Practical Veterinary Diagnostic Imaging

Suzanne Easton

• Publisher: Wiley-Blackwell
• Year: 2012
• ISBN:
  9781118278918
• Edition: 2
• Topic: Medicine
• Subtopic: Veterinary Medicine

Practical Veterinary Diagnostic Imaging is an essential and practical guide to the various diagnostic imaging modalities that are used in veterinary practice. It moves from basic mathematic and physical principles through to discussion of equipment and practical methods. Radiographic techniques for both small and large animals are covered. There is a separate chapter devoted to ultrasound, as well as discussion of advanced imaging techniques such as fluoroscopy, computerised tomography and magnetic resonance imaging. The book also covers legislation and safety issues in the context of their impact on the veterinary practice.

Presented with clear line diagrams and photographs, Practical Veterinary Diagnostic Imaging also provides revision points and self-assessment questions in each chapter to aid study. It is an ideal guide for student and qualified veterinary nurses. It is also a useful reference for veterinary students and veterinarians in general practice who want a basic guide to radiography and other imaging modalities.

KEY FEATURES

• Everything you need to know about diagnostic imaging in veterinary practice in a language you can easily understand
• The basic principles of physics presented in simple terms
• Improves your positioning techniques with practical tips for best practice
• Clear guidance on the use of digital imaging to improve image quality and reduce radiation doses to patients
• Companion website with additional resources (available at www.wiley.com/go/easton/diagnosticimaging )

Chapter 1

Essential Mathematics and Physics

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Chapter contents

Matter, energy, power and heat

Units and prefixes used in radiography

Radiological units

Useful mathematics

Proportions and the inverse square law

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Introduction

This chapter introduces and explores the principles of mathematics and physics that will make following chapters and the principles of radiography easier to understand. Although many of the concepts introduced in this chapter are only for revision, they are relevant to later chapters.

Matter, energy, power and heat

Matter

The entire world is made up of matter. Anything that occupies space can be termed ‘matter’. Matter is a collection of atoms, the basic building blocks. All matter has mass, that is, the measure of matter in an actual object. If gravity is involved, this mass is known as the weight of an object. If an object is placed in a lesser gravitational field, such as the atmosphere on the moon, the mass will remain the same, but the weight will decrease. The weight will also change if the object changes form, but, again, the mass will remain the same. An example of this is water in its three forms – solid (ice), liquid (water) and gas (steam). In these three forms, the mass is the same throughout, but the weight changes considerably.

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Matter	A collection of atoms and molecules
Mass	The measure of matter in an object
Weight	Mass under the influence of gravity

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Energy

The process of matter altering its state or form produces energy. Any object, however large or small, that is able to do ‘work’ is said to have energy. Energy has a number of different forms. Energy can be neither created nor destroyed, although it can change from one form to another (Table 1.1).

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Total energy is measured in joules (J):

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Table 1.1 Energy types, definitions and examples.

Energy type	Description	Example
Potential	The amount of work an object could do because of its position	An axe raised, ready to be brought down to chop, has potential energy
Kinetic	As an object leaves its state of potential energy, it gains kinetic energy	An apple gains kinetic energy as it falls out of a tree
Electrical	The movement of electrons inside a conductor after the application of a potential difference	The movement of electrons in a cable produces the electrical energy needed to make a bulb light up
Nuclear	Nuclear energy is the energy stored within the nucleus of an atom	This energy is formed when the nucleus of an atom is split
Thermal	The energy of a hot object. This is caused by the vibration of molecules within matter	A hot bath has faster moving molecules than a cool bath
Sound	The energy produced by sound vibrations	A musical instrument, engine noise, speech, thunder, diagnostic ultrasound, sonar
Chemical	The energy generated when a reaction occurs between two substances	Thermal energy produced when water is added to hot oil
Electromagnetic	Electric and magnetic energy moving in waves	X-ray production, radio waves, infrared light

Energy conversion

As energy cannot be created or destroyed, it changes form, and this process is known as energy conversion.

In radiography, the X-ray tube is an example where energy is converted from one form (electrical) into other forms (X-rays, heat, light). We also use ultrasound where an ultrasound transducer converts electrical energy into sound ene...