X-RAY PRODUCTION AND ITS INTERACTION WITH MATTER Flashcards
Properties of X -rays
-No mass, no charge
-0.01 to 10 nm
-0 to 25 MeV
-Highly penetrating
PRIMARY RADIATION TYPES;
Primary Beam & Exit Beam
SECONDARY RADIATION
-Leakage Radiation
-Scattered Radiations
-Off -focus radiation
This refers to the X -ray beam before any interaction
with the patient, grid, table, or image intensifier.
Primary Beam
Emitted through the window of X-ray tube and consists of photon.
Primary Beam
The beam that interacts with the detector is termed the exit beam and will have been significantly attenuated.(have been heavily
filtered and, consequently, will be
harder and more penetrating than the
primary beam.)
Exit Beam
This is leakage from the XRT housing.And is limited to a maximum of 1 mGy/hr at 1 meter from the focus and,in practice, is usually much less.
Leakage Radiation
It doesn’t contribute significantly to
staff dose.
Leakage Radiation
This is a direct result of the Compton effect in the patient that Contributes the most to staff
radiation dose.
Scattered Radiation
the emission of x -ray photons
that originate outside of the anode focal
spot.
Off-focus radiation
Primarily a form of scattered radiation,
photons produced in this manner may
result in blurring and are of no use for
diagnostic purposes.
Off -focus radiation
THREE REQUIREMENTS FOR X-RAY
PRODUCTION
*ELECTRON-GENERATION:A source of electrons.
*ACCELERATION:Means or rapidly accelerating
those electrons.
* ANODE
INTERACTION:A means of decelerating those electrons.
the source of electrons in the X -ray tube’s cathode side.
Filament
Electrons escaping from the metal(boiling off electrons) resulting from the absorption of
thermal energy.
Thermonuclear emission
When a large potential difference is applied across the tube electrodes, it causes the e- at the filament to accelerate at very high
Acceleration on electrons
True or False: The higher the voltage applied, the
greater the speed of these electrons as
they strike the target.
True
True or false: Mo re e ne rg e tic X-ra y p ho to ns that have shorter wavelengths, higher frequencies, and greater penetrating power.
True
T or F:When the slow projectile electrons bombard the target, their kinetic energy changes to other forms of energy.
F
necessary to prevent the x -rays from
scattering and interacting with gas molecules.
vacuum
X-RAY BEAM PRODUCTION
1)filament Supply; current to heat the filament through boiling of electrons.
2)Thermionic emission; released from the filament
3)anode interaction;Bremstruhlung and characteristic radiation
interacts with the whole atom
LOW-ENERGY X -RAY
MODERATE -ENERGY X -RAY
interacts with electrons
HIGH-ENERGY X -RAY
interacts with nuclei
5 interaction with matter
• Coherent
• Compton
• Photoelectric Effect
• Pair Production
• Photodisintegration
