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The Journal of the Korean Society for Therapeutic Radiology and Oncology 1998;16(4): 505-516. |
| Understanding the Response Characteristics of X-ray Verification Film |
| Inhwan J Yeo, Jinsil Seong, Sung Sil Chu, Gwi Eon Kim, Chang Ok Suh, Sandra E Burch, Chris K Wang |
1Department of Radiation Oncology, Yonsei University, College of Medicine, Seoul, Korea.
2Medical College of Georgia, Radiation Therapy Center, Augusta, GA, USA.
3Georgia Institute of Technology, Radiological Engineering Program, Atlanta, GA, USA. |
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| ABSTRACT |
PURPOSE:
This study is intended to understand the sensitometric charac teristics and the emulsion properties of the commercially available CEA TVS film in comparison with the Kodak X-Omat V film.
MATERIAL AND
METHODS:
For this purpose, we have formulated an analytic expression of the characteristic curves for x-ray film exposed to mixed radiation of electrons, photons, and visible light. This mathematical expression was developed based on reaction-rate and target-hit theories.
Unlike previous expressions, it relates optical density to emulsion properties such as grain size and silver bromide content. We have also developed a quantity which characterizes the film response to visible light relative to that to photons and electrons. This quantity could be expressed as a function of grain area. Thus, we have developed mathematical expressions and quantities with which the emulsion properties of the films can be revealed based on the sensitometric characteristics. Demonstrating the use of this analytical study, we exposed CEA and Kodak verification films to the mixed radiation of electrons, photons, and visible light, and interpreted the experimental results accordingly.
RESULTS:
We have demonstrated that: (1) the saturation density increases as the silver bromide content increases, (2) the time required to reach the threshold dose (to which the film begins to respond) when films are exposed to visible light decreases as the grain size increases, and (3) the CEA film contains more silver bromide, whereas the Kodak film contains larger grains. These findings were supported by the data provided by the manufacturers afterward.
CONCLUSION:
This study presented an analytical and experimental basis for understanding the response of X-ray film with respect to the emulsion properties. |
| Key Words:
X-ray film, Grain size, Silver bromide, Optical density (OD), Characteristic (H & D) curve |
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