Radiation Protection in Canada: Part VII. The Role of Industrial Hygiene in the Field of Radiation Protection

The main emphasis of a provincial radiation protection program is on ionizing radiation produced by machines, although assistance is given to the Federal Radiation Protection Division in its program relating to radioactive substances. The basis for the Saskatchewan program of radiation protection is the Radiological Health Act 1961. An important provision of the Act is annual registration of radiation equipment. The design of the registration form encourages a “do-it-yourself” radiation and electrical safety inspection.Installations are inspected every two years by a radiation health officer. Two hundred and twenty-one deficiencies were found during inspection of 224 items of radiation equipment, the commonest being failure to use personal film badges. Insufficient filtration of the beam, inadequate limitation of the beam, and unnecessary exposure of operators were other common faults.Physicians have a responsibility to weigh the potential advantages against the hazards when requesting radiographic or fluoroscopic procedures.     

Radiation Protection in Canada: Part I *

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.     

电磁辐射损伤机制与防护

电磁辐射可导致动物心血管、神经、生殖、免疫等多系统不同程度损伤,严重威胁人类健康,电磁损伤的诊断和防治已成为亟待解决的问题。本文针对电磁辐射对靶器官的损伤作一综述,为电磁辐射的预防、诊断、防治和护理提供依据。     

Radiation Protection in Canada: Part IV Factors of Importance in Minimizing Radiation Exposure of Patients,Operators and Others Involved in Diagnostic and Therapeutic Radiology

Factors that may reduce the dose of radiation, from diagnostic and therapeutic x-ray procedures, to the patient and to the occupational and non-occupational worker are outlined. Suitable basic radiation measuring apparatus is described. It is recommended that, in diagnostic radiography, relatively high kilovoltage, proper cones, collimation and adequate filtration be used. Some specific recommendations are made concerning fluoroscopic, photoroentgen and portable x-ray examinations. Film monitoring of personnel is advisable. Examples are given of protective devices to lessen the dosage to the occupational worker. It is the responsibility of the radiologist or physician in charge to ensure that the x-ray equipment is safe to operate and the radiation dose to the patient is kept to a minimum. The roentgen output for all radiographic examinations should be known by the responsible user.     

Radiation protection of operators and patients in a hybrid Angio-MR suite

This work investigates the patient eye lens dose and x-ray scatter to the operator expected for a proposed hybrid Angio-MR concept. Two geometries were simulated for comparative assessment: a standard C-arm device for neuro-angiography applications and an innovative hybrid Angio-MR system concept, proposed by Siemens Healthineers. The latter concept is based on an over-couch x-ray tube and a detector inside an MRI system, with the aim of allowing combined, simultaneous MRI and x-ray imaging for procedures such as neurovascular interventions (including x-ray fluoroscopy and angiography imaging, 3D imaging, diffusion, and perfusion). To calculate the scattered radiation dose to the physician, Monte Carlo simulations were performed. Dose estimates of simplified models of the brain and eyes of both the patient and the physician and of the physician’s torso and legs have been calculated. A number of parameters were varied in the simulation including x-ray spectrum, field of view (FOV), x-ray tube angulation, presence of shielding material and position of the physician. Additionally, 3D dose distributions were calculated in the vertical and horizontal planes in both setups. The patient eye lens dose was also calculated using a detailed voxel phantom and measured by means of thermoluminescent dosimeters (TLDs) to obtain a more accurate estimate. Assuming the same number of x-rays and the same size of the irradiated area on the patient’s head, the results show a significant decrease in the scattered radiation to the physician for the Angio-MR system, while large increases, depending on setup, are expected to patient eye lens dose.     

Regulatory Agencies and Food Safety

Prior to Confederation, food control legislation in Canada consisted of only a few simple laws governing the quality, grading, packing and inspection of certain staple foods. The Inland Revenue Act of 1875 provided the first real control in Canada over adulteration of liquor, foods and drugs. Since then, food legislation has evolved in scope and complexity as the industries involved have developed, as consumers have become better informed, and as scientific advances have provided a sound basis for regulations. Present regulations under the Food and Drugs Act are intended to give consumers broad protection against health hazards and fraud in the production, manufacture, labelling, packaging, advertising, and sale of foods. This principle is well illustrated by present requirements for the control of pesticide residues, chemical additives, and the addition of vitamins to foods. In today''s era of rapid technological change, application of current scientific knowledge to the food industry obviously involves the possibility of hazards to health. Regulatory agencies with responsibility for food safety must, therefore, fully utilize scientific knowledge in order to reduce the risks involved to a minimum.     

Radiation Protection in Canada: Part V. Radiobiological and Radiological Health Research in Canada

A recent survey was carried out with respect to radiobiological and radiological health projects in Canada. Letters of inquiry, followed by two questionnaires, were sent out to every institution where radiation research was likely to have been undertaken. Approximately 75% of those contacted replied. Of the total of 200 studies, 84% were classified as biological and medical studies, the remaining 16% as environmental radiation studies. Responses to the inquiry stressed the inadequacy of the present governmental budget for radiation research, the need for higher salaries for research workers, and the necessity of a more intensive teaching program for technicians and professional personnel. The granting of longer-term grants, rather than annually renewable grants, is urged.     

