TO BUILD UP MORE KNOWLEDGE IN RADIOLOGY AND UNDERSTANDING THE BASIC CONCEPTS OF RADIATION PHYSICS WHICH IS THE ATMOST IMPORTANT.THIS PPT WILL PROVIDE A CLEARCUT IDEA ABOUT HISTORY, VARIOUS TYPES OF RADIATIONS, FUNDAMENTAL CONCEPTS OF MATTER, RADIATION USED IN DENTAL XRAY MACHINE, PARTS OF XRAY MACHINE ,RADIOACTIVITY,UNITS OF MEASUREMENT,INTERACTION OF XRAYS WITH MATTER....YOU WILL BE ABLE TO GET A BETTER CLARITY ABOUT RADIATION PHYSICS.
2. contents
History
Physics
Basic model of an atom
Binding energy@ ionization
Nature of radiation
Properties
Radioactivity
Units of measurement
Dental xray unit
Interaction of Xrays with matter
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2
15. Quantum theory
EM energy cannot be radiated or absorbed
in any arbitrary amounts, but only in discrete
“quantum” amounts.
The energy of a “quantum” depends on frequency as
Equantum = h f
h = 6.6 x 10-34
Js
“Planck’s constant” 08/17/18
15
17. Natural radioactivity
Spontaneous disintegration of
nucleus of an unstable naturally
occurring isotopes.
Emission of alpha,beta,gamma
radiation.
Associated with only heavy
nucleus.
Cannot be controlled.
Tremendous amount of energy is
released.
Artificial radioactivity
Changing common stable nuclei of
atoms into unstable radioactive
nuclei.
Emission of positron,electron.
Induced in heavy or light nuclei.
Can be controlled.
Small amount of heat energy is
released.
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26. SHAPE Conical Closed pointed cone
Scattered radiation
Rectangular Not much scatter
Round Not much scatter
LENGTH Short 8 inches
Long 16 inches
Position indicating
device
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27. X ray
tube
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27
Glass vaccum tube
1.High atomic number
2.High melting
point(3380degree celsius)
3.Low vapour pressure
4.High specific heat
30. • Each tube has rating specification that describes the
operating limits of the tube
• Tube rating describes the longest exposure time the tube
can be energized for a range of kVp and mA values
without risk of damage to target from overheating
• Duty cycle – refers to how frequently successive
exposures can be made
Tube rating
and duty cycle
Hu=kVp X mA X sec
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30
39. 1.Textbook of Dental and Maxillofacial
Radiology-2E- Freny R Karjodkar MDS
2.Oral Radiology principles and interpretation-6E-
WHITE AND PHAROAH, DDS
3.Dental Radiology-third edition –Sikri
4.Textbook of Oral Radiology-Pillai
5. Essentials of Dental Radiography & Radiology –
Eric Whaites 5ed
08/17/18
39
References
