VET-120 Diagnostic Imaging
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Transcript of VET-120 Diagnostic Imaging
VET-120Diagnostic Imaging
Course Set-up5 Lessons (Webinars)5 Lesson ExamsFinal Proctored ExamRequired Reading
Diagnostic Imaging Study Guide Radiography in Veterinary Technology
(Lavin – 4th edition)
Studying for ExamsMake copy of Lesson PowerPointsTake excellent notes during WebinarsRead & highlight Assigned Readings
in Study Guide & Lavin bookPerform Self Checks in Study GuideLearn the Glossary at the beginning of
each Chapter in Lavin bookStudy Key Points & Review
Questions at end of each Chapter in Lavin book
Lesson 1 – X-ray Production and
Safety
Reading Prefaces to Lavin Textbook
Why?????
Online Resources
Animal Insides
Veterinary E-News Magazine
Animal Insideshttp://www.animalinsides.com/
Pulldown Menu
General Imaging Topics
Digital Practice Topics
Latest Imaging News
Books You
Need
Veterinary E-News Magazinehttp://www.vetxray.com/dyncat.cfm?catid=1393
Latest Issue
2 Major Goals in Course
Learn how to take quality “Diagnostic X-rays” with minimum retakes
Learn Radiation SafetyStaffAnimal
Glossary Terms – Page 4
X-ray Production
What Are X-rays?Definition
X-rays are a form of electromagnetic radiation similar to visible light, but with a much shorter wavelength
The Spectrum of Electromagnetic Waves
Physical Properties of X-raysWavelengthTravel
Straight lines Speed of light
FluorescenceCaptured on filmBiologic changes in living tissue
Glossary Terms – Page 10
Taking X-rays
Exposure Factors
Control PanelX-ray Machine
Exposure FactorsMilliamperage (mA)Peak Kilovoltage (kVp)Exposure Time (S)Focal-Film Distance (FFD)
Source-Image Distance (SID)
Control Panel – 3 Exposure Factors
On/Off Switch Milliamperage (mA) Exposure time (fractions of a second) kVp (peak kilovoltage)
Adjust this last
Exposure button/switch 2 stage button?
4th Exposure Factor – Focal-Film Distance (on machine, not control panel)
Anatomy of the
X-ray Machine
Parts of an X-ray Machine
X-ray Tube
Electrical Components
Collimator
Control Panel
The X-ray Tube (Ray Gun)Most expensive part of the machine
A “Ray Gun”An X-ray machine is
essentially a camera. Instead of visible light, however, it uses X-rays to expose the film.
The 5 Elements Needed to Make an X-ray Tube (Ray Gun)
Figure 2-1, Page 11
Source of electrons – cathode
Electron acceleration – transformers
Electron path open – vacuum
Electron target – anode
Outside envelope – glass envelope
The X-ray TubeFigures 2-1, 2-2 on pages 11-12
5 elements needed for x-ray production
Flow of electrons from cathode to anodeFigure 2-2, Page 12
Figure 2-7 Page 14
Example of a rotating anode.
Heel effect – The intensity of the primary x-ray beam is not uniform throughout all areas of the beam; the
intensity is greater toward the cathode side of the x-ray beam because of the angle of the anode target
area.
Figure 2-8Page 14
Demonstration of the heel effect.
Review of X-ray Tube Anatomy
Anatomy of an x-ray tube. A, Cathode. B, Anode. C, Tungsten filament. D, Focusing cup. E, Accelerating electrons. F, Tungsten target. G, Glass envelope. H, Aluminum filter. I, Generated x-rays. J, Beryllium window.
Summary:The Whole X-ray Story
The Patient
Making X-rays
Black & White on FilmsBlack – x-rays NOT absorbed by
animal’s body….. End up hitting filmWhite – x-rays absorbed by animal’s
body…. Fewer get to film
CollimatorMade of leadRestricts (collimates) SIZE of primary
x-ray beamLimits patient & staff exposure to beam Increases quality of x-ray beam
Less secondary (scatter) radiationDoes NOT intensify primary x-ray beamPermanent & adjustable types
Figure 2-18, Page 20 Collimator with lead shutters.
Collimator – ↓ Scatter Radiation
How Much to Collimate? Ideally, every film should have a
collimated edge around the entire filmUse of a smaller cassette is another
means of collimating
X-ray Positioning – X Marks the Spot!
