Radiation Hazard Prevention - GE HEALTHCARE Typhoon FLA 7000 User Manual

2.6

Radiation hazard prevention

Controlled area
Paragraph 1 of Article 1 of the Law Enforcement Rules for Prevention of Radiation Hazards
due to Radioisotope and so forth (Prime Minister's Office ordinance No. 56) defines the
controlled area as "a place where the dose equivalent related to external radiation
exceeds the dose equivalent determined by the Director General of the Science and
Technology Agency (hereinafter referred to as the Director General), the concentration
of radioisotope in the air exceeds the concentration determined by the Director General,
or the radioisotope density on the surface polluted by radioisotope exceeds the density
determined by the Director General."
Limit of superficial pollution
Paragraph 3 of Article 4 of Notice No. 15 of the Science and Technology Agency that
determines the quantity, etc. of radiating isotope specifies that the density of radioisotope
on the surface polluted by radioisotope must be one tenth of the density defined in Article
8.
Article 8 and Table 3 of this Notice define the limits as shown below:
1 Superficial density of radioisotope that radiates alpha rays: 4 Bq/cm
2 Superficial density of radioisotope that does not radiate alpha rays: 40 Bq/cm
Installation site of instrument
This instrument is capable of reading not only Storage phosphor screens but also
fluorescent pigment label samples (non-RI method). Therefore, it is recommended that
the user should install it outside the controlled area and use RI-indicated samples without
contacting them with Storage phosphor screens directly.
However, as described above, the Storage phosphor screen surface may be polluted by
radioisotope (RI), depending on the sample condition, since the instrument sticks the
sample to the
auto-radiography experiment of the
When a sample is in direct contact with a Storage phosphor screen, it is generally known
that the sample for making an auto-radiogram contains a relatively small quantity of
radioisotope. However, the degree of superficial pollution of the Storage phosphor screen
is greatly influenced by the dryness of the sample and dose of radioisotope in an
experiment and may exceed the limits mentioned in Limit of superficial pollution , on
page 17.
When the instrument reads a Storage phosphor screen with a polluted non-exposure
area, it may be polluted. The degree of such superficial pollution greatly differs with
users' operation conditions. Superficial pollution may exceed the limit mentioned above.
Note:
Typhoon FLA 7000 User Manual 28-9607-62 AC
3
H-compatible Storage phosphor screen surface and exposes it in an
As mentioned above, install this instrument in the RI controlled area if
the user uses RI-indicated samples that will be in direct contact with
Storage phosphor screens.
2.6 Radiation hazard prevention
3
H label sample.
2 Safety instructions
2
2
17