Radiology

Question 1

what are the principles of radiation protection?

Answer 1

justification- must be beneficial to the patients

optimisation - ALARP

dose limitation

Question 2

define processing of an image, how are the ways of doing this?

Answer 2

conversion of the latent image to the permanent visible image.

digital
chemical

Question 3

list the 3 ways x-rays can interact?

Answer 3

no effect

complete absorption - transfer of energy to the patient

absorption and scatter - partial absorption and direction of beam changes

Question 4

What colour does a material that completely absorbs the x-rays appear as on a radiograph?

Answer 4

white

Question 5

define attenuation.

Answer 5

combination of absorption and scatter and how it reduces the intensity of the beam in some areas.

Question 6

list the types of radiographs.

Answer 6

intra-orals
bite wings
periodicals
occlusal

extra-orals
panoramic
cephalometric
cone beam CT

Question 7

what teeth are bitewings used on?

Answer 7

premolars

molars

Question 8

what do we aim to capture In bitewings?

Answer 8

Symmetry of uppers and lowers - equal image of upper and lowers.

Mesial side of first premolar to the most distal contact point/surface of the last tooth.

Minimal overlap of teeth.

Enamel-dentine junction Coronal pulp morphology
Interdental bone

Question 9

when using the paralleling technique, what beam is perpendicular/at a right angle to the image receptor?

Answer 9

the central ray/beam

the others are slightly divergent

Question 10

what occurs if there is a short focus to skin distance?

Answer 10

outer beams are more divergent = increased magnification

Question 11

what occurs if there is a long focus to skin distance?

Answer 11

less magnification

Question 12

what is the recommended focus to skin distance?

Answer 12

20cm

Question 13

how are film packets held in place?

Answer 13

rinn holders

Question 14

what radiographs are the blue rinn holders used for?

Answer 14

anterior perioapicals

Question 15

what radiographs are the yellow rinn holders used for?

Answer 15

posterior periapicals

Question 16

what radiographs are the red rinn holders used for?

Answer 16

bitewings

Question 17

what occurs if the rinn holder is not assembled correctly?

Answer 17

coning off

Question 18

what is collimation?

Answer 18

equipment that allows you to control the shape, size and reduce the dosage of the x-ray beam

Question 19

according to the law what is the maximum beam diameter of circular beam measured at the patient end of the spacer cone?

Answer 19

60mm

Question 20

why is a focus to skin distance of 20cm used?

Answer 20

to reduce magnification and divergent beams

Question 21

when is a size 0 bitewing image receptor used?

Answer 21

small children

deciduous teeth

Question 22

when is a size 2 bitewing image receptor used?

Answer 22

used in adults

used in permanent dentition

Question 23

where must the image receptor be in relation to the line of arch?

Answer 23

parallel to the line of arch

Question 24

what is the ideal vertical angle for a radiograph?

Answer 24

5-10 degrees (related to the curve of monson)

Question 25

what occlusal plane curve is buccolingual?

Answer 25

curve of monson

Question 26

what occlusal plane curve is anteroposterior?

Answer 26

curve of spee

Question 27

what legislation protects the exposure of patient to radiation?

Answer 27

IRMER 17

Question 28

what legislation protects the exposure of healthcare workers and the general public?

Answer 28

IRR17

Question 29

According to IRR17 how far away must everyone in the room be for the primary beam whilst the x-ray is being taken?

Answer 29

1.5m

Question 30

According to IRR17 what is the dose limit for unclassified staff for the whole year?

Answer 30

6mSv/yr

Question 31

According to IRR17 what is the dose limit for the public for the whole year?

Answer 31

1mSv/yr

Question 32

who is the referrer?

Answer 32

registered healthcare professional, supervising dentist/clinician.

Question 33

what is the responsibility of the referrer?

Answer 33

provide sufficient medical data to the practitioner to enable justification.

Question 34

who is the practitioner?

Answer 34

registered healthcare professional

Question 35

what is the responsibility of the practitioner?

Answer 35

Decides if exposure is justified - ensures benefits outweighs the detriment. Ensure dosages are ALARP Complies with the employers procedures. = authorises the radiograph

Question 36

a radiograph must be justified by a practitioner, what must be considered?

Answer 36

Efficacy Benefits - directly and in society Risk to the individual Alternatives

Question 37

who is the operator?

Answer 37

anyone who carries out the practical aspects that can affect patient dose

Question 38

is there a dose limit for patients?

Answer 38

no, as if the dose is justified and optimised then it is of benefit to the patient

Question 39

what does the practitioner require before authorising the radiograph?

Answer 39

patient ID - name, DOB, CHI number clinical info unique identifying signature

Question 40

is pregnancy a contraindication to taking a radiograph?

Answer 40

no - some woman air on the side of caution however and decide not to.

Question 41

how often should bitewings be taken in a high caries risk patient?

Answer 41

6 months

Question 42

how often should bitewings be taken in a moderate caries risk patient?

Answer 42

annually

Question 43

how often should bitewings be taken in a low caries risk patient?

Answer 43

primary = 12-18 months permanent = 2 years

Question 44

what metal absorbs excess heat when taking a radiograph?

Answer 44

copper

Question 45

list the ways we can reduce patient dose? (3)

Answer 45

FSD 20cm Using a faster film speed rectangular collimation

Question 46

what positioning factors would make anterior teeth appear horizontally magnified? explain (3)

Answer 46

Canine BEHIND the vertical canine guideline = teeth are closer to the x-ray source than expected = the speed of beam is slow and the speed through the IR is fast = unmatched speeds causes distortion

Question 47

what factor would make posterior teeth on one side appear horizontally magnified? (1)

Answer 47

patient movement