Vet Tech Diagnostic Imaging Terms & Definitions Study Set

radiation causes damage to

cells

damage to cells from radiation may be

repaired without incident; the vast majority of damage to cells is repaired successfully

damage to cells can be lethal. high doses of radiation can

kill cells, leading to tissue damage (for example, cataracts to the lens of the eye

damage to cells from radiation may be repaired with errors:

■ Increased risk of cancer (including skin cancer, leukemia)

■ Risk of birth defects

The unit absorbed dose equivalent used for radiation safety is

the Sievert (Sv)

an older unit, which is still used in some instances, is the radiation equivalent in

man (rem).

maximum permissible dose limit for annual radiation exposure for whole body

50 mSv 5 rem)

maximum permissible dose limit for annual radiation exposure for skin and extremities

500 mSv (50 rem)

maximum permissible dose limit for annual radiation exposure for eye or lens

150 mSv (15 rem)

maximum permissible dose limit for annual radiation exposure for pregnant women may not exceed

5 mSv or 0.05mSv in any month. Most important the first 3 months of pregnancy

the occupational dose limit of radiation exposure for individuals under 18 is

10% of the limit for adults

Most states require individual monitoring devices to be worn by workers who are likely to receive a radiation dose of

> 10% of the legal limit in one year. It is unlikely that vet techs will reach this but most clinics monitor anyway

Registered veterinary technicians may operate radiographic equipment under

indirect supervision of a licensed veterinarian.

The principle guiding radiation protection is

ALARA (as low as reasonably achievable)

This principle reflects that even if individuals do not approach annual dose limits, steps should always be taken to minimize radiation absorbed dose to as low as is reasonably achievable

Use chemical or mechanical restraints when possible so that

individuals do not need to be in the x-ray room during the exposure

plan x ray positioning carefully to avoid

retakes and more exposure

Use rare-earth screens to

decrease exposure needed to create a well-exposed image.

increase your ________ from a radiation source

distance

If an operator triples the distance from a radiation source, their exposure is decreased to

one ninth (decreased by the square of the distance: 9 is 3-squared).

Also increase _____ between individuals and a radiation source

shielding

Protective barriers are an important way to

decrease dose with shielding.

Individuals in an x-ray room during exposure should be behind a protective barrier or wear a protective apron of at least

0.25mm (ideally 0.5mm) lead equivalent.

what is used to make x ray gloves and aprons

Lead impregnated vinyl or leather

0.25 mm lead equivalent material reduces a 100kVp x-ray beam by ______ while 0.5 mm lead equivalent reduces it by _____.

60% and 85%

Aprons and gloves must be periodically evaluated for tears and cracks by

taking a radiograph of the equipment

shielding devices only protect you from

scatter radiation ONLY

These devices do not sufficiently reduce the primary x-ray beam, which is made up of higher energy x-rays with better penetrating ability.

commonly used personnel monitoring devices for radiation are

○ Film badges

○ Thermoluminescent dosimeters (TLDs)

○ Pocket dosimeters

○ Ring or wrist badges

the radiation monitoring device should be worn at

thyroid level on the collar outside of apron ○ A ring or wrist badge should be worn for fluoroscopy procedures