Scattered dose rate was measured at distance of 50-150 cm from the scanning plane. And, surface dose was measured at distance of 4-21 cm from the scanning plane on the phantom. On operator's standing position, scattered dose rates were from 8.4 to 11.6 micro Gy/sec at CT examination. The lead curtain and the lead drape reduced scattered dose rate at distance of 50 cm from the scanning plane by 66% and 58.3% respectively. Surface dose rate were 118 micro Gy/sec at distance of 5 cm from the scanning plane at CT-fluoroscopy. The lead drape reduced the surface dose by 60.5%. High scattered exposure to personnel may occur during interventional procedures using CT. They were considerably reduced during CT-arteriography by attaching the lead curtain in CT equipment. And they were substantially reduced during CT-fluoroscopy by placing the lead drape adjacent to the scanning plane, in addition, operator's hand would be protected from unnecessary radiation scattered by phantom. It was suggested that the scattered exposure to personnel could be sufficiently reduced by using radiation protection devices in IVR-CT. The radiation protection devices and the CT equipment should be improved or developed based on the radiation protection.