The document discusses x-rays and how they are produced and used. It explains that Wilhelm Roentgen discovered x-rays in 1895 while experimenting with cathode rays. X-rays are a form of electromagnetic radiation produced when high-voltage electrons interact with a metal target. X-ray film contains silver halide that darkens when exposed to x-rays, allowing radiographic images to be viewed. The document also covers x-ray positioning terminology, different body positions used for x-rays, and factors that define a technically adequate chest x-ray.

1. Reading x-rays

3. • Wilhelm Conrad Roentgen, a german physicist, discovered x rays
on November 8,1895.
• Roentgen was investigating the behavior of cathode rays in high
energy cathode ray tube which was enclosed in black card board
to prevent escape of light.
• On passing high voltage discharge through tube, he noticed a faint
light glowing on a workbench about 3 feet away.

4. • He discovered that the source of light was the fluorescence of
a small piece of paper coated with barium platinocyanide.
• Because electrons could not escape the glass envelope to
produce fluorescence, & because
card board permitted no light to escape from tube, he concluded
that some unknown type of ray (X) was produced when the
tube was energised.
• He called them X-RAYS.

5. • X - rays is a form of electromagnetic radiation.
• They are produced by the X-ray tube, using the high voltage to
accelerate the electrons produced by the cathode.
• The produced electrons interact with the anode, thus producing
X-rays.

7. • Less than 1% of energy is converted into X-ray production.
• Anode is made of tungsten disc in ordinary diagnostic x ray
tube.

9. • X-ray film displays the radiographic image and consists of
emulsion (single or double) of silver halide (AgBr is most
common) which when exposed to light, produces silver ion
(Ag+) and electron.
• The total thickness of the film is about 0.25 mm.

10. Advantages
• Cost
• Availability

11. Disadvantages
• Ionising radiation
• 2D information - overlap

12. Radiographic positioning terminology
• Anterior
• Posterior
• Superior
• Inferior
• Medial
• Lateral
• Proximal
• Distal
• Superficial
• Deep
• Ipsilateral
• Contralateral

13. Body positions
• erect: either standing or sitting
• decubitus: lying down
• supine: lying on back
• prone: lying face-down
• lateral decubitus: lying on one side
– right lateral: right side touches the cassette
– left lateral: left side touches the cassette

14. Projections
• antero-posterior: central ray passes from anterior to posterior
• postero-anterior: central ray passes from posterior to anterior
• lateral: central ray passes from one side of body to the other
through the axial plane
• oblique: central ray passes through the body/body part through a
plane which is at an angle to the transverse plane/coronal plane

15. Different tissues in our body absorb X-rays at different
extents:
• Bone- high absorption (white)
• Tissue- somewhere in the middle absorption (grey)
• Air- low absorption (black)

17. • Technically adequate chest x-ray

18. • Penetration
• Inspiration
• Rotation
• Angulation

19. Penetration

20. Under penetration

21. See the spine through the heart

22. Inspiration
• 10 anterior ribs are visualised

24. • Anterior ribs – harder to see
• Posterior ribs – horizontal

25. Anterior vs posterior ribs

26. Poor inspiration

27. • Poor inspiration – crowd lung markings – disease in lung bases

28. Disease in lung bases

29. Rotation

30. • Spinous process equidistant to the medial ends of the clavicles
• Spinous process closer to right clavicle – patient rotated to his
left
• Spinous process closer to left clavicle – patient rotated to his
right

32. Marked rotation

33. AP vs. PA
• PA film – heart close to film – less magnified
– Standard film
• AP film – heart away from film – more magnified
– Portable films

36. Angulation
• Apical lordotic view – beam angulated toward the head
• Anterior structures projected higher than the posterior
structures

37. Angulation

38. Factors
• See spine through heart
• At least 9 – 10 ribs
• Spinous process between clavicles
• Clavicle over 3rd rib