Safety, QA, Prescribing Radiographs- Day 3

Question 1

Exposure measures

Answer 1

Measures capacity of x-rays to ionize AIR
Unit: roentgen (R) = coulombs/kg
Measures intensity of radiation field; NOT radiation absorbed

Question 2

Absorbed dose measures

Answer 2

Measure of total energy absorbed by any type of ionizing radiation PER UNIT MASS OF MATTER
Unit: gray (Gy) = J/kg

Question 3

Effective dose

Answer 3

Estimates risk in humans

Question 4

Primary risk of dental radiography is

Answer 4

Cancer

Cancer risk well established for high dosage
Less certainty regarding low-dose procedures

Question 5

Linear non-threshold hypothesis

Answer 5

Widely accepted in radiation safety and protection
Linear relationship between dose and risk of inducing a new cancer
No threshold = no “safe dose”

Question 6

3 guiding principles in radiation protection

Answer 6

Justification
Optimization
Dose Limitation

Question 7

Justification

Answer 7

Patient benefit vs. risk of harm

Which patients need which examinations

Question 8

Optimization

Answer 8

Use every reasonable means to reduce unnecessary expsosure

Question 9

ALARA =

Answer 9

As Low As Reasonably Achievable

Question 10

Dose Limitation

Answer 10

Limits for workers and public but NOT patients

Question 11

Patient selection

Answer 11

Radiographic screening for the purpose of detecting disease before clinical examination should not be performed. A thorough clinical examination, consideration of the patient history, review of any prior radiographs, caries risk assessment and consideration of the dental and general health needs of the patient should precede the radiographc examination.

Question 12

___speed film twice as fast as group D (half the exposure)

Answer 12

E/F

Question 13

Source to skin distance

Answer 13

Use of long source to skin distances of 20 cmto 40 cm are appropriate, but longer distances are optimal

Question 14

Preferred collimation shape and why

Answer 14

Rectangular>circular because rectangular will decrease radiation dose by up to fivefold as compared with a circular one.

Question 15

What part of the body is very susceptible to radiation

Answer 15

Thyroid, esp. in children

Use leaded aprons and thyroid collars

Question 16

ADA and NCRP concluded

Answer 16

leaded aprons unnecessary

Question 17

Film holders recommended

Answer 17

that align the film precisely with the collimated beam are recommended for periapical and bitewing radiographs

Question 18

The optimal operating potential of dental x-ray units is between

Answer 18

60 and 70kVp

Question 19

Usually kVp and mA are fixed; only what changes?

Answer 19

time

Question 20

To protect office staff, barriers should contain a

Answer 20

leaded glass window

Question 21

When shielding is not possible, the operator should stand

Answer 21

at least 2 meters from the tube head and out the path of the primary beam.

Question 22

Position-and-distance rule

Answer 22

Used when use of barrier is impossible
Operator is at least 6 feet from patient at an angle of 90 to 135 degrees to the central ray of the x-ray beam
Used when use of barrier is impossible
Operator is at least 6 feet from patient at an angle of 90 to 135 degrees to the central ray of the x-ray beam

Question 23

Workers may not receive an annual dose

Answer 23

greater than 1 (ONE) mSv

Question 24

New patient: Child with Primary Dentition

Answer 24

Selected periapicals/occlusal/bitewings if proximal surfaces cannot be visualized

Question 25

New patient: Child with Transitional Dentition

Answer 25

Individualized exam consisting of posterior bitewings with panoramic exam or selected periapical

Question 26

New patient: Adolescent with Permanent Dentition

Answer 26

Individualized exam consisting of posterior bitewings with panoramic exam or selected periapicals
Full mouth recommended when patient has generalized disease or history of extensive dental treatment

Question 27

Pregnancy

Answer 27

Fetal exposure is ~1 microGy for a full-mouth examination

ADA recommends use of thyroid colar and aprons during dental radiography of pregnant patients