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(BQ) Part 2 the book "Clark's essential physics in imaging for radiographers" presents the following contents: Principles of radiation detection and image formation, image quality, radiation dose and exposure indicators, image display and manipulation in medical imaging, radiation protection and safety,. | CHAPTER 6 PRINCIPLES OF RADIATION DETECTION AND IMAGE FORMATION INTRODUCTION The aim of this chapter is to explore how radiation is detected measured quantified and used in order to produce images. There are various types of radiation detector which are designed for different purposes within medical imaging. There are automatic exposure devices and computed tomography CT detectors as well as those used within general radiographic and fluoroscopic imaging. This chapter will begin by looking generally at the types of detector we may come across in the radiography department but the focus and bias later in the chapter revolves specifically around large field detectors used in general radiography. Learning objectives The students should be able to Discuss how radiation is detected measured quantified and used in order to control exposure as well as produce images. Discuss various detectors and how they are used for different clinical purposes. Discuss the benefits and limitations of various detector types used within different imaging systems. 71 Principles of Radiation Detection and Image Formation DESIRABLE CHARACTERISTICS OF RADIATION DETECTORS There are a number of characteristics which are considered for any kind of radiation detector. The main ones include Absorption efficiency is clearly desirable that a detector is able to absorb as many of the incident X-rays as possible. The overall absorption is dependent on the physical density atomic number size thickness . Conversion efficiency is essentially the ability of a detector to convert absorbed X-ray energy into a usable electronic signal. Capture efficiency is dependent on the physical area of the face plate minus the interspace between individual detectors and side and end walls. Dose efficiency is influenced by both conversion and capture efficiency. Typical dose efficiency is anywhere between 50 and 80 per cent for individual detector designs but nearer 30-60 per cent for flat panel detectors. Temporal .