MCQs in Oral Radiology - Radiation Physics


# The target of the X ray tube is angulated to produce all of the following except:
A. To decrease the effective focal spot
B. To increase the image sharpness
C. To energize the photons
D. To dissipate heat

# Which of the following statements is false?
A. X rays travel at the speed of 297600 km/sec
B. X rays can be focused
C. The nucleus of an atom contains protons and neutrons
D. Cathode rays can be converged to a point


# The 'heel effect' results:
A. In low intensity X ray beam on anode side of central ray
B. In high intensity beam of X rays towards cathode
C. Both of them are true
D. None of the above are true

# Half value layer refers to:
A. The rate at which an X ray photon transfer its energy to irradiated matter
B. The thickness of a substance required to reduce the number of X ray photons by half
C. The time taken for X ray photons to travel half the distance from the source to the object
D. The heel effect seen when the anode is placed at an angle to the electron stream in the X ray cathode tube

# What is the function of filtration process while taking radiographs?
A. Remove the short wavelength photons
B. Remove the portion of long wavelength photons
C. To increase the radiation dose to patient
D. To increase scatter of secondary radiation

# At 90 kVp and 15 mA at a source film distance of 8 inches, the exposure time for a film is 1/2 second using the same amount of kVp and mA the exposure time at 16 inches is:
A. 1/2 second
B. 1.5 second
C. 1 second
D. 2 seconds

# The maximum penetration among the following is seen with which ray:
A. Alpha
B. Beta
C. Gamma
D. Electron beam

# Mathematical representation of inverse square law is:
A. I2/I1=(D2)^2/(D1)^2
B. I1/I2=(D2)^2/(D1)^2
C. I2/I1=(D2)/(D1)
D. I1/I2=(D2)/(D1)

# X rays are produced in:
A. Anode
B. Cathode
C. Glass wall
D. Molybdenum focusing cup

# Quality of the X ray beam is governed by:
A. kVp
B. mAs
C. Filament current
D. Length of the X ray tube

# _________ is not a property of X rays.
A. Ionization
B. Action on photographic film
C. Excitation
D. Collimation

# Reducing the size of X ray beam is achieved by:
A. Filtration
B. Photoelectric effect
C. Collimation
D. Bezold-Brucke effect

# The wavelength of X ray photon depends upon:
A. Milliampearage
B. Kilovoltage
C. Distance between the source and object
D. Quantity of electrons in the cathode stream

# The X ray collimators commonly used in dentistry include the followiing EXCEPT:
A. Diaphragm collimator
B. Tubular collimator
C. Rectangular collimator
D. Square collimator

# A film badge is a type of:
A. Identification plate
B. Sonometer
C. Dosimeter
D. Tachometer

# To restrict X ray beam, which of the following is done?
A. Collimation of the beam
B. Increase kVp
C. Decrease target object distance
D. Use a grid

# Filter of which metal is used to remove long wave length X rays from the primary beam?
A. Platinum
B. Aluminium
C. Copper
D. Lead

# The speed with which the electrons travel from the filament of cathode to anode depends upon:
A. Potential difference between the two electrodes
B. Number of milliamperes in the tube circuit
C. Angle between the filament and the target
D. Voltage of the filament

# The principal reason for placing an aluminium filter in the primary beam of radiation is:
A. Potential difference between the two electrodes
B. Number of milliamperes in the tube circuit
C. Angle between the filament and the target
D. Voltage of the filament

# In a patient having dense bones, penetration is best achieved by:
A. Increase in mA
B. Increase in kVp
C. Increased exposure time
D. Increased developing time

# The X ray which are most likely to be absorbed by the tissues and produce an injury:
A. X rays of long wavelength
B. X rays of short wavelength
C. Filtered X rays
D. Central rays

# X rays are type of:
A. Atomic radiation
B. Ultrasonic radiation
C. Electromagnetic radiation
D. Particulate radiation

# X rays were discovered in:
A. Nov 1897
B. Oct 1895
C. Nov 1895
D. Nov 1890

# Collimating the X ray beam reduces the formation of scattered radiation by:
A. Selective removal of soft radiation
B. Selective removal of hard radiation
C. Reducing the size of X ray beam
D. Reducing the beam intensity by 50%

# Quantity of current can be increased by:
A. Increased milliampearage
B. Increased time
C. Increased tube current
D. All of the above

