Foto: argus/ Maik Schröder mit freundlicher Genehmigung des Instituts für Mikrotechnik Mainz GmbH Quelle: DLR Göttingen Quelle: DLR Göttingen
Physik im Kontext
What are X-Rays
Röntgen's Discovery
History of Radiology
X-Ray Production
X-rays & Matter
Detection Issues
Detection Methods
Background: Fluorescence

Physics & the Detection of Medical X-Rays
Methods of Detection: Introduction

For medical purposes x-rays are detected primarily by three systems -- film, fluoroscopes and electronic detectors. Most people have seen x-ray films that have been taken by either our dentists or physicians. Some may have seen the images from the other two methods. The electronic system are becoming increasingly popular, especially with dentists.

Fluoroscopy and film are very closely related. In these cases the x-ray radiation is converted to visible light. For film this visible light is absorbed by molecules which change the film so that we see images. Thus, the process involves two common everyday processes: fluorescence and chemical changes in film.

Fluoroscopy differs from film in the way the visible light is treated. The visible light may be created by a fluorescent screen, similar to a TV screen or it may be directed to an electronic device which converts the information an image. In preparing to understand these methods of x-ray detection one needs to start with an understanding of fluorescence. 

Because of the importance of fluorescence a separate page on background has been created.  To make the presentation concrete the discussion there is primarily about visible light.

The electronic systems rely on the same basic physics that applies to radiation damage to tissue. The x-ray’s energy is transferred to atoms and electrons are released. In this case instead of creating damage to a living cell the result is an electrical current which provides a signal for interpretation by a computer system.

For each of these detection systems sophisticated applications of physics allows for detection of very small intensities of x-rays. Thus, these systems provide high quality images and minimize the risk to the patient.

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In cooperation with
Modern Miracle Medical Machines
Physics Education Research Group
Kansas State University