Introduction to Radiation Protection

radiation

kinetic energy that moves from one place to another in a form that can be described as waves or particles

- particulate radiation

- electromagnetic radiation

forms of radiation (2):

particulate radiation

are subatomic particles that are ejected from the nucleus of atoms at very high speeds

particulate radiation

possess sufficient kinetic energy to be capable of causing ionization by direct atomic collision

particulate radiation

has a finite range in matter, and that range depends on the particle's energy

- alpha particles

- beta particles

- neutrons

- protons

particulate radiation (4):

electromagnetic radiation

photon radiation loses intensity with distance but theoretically never reaches zero

- ionizing radiation

- non-ionizing radiation

electromagnetic radiation (2):

- somatic effects

- genetic effects

classification of effect from ionizing radiation exposure (2):

somatic effect

may become evident in the irradiated individual; not usually to be expected in individuals exposed in the course of their work in the medical field

somatic effect

includes skin erythema, cataracts, and radiation-induced malignancies

genetic effects

do not produce any significant observable effect in the exposed individual, but may appear in the descendants of the exposed individual

genetic effects

unlikely that any worker in the medical environment would be exposed to ionizing radiation at a level high enough to cause the transmission of appreciable genetic effects

- deterministic effect

- stochastic effect

serious radiation-induced effects of concern in radiation protection (2):

deterministic effect

one that increases in severity with increasing radiation dose above a threshold dose

deterministic effect

occurs only after relatively large doses, but the threshold dose and the severity of the effects may be influenced by individual susceptibility and other factors

stochastic effect

one for which the probability of the effect occurring increases with increasing absorbed dose, while the severity of the effect is independent of the magnitude of the absorbed dose to the affected individuals

stochastic effect

all-or-none response; assumed to have no dose threshold

stochastic effect

its induction is considered to be the principal effect that may occur following exposure to low doses of ionizing radiation

radiation protection

may be defined simply as effective measures employed by radiation workers to safeguard patients. personnel, and the general public from unnecessary exposure to ionizing radiation

1. prevent the occurrence of clinically radiation-induced deterministic effects by adhering to dose limits that are below the apparent threshold

2. limit the risk of stochastic effects to a reasonable level

specific objectives of radiation protection (2):

- planned exposure situation

- emergency exposure situation

- existing exposure situation

types of exposure situations (3):

planned exposure situations

are situations involving the deliberate introduction and operation of sources

emergency exposure situations

are situations that may occur during the operation of a planned situation, or from a malicious act, or from any other unexpected situation, and require urgent action in order to avoid or reduce undesirable consequences

existing exposure situations

are exposure situations that already exist when a decision on control has to be taken, including prolonged exposure situations after emergencies

- occupational exposure

- public exposure

- medical exposure

categories of exposure (3):

occupational exposure

all radiation exposures of workers incurred as a result of their work

public exposures

all exposures other than occupational exposures and medical exposures

medical exposures

occurs in diagnostic, interventional, and therapeutic procedures

- workers

- public/members of the public

- patient

categories of exposed individuals (3):

workers

any person who is employed, whether full time, part time, or temporarily, by an employer and who has recognized rights and duties in relation to occupational radiological protection

public, members of the public

any individual who receives an exposure that is neither occupational nor medical

patients

an individual who receives an exposure associated with a diagnostic, interventional, or therapeutic procedure

- controlled area

- supervised area

classification of areas of work (2):

controlled areas

a defined area in which specific protection measures and safety provisions are, or could be, required for controlling normal exposures or preventing the spread of contamination during normal working conditions, and preventing or limiting the extent of potential exposures

supervised areas

working conditions are kept under review but special procedures are not normally needed

- justification

- optimization of protection

- application of dose limits

fundamental principles of radiological protection (3):

justification

any decision that alters the radiation exposure situation should do more good than harm

optimization of protection

the likelihood of incurring exposures, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable

- shielding

- time

- distance

cardinal principles in optimizing occupational exposure to radiation (3):

- does constraint (planned exposure situations)

- risk constraint (potential exposures)

- reference level (emergency & existing exposure situations)

levels of radiological protection (3):

diagnostic reference levels

are used in medical imaging to indicate whether, in routine conditions, the levels of patient dose form, or administered activity for a specified imaging procedure are unusually high or low for that procedure

20 mSv per year, averaged over 5 years

effective dose: occupational

1 mSv in a year

effective dose: public

150 mSv

lens of the eye: occupational

15 mSv

lens of the eye: public

500 mSv

skin: occupational

50 mSv

skin: public

500 mSv

hands and feet: occupational

n/a

hands and feet: public

100 mGy

absorbed doses below ___ to the embryo/fetus should not be considered for a reason for terminating a pregnancy