Chapter 2 - Radiation Protection Flashcards
Discovered calcium tungstate as an intensifying phospor and developed the fluoroscope
Thomas Edison
Early effects of radiation exposure
Deterministic Effect
Late effects of radition exposure, low dose of radiation exposures and may not occur for years is called
Stochastic effect
Deterministic Effect are
☑️ Hematologic Depression - whole body(25rad)
☑️ Death - whole body (100rad)
☑️ Skin Erythema - small field (200rad)
☑️ Epilation - small field (300rad)
☑️ Chromosome Aberration - whole body (5rad)
☑️ Gonadal Dysfunction - local tissue (10rad)
100 rad - 1 Gy
1 Becquerel = _____ Curie
3.7 x 10 10 dis/sec
Unit of exposure is
Roentgen or C/kg (SI)
* 1 R = 10 mGy
Deposition of energy by radiation exposure is called
Absorbed dose
- measured in Rads
- SI Unit - gray
- 1 Gy = 100 rad = 1 J/kg
Dose equivalent is measured in
Rem
* 1 Rem = 1 erg/g * 100 Rem = 1 Sv (SI) * 1 Sv = 1 J/kg * used only for radiation protection purposes, use only for occupational exposure
The average occupational exposure receive by a radiographer is approximately
50mrem/yr
3 principal sources of natural background radiation are
- Terrestrial radiation - naturally ocurring radionuclides on earth
- Cosmic Radiation - sun, sources outside our solar system and galaxy
- Internal exposure from radionuclides - K40
The dose response relationship for deterministic effect is
Non-Linear threshold
* there is a dose below which that response will not occur
The dose response relationship for stochastic effects are
Linear non-threshold
* suggest that no radiation dose regardless how small is safe
Unit of effective dose is
Sievert
The dose limit to the skin is
500 mSv/yr
The dose limit for lungs, gonads, thyroid and extremities is
500 mSv/yr
The dose limit for the lens of the eye, tissues and organ is
150 mSv/yr
The dose limit for fetus (unborn child) is
5 mSv/9months
*0.5 mSv/month
Dose limit for public exposure
1 mSv/yr
The dose received by patient during diagnostic radiologic examinations are usually expressed in one of three ways:
- ESE
- Organ dose
- Fetal dose
Bone marrow dose is used to estimate the population ___________ as an index of somatic effect of radiation exposure.
MMD - Mean Marrow Dose
A helpful way to estimate the occupational radiation exposure to the radiographer during either dluoroscopy or radiography is to apply the _____
- 1% rule
* the exposure 1 meter laterally from the patient is approximately 0.1% of the ESE
A minimum of ________ mm Aluminum equivalent total filtration is required on all fluoroscopic xray tubes and radiographic tubes operating above 70 kVp
2.5 mm Aluminum
Purpose of filtration
Is to reduce the intensity of low energy xrays which do not contribute to the image, from reaching the patient
Gonald shields should be used in what situations
- When a patient is of reproductive age
- When the gonalds lie in or near the useful beam
- When the use of such shielding will not compromise the required diagnostic information
