Lecture 4 Flashcards
DISCOVERY OF X-RAYS
Wilhelm Konrad Roentgen November 8, 1895. The discovery took place in Dr. Roentgen’s physics laboratory at the University of Wurzburg, Germany.
DISCOVERY OF X-RAYS
Shortly after the discovery, the medical field recognized x-rays as a valuable diagnostic tool, especially for detecting skeletal fractures. X-rays became essential in diagnosing diseases, and treatment of tumors.
Medical recognition and use
CHARACTERISTICS OF X-RAY
Electromagnetic Radiation: X-rays are a form of electromagnetic radiation, part of a spectrum that includes visible light.
Wavelength and Energy: X-rays have a significantly shorter wavelength and greater energy compared to visible light.
Wave-like Motion: X-ray photons travel in a wave-like motion through air or matter.
Ionizing Radiation and Safety Guidelines
X-radiation can ionize tissue,
causing
Biologic changes
Ionizing Radiation and Safety Guidelines
Operators of
radiographic equipment must follow guidelines to prevent unnecessary exposure and protect patients and radiology personnel from the dangers
of ionizing radiation.
Importance of guidelines
Protection Measures for Radiographers
-Limit time
-increase distance
-use shielding
Rules of Time, Distance, and Shielding:
* : Use the shortest possible exposure time.
Time
Rules of Time, Distance, and Shielding:
- : Always stand behind a shield containing
the prescribed amount of lead or lead equivalent.
Shielding
Rules of Time, Distance, and Shielding:
- : Maintain the longest distance possible
from the source of x-rays.
Distance
Most radiographic
departments are designed to accommodate
these basic rules.
Department Design
By adhering to these
rules, radiographers can expect to be
protected from exposure to ionizing
radiation.
Adherence to rules
X-ray photons are to the human
eye
Invisible
As x-rays travel through air, they ionize it,
producing an electrical charge. This makes the
photons detectable by ionization chambers, which
measure the ions produced.
IC – to detect # xray photons
Ionization
X-ray photons travel at the speed of light,
approximately 3 x 10^8 m/sec.
Speed
X-ray photons travel in
straight lines and diverge from their point of
origin.
Straight-line travel
X-ray photons cannot be
deflected by mirrors or other devices.
Non-deflectability
X-ray photons cannot be focused by a lens,
as with .
Photography
X-ray photons travel in straight lines and
diverge from the .
Point of origin
X-ray photons cannot be deflected by
or other devices.
Mirrors
When x-ray photons STRIKE CERTAIN SUBSTANCES,
visible light is emitted. This is called
Luminescence
X-ray photons will cause changes to occur in the
of photographic film.
Sensitive emulsion
When x-radiation interacts with matter,
radiation and radiation are produced
Secondary, scatter
When x-ray photons strike certain
substances, visible light is emitted, a phenomenon
known as .
Luminescence
X-ray photons cause
changes in the sensitive emulsion of photographic
film
Photographic Effects
Interaction with
matter produces
radiation and
radiation.
Secondary and scatter radiation
X-ray photons cannot be focused by
a lens, unlike visible light used in photography
Inability to focus
– Magnification, Elongation and
Foreshortening
Recorded detail
Shorter the wavelength the the frequency. It is inversely proportional
Higher
Frequency and energy . It is directly proportional
Goes up/Increase/higher
Increase in Energy and shorter wavelength is inversely proportional
Only energy wavelength is inversely proportional and frequency and energy is the only directly proportional
2 chemicals that are used for processing latent image to visible image -
Developer and fixer
SID - SOURCE TO IMAGE DISTANCE, FAR has great image
OID - OBJECT TO IMAGE, NEAR has great image
SOD - SOURCE TO OBJECT, FAR has great image
Only OID has great image in near
Gurney mott theory
Formation of latent image
When x-rays strike
substances inside film holders, such as intensifying
screen phosphors, they produce light
Intensifying Screen Phosphors
Heart of radiographic or x-ray film
Emulsion
Role of Light: This light plays a crucial role in exposing
the sensitive film emulsion, enhancing the action of
the x-rays.
Light = xray film (emulsion) latent image
(chemicals) = visible image
_: The
object exposed to x-radiation
becomes a source of scatter
and secondary
_.
Source of radiation, rays
__: Radiographers
and other personnel must
protect themselves from
scatter and secondary radiation
using lead barriers, such as
leaded glass or lead-lined walls
and doors.
Lead barriers
