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 