rads 2 - study guide portion

Question 1

What is the heel effect

Answer 1

when the thickest part of the patient is placed toward the cathode side

Question 2

how does mA affect the quantity of the x-ray beam

Answer 2

affects the contrast if to much mA is used, density / overall blackness

Question 3

what does mA affect most when evaluating the radiograph

Answer 3

primarily affects the density, or the overall blackness of the radiograph - too little = overall grayness, too much = overall blackness

Question 4

why do we want to decrease exposure times

Answer 4

to decrease patient motion blur

Question 5

kVp is said to affect the quality of the x-ray beam. why is this true. what happens as kVp is increased / decreased

Answer 5

when decrease, there is little definition or detail. when increased there will be an increa in the radiographic density

Question 6

how are we determining our kVp setting? what devise do we use, what do we do with this measurement

Answer 6

determined using the santes rule ( 2 x thickness in cm) + distance

Question 7

what is the relationship between kVp and mA

Answer 7

higher kVp settings allow for lower mA’s. it is an inverse relationship, that also allows for a shorter exposure time

Question 8

what is density

Answer 8

the darkness / blackness on the finished radiograph

Question 9

what is the scale of density of objects

Answer 9

thick (bones, metal) –> thin (gas)
metal, bone, fluid, fat, gas

Question 10

do denser objects appear lighter or darker

Answer 10

lighter

Question 11

what is contrast

Answer 11

the difference between neighboring structures, when too high there will be a lot of black and white

Question 12

what is a collimator, and why do we use this device

Answer 12

controls the size of the x-ray beam, to reduce scatter radiation

Question 13

what is a grid? what is it composed of, and why do we use it

Answer 13

the grid allows only the primary beam to pass through. it is composed of lead strips interfaced with radiolucent spacers that can be made of plastic or aluminum. we use it to help absorb scatter radiation

Question 14

what is a cassette

Answer 14

the film holder, it protects the screens and films from physical damage

Question 15

what is an intensifying screen

Answer 15

covers the inside of the cassette, they emit light after being exposed to the xray beam

Question 16

what do you include when labeling a radiograph

Answer 16

patient and owner name, date of image, name of practice, initials of radiographer

Question 17

what must be included on a radiology log

Answer 17

owner / patient name, area of study, technique used, initials of the radiographer, and date
kept for 3-5 years

Question 18

benefits of digital radiography

Answer 18

the machine automatically sets the mA and kVp settings, easily make adjustments, corrects films if too light / dark, faster radiographs

Question 19

difference between a CR and DR unit

Answer 19

DR - an xray tube coupled to a specialized detector panel that changes xrays into electrical signals is used
CR - an xray detector similar to a cassette is used and must be processed in a special machine

Question 20

what image format is used for radiographs

Answer 20

DICOM

Question 21

manual flim processing

Answer 21

developing, rinse bath, fix, wash bath

Question 22

requirements for a dark room

Answer 22

used only to process exposed radiographs, completely light proof, in use sign, using the safelight only in that room 4 ft away from the image / work area

Question 23

technique chart and how put together

Answer 23

provides suggested exposure factors to use based on the part being radiographed, the thickness of the tissue, and the position of the pt
normally produced by the manufacturer
select pt, measure for you view for kVP settings, find the mA, time and mA settings

Question 24

why is radiation safety important

Answer 24

so we are able to keep ourselves protected, and do not cause harm to the patient

Question 25

what cells are most sensitive to ionizing radiation

Answer 25

white blood cells

Question 26

stochastic damage

Answer 26

damage at random

Question 27

somatic damage

Answer 27

damage of the body tissues

Question 28

genetic damage

Answer 28

cancer

Question 29

who should never be involved in radiographic procedures

Answer 29

pregnant women, and anyone under the age of 18

Question 30

what is MPD

Answer 30

maximum permissible dose - the max dose of radiation a person is allowed to recieve during occupational exposure
determined by the ICRP

Question 31

how is MPD measured

Answer 31

by a dosimeter

Question 32

how much can people be exposed to per year

Answer 32

0.05 Sv / yr

Question 33

three ways we are exposed to radiation

Answer 33

primary beam, scatter radiation, leakage radiation

Question 34

PPE do we use

Answer 34

apron, thyroid shield, gloves, lead glasses, dosimeter

Question 35

3 rules of thumb when it comes to being safe

Answer 35

always wear PPE, avoid retakes, proper exposure factors, collimation