Rad 110

1
Rad 110

• Units of Exposure
• And
• Exposure Limits

2
Roentgen(R)

• Unit of radiation exposure or intensity
• 2.08 x 108 ion pairs in one cubic centimeter of
  air
• Or, 2.58 x 10-4 C/kg
• Beam intensity or beam output is measured in R

3
Rad

• Radiation absorbed dose
• This is a measure of tissue exposure to radiation
• 1 rad 100ergs/g
• Rad is a measure of patient dose

4
Rem

• Radiation Equivalent Man
• Rem rad x wf(or qf)
• Rem measures occupational dose and population
  dose
• Rem records your exposure as a student and in the
  future as a technologist.

5

• In diagnostic radiography
• 1 R 1 rad 1 rem
• This is only true due to the nature of the
  photons we interact with

6
SI units

• 100 rads 1 gray
• 100 rems 1 Sievert

7
Dose LimitsOccupational Exposure

• Whole body
• 5000 mrem or 50 mSv
• Lens of the eye
• 15000 mrem or 150 mSv
• Extremities
• 50000 mrem or 500 mSv
• Lifetime limit
• Age x 1000 mrem

8
Dose limitsPregnancy

• Pregnancy
• 500 mrem or 5 mSv
• Or 50 mrem per month
• Fetal exposure limit is the same as moms

9
Dose limitPublic

• Public
• 100 mrem or 1 mSv
• This is also the educational limit

10
Weighting Factors

• X-ray, gamma, and electrons 1
• Neutrons lt10 keV 5
• 10 to 100 keV 10
• gt100 keV to 2 MeV 20
• 2 to 20 MeV 10
• gt20 MeV 5
• Protons 2
• Alpha particles (helium nucleus) 20

11

• R
• Rad
• Rem
• An easy way to remember this is that the units of
  measure are alphabetical from the tube. R is
  tube output, rad is patient exposure, and rem is
  occupational exposure.