RAPHEX 1996 Questions



A cobalt-60 teletherapy machine has an activity of 10,135 curies and decays by emission of beta-minus particles. If the emission of these electrons is considered to be an electric current what is its magnitude

(electron charge = 1.6 x 10-19 Coulomb)


A. 1 x 10-6Amp

B. 10 x 10-6Amp

C.6 x 10-6Amp

D.60 x 10-6 Amp

E.600 x 10-6Amp




How many electrons per gram are there for the hydrogen atom (Avogadro's number =6.0228 x 1023


A. 3.0 x 1023

B. 6.0 x 1023

C. 9.0 x 1023

D. l.0 x 1023

E. 1.6 x 1023








An 92Ir source has an activity of 3.7 x lO9Bq. What is the activity in mCi?


A. 100

B. 0.1

C. 10

D. 1000

E. 0.0001








Which of the following is not equal to a centigray?


A. 100 erg/gram

B. 1 rad

C. 1/0.873 roentgen absorbed in air

D. 1/0.873 roentgen absorbed in tissue










Match the quality factor (Q) used in radiation protection with the type of radiation:


A. 10

B. 2

C. 1

D. 0.693

E. 20


G5. 1.25 MeV gammas

G6. 100 keV x-rays

G7. Fast neutrons

G8. 99Mo betas



A given exposure:


A. always results in the same absorbed dose to muscle or bone

B. is a measure of the ability of a photon beam to ionize air

C. is a measure of the ability of a particle beam to ionize air

D. can be measured in roentgen in the SI system

E. all of the above









It has been said that a hydrogen atom consists mostly of empty space. This is because the ratio of the nominal radius of the electron orbit to the radius of the nucleus is approximately:


A. 102

B. 104

C. 107

D. 108

E. 1010








A muon is a sub-atomic particle which has a mass 207 times that of the mass of an electron. What is the approximate mass of the muon in units of MeV?


A.  207 MeV

B.  400 MeV

C. 106 MeV

D. 500MeV

E. 300 MeV








Directly ionizing radiations do not include:


A. electrons

B. positrons

C. neutrons

D. alpha particles

E. beta-rays









An electron, proton, and photon each have 1000MeV total energy (kinetic energy + rest mass energy). Which of the following statements is true?


A. the electron travels at almost the speed of light

B. the proton travels at almost the speed of light

C. the photon travels at almost the speed of light

D. the proton has the most kinetic energy

E. the electron and the proton have the same rest mass








Which of the following is never emitted during radioactive decay?


A. alpha particle

B. proton

C. positron

D. gamma-ray

E. neutrino









Electron binding energy:


A. is greater in the K-shell than the L-shell

B. is greater for the K-shell of barium than the K-shell of hydrogen

C. increases with increasing Z

D. all of the above

E. none of the above









For the elements Z = 16, 17,18, and 19 (sulfur, chlorine, argon, and potassium), how many have 8 electrons in the M-shell?



B. 1











Of the following radioactive isotopes which one has the shortest half-life?


A. 226Ra

B. 103Pd

C. 198Au

D. 222Rn

E. 60Co








If it is assumed that a 60Co beam is monoenergetic and that its half-value layer is 1.1 cm of lead, how much lead is required to attenuate a 60Co beam by approximately a factor of 1000?


A. 110 cm

B. 550cm

C. 11 cm

D. 550cm

E. 220 cm








The half-life of a radionuclide is 60 days. After how long will a source of this nuclide have only 0.1% of its original activity.


A. 200 days

B. 300 days

C. 600 days

D. 720 days

E. 800 days








Which type of nuclear radiation has the shortest range in tissue?


A. alpha particles

B. beta particles

C. positrons

D. neutrinos

E. gamma rays









Radionuclide X decays to Y which decays to Z. The half-lives of X and Y are 1000 years and 1 day respectively. When equilibrium is reached, how does Ax (the activity of X) compare to Ay.


A.  Ax = 0

B.  Ax = Ay

C.  Ax = 0.001Ay

D.  Ax = 1000Ay

E. Ay>Ax







What kind of radioactive equilibrium can occur when a very long-lived radionuclide decays to a very short-lived one?


