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Film processing and darkroom

Introduction

Photographic processing of radiographic films is a critical, but often overlooked, part of the medical imaging process. All of the science and technology of the screen-film system can be easily negated with less than optimum photographic processing. It is important to understand the various steps in the photographic process and the issues associated with each of these relative to quality images. In addition, processing quality control is a key component of medical imaging quality assurance and essential to assure quality screen-film images.

Important principles

The photographic process includes film development, fixing, and washing. Each of these is sensitive to the chemical activity, time of the process, and process temperature. The last step, washing, removes residual chemicals from the fixing process. If the residual fixer is not adequately removed, the photographic image will be stained and start to fade prematurely. Automatic film processors are often used for fast throughput with control of the processing steps. Furthermore, the darkroom for film handling and processing must be properly designed and maintained.

Quality assurance

Film sensitometry describes how a photographic material will react to different conditions, e.g., changes in developer concentration or temperature. Understanding sensitometry is an important aspect of understanding screen-film and processing systems.

Introduction to references

There are several good references for the photographic process, in addition to those listed here. Haus and the three IAEA documents are excellent. Sprawls provides an outstanding online resource relative to photographic processing. Herz, although an older text, is also an outstanding reference for all aspects of the photographic system. Quality control of photographic processing is covered in the quality control references.

Film sensitometry is covered in Sprawls and Herz and discussed in many of the other references.