Radiation Protection in Canada: Part III. * The Role of the Radiation Protection Division in Safeguarding the Health of the Public

The current status of radiation protection in Canada is discussed in the last 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. A radioactive fallout study program has been established involving the systematic collection of air and precipitation samples from 24 locations, soil samples from 23 locations, fresh-milk samples from 16 locations, wheat samples from nine areas and human-bone specimens from various hospitals throughout Canada. A whole-body-counting facility and a special study of fallout in Northern areas have also been initiated. For any age group, the highest average strontium-90 concentration in human bone so far reported has been less than four picocuries per gram of calcium compared with the maximum permissible level of 67 derived from the International Committee on Radiation Protection (ICRP) recommendations. By the end of 1963 a general downward trend of levels of radioactivity detected in other parts of the program has been observed. Programs to assess the contribution to the radiation exposure of members of the population from medical x-rays, nuclear reactor operations and natural background-radiation sources have also been described. The annual genetically significant dose from diagnostic x-ray examinations in Canadian public hospitals has been estimated to be 25.8 mrem. Results from the reactor-environment monitoring programs have not suggested the presence of radioactivity beyond that contributed from fallout.     

磁共振成像对乳腺肿瘤的诊断价值

乳腺癌是危及女性健康的常见恶性肿瘤之一,病死率较高,且发病年龄呈年轻化趋势。目前临床对乳腺疾病的检查方法很多,既往检查主要包括钼靶、超声等,因价格便宜、操作方便,已成为常规的乳腺疾病检查方法,但两者的敏感性和特异性较低并有自身的局限性。CT软组织分辨率较高,但检查过程中的X线剂量较大,并且动态增强时间较长,故作为乳腺钼靶的补充检查手段。这些检查方法对乳腺疾病均有不同的诊断意义,在当前众多诊断乳腺疾病方法中,具有无辐射,较高软组织分辨力及可多方位多层面成像的乳腺磁共振(MRI)成像有其独到的优势,某些方面能弥补超声和钼靶检查的局限性,乳腺磁共振可提供病灶形态学和增强血流动力学表现,可用于常规检查方法不能确诊病灶的鉴别诊断。乳腺肿瘤MRI成像对临床诊断、鉴别诊断及手术方案的选择有着极其重要的作用。本文就乳腺MRI影像技术、MRI影像学表现及其临床应用予以综述,探讨MRI在乳腺肿瘤中的应用。     

Is it possible to "achieve a balance" and meet the "safety net"? Paediatric Advisory Subcommittee to the North West Thames Regional Health Authority.

The government''s document Hospital Medical Staffing--Achieving a Balance--Plan for Action introduced the concept of a "safety net"--that is, a minimum safe level of staffing--of junior doctors in the acute specialties. The North West Thames Paediatric Advisory Group has therefore reviewed the implications and consequences of implementing the safety net in respect of children''s services. The group found that if a reasonable safety net was to be provided that enabled the services to stay within the projected junior staffing levels, maintain a balance, meet training needs, and reduce junior doctors'' hours of work, then changes in the organisation of the services would be required. Examining the options available showed that to achieve a safety net within the projected numbers of junior staff at least six paediatric units in the region would have to close. It is doubtful if there is the political will to support the very radical changes that would be needed in the distribution of services if the government''s recommendations in Achieving a Balance were to be implemented. The profession, the Department of Health, and the public must be made aware that the proposed changes in medical staffing will cause a fundamental change in the traditional pattern of delivery of health care.     

Radiation scientists and homeland security

Radiation scientists represent an important resource in homeland defense. Security analysts worry that a crude but deadly radiological bomb might be fashioned from stolen nuclear material and a few sticks of dynamite. Such a device could kill dozens, hundreds, and possibly thousands and could contaminate a square mile or more. Emergency workers may call upon radiation scientists to aid the injured. Educational materials are available on the ACR, ASTRO, and RRS websites, linked to the Armed Forces Radiobiology Research Institute and the Oak Ridge National Laboratory, to provide radiation workers material that they can use to help emergency room and civil defense personnel after a terrorist attack. Radiation scientists are urged to obtain these materials and contact their local hospital and public health authorities to volunteer their services and expertise.     

Artificial Optical Radiation photobiological hazards in arc welding

Occupational Health and Safety (OHS) is associated with crucial social, economic, cultural and technical issues. A highly specialized OHS sector deals with the photobiological hazards from artificial optical radiation (AOR), which is divided into visible light, UV and IR emitted during various activities and which is legally covered by European Directive 2006/25/EC. Among the enormous amount of sources emitting AOR, the most important non-coherent ones to consider for health effects to the whole optical range, are arcs created during metal welding. This survey presents the effort to assess the complicated exposure limits of the Directive in the controlled environment of a welding laboratory. Sensors covering the UV and blue light range were set to measure typical welding procedures reproduced in the laboratory. Initial results, apart from apparently justifying the use of Personal Protective Equipment (PPE) due to even subsecond overexposures measured, also set the basis to evaluate PPE’s properties and support an integrated risk assessment of the complex welding environment. These results can also improve workers’ and employer’s information and training about radiation hazards, which is a crucial OHS demand.     

