Sigma 130Ci 관리 매뉴얼

7.2

Access to restricted areas
The site where radiography is performed must be separated from other work areas by as

much distance as possible. If applicable, check for occupation of the areas above and below

the radiography site.
Clearly defined boundaries must be set up and warning signs displayed to provide

warning and prevent access to the radiography site by unauthorized personnel before

any exposure begins.
No one should enter the boundary marking a ‘Restricted Area’ or ‘Controlled Area’ without

a film badge or TLD, direct reading pocket dosimeter (or electronic pocket dosimeter) and

alarm ratemeter (if required).
A pocket ‘chirper’ alarm is required in some countries to provide radiography personnel with

an immediate audible warning of a high radiation intensity.
United States regulations
‘High Radiation Area’ signs must be posted where a dose of 100mRem (1mSv) could be

received in any one hour. The radiographers must provide continuous direct surveillance of

the area or when a permanent installation is used, the entrance must be equipped with door

interlocks, audible and visual warnings.
‘Radiation Area’ signs must be posted where dose of 5mRem (5µSv) could be received in any

one hour.
‘Restricted Area’ must be identified and posted where a dose of 2mRem (20µSv) could be

received in any one hour or 100mRem (1mSv) in one year.
In practice, the ‘Radiation Area’ and ‘Restricted Area’ are combined and identified by the use

of a rope barrier. The area is posted with the ‘Radiation Area’ signs where the maximum

dose will not exceed 2mR (20µSv) in any one hour or 100mRem (1mSv) in a year. The

practice of using the ‘Radiation Area’ sign at the ‘Restricted Area’ boundary clearly defines

why the area has been restricted. Additionally, the trefoil (radiation) symbol provides a visual

warning for those individuals who cannot read.
During a radiographic exposure, a calibrated and operable survey meter must be used to

confirm the dose rate at the ‘Restricted Area’ boundary and adjusted if the dose rate

exceeds the limit of 2mRem (20µSv) in one hour.
During the radiographic exposure, the radiographers must maintain continuous direct

surveillance of the ‘High Radiation Area’ in addition to ensuring that no one enters their

posted ‘Restricted Area’.
EU Regulations
A ‘Controlled Area’ must be marked with a barrier at a distance where the radiation intensity

will not exceed 0.75mR/hr (7.5µSv/hr). The boundary dose rates must be noted and the

record kept for 2 years. During radiographic operations, only classified radiation workers are

allowed inside this area.
A ‘Supervised Area’ is defined as the area where the boundary dose rate limit must not

exceed 0.25mR/hr (2.5µSv/hr). No barriers or notices are required here, but the radiographer

must be vigilant to ensure that personnel in this area do not enter the ‘Controlled Area’.
Personnel monitoring
All personnel who enter a ‘Restricted’ or ‘Controlled’ area or are present during radiographic

operations are required to wear the appropriate personnel monitoring devices as required by the

regulatory jurisdiction. These devices can include; film badges; thermoluminescent dosimeters

(TLD); optically stimulated luminescence badges; direct reading pocket dosimeters; electronic

pocket dosimeters; alarm ratemeters; and audible alarms. Calibrated and operable survey meters

must be used to determine radiation levels when conducting radiographic operations.