A. thermal

B. secular

C. transient

D. non-stable

E. No equilibrium will occur









How many mCi of a radioactive isotope (T1/2 = 2.7 days) are required so that the sample's activity will be 10 mCi 24 hrs later?


A. 11.29

B. 15.89

C. 12.93

D. 47.34

E. 22.57








Heavy radioactive nuclei decay most frequently with the emission of which of the following:


A. beta particle

B. alpha particle

C. gamma ray

D. Auger electron

E. characteristic X-rays








Which of the following is a true statement?


A. naturally occurring radioactive elements are grouped into 3 series : uranium, actinium, and radium

B. in beta decay, the emitted particle is monoenergetic

C. positron-emitting nuclei have a deficit of neutrons

D. in alpha decay, the emitted alpha particle has a spectrum of energies

E. in positron decay, a neutrino is not emitted








Characteristic x-rays are a consequence of an inner atomic shell vacancy caused by which of the following processes (choose all that apply)?


1. Internal conversion

2. Negatron decay

3. Electron capture

4. Gamma ray emission

5. Alpha decay

A.  all of the above

B.  none of the above

C.1 and 3 only

D. 4 and 5 only

E. 2 only


G27. For the decay schemes for radionuclides X and Y shown below, how many beta rays and gamma rays are emitted per disintegration for X and Y?

A. one beta and two gammas from x; one beta and one gamma from Y

B. one beta and one gamma from x; one beta and one gamma from Y

C. no betas and one gamma from x; two betas and two gammas from Y

D. no betas and two gammas from x; two betas and one gamma from Y

E. no betas and no gammas from x; no betas and no gammas from Y


Match the device found in an x-ray circuit with its purpose.


A. allows current to flow in one direction only

B. increases or decreases voltage

C. thermionic emission

D. measures time of exposure

E. measures tube current


G28. Transformer

G29. Milliammeter

G30. Rectifier





Which of the following does not improve the heat capacity of the x-ray tube?


A. rotating anode

B. small target angle

C. dual focus

D. thermionic emission

E. all of the above









The effective energy of any x-ray beam:


A. is proportional to the atomic number (Z) of the anode material

B. is proportional to the mAs

C. is not affected by the added filtration

D. will affect image density but not subject contrast

E. is always less than the kVp








The quality of an x-ray beam cannot be characterized only in terms of the peak voltage because beams with the same voltage may have different


1. Amounts of filtration

2. Half-value layers

3. Maximum wavelengths

4. Minimum wavelengths


A. only 1 and 2 are true.

B. only 1 and 3 are true.

C. 1, 2, and 3 are true

D. all are true

E. none are true


G34-43. Compare spectra I and II in the diagram below (tungsten target). Choose the most appropriate answer from the list below for the next 10 questions.

A. spectrum I

B. spectrum II

C. both

D. neither

E. cannot be determined

G34. Characteristic radiations appear between 50 and 70 keV.

G35. Low energy photons have been removed by filtration.

G36. Maximum photon energy is 100 keV.

G37. Minimum photon energy is 50 keV.

G38. The K characteristic x-rays have been removed by filtration.

G39. Maximum kVp is 50 kVp.

G40. Higher exposure rate.

G41. Higher HVL.

G42. Produced by three-phase or constant potential generator.

G43. Will produce relatively less scatter in soft tissue.












In an electromagnetic wave, the component electric and magnetic fields are oriented at what angle with respect to each other?


A. 300

B. 600

C. 900

D. 12O0

E. 1500








Of the following, which is the most penetrating electromagnetic radiation?


A. infrared

B. ultrasound

C. radio waves

D. gamma rays

E. ultraviolet radiation








Some substances when exposed to incident light will emit light of their own. Substances for which the emission of light ceases immediately after the excitation is removed are called:


A. incandescent

B. phosphorescent

C. fluorescent

D. photonic

E. nascent








Electromagnetic waves are transverse waves, unlike sound waves which are longitudinal waves. Of the following experiments, which can be used to reveal the transverse nature of electromagnetic radiation?


