radiation safety Flashcards

1
Q

what are the biological effects of radiation?

A
  • Those we know WILL occur = deterministic (non stochastic)
  • Those which MAY occur = non-deterministic (stochastic)
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2
Q

describe deterministic effects

A
  • definitely occur with specific doses
  • threshold dose
  • below threshold the effect does not occur
  • all the damage effects the person exposed to the radiation
  • Somatic effects
  • think about a patient who is being treated for cancer with radiotherapy
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3
Q

describe deterministic effects (acute and chronic)

A

(a) AcuteRadiation sickness 2-10 Sv whole bodyirradiationDeath >10 Sv whole body irradiation(b) ChronicHair lossCataractsSterilityObliterative endarteritis

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4
Q

describe non-deterministic effects

A
  • occur at random - chance or probability
  • “just like playing the lottery”
  • no threshold dose
  • damage affects patient & also future children
  • somatic and genetic effects
  • amount of damage not related to dose
  • less chance of damage with low dose
  • somatic effects - development of malignancy
  • genetic effects - congenital abnormality which may include malignancy
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5
Q

which type of effects are we likely to have in dentistry?

A

Non-deterministic and that is the problem

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6
Q

factors affecting dose of radiation

A

1) type of radiation - we are interested only in x-rays
2) tissues being irradiated
3) age of the patient

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7
Q

what are the dose limits per annum?

A

classified worker - 50 mSv (old), 20 mSv (new)
non-classified worker - 15 mSv (old), 6 mSv (new)
general public - 5mSv (old), 1 mSv (new)

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8
Q

Dose limitation

A
  • Applies to workers
  • NRPB estimated mean dose for dental workers <0.1mSv
  • recommended that should never exceed 1mSv (dose limit for public)
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9
Q

What does ALARP stand for?

A
  • As
  • Low
  • As
  • Reasonably
  • Practicable
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10
Q

what are some food that are radioactive - mainly from radioactive potassium?

A
  • brazil nuts
  • butter beans
  • bananas
  • potatoes
  • carrots
  • red meat
  • avocado
  • beer
  • water
  • peanut butter
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11
Q

What are some practical means of dose reduction?

A
  • Avoid unnecessary radiographs
  • use of selection criteria
  • film speed - preferably use F speed
  • digital radiography may help
  • kV of machine - higher the kV, lower the dose
  • rectangular collimation
  • collimated DPT views
  • regular servicing of machines
  • knowledge & understanding
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12
Q

intensity & the inverse square law why are they important?

A

the number of “photons” in a beam at a specific place

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13
Q

describe controlled area

A

Only the patient can be in the controlled area during exposure Size depends on kV of machine 1.5m for under 70kV BUT size depends on Local Rules DDH stand 2m away for all machines Or behind appropriate shielding

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