Introduction to Rad Protection & Dose metrics (Imaging)

Jennys class

What are the measures of Dose Metrics?

exposure, dose, & risk

exposure measures what, unit

ions in air and how much: Roentgen (R, c/kg, Gy_a)

dose measures what, unit

radiation absorbed dose, RAD (Gy, Gy_t)

risk measures what, unit

Radiation equivalent man, occupational dose: REM (Sv), efd & eqd

What is equivalent dose (EqD)

partial body dose, varying rad sources

EqD formula

EqD (Sv)= RAD (Gy) x W_R

Xray/gamma= 1

alpha= 20

beta= 1.7

What is effective dose (EfD)

overall risk to ionizing radiation of whole body based on sensitivity of tissues and organs

EfD formula

EfD= RAD x W_R x W_T

types of dosimeters

OSL, flim, TLD

3 cardinal rules of rad protection

time, distance, shielding

patient protection measures

time/repeats, shielding, collimation, technique (kVp, mAs)

inverse square law

invsersely proportional to distance, I1/I2= D2²/ D1²

give examples of primary, secondary, protective protection

aprons

lead walls, windows

lead gloves, glasses

when it comes to immobilization, what can techs and students do?

only in life threatening situations, students NEVER

occ exposed maximum exposure limit

5000 mRem= 5Rem/yr= 50 mSv/yr

public maximum exposure limit

100 mRem/yr= 0.1 Rem/yr= 1mSv/yr

declared preg worker max exposure limit

500 mRem/yr= 0.5Rem/yr= 5mSv/yr= 0.5 mSv/month

patient max exposure limit

unlimited

whats the lowest rad dose modalities for pt

x-ray, mammo, MRI

whats the lowest rad dose modalities for techs

x-ray, mammo, MRI, CT