A. reflection

B. refraction

C. polarization

D. interference

E. diffraction







G48-52. Match the effect in tissue and type of radiation with the name of the radiation (answers may be used more than once).


A. ionizing elementary particles

B. non-ionizing elementary particles

C. ionizing photons

D. non-ionizing photons

E. none of the above


G48. Beta-rays

G49. Heat radiation

G50. Visible light

G51. X-rays

G52. Ultrasound



Which of the following is most descriptive of the difference between x-rays and gamma-rays?


A. energy

B. velocity

C. field

D. origin

E. all of the above









Visible light has a wavelength of approximately 6 x 10-7 m. Cobalt-60 gamma-rays have a wavelength of 1 x 10-12 m and an energy of 1.2MeV. What is the approximate energy of the light photons?


A. 720 MeV

B. 2eV

C. 2 x 10-6eV

D. 2 x 10-4eV








The ratio of Compton interactions in one gram of hydrogen to one gram of water is about:


A. 0.5

B. 1.0

C. 2.0

D. dependent on the photon energy

E. the ratio of the density of hydrogen to water









Which of the following statements about Compton interactions is true?


A. Compton electrons can be ejected in both the forward and backward direction

B. Compton interactions have no effect on backscatter

C. the most energetic Compton electrons are those ejected at angles close to 90 degrees of the photon's incidence angle

D. a secondary photon scattered in the direction of the primary photon loses the most energy.

E. a secondary photon scattered at 180 degrees cannot have an energy greater than 256 keV.






The figure below shows the energy spectrum of photons after Compton scattering. What is the initial energy of the photon?

A. 600 keV

B. 511 keV

C. 256 keV

D. 176 keV

E. insufficient information is given


For questions G58-61, match the description of the process with the type of photon interaction.


A. coherent scattering

B. photoelectric interaction

C. Compton interaction

D. none of the above

E. B and C are both true


G58. No energy is transferred to an orbital electron.

G59. The incident photon wavelength decreases.

G60. The incident photon can be back-scattered.

G61. The incident photon is completely absorbed.




For questions G62-65, match the interacting particles or fields with the type of photon interaction (use each answer once and only once):

A. coherent (Rayleigh) scatter

B. photoelectric effect

C. Compton effect

D. pair production

E. triplet production


G62. Tightly bound atomic electron

G63. Electrostatic field of the nucleus

G64. Loosely bound atomic electron

G65. Electrostatic field of an atomic electron

G66. Electrons in the entire atom



The outstanding characteristic of a charged particle beam's interaction with matter is its:


A. high LET

B. high degree of skin sparing

C. limited range

D. low RBE

E. high keV









What is the LET of a 9 MeV electron in soft tissue?


A. 1MeV/cm

B. 2MeV/cm

C. 5MeV/cm

D. 10MeV/cm

E. 12MeV/cm








The dominant mode of energy loss for a therapeutic electron beam is:


A. bremsstrahlung radiation

B. ionization

C. Compton interactions

D. collision with protons

E.  pair production









The dominant mode energy loss for a therapeutic neutron beam is:


A. bremsstrahlung radiation

B. ionization

C. Compton interactions

D. collision with protons

E. pair production









The Bragg peak is not seen in the depth-dose curve of an electron beam because of:


A. scattering

B. nuclear absorption

C. emission of Bremsstrahlung radiation

D. Compton effect

E.  x-ray production








Some patients with brain malignancies located near the eyes notice a faint blue light during treatment with high-energy electrons. This phenomenon is most likely due to:


A. fluorescence

B. the physiology of human vision

C. magnetic fields of the moving electron

D. Cerenkov radiation

E. luminescence








The slope or gradient of the characteristic curve (or H and D curve) for a film is also known as the film's:


A. density

B. gamma

C. transmittance

D. opacity

E. lambda








Two x-ray films, each with optical density of 1.5, are placed on top of one another. The fraction of incident light transmitted through the "sandwich" is:


A. 0.03

B. 0.015

C. 0.001

D. 0.0225









A grid improves the quality of a diagnostic x-ray primarily by:


A. attenuating primary photons

B. attenuating Compton scattered photons

C. attenuating electrons produced by Compton scatter

D. attenuating electrons produced by photoelectric effect

E. attenuating coherently scattered photons









In a diagnostic radiograph the process mostly responsible for differential attenuation is:


A. coherent scatter

B. Compton interaction

C. photoelectric interaction

D. pair production









The probability of "outcome A" from an experiment is 0.001. The experiment is repeated 1000 times. If each experiment is independent of all other experiments, what is the probability that "outcome A" will occur at least once?


