Tenth lecture

Principles of radiation protection

I-External radiation hazard: when dealing with a source of radiation outside the body.

II-Internal radiation hazard: is the source of radiation deposited within the body.

(1)-Time

(2)-Distance

(3)-Shielding

I-Protection from external Radiation hazards is provided by employing one or more of the following three principles:

)1-(The time principle

• The total radiation dose one receives while working around sources of radiation is a function of the dose rate and the time spent at that dose rate.

Total dose = dose rate x time

• Occasionally it may be necessary to work in areas of high dose rates. This can be done safely by limiting the exposure time.

Control of Time

• Practice Mission in Background/Low Dose Area

• Spend Down Time in Low Dose Location

• (Dose Rate)(Time) = Dose

• 10 mR/hr x ½ Hour = 5 mR

• Use Respirators to Minimize Internal Intake

)2-(The distance principle• Distance is very effective at reducing the dose

rate due to a radiation source external to the body.

• Control of Distance• Remote operation

– manipulating devices, remote handling tools

• Moving away from Sources– remain near a source only when necessary– treat medical needs of patient/victim first

• Secure and Remove Other Radiation Sources– waste containers at Hot Zone/Cold Zone

)3-(Shielding for , and

The basic concept is to:Place materials between the source and person to absorb some or all of the radiation

radiation: no shield required for external exposures; clothing, dead skin layer stops ’s,

radiation: ranges of meters in air; some can penetrate dead skin layer; thin plexiglass shields adequate, bunker gear effective for low energy

x and radiation: highly penetrating, best shields are dense materials (lead), vehicles can be used as shields

)3-(Shielding for , and