RadiographyRadiography

IntroductionIntroduction

ObjectivesObjectives

To describeTo describe Properties of x-raysProperties of x-rays Production of x-raysProduction of x-rays Formation of radiographic imageFormation of radiographic image Components of an x-ray roomComponents of an x-ray room The projectionsThe projections The radiographic techniqueThe radiographic technique

What are x-rays?What are x-rays?

Kind of Kind of electromagnetic electromagnetic radiationradiation

Means of Means of propagation of propagation of energyenergy

Nature of x-raysNature of x-rays Two theories to describe the natureTwo theories to describe the nature

1. Wave theory (Propagate as waves)1. Wave theory (Propagate as waves) C = f C = f λλ ; Speed = frequency x wavelength ; Speed = frequency x wavelength 2. Corpuscular theory (Involved in 2. Corpuscular theory (Involved in

interactions as particles)interactions as particles) E = h f ; E = h f ; Photon Energy = Plank’s constant x Photon Energy = Plank’s constant x

Frequency Frequency

Properties/Characteristics of EM Properties/Characteristics of EM RadiationRadiation

Common propertiesCommon properties

Properties Specific to x-raysProperties Specific to x-rays

1.1. X-rays are invisibleX-rays are invisible..

2.2. X-rays are electrically neutral. They have neither X-rays are electrically neutral. They have neither a positive nor a negative charge. a positive nor a negative charge.

3.3. They cannot be accelerated or made to change They cannot be accelerated or made to change direction by a magnet or electrical field.direction by a magnet or electrical field.

4.4. X-rays have no mass.X-rays have no mass.

5.5. X-rays travel at the speed of light in a vacuum.X-rays travel at the speed of light in a vacuum.

6.6. X-rays cannot be optically focused.X-rays cannot be optically focused.

7.7. X-rays form a polyenergetic or heterogenous X-rays form a polyenergetic or heterogenous beam. beam.

Characteristics of X-RaysCharacteristics of X-Rays

8.8. The x-ray beam used in diagnostic radiography The x-ray beam used in diagnostic radiography comprises many photons that have many comprises many photons that have many different energies.different energies.

9.9. X-rays travel in straight lines.X-rays travel in straight lines.

10.10. X-rays can cause some substances to fluoresce.X-rays can cause some substances to fluoresce.

11.11. X-rays cause chemical changes to occur in X-rays cause chemical changes to occur in radiographic and photographic film.radiographic and photographic film.

12.12. X-rays can be absorbed or scattered by tissues X-rays can be absorbed or scattered by tissues in the human body.in the human body.

13.13. X-rays can produce secondary radiation.X-rays can produce secondary radiation.

14.14. X-rays can cause chemical and biologic damage X-rays can cause chemical and biologic damage to living tissue.to living tissue.

1.1. Rectilinear propagationRectilinear propagation2.2. Penetration abilityPenetration ability3.3. Differential absorptionDifferential absorption4.4. Fluorescent effectFluorescent effect

5.5. Photographic effectPhotographic effect

6.6. Ionization of mediumIonization of medium

7.7. Biological effectsBiological effects

1.1. Prediction of the pathPrediction of the path2.2. Basis of radiographyBasis of radiography3.3. Tissue differentiationTissue differentiation4.4. Intensification of image Intensification of image

& fluoroscopy& fluoroscopy5.5. Image recording on Image recording on

photographic emulsions photographic emulsions (films)(films)

6.6. Detection & Detection & measurement of measurement of radiationradiation

7.7. Radiotherapy & Need for Radiotherapy & Need for radiation protectionradiation protection

Properties & uses of x-raysProperties & uses of x-rays

Production of X-raysProduction of X-rays

X-rays are produced in an X-Ray tube by X-rays are produced in an X-Ray tube by two processes:two processes:

1.1. Deceleration of Deceleration of fast moving electronsfast moving electrons either by stopping, reducing speed or by either by stopping, reducing speed or by changing its directionchanging its direction

2.2. The transfer of an electron between two The transfer of an electron between two inner orbits of an atominner orbits of an atom

Target of an X-ray tubeTarget of an X-ray tube

(Continuous spectrum)

Characteristic radiation

Lay out of an X-ray room

1.1. Tap and sink Tap and sink 2.2. Hand gel Hand gel 3.3. Detergent wipes Detergent wipes 4.4. Soap and towel dispenser Soap and towel dispenser 5.5. Vomit bowels Vomit bowels 6.6. Latex gloves / non latex gloves for those Latex gloves / non latex gloves for those

with allergies with allergies 7.7. Equipment needed for IVPs Equipment needed for IVPs 8.8. General waste bin General waste bin 9.9. Sharps bin Sharps bin 10.10. Emergency resuscitation mask/oxygen Emergency resuscitation mask/oxygen

connectors connectors 11.11. Oxygen outlet Oxygen outlet 12.12. Suction outlet Suction outlet

13.13. X-ray table X-ray table 14.14. Overhead x-ray tube Overhead x-ray tube 15.15. Lead gowns Lead gowns 16.16. Moveable seat for patient positioningMoveable seat for patient positioning17.17. Long leg x-ray film holder Long leg x-ray film holder 18.18. Wall bucky Wall bucky 19.19. Arm extension for vertical bucky Arm extension for vertical bucky 20.20. External film holder External film holder 21.21. Contrast warmer Contrast warmer 22.22. Filters for x-ray tube Filters for x-ray tube 23.23. Positioning Aids Positioning Aids 24.24. Lead shieldingLead shielding

Principle of Image formationPrinciple of Image formation

X-ray beam of uniform intensity falls onX-ray beam of uniform intensity falls on object consists of structures with different object consists of structures with different

absorption properties.absorption properties. It attenuates in different amounts by It attenuates in different amounts by

different structuresdifferent structures The transmitted beam consists of different The transmitted beam consists of different

intensities – called the ‘aerial image’intensities – called the ‘aerial image’ The aerial image falls on the image The aerial image falls on the image

receptor, usually on a cassette containing receptor, usually on a cassette containing x-ray film & intensifying screensx-ray film & intensifying screens

X-ray tube

Object

Plot of incident x-ray beam intensity

Plot of transmitted x-ray beam intensity

Invisible x-ray image

Invisible x-ray imageInvisible x-ray image

B2 T1 T2 T3

E

E B1 E B2

ET1EM

ET2

ET3

EA

kV mA Sec FFD

BB1 Air

Supporting tissue (m)

EM

Invisible X-ray image consists of different x-ray intensities

Focal spot

X-ray beam

Cross section

Plot of x-ray intensities

Radiographic projectionsRadiographic projections

APAP PAPA LateralLateral Obliques:- RAO, LAO, RPO, LPOObliques:- RAO, LAO, RPO, LPO Decubitus (patient lying down and the x-ray Decubitus (patient lying down and the x-ray

beam horizontal)beam horizontal)

Description of TechniquesDescription of Techniques

Position of patientPosition of patient Position of body partPosition of body part Position of cassette related to body partPosition of cassette related to body part Direction and centre of x-ray beamDirection and centre of x-ray beam Breathing statusBreathing status Exposure factorsExposure factors Radiographic appearance - criteriaRadiographic appearance - criteria

ConclusionConclusion

The accuracy of diagnosis depends on the The accuracy of diagnosis depends on the quality of the Image.quality of the Image.

The radiographic image should have,The radiographic image should have,– Optimum contrastOptimum contrast– High resolutionHigh resolution– Minimum unsharpnessMinimum unsharpness– Less noiseLess noise– No artefactsNo artefacts– High definitionHigh definition

ENDEND

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