A.  0.001

B. 0.500

C. 0.632

D. 0.999

E. 1.000








A radioactive sample is counted for a ten minute interval many times, yielding a mean count rate of 1000 cpm. The most probable distribution is:


A. 68% of the measurements fall between 990 and 1010 cpm

B. 68% of the measurements fall between 936 and 1064 cpm

C. 68% of the measurements fall between 900 and 1100 cpm

D. 95% of the measurements fall between 936 and 1064 cpm

E. 95% of the measurements fall between 800 and 1064 cpm








To achieve a standard deviation of 2%, counts must be collected.


A. 400

B. 1414

C. 2500

D. 10000

E. 40000








A measurement is made in which 2500 Counts are collected. There is a 96% probability that repeated measurements will yield between and counts.


A. 2300, 2500

B. 2400,2500

C. 2400, 2600

D. 2450, 2550

E. 2500, 2700







G81-84. For questions G81 to G84, match the computer storage device to its letter position on the graph above. The graph depicts the relative advantage of each device in terms of the relative storage capacity (ordinate) and relative access speed (abscissa).


G81. Floppy Disk Drive

G82. Hard Disk Drive

G83. Optical Disk Drive

G84. RAM


Which of the following is the term for 1012 bytes?


A. gigabyte

B. megabyte

C. overbyte

D. terabyte

E. petabyte









A "mouse" or trackball is connected to which computer interface?


A. serial port

B. parallel port

C. SCSI port

D. Ethernet port

E. air port









Which of the following files can be read and understood by using a text-editing program?


A. pixel file

B. vector file

C. ASCII file

D. binary file

E. tertiary file









Approximately how many Megabytes (MB) of disk space are needed to store a single raw image file consisting of 512 x 512 pixels with each pixel having a 16-bit pixel depth?


A. 0.25 MB

B. 0.50 MB

C. 0.75 MB

D. 1.00 MB

E. 1.25 MB








Which of the following is the name for a particular data compression scheme?


A. Newton-Raphson

B. Huffman

C. Runge-Kutta

D. Savitsky-Golay

E. Wiener








The binary number 10000001 has what hexadecimal value?


A. 11

B. 16

C. 61

D. 81

E. 18









The most recent International Commission on Radiological Protection estimate of the lifetime risk of cancer induction to the general population by low dose rate ionizing radiation is approximately how many cases per Sv?


A. 4 x 10-4

B. 4 x 10-3

C. 4 x 10-2

D. 4 x 10-1

E. 4 x 10-0







Which of the following is true for low-level radioactive wastes, such as tubing and swabs contaminated with 99mTc?


A. they can never be thrown away, since some activity always remains

B. they can be thrown away immediately, since the amount of activity is generally harmless

C. they can only be disposed of by a commercial rad-waste service

D. they can be stored until reaching background levels, then disposed of with other medical trash








A person's exposure rate is 100 mR/hr at 1m from an I-125 source. A 0.04 mm thick lead shield is place between the source and the person. What is the new exposure rate? [HVL in lead is 0.02 mm.]


A. 1 mR/hr

B. 25 mR/hr

C. 50 mR/hr

D. 75 mR/hr

E. 100 mR/hr








A radiotherapy clinic is located near a local power line. Do the patients receive a radiation dose from the power line? If so, how should this dose be taken into account?


A. proportionally to the time spent in the clinic

B. mostly during the hours of peak energy consumption

C. only for very high voltage lines

D. only for alternating current lines

E. no dose at all







The above graph shows the response curve for a gas filled detector. Give the appropriate region for each of the following descriptions (answers can be used more than once):

G95. The region where current is passed in the absence of radiation.

G96. The pulse heights are proportional to the incident particle energy.

