Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
Damaging effects of radiation may be...
|
reversible
conditional irreversible |
|
|
at a molecular level damage may occur....
|
directly- radiation energy absorbed by molecules
Indirectly- oxidation reactions |
|
|
At a cellular level, the most sensitive cells are...
|
more prone to interrupted mitosis and hence lack of replacement
|
|
|
at a cellular level, less radiosensitive cells are....
|
more prone to effects of capillary damage which gives impaired )2 and nutrient exchange
|
|
|
What are precursor cells have a high rate of?
|
mitosis
|
|
|
Order sensitive cells in decreasing sensitivity
|
precursor or sperma and ova, haemopoietic system
fibroblasts, vascular endothelial cells cells of salivary glands, thyroid, liver kidney neurons, muscle cells, squamous cell of oral mucous membrane |
|
|
extent of tissue damage varies with
|
type of tissue irradiated
area irradicated type of radiation dose and rate applied previous exposure modifying factors presence of O2 |
|
|
What do low doses of ionizing radiation cause?
|
don't cause any unique disease
cause a statistical increase in diseases already present in the population |
|
|
What can happen if get genetic damage to tissue?
|
mutations in offspring
|
|
|
what are of little significance in dental x-rays?
|
gonadal doses
|
|
|
What is the estimated risk of harmful mutation in FMS
|
0.03/million
|
|
|
Damage to what tissue may result in acute cell death, atrophy or malignant change?
|
somatic tissue
|
|
|
what is the most important effect of somatic tissue?
|
carcinogenesis
|
|
|
some reports suggest a linear relationship between ratiation dose and the incidence of cancer, what doe this imply?
|
an infinite risk no matter how small the dose
|
|
|
What is the exposure unit?
|
Unit of measure
amount of radiation that produces a given unit of charge in a standard amount of air. |
|
|
Go over radiation measures!!
|
don't understand need to :) equivelant dose, absorbed dose, effective dose
|
|
|
What are the 3 sources of radiation that exist
|
natural background
fallout, industrial waste medical, dental x-ray machines |
|
|
give examples of natural background
|
cosmic radiation
external terrestrial radiation- radon gas from uranium internal terrestrial radiation- from naturally occurring radioisotopes in body, potassium |
|
|
What is the maximum permissible doses
|
amount of radiation an individual is allowed to receive over the above natural background levels from artificial sources, e.g. x-ray machines
|
|
|
What are the 13 radiation protection measures?
|
1. stand behind protective barrier if provided, if not 2 meters away
2. don't hold the cone or tube during exposure 3. film holding devices 4. lead apron, and thyroid shield where appropriate, pregnancy, children for certain exposures 5. no unnessesary person in the room while exposing a film 6. warning light/buzzer on machine to show when exposure is made 7. dead-man exposure switch 8. aluminium dix to filter longer wavelength x-rays 9. open ended lead lined cone and lead disc to collimate beam consider additional rectangular collimation 10. correct size film, not 2 small films where 1 larger film would do 11. fast film to reduce exposure time 12. high kVp to produce a greater number of short wave length x-rays 13. correct exposure positioning and processing techniques |
