Understanding X-Ray Production and Interactions in Radiology

RADIOLOGY-3
Fourth Professional UNIT 3
Dr. Ramesh Tiwary
Assistant Professor
Deptt. of Vet. Surgery and Radiology
“PRODUCTION
OF
X-RAYS”
Ionising Radiation
Particulate or corpuscular – 
alpha
, 
beta
particle
, 
protons
, 
electrons
, 
neutrons
, nuclear
fragments.
Electromagnetic radiation – 
Heat waves
, 
light
waves
, 
infra-red rays
, U/V-rays, 
x-rays
, 
gamma
rays.
Wave length to x-ray – 
0.1 to 0.5 A
0
 
(1A
0
 = 10
-
10
 cm)
 
Energy  - 25 to 125 Kev.
Diagnostic x-ray: 30 – 150 kVp
.
Coherent scattering: A photon interacts with
an object and changes its direction.
        Subject does not absorb the photon and
 
photon energy does not changed.
       Degrade image quality, strike radiographer,
 
increased personal exposure.
 
Interaction of Photons with Matters
Photoelectric effect
When x-ray photons interact with 
inner shell (K,
L, M shell) electron of atom
, free electron fly off
as photoelectric and get absorbed in the body.
Outer electrons shift to the inner shell gives off
energy in the form of radiation called
characteristic radiation or line radiation.
Photoelectric effect 
α
 z
3 
and inversely
proportional to 1/E
3
.
By using high kVp photoelectric effect decrease
thus patient dose decreased.
Photoelectric effect is responsible for formation
of image on radiographs of object.
Bremstrahlung or breaking or General or
white radiation
 – when electron passing
through positive nucleus of target get
deflected or slow lose in kinetic energy
Compton effect
: - Moderate or high energy
photon encounters free electron of the 
outer
shell of the atom.
Compton effect produces 
almost all the
scatter radiation encountered in diagnostic
radiology.
Compton effect of x-ray independent of
atomic number of absorbing material.
 
 
 
X-RAY TUBE
It consists of a 
glass tube (12-18cm L, 9cm D) 
which has been
evacuated to produce a high vacuum and into which are sealed two
electrodes, the 
cathode (-
) and the 
anode 
(+) placed 1-3cm apart.
 
 
 
Cathode
 
Anode
 
Glass Envelope
 
                  
  
CATHODE
Spiral  filament  in focusing cup.
 
Tungsten  target set in
anode face.
Cathode
:- Negative side of the x-ray tube, its
filament consists of tungsten atomic no. 74
and melting point 3370
0
C.
 
Tungsten has little tendency to vaporise, thus
it prolongs the life of the x-ray tube.
Focusing cup
: - Filament is embedded in a
concave metal shroud called focusing cup
made of nickel or molybdenum.
CATHODE
.
Positive side of the x-ray tube.
It is termed the 
target,
 because it is the origin
of the X-ray beam it is also spoken of as the
focus or focal spot
.
99% of kinetic energy 
in the collision
converted into thermal energy and 1%
irradiated as x-rays.
Cathode filament and its focusing cup are so
constructed that the beam of electrons focused
on this relatively small area.
 
ANODE
Types of Anod
Stationary type – used in dental x-ray machine
as portable x-ray units where high current
power not required.
Consists of copper block embedded with
tungsten rhenium alloy metal.
Rotating type
Rotating type –Consists of a molybdenum disc
coated with a strip of tungsten –rhenium alloy.
Advantage over stationary type is better heat
dissipation, provides larger target area for
electron beam to interact.
Size of focal spot in x-ray machines varies from
0.3 to 3 mm and angle should not less than
15
0
.
 
Rotating   disc target of anode
Diagram Of A Rotating Anode Tube
 
G
l
a
s
s
 
T
u
b
e
 
C
a
t
h
o
d
e
 
E
m
i
t
t
e
d
 
R
a
d
Heel effect
Heel effect
: - Radiation intensity as high as 40%
on the cathode side of the x-ray beam than on
the anode side is called heel effect.
while taking radiograph of unequal thickness,
thicker or denser side should be positioned
towards the cathode.
Smaller angle of anode more pronounced heel
effect.
When film size larger and focal film distance are
less heel effect more noticeable.
Tube current (Milliamperage or mA
) – Increasing
mA increases the x-ray output.
Tube potential (KVP)
:- If KVP is doubled the x-ray
quantity increase by a factor of four.
Increase in KVP by 15% would require a reduction
in mAs by one half.
Focal film distance
: - X-ray intensity varies inversely
to the squire of the distance between the target
and focal spot.
 
Quantity of x-ray production
Portable x-ray machine – 70 to 110 
kv
 and 15
to 35 mA.
Mobile x-ray machine - 90 to 150 KV and 40 to
300 mA.
Fixed x-ray machine – 120 to 150 KV and 300
to 1000 mA.
 
