Concepts of Radiologic Science

CONCEPTS OF RADIOLOGIC
SCIENCE

April 18, 2014concepts of radiological science

Man made radiation---60 mrem.
Medical
Nuclear medicine
Occupational
Nuclear power
Industrial
Consumer products

Discovery of X rays
During 1870s and 1880s
Conduction of cathode rays through Crookes tube–
invented by Sir William Crookes.
Crookes tube—forerunner of modern fluorescent
lamps & X rays tubes.

In 1895, Wilhelm Roentgen was working in his lab in
Wuzburg Germany.
Completely enclosed his Crookes tube in black
photographic paper.
Barium platinocyanide coated plate
The plate glowed.

Intensity of the glow increased as plate was brought
closer
Glow—fluorescence
Roentgen named the invisible light-- X light

Development of modern radiology
2 types of X ray examinations
Radiography—uses X ray films
 X ray tube is mounted from ceiling on a track
 X ray tube can be moved in any direction
 Fixed images

Fluoroscopy
 X ray tube usually located under examination
table.
 Moving images are provided to radiologist

X ray voltage is measured in kilovolt peak(kVp)
X ray currents are measured in milliamperes(mA)

OTHER DEVELOPMENTS
Radiographic intensifying screens—by Micheal
Pupin in 1896 to reduce the exposure time.
Double emulsion films in 1904—further reduced
the exp. Time.
Cellulose nitrate—substitute for glass plate
Fluoroscope—1898 by Thomas A. Edison

In 1907, H.C.Snook—a high voltage power supply—
interrupterless transformer.
In 1913,William Coolidge---hot cathode x ray tube. A
vacuum tube that allowed x ray intensity & energy to
be selected separately & with accuracy.

Further developments…

Reports of radiation injury
The first x ray fatality– in 1904, Edison’s assistant &
friend- Clarence Dally.
Suffered severe X ray burns that eventually resulted
in amputataions of both arms.

In coming years—the frequency of injuries increased.
Skin damage, loss of hair and anemia.
Blood disorders; aplastic anemia and leukemia—
more in radiologists.
By introduction of Coolidge tube and Snook transf. –
reduction in frequency of injuries.

Basic Radiation Protection
After 1910, biologic effects of x rays were
scientifically investigated & reported.
X ray workers were routinely investigated.
Provided with personnel radiation monitoring
devices.

Radiation protection devices
Filtration—Al or Cu filters—low energy x rays are
absorbed.
Collimation---restricts useful beam to the part of
body to be imaged, reduces scatter radiation,
improves image contrast.
Intensifying screens—reduce exposure to x rays by
more than 95%

Protective apparel—lead impregnated material used
to make aprons & gloves
Gonadal shielding—lead impregnated gonadal
shields in persons of child bearing age.
Protective barriers--Radiographic control console
should be located behind a protective barrier-often
lead-lined & a leaded glass window.

Always practice ALARA;
keep radiation exposures
As Low As Reasonably Achievable.

The Ten Commandments of Radiation Protection
1. Understand and apply the cardinal principles of
radiation control: time, distance, and shielding.
2. Do not allow familiarity to result in false security.
3. Never stand in the primary beam.
4. Always wear protective apparel when not behind a
protective barrier.

5. Always wear a radiation monitor and position it
outside the protective apron at the collar.
6. Never hold a patient during radiographic
examination. Use mechanical restraining devices when
possible. Otherwise, have parents or friends hold the
patient.
7. The person holding the patient must always wear a
protective apron and, if possible, protective gloves.

8. Use gonadal shields on all people of childbearing
age when such use will not interfere with the
examination.
9. Examination of the pelvis and lower abdomen of a
pregnant patient should be avoided whenever
possible, especially during the first trimester.
10. Always collimate to the smallest field size
appropriate for the examination.

THANKS

MCQ’s

X-rays voltage is measured in
1. milli ampere
2.milli joules
3.Electron volt
4.Kilo volt peak

Removal of an electron from atom is
1. Radiation
2.Ionization
3.X-rays
4.Amplification

Largest source of natural environmental radiation is
1. Cosmic rays
2.Radon
3.X-rays
4.Potassium 40

Which of these have the longest wavelenght?
X rays
Micro waves
Infra red
Gamma rays

Concepts of Radiologic Science

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