Radiation Safety
Glossary Terms – Page 24
Ionizing RadiationDefinition
The use of electrons (an ionic subatomic particle) to produce x-rays
X-rays – an electromagnetic radiation that is a wave
Fundamental – Radiation should be respected, not feared!
Hazards of Ionizing RadiationRapidly dividing cells are at the greatest
risk of damage Nuclear membrane dissolves during
mitosis and meiosisSomatic damage
Yourself Genetic damage
Your future children/grandchildren
Exposure to Ionizing RadiationPatient exposure
Most animals will not have multiple x-rays in their lifetime……… exposure minimal
Personnel exposure All personnel taking x-rays are at risk Film Badges – Figure 3-2, Page 27 Dosimetry Services – Table 3-2, Page 27
Figure 3-2, Page 27Example of a radiation detection device called a film badge, which consists of a plastic holder containing radiation-sensitive film.
Monitoring DevicesFigure 3-2, Page 27
1-Badge System
Practical Application of Radiation Safety
Primary Beam Exposure
Secondary (Scatter) Radiation Exposure
Radiation “leakage” From Tube Housing
Primary Beam RadiationActual beam of x-rays from tubeMost intense radiationFundamental!!! No human body parts
should EVER be in an x-ray film, even if covered by lead!!!
Fundamental!!! Use of collimator on all films Limits size of the primary beam
Primary RadiationTherefore…Cover your rapidly dividing cells with
lead and stay out of the primary beam – or else!
Secondary RadiationFigure 3-4, Page 28
AKA “scatter radiation”Occurs when primary beam interacts
with objects in its path Patient Tabletop Floor
Figure 3-4, Page 29 – Example of scatter radiation due to interaction of the primary x-ray beam with the table-top.
Figure 3-8, Page 30 A, Appropriate posture for manual restraint during exposure. B, Improper posture for manual restraint during exposure.
Secondary RadiationThis is THE MAJOR SOURCE of
radiation exposure for RVT’s2 major factors
kVp level (higher = more scatter)Thickness of patient
Therefore…AVOID RETAKES!!!
PPPPP
Radiation Safety FundamentalOne of the best ways to minimize
radiation exposure in the workplace is to avoid the occurrence of retakes. It should be the radiographer's goal to achieve a quality radiograph on the first attempt. This not only reduces radiation exposure to the patient and restrainers, but it is also cost effective and saves time.
Radiation Safety ChecklistPage 31
Minimal personnelLess than 18 years old or pregnantRotate personnelUse of mechanical restraints
Gauze, tape, foam positioning devicesUse of chemical restraintProtective apparelNEVER any body parts in primary beam
Figure 3-9, Page 30 A poor radiation safety practice. Hands should
never be positioned within the field of the primary x-ray beam, even with lead gloves on.
What’s Wrong in This X-ray?
Mechanical Restraints
Easy to position animals for a variety of procedures. Made from medical-grade, non-sterile aesthetic foam.
Sandbag/Gauze
Positioning Devices
Protective ApparelUsed mainly to absorb scatter radiation
Made of leadGownsGlovesThyroid shieldsGlasses
Suit Up!
Care of ApparelFigures 3-11, 3-12, Pages 32-33
It is important to keep the apron on a stand and the gloves well aerated when not in use to increase the useful life of the apron and gloves.
Figure 3-11, Page 32 – A, Vertical storage of lead aprons and gloves. B, Lead gloves stored in a horizontal position with cans placed inside to allow air circulation. C, Lead aprons draped over a “homemade” hanger. The hanger consists of a cylindrical tube that is 4 inches or greater in diameter.
Figure 3-12, Page 33 Radiograph of a lead glove showing a crack in the lead lining.
Out of Primary Beam!
Equine Extremity X-rays
Large animal radiography unit with special film cassette holders for equine extremities.
The 4 Pillars of Veterinary Radiation Safety
from http://www.animalinsides.com TimeDistanceShieldingCommon Sense
Time
Distance
Shielding
Common Sense
Radiation Safety ProgramFundamental – have one! If you don’t have one – develop oneProper Planning Prevents Poor
Performance – (PPPPP)
Radiation Safety Program6 items minimum
Adequate technique chart Positioning aids Protective clothing Personnel dosimetry devices Quality control Emergency procedures
Does Your
DAWG Miss YOU When
You Are Gone?