Principles of Radiation Protection Janusz Winiecki Chair and Clinic Oncology and Brachytherapy, Collegium Medicum in Bydgoszcz, UMK in Toruń Medical Physics Department,  Oncology Center in Bydgoszcz Protective clothing in the past  (Source: "A Century of X-Rays and Radioactivity in Medicine", published by Institute of Physics, UK. (1993))

Radiation protection (radiological protection), (IAEA): The protection of people from harmful effects of exposure to ionizing radiation, and solutions (means) for achieving this

-minimize health effects due to radiation What are the objectives and basic principles of radiation protection? -minimize health effects due to radiation Biological effects of radiation are mainly classified into: "Deterministic Effect" and "Stochastic Effect". For the former (deterministic), a threshold level of absorbed dose exists, above which the radiation will bring detrimental effect to the health. For the stochastic effect, a threshold does not exist, but the probability of having detrimental effect is proportional to the dose absorbed.

reduction of expected dose - measurement of human dose uptake Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard. Fundamentals to radiation protection are: reduction of expected dose - measurement of human dose uptake

 avoid the deterministic effects Based on the characteristics of the above biological effects, aims of radiation protection are to:  avoid the deterministic effects  lower the probability of stochastic effects to an acceptable level.

occupational radiation protection, which is the protection of workers, PROTECTION GROUPS Radiation protection can be divided into: occupational radiation protection, which is the protection of workers, medical radiation protection, which is the protection of patients, public radiation protection, which is protection of individual members of the public, and of the population as a whole. The types of exposure, as well as government regulations and legal exposure limits are different for each of these groups, so they must be considered separately.

EXCLUSION:  Any exposure whose magnitude or likelihood is essentially impossible / infeaslible to control  K-40 nuclides in the body  Cosmic radiation at earth’s surface  Unmodified concentrations of radionuclides in most raw naterials

FACTORS IN DOSE UPTAKE There are three factors that control the amount, or dose, of radiation received from a source. Radiation exposure can be managed by a combination of these factors: Time - Reducing the time of an exposure reduces the effective dose proportionally. An example of reducing radiation doses by reducing the time of exposures might be improving operator training to reduce the time they take to handle a source. Distance - Increasing distance reduces dose due to the inverse square law. Distance can be as simple as handling a source with forceps rather than fingers. Shielding - The term 'biological shield' refers to a mass of absorbing material placed around a reactor, or other radioactive source, to reduce the radiation to a level safe for humans.[2] The effectiveness of a material as a biological shield is related to its cross-section for scattering and absorption.

REGULATION OF DOSE UPTAKE In most countries a national regulatory authority works towards ensuring a secure radiation environment in society by setting dose limitation requirements that are generally based on the recommendations of the International Commission on Radiological Protection (ICRP). These use the following overall principles: Justification: No unnecessary use of radiation is permitted, which means that the advantages must outweigh the disadvantages. Limitation: Each individual must be protected against risks that are far too large through individual radiation dose limits. Optimization: Radiation doses should all be kept as low as reasonably achievable. This means that it is not enough to remain under the radiation dose limits. As permit holder, you are responsible for ensuring that radiation doses are as low as reasonably achievable, which means that the actual radiation doses are often much lower than the permitted limit.

ALARA or ALARP is an acronym for an important principle in exposure to radiation and other occupational health risks and stands for "As Low As Reasonably Practicable". The aim is to minimize the risk of radioactive exposure or other hazard while keeping in mind that some exposure may be acceptable in order to further the task at hand. The equivalent term ALARA, "As Low As Reasonably Achievable", is more commonly used outside the UK. This compromise is well illustrated in radiology. The application of radiation can aid the patient by providing doctors and other health care professionals with a medical diagnosis, but the exposure should be reasonably low enough to keep the statistical probability of cancers or sarcomas (stochastic effects) below an acceptable level, and to eliminate deterministic effects (e.g. skin reddening or cataracts).

JUSTIFICATION OF PRACTICES RADIATION PROTECTION REQUIREMENTS: JUSTIFICATION OF PRACTICES Practices should not be authorized unless the benefits are greater than the detriments, taking account of social, economic and other factors.

RADIATION PROTECTION REQUIREMENTS: DOSE LIMITATION The normal exposure of individuals from authorized practices shall not exceed the dose limits

OPTIMIZATION OF PROTECTION AND SAFETY Doses to individuals, the number of persons and the likelihood of incurring exposures shall be kept as low as reasonably achievable, economic and social factors taken into account

DOSE CONSTRAINTS Optimization of protection and safety measures associated with a particular source within a practice shall be subject to dose constraints

INTERACTION OF RADIATION WITH SHIELDING Diagram showing various forms of ionizing radiation, and the sort of material that is used to stop or reduce that type. Different types of ionizing radiation interact in different ways with shielding material. The effectiveness of shielding is dependent on the Stopping power of radiation particles, which varies with the type and energy of radiation and the shielding material used. Different shielding techniques are therefore used dependent on the application and the type and energy of the radiation.

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