How much radiation do you use?

Question 1

what are the three factors that determine the risk to patients?

Answer 1

how much radiation is absorbed?
how ionising or damaging that type of radiation is?
how radiosensitive are the tissues we are irradiating?

Question 2

what are the three different ways can the radiation dose can be described?

Answer 2

absorbed, equivalent and effective

Question 3

what is an absorbed dose?

Answer 3

the amount of radiation energy deposited in the tissue. it is also very easy to measure.

Question 4

what is absorbed dose measured in?

Answer 4

gray
1 gray= 1joule/kilogram

Question 5

what are the qualities of the absorbed dose?

Answer 5

It is a useful quantity to measure, the amount of biological harm produced to an individual depends on other factors.
These are considered by the equivalent and effective dose.

Question 6

what risk factors does the equivalent dose take into account

Answer 6

how much radiation is absorbed in the tissues and also how damaging that type of radiation is.

Question 7

what is the unit of the equivalent dose?

Answer 7

absorbed dose is equal to the equivalent dose so:
1Sv (sievert) = 1J/kg

Question 8

why can you not compare two different radiographs from two different parts of the body?

Answer 8

the absorbed and equivalent dose does not take into account how radiosensitive different tissues are when the tissues are irradiated.

Question 9

why is effective dose the gold standard of dose?

Answer 9

Takes into account all three risk factors. However it is difficult to measure and calculate.

Question 10

how to measure the effective dose?

Answer 10

effective dose = equivalent dose x weighting factor

Question 11

what is the most radiosensitive tissue?

Answer 11

the bone marrow followed by the thyroid gland

Question 12

what is the effective dose measured in?

Answer 12

Sieverts (Sv).

Question 13

how does the effective dose correlate with the risk of inducing cancer?

Answer 13

positive correlation

Question 14

what is the risk of cancer induction from dental radiographs?

Answer 14

1 in 15000000 uSv for men
1 in 18000000 uSv for women

Question 15

how much background radiation is a person exposed to in the UK?

Answer 15

Everyone in the UK is exposed to 2700 uSv per person per year. So 7 uSv per person per a day.

Question 16

What dose of radiation is in a chest x-ray scan?

Answer 16

14 uSv

Question 17

What dose of radiation is in a CT scan of a patient’s lungs?

Answer 17

6600uSv

Question 17

What dose of radiation is in a CT scan?

Answer 17

1400 uSv

Question 18

what are the two different intraoral radiographs?

Answer 18

bitewing
periapical

Question 19

what is the dose when using modern imaging for a dental radiograph?

Answer 19

2uSv.

Question 20

What dose of radiation is in a panoramic radiograph?

Answer 20

14-24uSv

Question 21

what type of dental radiograph is a panoramic radiograph/DPT?

Answer 21

extra-oral radiograph

Question 22

What dose of radiation is in a cephalometric radiograph?

Answer 22

6uSv and this radiograph gives a lateral view.

Question 23

What dose of radiation is in a CBCT radiograph?

Answer 23

Uses a lower dose than a CT scan but it is still higher than 2D X-rays. commonly used in implants.

On average the dose is 84uSv.

Question 24

If the dose from a dental x-ray is so low what is the issue?

Answer 24

As a profession, we take a large number of radiographs. The population dose will increase.

Question 25

What are the guiding principles of the internal commission of radiological protection?

Answer 25

justification - the patient should only be exposed if the benefits outweigh the risks
optimisation - must be made to reduce unnecessary doses to patients, staff and the public.
dose limitation

Question 26

what is the ALARP principle?

Answer 26

Doses to ionising radiation should be as low as reasonably practicable with economic and social factors being taken into account.

Efforts made to reduce exposure to patients also reduced exposure to dental staff.

Question 27

explain the guideline dose limitation?

Answer 27

Law provided for occupational exposure and public exposure.
ensuring no individual is exposed to unacceptable high doses.