Will learn how radiation forms xray image

1. Image Formation in
Radiology using
Radiation
Presented By: Sarbari Saha.
B.sc,PGDRIT,MIT in Radiology & Imaging
Technologist (Gold Medalist)
Asst Professor Radiology
Founder Rad Easy Learners Group

2. Outline
• Introduction.
• The invisible and visible image.
• Image formed by visible light.
• Image formed by radiation.
• Image made permanent form to hand over to
patient.
• Reference: John Ball & Tony prices.Chesney's Radiographic
imaging (4th Edition)

3. Image
• The term image describe a recognizable pattern
carrying information.
• Otherly preferred as optical, mental, Form or
semblance.Idea or conception based.

4. Visible images are of two types
Real images: Those have real existence such
as photographic or radiographic images.
• Static (Radiographic or photographic).
• Dynamic(On a television screen).
Mental Images: Pictures those generated
within our minds( imagination).

5. Image formation
• Medical imaging is essential for the extraction of
anatomical and physiological information from the
patient and interpretation are made for diagnosis
and treating the diseases.
• The flow of the information from the patient to
the observer is through three stages:
The formation of images.
The conversation of the invisible image into a
visible light image & recording the image.
Production of image in permanent form.
Interpretation of the visible image.

6. Before we create invisible images
we create visible or light field,or
optical field.

7. Formation of an image
• Formation of image : Here the optical image is
produced when divergent rays from patient
/object are made to converage by lens(pupil).
• In radiography we form shadow image when
object is interposed or projected with xray beam.
• The field which we see is our optical field or light
field or visible field.
• The field which we make on our assumption is the
invisible field or radiation field.

8. Formation of invisible field
• During radiographic examination xray passes the
patient.
• As xray penetrate through the body tissues it
modifies the beam on following:
• Tissue type (Based on densities)
• The intensity of the beam.
• Thickness of the beam.

9. Images produced by radiation
• Radiography is the making of images by means of x-
ray. We use light sensitive like film, to respond to X-
radiation as they do produce light.
• The images after giving exposure to x-rays are
developed and darken the images when radiation
reach them.

10. Transmission of x-rays through
human body
• The transmission of x-rays depends on densities
of the matter. e.g. Bone, soft tissue,air.
• Higher the densities more will be absorbtion,
more brighter will be negative images.
• So in radiography any bony structure on xray
recorded on film shows bright ,soft tissue Greg
and air filled structure black.

12. Recording of image
• In the first instance the image exists as a
hidden one within the material used for record
and these subjstance when light reacts.
• These hidden image is called latent image.

13. Production of image in
permanent form
• This involves the action of chemical agents
to make the hidden invisible image vidible
to us.These stage is known as
development and further image is fix and
make permanent by further chemical
processing.

15. Types of conversation
• Using photographic effect- X-ray on a sensitive
sheet ( x-ray film).
• Using xeroradiographic effect process-Through
exposing an electrical charged imaging plate.
• Using fluroscent effect of x-ray on sensitive
screen.
• Using the process of photon stimulated luminance
where a phosphor coated plate is exposed to xray,
the absorbed energy is stored in the phosphor
layer until stimulated by laser photons to form the
visible light image

17. Why you see what you see....
• The image has different levels of density or
shades of Grey.
• Xray show different features of the body in
various grey shades.
• The grey is dark to those areas who do not
absorb xray well and allow it to pass(
Radiolucent).
• The image is bright in dense areas where
radiation persists and absorb more of the X-
rays(Radio opaque).

20. Viewing-Interpretation of the
image.
• The final image whether it be on a film on a
sheet or on a television screen should be
viewed under soecific conditioned to evaluate
its quality and then pass on for diagnosis.

21. Types of viewing
• Viewing by reflected light from a surface.(
Texts,books etc.)
• Viewing by transmitted light ( Through a
semitransparent layer e.g. radiograph).
• Viewing by emitted light from fluroscent layer (e.g
Fluroscopic image on the TV screen).

22. Image Characteristics
cont'd....