Radiography Introduction

Objectives To describe  Properties of x-rays  Production of x-rays  Formation of radiographic image  Components of an x-ray room  The projections  The radiographic technique

What are x-rays?  Kind of electromagnetic radiation  Means of propagation of energy

Nature of x-rays  Two theories to describe the nature 1. Wave theory (Propagate as waves) 1. Wave theory (Propagate as waves) C = f λ ; Speed = frequency x wavelength C = f λ ; Speed = frequency x wavelength 2. Corpuscular theory (Involved in interactions as particles) 2. Corpuscular theory (Involved in interactions as particles) E = h f ; E = h f ; Photon Energy = Plank’s constant x Frequency Photon Energy = Plank’s constant x Frequency

Properties/Characteristics of EM Radiation  Common properties  Properties Specific to x-rays

1.X-rays are invisible. 2.X-rays are electrically neutral. They have neither a positive nor a negative charge. 3.They cannot be accelerated or made to change direction by a magnet or electrical field. 4.X-rays have no mass. 5.X-rays travel at the speed of light in a vacuum. 6.X-rays cannot be optically focused. 7.X-rays form a polyenergetic or heterogenous beam. Characteristics of X-Rays

8.The x-ray beam used in diagnostic radiography comprises many photons that have many different energies. 9.X-rays travel in straight lines. 10. X-rays can cause some substances to fluoresce. 11. X-rays cause chemical changes to occur in radiographic and photographic film. 12. X-rays can be absorbed or scattered by tissues in the human body. 13. X-rays can produce secondary radiation. 14. X-rays can cause chemical and biologic damage to living tissue.

1.Rectilinear propagation 2.Penetration ability 3.Differential absorption 4.Fluorescent effect 5.Photographic effect 6.Ionization of medium 7.Biological effects 1.Prediction of the path 2.Basis of radiography 3.Tissue differentiation 4.Intensification of image & fluoroscopy 5.Image recording on photographic emulsions (films) 6.Detection & measurement of radiation 7.Radiotherapy & Need for radiation protection Properties & uses of x-rays

Production of X-rays X-rays are produced in an X-Ray tube by two processes: 1.Deceleration of fast moving electrons either by stopping, reducing speed or by changing its direction 2.The transfer of an electron between two inner orbits of an atom

Target of an X-ray tube

(Continuous spectrum)

Characteristic radiation

Lay out of an X-ray room

1.Tap and sink 2.Hand gel 3.Detergent wipes 4.Soap and towel dispenser 5.Vomit bowels 6.Latex gloves / non latex gloves for those with allergies 7.Equipment needed for IVPs 8.General waste bin 9.Sharps bin 10.Emergency resuscitation mask/oxygen connectors 11.Oxygen outlet 12.Suction outlet

13.X-ray table 14.Overhead x-ray tube 15.Lead gowns 16.Moveable seat for patient positioning 17.Long leg x-ray film holder 18.Wall bucky 19.Arm extension for vertical bucky 20.External film holder 21.Contrast warmer 22.Filters for x-ray tube 23.Positioning Aids 24.Lead shielding

Principle of Image formation  X-ray beam of uniform intensity falls on object consists of structures with different absorption properties. object consists of structures with different absorption properties.  It attenuates in different amounts by different structures  The transmitted beam consists of different intensities – called the ‘aerial image’  The aerial image falls on the image receptor, usually on a cassette containing x-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

B2 T1 T2 T3 E E B1 E B2 E T1 EMEM E T2 E T3 EAEA kV mA Sec FFD B B1 Air Supporting tissue (m) EMEM Invisible X-ray image consists of different x- ray intensities

Focal spot X-ray beam Cross section Plot of x-ray intensities

Radiographic projections  AP  PA  Lateral  Obliques:- RAO, LAO, RPO, LPO  Decubitus (patient lying down and the x-ray beam horizontal)

Description of Techniques  Position of patient  Position of body part  Position of cassette related to body part  Direction and centre of x-ray beam  Breathing status  Exposure factors  Radiographic appearance - criteria

Conclusion  The accuracy of diagnosis depends on the quality of the Image.  The radiographic image should have, –Optimum contrast –High resolution –Minimum unsharpness –Less noise –No artefacts –High definition

END Thank you