抄録
In order to measure the radiation dosage received by means of X-ray film, the relation between the radiation dosage and the blackening of the film has to be investigated. Firstly, by using X-ray dosimeter, pocket dosimeter and film badge commercially available, the radiation dosage was found and compared to standard blackened film. Then by applying Yamabe's densitometer the blackening was measured.
This result indicated that the X-ray film was found to be suitable for the measurement of radiation dosage received, since the condition of the film-blackening was consistent with the small radiation dosage. At this sanatorium satisfactory results were obtained in the measurement of the radiation dosage received by the workers in the X-ray service, by having them carry X-ray film as well as the pocket dosimeter.
The present study is summarized as follows:
1) By giving the same graded radiation to the four rolls of Fuji film, which was recently manufactured, with different emulsion numbers, it was found that the blackening variation caused by the radiation was accurate.
2) These roll films with conditioned radiation were developed at 20 C temperature, dividing the time into four different steps such as 3, 5, 7 and 10 seconds. The blackening to the small radiation dosage up to 60mr was found, except for the original fog of the film, to have no great difference. And the errors in the process of development was unable to measure differences under 10mr in the radiation dosage received.
3) In the purpose of making easy blackening measurement the film, which was prepared to measure the radiation dosage received, was with 0.5mm thick leaden plate covered at the half of the film. Consequently this unsensitized part could get rid of the factor which caused blackening to film other than those for the X-ray use.
4) When the radiation dosage received was identical there was no difference of blackening 153-600mr per hour.
5) The relation between the radiation dosage and the blackening revealed that according to the X-ray dosimeter, between 0-150mr, at the value of 10mr, the blackening increased 0.1-0.13. Upon further increasing of the radiation dosage, the rise of the blackening curve became gradual and gentle indicating that the blackening was not consistent with the radiation dosage. To measure a small radiation dosage it was found that the film was adequate to use.
6) X-ray dosimeter, pocket dosimeter and film badge on the market showed following values:
Assuming 1.0 as the graduation reading of X-ray dosimeter, the pocket dosimeter registered from 1.5 to 1.9 and the film badge showed from 1.5 to 2.2.
