| 摘要 |
PURPOSE:To decide on the amount of exposure simply and accurately by operating the amount of exposure corresponding to predetermined film density from the relation between the amount of exposure and film density as to a film having the film sensitivity corresponding to a coefficient of absorption of radiation. CONSTITUTION:The dose rates of X rays passed through two filters 4 and 4' which are different in thickness are calculated, and an operator 6 calculates the coefficient of absorption of X rays from the rates. Then, the relation between the coefficient of absorption and sensitivity values of various films is stored in a storage means 73, and the relation between the amount of exposure and film density as to the film whose sensitivity is calculated previously is selected by a selecting means 74. Then, the amount of exposure corresponding to the predetermined film density is calculated by an arithmetic unit 75. Thus, the amount of exposure is determined easily and accurately. |