G97. An ionization chamber is operated in this region.

G98. A Geiger survey meter is operated in this region.

G99. The saturation region where all charges are collected without multiplication.




Which of the following is not correct: the x-ray tube current is:


A. used to heat the tube filament

B. measured in milliamperes

C. limited by the space charge effect

D. defined as electrons moving from the filament to the anode

E. caused by thermionic emission






Increased ripple in the kVp waveform of some types of x-ray generators has all the effects listed below, except:


A. lower maximum photon energy

B. lower average photon energy

C. lower x-ray intensity

D. lower heat load ratings for the x-ray tube

E. lower tissue penetration









The _______ rating of an x-ray tube is the maximum cumulative heat load that the x-ray tube target can sustain without damage.


A. kW

B. single exposure

C. cathode KHU

D. anode heat capacity

E. housing beat capacity









Small anode angles in x-ray tubes are used to:


A. increase the field-of-view

B. increase the anode heat capacity

C. decrease the heel effect

D. decrease filament size

E. decrease anode mass









Methods to assess spatial resolution of an imaging system include all of the following ways, except:


A. bar patterns

B. step wedges

C. wire mesh pattern

D. hole patterns

E. wire impulse response









Concerning grid controlled x-ray tubes, the grid:


1. Controls the tube current

2. Collimates the x-ray beam

3. Allows fast exposures

4. Can be used to synchronize the exposures with the cine film

5. Causes an increase in tube heating


A.  only 3 is correct

B.  both 2 and 3 are correct

C.  1, 3, and 4 are correct

D.  2 and 5 are correct

E.  1 through 5 are all correct



For a fixed mAs and kVp, increasing the exposure time will significantly affect the:


A. overall film density

B. overall film latitude

C. speed of film/screen combination

D. motion unsharpness

E. patient exposure









The visualization of low contrast objects is primarily limited by:


A. focal spot blur

B. motion

C. screen unsharpness

D. film grain

E. radiographic mottle









 ______ is the decrease in film density due to delays between x-ray exposure of film-screen and the film processing.


A. heel effect

B. space charge effect

C. reciprocity failure

D. latent image fading

E. recombination loss








 ______ is the decrease in film density due to either very long or very short radiation exposures while using appropriate mAs values.


A. heel effect

B. space change effect

C. reciprocity failure

D. latent image fading,

E. recombination loss








Match the following items with the questions listed below:

A. GI abdomen radiography

B. extremity radiographs

C. mammography

D. chest radiographs

E. pelvimetry radiography

D11. The characteristics of a ______ film-screen system include: a spatial resolution of 15 to 20 Ip/mm; high contrast gradient; and a relative speed less than 100.

D12. The characteristics of a ______ film-screen system include: a spatial resolution of 8 to 12 lp/mm; high contrast gradient; and a relative speed less than 100.

D13. The characteristics of a ______ film-screen system include: a spatial resolution of 6 to 10 lp/mm; low contrast gradient; and a relative speed of 200 to 300.

D14. The characteristics of a ______ film-screen system include: a spatial resolution of 4 to 8 lp/mm; medium contrast gradient; and a relative speed of 400.

D15. The characteristics of a ______film-screen system include: a spatial resolution of 1 to 4 lp/mm; medium contrast gradient; and a relative speed greater than 400.


The use of a film/screen combination receiving system will:


A. decrease exposure to the patient by a factor of 1000 when compared with the use of film without a screen

B. increase spatial resolution when compared with film alone

C. absorb photons of a lower energy than it emits

D. absorb less photons than it emits

E. increase absorption at energies slightly lower than the K edge of the screen phosphor as opposed to slightly higher than the K edge.









In a film/screen system, how can one obtain increased speed with no change in the image noise?


A. use a phosphor with a higher x-ray-to-light conversion efficiency

B. use a faster film

C. increase the phosphor layer thickness

D. add a light absorbing dye to the phosphor

E. all of the above








Failure to use adequate fixer for the processing of radiographs will:


A.  decrease film contrast gradient

B. decrease film speed

C. increase quantum mottle

D. increase silver reclamation

E. decrease archival storage









 ______ is the persistence of an image on the fluoroscopic TV monitor; and with motion, the image becomes blurred because of this persistence.