# Which of the following is electromagnetic radiation?
A. X rays
B. Alpha rays
C. Beta rays
D. None of the above

# Commonly used collimating device:
A. Aluminium filter
B. Lead diaphragm
C. Molybdenum cup
D. Tungsten filament

# The inherent filtration of x ray machines range from _________ thickness of aluminium.
A. 0.5-2 mm
B. 1.5-2.5 mm
C. 2.5-5 mm
D. 1.0-2.5 mm

# Rotating anode is mainly used to:
A. Focus photons
B. To avoid heel effect
C. To dissipate heat from focal spot
D. Increase the energy of photons

# The size of actual focal spot is:
A. 1*3 mm
B. 1*1 mm
C. 1*4 mm
D. 1*2 mm

# Which one of the following has the maximum ionization potential?
A. Electron
B. Proton
C. Helium ion
D. Gamma photon

# Density of radiograph is affected by all EXCEPT:
A. mAMP
B. kVp
C. Cone angulation
D. Thickness of object

# The conversion of kinetic energy to X ray energy by the deceleration of a fast moving electron produces:
A. Bremsstrahlung radiation
B. Characteristic radiation
C. Particulate radiation
D. Orbital radiation

# The milliampearage affects the:
A. Speed at which electrons move from cathode to anode
B. Cooling of the target
C. Heating the filament
D. Penetrating ability of X rays produced

# The term used to designate a single unit of electromagnetic radiation is:
A. Particle
B. Proton
C. Photon
D. Quanta

# Penetration power is more for:
A. Hard X rays
B. Soft X rays
C. X rays with long wavelength
D. Grenz rays

# The following is not an ionizing radiation:
A. MRI
B. CT
C. USG
D. Both A and C

# Units of radiation exposure is:
A. Rad
B. Roentgen
C. Rem
D. Sievert

# The darkening of radiograph depends on all except:
A. Thickness of object
B. Quality and quantity of X rays
C. Angulation cone
D. Velocity of electron emitted from cathode

# Consistent radiographs require:
A. Long cone technique
B. Fixed kVp and mA
C. Automatic processing
D. Proper developing

# The quantity of X rays is controlled by:
A. Kilovoltage
B. Milliampearage
C. Total filtration
D. Exposure time

# Disadvantages of grids are:
A. Skin exposure of patient
B. Increase exposure time
C. Doesn't improve image
D. Overall density of radiograph is increased

# Use of an angled target in the X ray tube:
A. Increases the penetrating power of X rays
B. Reduces penetrating power of X rays
C. Increases image sharpness
D. Reduces image sharpness

# Size of focal spot influence radiographic:
A. Definition
B. Density
C. Contrast
D. All of the above

# Which one of the following is a type of electromagnetic radiation?
A. Alpha rays
B. Beta rays
C. X rays
D. Cathode rays

# Effective dose in radiation at 2 m is 1 Gray. At 1 m, it will be:
A. 0.25
B. 0.5
C. 2
D. 4

# Among the following, example of non-ionising radiation is:
A. UV
B. X rays
C. Gamma rays
D. Cosmic rays

# Which of the following is false?
A. Tungsten target is set in a copper block
B. Dental X ray tube is self rectified
C. Filtration reduces the exposure time
D. Grid reduces the secondary radiation reaching the film

# During the production of X rays, how much of electron energy is converted into heat?
A. 99%
B. 94%
C. 89%
D. 84%

# The unit of measurement of absorbed dose in X ray is:
A. Curie
B. Sievert
C. Gray
D. Kerma

# Which of the following is true:
A. Cathode is negatively charged
B. Cathode is positively charged
C. Anode emits electrons
D. Anode is connected to step down transformer

# An example of a isotope that is predominantly a beta emitter is:
A. 125 iodine
B. 32 phosphorous
C. 51 chromium
D. 99m Technetium

# Which of the following interactions does not cause film fog?
A. Coherent scattering
B. Transient scattering
C. Photoelectric absorption
D. Compton scattering

# The maximum interactions with matter in a dental X ray beam occurs in the form of:
A. Coherent scattering
B. Photoelectric absorption
C. Compton scattering
D. Characteristic radiation

# To take bite wing radiography which ISO film is used?
A. ISO #2 / ISO#1
B. ISO #1
C. ISO #3
D. ISO #4

# When the time of exposure is doubled:
A. The number of photons generated is doubled
B. The energy of photons generated is doubled
C. The velocity of photons is doubled
D. The mass of photons is doubled

# In medical radiotherapy linear particle accelerator emits:
A. Electrons and photons
B. Electrons and positrons
C. Neutrons and positrons
D. Neutrons only

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