The persons who are exposed to radiation should not have the dose greater than upper limit and this limit is called maximum permissible dose (MPD) or smiply the dose limit. The MPD is different for occupationally exposed persons and general public. MPD include contributions from radiation source both inside and outside th ebody but excludes contributions from medical exposure and background radiations. The total dose in rems accumulated by an occupationally exposed person should not exceed 5(N-18) where N is the age of the person in years.
An area where a yearly whole body dose of 1.5 rem or more should be considered as a controlled area. Persons working in a controlled area should carry personal monitors such as TLD, pocket ionisation chamber etc. For the measurement of radiation dose personal monitors are not feasible for members of the public exposed occasionally to radiation. The protective measures for these persons is evaluated indirectly by sampling the air, water, soil and other elements of environment.
An area where a yearly whole body dose of 1.5 rem or more should be considered as a controlled area. Persons working in a controlled area should carry personal monitors such as TLD, pocket ionisation chamber etc. For the measurement of radiation dose personal monitors are not feasible for members of the public exposed occasionally to radiation. The protective measures for these persons is evaluated indirectly by sampling the air, water, soil and other elements of environment.
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