test 1

Question 1

what does the milliamperage control

Answer 1

amount of radiation generated

directly proportional to image density and amount of electrons/photons being produced

determines quantity of xrays produced (amount)

Question 2

what does the kilovoltage control

Answer 2

quality and penetrating power of the xray beam

directly proportional to image density

inversely proportional to image contrast

Question 3

types of barriers that protect from scatter radiation

Answer 3

plaster
cinderblock
thick drywall (3 inches)
steel (3/16 in.)
lead (1 mm)

Question 4

types of dosimeters

Answer 4

film badge
tld
osl
dis

Question 5

What is the annual limit for the maximum permissible dose for occupationally exposed worker?

Answer 5

50 mSv / 5 rem per year

average dose to US pop: 3 mSv / 300mrem per year

Question 6

what are the 3 radiation protection organizations

Answer 6

• american dental association
• american academy of oral and maxillofacial radiology
• international commission on radiological units and measurements

Question 7

What dental x-ray machine parameters are considered ideally suited to producing quality digital radiographic images?

Answer 7

Direct current, 60 kV or lower, Low 5 mA

Question 8

what is density, how do you increase/decrease it

Answer 8

1. the overall darkness or lightness of an image; related to the amount of radiation reaching the image receptor
2. decreasing the mA/time exposure setting decreases density; increasing mA/time exposure setting increases density

Question 9

what is contrast in digital imaging

what is high contrast

what is low contrast

how do you increase/decrease contrast

Answer 9

1. difference in density between various regions of a radiograph
2. High contrast/short scale means the image exhibits black and white with LITTLE gray shade variant in between
3. low contrast/long scale means the image is black and white with a SIGNIFICANT gray shade variant in between
4. decreasing kV exposure setting increases contrast, increasing kV decreases contrast

Question 10

what is spatial resolution

Answer 10

1. ability to distinguish between closely spaced objects; determined by number of pixels; image improves with more pixels
2. measured in lp/mm; greater the resolution, the sharper the image
3. digital images are approx. 70 lp/mm while film is around 200 lp/mm

Question 11

advantages of digital vs film

Answer 11

1. requires less exposure
2. instant viewing saves time
3. no need for darkroom/chemicals
4. can improve image via software instead of re-exposing
5. improved gray scale aids in diagnosis
6. enhances patient education

Question 12

limitations of digital vs film

Answer 12

1. retakes seem justifiable
2. larger physical dimensions and infection control
3. reliability of computer records and viruses