A. vignetting

B. flare

C. lag

D. veiling glare

E. blooming







During GI fluoroscopy with automatic brightness control (ABC), the typical patient entrance radiation exposure rate is R/min and the maximum is R/min.


A. 0.5,1.0

B. 1.0, 3.0

C. 2.0, 5.0

D. 2.0, 10.0

E. none of the above








Compared with an iodine IVP exam, a barium exam produces better contrast resolution because:


A. the mass attenuation coefficient of barium is much greater than that of iodine

B. the K-edge of barium is much greater than the K-edge of iodine

C. the caliber of the bowel is bigger than the caliber of the ureter

D. the atomic number of barium is significantly greater than the atomic number of iodine

E. a higher concentration of barium can be achieved than with iodine







Which of the following is not true? In the diagnostic x-ray range, as the tube kVp is increased, the:


A. bremsstrahlung radiation intensity increases

B. characteristic radiation energy increases

C. scatter becomes increasingly forward

D. mAs must be reduced to produce an equivalent exposure

E. effective focal spot size decreases









Added filtration in a diagnostic x-ray tube:


A. decreases the intensity of the x-ray beam at the lower end of the energy spectrum

B. decreases the intensity of the x-ray beam at the higher end of the wavelength spectrum

C. decreases patient skin exposure

D. decreases the linear attenuation coefficient

E. all of the above







Match the following x-ray tube operation characteristics with one given answer:

A. 25kJ

B. 2.5kJ

C. 50kW

D. 5kJ

E. 60kJ

D24. The anode heat loading for 4 minutes of fluoroscopy at 100 kV and 2.5 mA.

D25. The anode head loading for 5 seconds digital run at 100 kV, 100 mA, 10 ms, and 5 frames per second

D26. The anode heat loading for 100 kV 500 mA, 100 ms exposure.

D27. The x-ray tube rating at 100 kV, 500 mA, 100 ms exposure.

D28. The x-ray anode tube loading after four successive exposures at 100 kV, 250 mA, 250 ms.



A detail screen with an effective blur of 0.2 mm is used in a radiographic procedure with the small focal spot (0.6 mm) for the x-ray tube. If less than 1.1 magnification of the object being imaged is achieved, what is the resultant blur for 'the film/screen radiograph?


A. 0.2 mm

B. 0.3mm

C. 0.4mm

D. 0.5 mm

E. 0.6 mm







If an imaging system is said to have a resolving power of about 5 lp/mm, then this represents a system MTF response of about:


A. 90%

B. 75%

C. 50%

D. 20%

E. 10%









Changes in subject contrast are affected by changes in:


1. Film-screen contact

2. Tissue atomic number

3. Object-film distance

4. Beam quality

5. Development time and temperature


A. 1

B. 3 and 5

C. only 2

D. both 2 and 4

E. all of the above



If the exposure time, the focus film distance, and the screen thickness are all doubled:


A. screen unsharpness will not change

B. patient skin exposure will increase

C. geometric unsharpness will decrease

D. film density will decrease

E. heel effect will increase








Regarding film density, which of the following is correct?


1. As optical density increases, transmittance decreases

2. Two superimposed films with 10% transmittance each would have a total optical density of 1

3. Fast films require more radiation to produce a given film density

4. A film characteristic curve with a gradient of 3.0 is suitable for mammography

5. The ratio of highest to lowest exposure that can be usefully detected is 40:1

A. both 2 and 3

B. 1 only

C. 1, 4, and 5

D.1, 2, and 3

E. all of the above



Which of the following is not a contributing factor to average glandular dose in a mammogram?