Ethical Study on the Reform and Development of Medical and Health Services in China

At an early stage of its foundation, new China became clear about the nature of public welfare and quickly developed medical and health services, which was well received by the World Health Organization. The marketization and the reduction of input into medical and health services from the 1980s created severe adverse consequences. After the SARS' outbreak in 2003, China started to give serious consideration to its medical and health system, and to work at developing medical and health services. The new healthcare reform launched in 2009 re‐emphasizes fairness and public welfare, and China's achievements have been remarkable. Of course, there are still many problems to be solved in the reform, which also paves the way for increasing the reform in future.     

Direct estimates of low-level radiation risks of lung cancer at two NRC-compliant nuclear installations: why are the new risk estimates 20 to 200 times the old official estimates?

An official report on the health hazards to nuclear submarine workers at the Portsmouth Naval Shipyard (PNS), who were exposed to low-level ionizing radiation, was based on a casual inspection of the data and not on statistical analyses of the dosage-response relationships. When these analyses are done, serious hazards from lung cancer and other causes of death are shown. As a result of the recent studies on nuclear workers, the new risk estimates have been found to be much higher than the official estimates currently used in setting NRC permissible levels. The official BEIR estimates are about one lung cancer death per year per million persons per rem[s]. The PNS data show 189 lung cancer deaths per year per million persons per rem.     

Health care cost effects of public use of a regional poison control center.

Poison control centers in the United States are threatened with closure, and attempts at a cost-benefit analysis of these services have been indeterminate. The purpose of this study was to compare the operating costs of a regional poison control center resulting from public use of its telephone hotline services with those of hypothetical alternative sources of advice and care. We conducted a follow-up telephone survey among 589 public callers to the San Francisco Bay Area Regional Poison Control Center who had been managed at home without medical referral after an unintentional poisoning. All survey respondents were asked what alternative action they would have taken had the poison control center not been available to assist them by telephone consultation. We then surveyed emergency departments and physicians'' offices cited as alternatives by the callers to determine their response and charges for evaluating a suspected poisoning case. A total of 464 (79%) of the callers surveyed would have sought assistance from their local emergency health care system had the poison control center not been available. We conservatively estimated that the total charges for such evaluations would be +71,900. Comparatively, the total actual operating cost of services provided by the poison control center for all 589 poisoning cases was +13,547. Most of the study subjects (429 [73%]) had private insurance coverage. Direct public access to these services probably reduces the use of emergency health care resources, thus lowering health care costs.     

X-Ray Survey Results and Costs—A Health Officer's Viewpoint,A Preliminary Report

The obvious results of a mass chest x-ray survey from a health officer''s viewpoint are:1. The early discovery of unknown cases of pathologic conditions of the chest—tuberculosis, neoplasms, heart abnormalities.2. Increase in the community''s awareness of its tuberculosis problem.3. Opportunity to work closely with the medical society and the individual private physicians.4. Stimulation of all agencies in a community, health and non-health, to work together on a health project for the good of all of the people.5. Increased cooperation between the local department of public health and other health agencies in a community.6. Opportunity to underline to a staff of a local department of public health the importance of thinking in terms of the department as a whole, rather than in terms of respective divisions or bureaus.7. Opportunity to focus the awareness of the community on its public health services.In relation to costs, there are three aspects from a health officer''s viewpoint:1. The planning, together with other agencies, of an adequate budget with full recognition of community resources.2. The planning for estimated expansion of tuberculosis control services both in terms of increased expense for maintenance and operation, and of assignment of personnel to survey staff with resulting curtailment or postponement of other programs.3. The planning for completion of the follow-up program of the x-ray survey and of future continued extension of the total tuberculosis control program as the result of increased community awareness of the tuberculosis problem.     

Radiation protection: the NCRP guidelines and some considerations for the future.

The National Council on Radiation Protection and Measurements (NCRP) in the USA and the International Commission on Radiological Protection (ICRP), worldwide, were formed about 1928 and have since made recommendations on appropriate levels of protection from ionizing radiation for workers and for the public. These recommendations and much of the guidance provided by these organizations have usually been adopted by regulatory bodies around the world. In the case of the NCRP, the levels have fallen from 0.1 roentgen per day in 1934 to the current 5 rem per year (a factor of about 5). The present levels recommended by both the ICRP and the NCRP correspond to reasonable levels of risk where the risks of harm from ionizing radiation are compared with the hazards of other, commonly regarded, as safe, industries. Some considerations for the future in radiation protection include trends in exposure levels (generally downward for the average exposure to workers) and improvements in risk estimation; questions of lifetime limits, de minimis levels, and partial body exposures; plus problems of high LET radiations, acceptability of risk, synergisms, and risk systems for protection.