Quality assurance

Question 1

what does a radiation safety officer (RSO) do?

Answer 1

makes sure all quality-control measures are in place and the clinic is compliant with applicable regulations

Question 2

image detail

Answer 2

degree of sharpness of an image
appropriate detail is needed to properly evaluate the borders of anatomical structures

Question 3

focal-film distance (FFD)

Answer 3

distance from the tube head to the image receptor
should use the same distance each time

Question 4

what happens to the beam intensity if the tube head is too far away (FFD) from the image receptor?

Answer 4

decreased beam intensity

Question 5

what happens to the beam intensity if the tube head is too close (FFD) to the image receptor?

Answer 5

magnification and loss of distinction of margins of the structure

Question 6

what is the focal-film distance commonly set at?

Answer 6

36-48 inches

Question 7

what happens to the detail if the focal spot is greater?

Answer 7

less detail

Question 8

how can you control movement of the patient?

Answer 8

sedation or restraint tools

Question 9

how does density occur?

Answer 9

occurs based on the amount of light transmitted to the film after the x-ray beam interacts with the crystals of the intensifying screen

Question 10

how can thickness play a role in the quality of density in a film?

Answer 10

thicker tissues absorb more radiation and denser organs/ structures absorb more radiation than tissues

Question 11

what is the major factor of density?

Answer 11

mAs which determines the quantity of x-rays

Question 12

if mAs is increased what happens to density?

Answer 12

it also increases

Question 13

if kVp is increased what happens to the energy level of the x-rays?

Answer 13

it also increases

Question 14

if the tube head is closer to the image receptor (FFD) what happens to the density?

Answer 14

it increases

Question 15

if FFD is doubled what happens to the intensity of the x-ray?

Answer 15

the intensity of the x-ray is 1/4 of its original strength

Question 16

contrast

Answer 16

opacity difference between 2 areas or structures

Question 17

what are the two types of contrast?

Answer 17

high: black and white
low: shades of gray

Question 18

what has the most impact on contrast?

Answer 18

kVp

Question 19

if kVp is increased what happens to contrast?

Answer 19

it decreases

Question 20

how can you fix film quality?

Answer 20

1. determine if anatomical structures are easily visible
   if not… too dark= decrease kVp by 10-15%, too light= increase kVp by 10-15%
2. evaluate density
   if structures are visible but image is too dark decrease mAs by 30-50%, if too light increase mAs by 30-50%
3. ensure that anatomical structure requested is centered on film with proper positioning

Question 21

how do you make a technique chart if needed?

Answer 21

1. begin with abdominal radiographic imaging (use a dog of normal body condition that is about 40 lbs)
2. measure over liver region of the abdomen
3. tube head settings: 40 inches from tube head to tabletop and 43 inches from tube head to grid tray, start with a setting of 80 kVp and 7.5 mAs
4. take radiograph and evaluate for diagnostic quality
5. adjust kVp as needed
6. fill in the rest of the chart (Sante’s rule): for every 1 cm decrease in size and decrease kVp by 2, for every 1 cm increase kVp by 2 up to 80 kVp, from 80-100 kVp add 3 to every kVp for every 1 cm, and from 80-125 kVp add 4 to kVp for every 1 cm