Type of x-ray machines
Slide Note
Embed
Share

Explore the fundamentals of X-ray production, including the types of ionizing radiation and interactions of photons with matter. Learn about the photoelectric effect, Compton effect, and characteristics of X-ray tubes, essential for radiology professionals and students. Delve into the mechanisms behind the generation of X-rays, their wavelengths, energies, and their applications in diagnostic imaging. Gain insights into the components of X-ray tubes and the processes involved in creating high-quality radiographic images.


Uploaded on Jul 19, 2024 | 0 Views


Download Presentation

Please find below an Image/Link to download the presentation.

The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.

E N D

Presentation Transcript


  1. RADIOLOGY-3 Fourth Professional UNIT 3 Dr. Ramesh Tiwary Assistant Professor Deptt. of Vet. Surgery and Radiology

  2. PRODUCTION OF X-RAYS

  3. Ionising Radiation Particulate or corpuscular alpha, beta particle, protons, electrons, neutrons, nuclear fragments. Electromagnetic radiation Heat waves, light waves, infra-red rays, U/V-rays, x-rays, gamma rays.

  4. Wave length to x-ray 0.1 to 0.5 A0 (1A0 = 10- 10 cm) Energy - 25 to 125 Kev. Diagnostic x-ray: 30 150 kVp. Coherent scattering: A photon interacts with an object and changes its direction. Subject does not absorb the photon and photon energy does not changed. Degrade image quality, strike radiographer, increased personal exposure.

  5. Interaction of Photons with Matters

  6. Photoelectric effect When x-ray photons interact with inner shell (K, L, M shell) electron of atom, free electron fly off as photoelectric and get absorbed in the body. Outer electrons shift to the inner shell gives off energy in the form of radiation called characteristic radiation or line radiation. Photoelectric effect z3 and inversely proportional to 1/E3. By using high kVp photoelectric effect decrease thus patient dose decreased. Photoelectric effect is responsible for formation of image on radiographs of object.

  7. Bremstrahlung or breaking or General or white radiation when electron passing through positive nucleus of target get deflected or slow lose in kinetic energy Compton effect: - Moderate or high energy photon encounters free electron of the outer shell of the atom. Compton effect produces almost all the scatter radiation encountered in diagnostic radiology. Compton effect of x-ray independent of atomic number of absorbing material.

  8. X-RAY TUBE It consists of a glass tube (12-18cm L, 9cm D) which has been evacuated to produce a high vacuum and into which are sealed two electrodes, the cathode (-) and the anode (+) placed 1-3cm apart. Cathode Anode Glass Envelope CATHODE Tungsten target set in anode face. Spiral filament in focusing cup.

  9. CATHODE . Cathode:- Negative side of the x-ray tube, its filament consists of tungsten atomic no. 74 and melting point 33700C. Tungsten has little tendency to vaporise, thus it prolongs the life of the x-ray tube. Focusing cup: - Filament is embedded in a concave metal shroud called focusing cup made of nickel or molybdenum.

  10. ANODE Positive side of the x-ray tube. It is termed the target, because it is the origin of the X-ray beam it is also spoken of as the focus or focal spot. 99% of kinetic energy in the collision converted into thermal energy and 1% irradiated as x-rays. Cathode filament and its focusing cup are so constructed that the beam of electrons focused on this relatively small area.

  11. Types of Anod Stationary type used in dental x-ray machine as portable x-ray units where high current power not required. Consists of copper block embedded with tungsten rhenium alloy metal.

  12. Rotating type Rotating type Consists of a molybdenum disc coated with a strip of tungsten rhenium alloy. Advantage over stationary type is better heat dissipation, provides larger target area for electron beam to interact. Size of focal spot in x-ray machines varies from 0.3 to 3 mm and angle should not less than 150.

  13. Diagram Of A Rotating Anode Tube Rotating disc target of anode Glass Tube Emitted Rad Cathode

  14. Heel effect Heel effect: - Radiation intensity as high as 40% on the cathode side of the x-ray beam than on the anode side is called heel effect. while taking radiograph of unequal thickness, thicker or denser side should be positioned towards the cathode. Smaller angle of anode more pronounced heel effect. When film size larger and focal film distance are less heel effect more noticeable.

  15. Quantity of x-ray production Tube current (Milliamperage or mA) Increasing mA increases the x-ray output. Tube potential (KVP):- If KVP is doubled the x-ray quantity increase by a factor of four. Increase in KVP by 15% would require a reduction in mAs by one half. Focal film distance: - X-ray intensity varies inversely to the squire of the distance between the target and focal spot.

  16. Type of x-ray machines Portable x-ray machine 70 to 110 KV and 15 to 35 mA. Mobile x-ray machine - 90 to 150 KV and 40 to 300 mA. Fixed x-ray machine 120 to 150 KV and 300 to 1000 mA.

  17. THANKS

Related


More Related Content

giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#giItT1WQy@!-/#