Quantities and Units of Radiation Protection NOT DONE (RADS 349)

National Council on Radiation Protection (NCRP) goal:

keep radiation below level of any known adverse effects

4 agencies that assist with coming up with the quantities and units for radiation protection

NCRP, Center for Devices of Radiologic Health, Environmental Protection Agency (EPA), ICRU or ICRP

National Council on Radiation Protection (NCRP) purpose:

review results of studies conducted, observe effect of radiation on tissue, develop standard based on observations, make recommendations for standards

Center for Devices and Radiological Health (CDRH) works under the...

FDA (food and drug administration) and they will set standards for radiology equipment

The Center for Devices of Radiologic Health is responsible for:

manufacturing standards for all x-ray equipment, following up on compliance with manufacturing standards (make sure stuff works), studying the biological of radiation, overseeing the fields of radioactive materials and nuclear medicine

Environmental Protection Agency (EPA)

works closely with the center for devices of radiological health

ICRU (International Council on Radiation Units) or ICRP (International Council on Radiation Protection)

established units for the special quantities of radiology and other related units

-make and change the units

5 Basic Quantities of Radiology

1. Exposure (what's coming out of a-ray tube)

2. Air KERMA (what's coming out of x-ray tube)

3. Dose (what patient receives)

4. Dose Equivalent (what worker receives)

5. Effective Dose (what body part gets)

Conventional/ Customary unit for Exposure or Intensity

R or Roentgen

SI unit for Exposure or Intensity

C/kg

Exposure

A measurement of the ionizations of air as x-rays pass through it, the total electrical charges of either charge (+ or -), that are created as x-ray pass through the body

-how many charges does it create when x-rays pass through the body

R in terms of electrical charges is

2.58 x 10^-4 C/kg

The R electrical charge ( 2.58x10^-4 C/kg) is liberated in...

1kg of air from X or gamma radiation/photons

1R will produce how many ionizations?

2.08x10^9 ionizations in a cc of air at standard temperature and pressure (25 C)

How to convert R to C/kg

divide the number of R's by the C/kg which is 3876

ex. 100R = 100/3876 =0.0258 C/kg

1 C/kg =

3876 R

How to convert C/kg to R

The number of C/kg x 3876

ex. 0.01 C/kg x 3876 =38.8 R

Proper use of the units ( R or C/kg ) is the

exposure, what/ how much is coming out of the machine (x-ray tube) and when the machine is calibrated

Unit for Air KERMA

Gya

Air KERMA (Gya)

the specialized unit to express how energy is transferred from a beam of radiation to a material (ex. patients skin)

-how much much R/ C/kg is transferred to patient

Air kerma is measured in ________.

joules per kilogram (J/kg) where 1 J/kg is 1 (GYa) (Air KERMA).

KERMA is an acronym for ...

Kinetic Energy Released in Matter or Mass

How to convert to Gya (Air KERMA) when given R?

multiple the number of R by 0.01 Gya (just move 2 decimal places to the left of R)

Modern radiographic and fluoroscopic units have the ability to determine the entire amount of energy delivered to the patient by the beam this would be the...

Dose Area Product (DAP)

Dose Area Product (DAP)

The sum total of air kerma over the exposed area of the patient's surface.

-the amount in radiation energy that is thrust into a portion of the patients body

Units for Dose Area Product (DAP)

mGya-cm^2, milli Air KERMA and cm from patients body

How to find DAP when given mGya and cm^2 example

if a patient receives 20mGya, and the area irradiated is 100 cm^2, then the DAP is 20 mGya, X 100 cm^2 = 2000 mGya - cm^2

-figuring out how much radiation is delivered to patient