A. x-ray tube target material

B. x-ray tube focal spot size

C. kVp applied

D. HVL of the beam

E. degree of compression









The MTF of a composite imaging system at a given spatial frequency is:


A. equal to the product of the MTFs of the individual components of the system at that frequency

B. less than the product of the MTFs of the individual components of the system at that frequency

C. always less than the MTF of the system component with the poorest resolution at that frequency

D. better with increased number of system components

E. only A and C






Match the following digital subtraction angiography characteristics:


A. logarithmic transformation

B. vignetting

C. frame integration

D. narrow windowing

E. hybrid subtraction


D36. Assures direct relation of absorption over a wide range of patient thickness

D37. Reduces image noise

D38. High contrast in the image

D39. Decreases artifact from motion in bones

D40.. Fall off in brightness at the periphery of an image intensifier


D41. Given the conversion table, calculate the average glandular dose (AGD) for a 4.5-cm compressed breast imaged at 27 kVp with an x-ray beam half value layer of 0.31 mm Al and a measured entrance skin exposure (ESE) of 0.8 R

    Glandular Tissue Dose (mrad) for 1 R ESE

HVL (mm Al)         Compressed Breast Thickness (cm)

                                    3                     4                     5

0.30                             220             175                 140

0.32                             230             184                 147

0.34                             250             202                 161

A. 112mrads

B. 129mrads

C. 140mrads

D. 147mrads

E. none of the above



In mammography quality assurance:


A. federal performance standards allow a field size extension of up to 5% of SID at the chest wall edge of the image receptor

B. the chest wall edge of the compression paddle should be seen in the mammogram

C. the average glandular dose to an average breast should not exceed 0.3 mGy per view for grid screen/film mammography

D. measured kVp accuracy should be within +/-5% of nominal kVp setting

E. darkroom fog should be no greater than 0.18







The filtration in mammography units primarily transmits the characteristic x-rays. The very low energy bremsstrahlung x-rays are filtered because they contribute_____ to and the higher energy bremsstrahlung x-rays are filtered because they contribute to_____.


A. tube heating, off-focus radiation

B. heel effect, focal spot blooming

C. radiation dose, loss of contrast

D. grid cut-off, septal penetration

E. coherent scatter, K-edge photons








The following film processor parameters all affect mammography image quality, except:


A. replenishment rates

B. developer concentration

C. developer temperature

D. nitrate depletion

E. developer immersion time








During a typical fluoroscopy procedure a radiologist wearing a protective apron and no protective eyeware receives a uniform whole-body exposure of 20 mR. How many of these procedures can the radiologist perform in one week and not exceed the NCRP maximum occupational radiation exposure?


A. 15

B.  50

C. 100

D. 250

E. none of the above







Concerning fluoroscopic imaging systems, which of the following is not true?


A. CsI is commonly used for the input phosphor

B. a modern image intensifier has a modulation transfer function similar to radiographic film MTF used for GI examinations

C. with automatic brightness control (ABC) systems, patient dose will increase when the image intensifier input size is reduced

D. different electronic lenses are employed to obtain magnified images

E. with ABC systems, patient dose will increase when patient to image intensifier distance is increased






In fluoroscopy with an image intensifier, for a given output phosphor area, increasing the input phosphor size from 4.5 to 9 inches will:


A. double the minification gain

B. have no effect on the minification gain

C. increase the minification gain 4 times

D. increase patient skin exposure 4 times

E. increase image resolution









In order to reduce the radiation dose to both patients and personnel, a radiologist chooses to use the C-arm fluoroscopy unit in the lowest sensitivity mode. What effect does this have on image quality?


A. high contrast resolution increases

B. high contrast resolution decreases

C. low contrast resolution increases

D. low contrast resolution decreases

E. none of the above






D49. In a digital radiography device, a plumbicon tube is used to obtain the video image. If the tube is driven at standard broadcast TV rates, how long does it take to scan one line?


A. 5.29 μsec

B. 31.7 μsec

C. 63.5 μsec

D. 90.1 μsec

E. none of the above








D50. In ultrasound a 4 MHz transducer has a useful range of 10 cm. What is the maximum pulse repetition frequency for this transducer?


A. 7.7kHz

B. 10kHz

C. 40kHz

D. 154kHz

E. 10MHz









In order to have fat appear darker than surrounding tissues, spin echo (SE) pulse sequences require a _____ TE and a _____TR.


A. short, short

B. short, long

C. long, short

D. long, long

E. long, medium









The spatial resolution with MRI is about the same as that obtained with:



B. mammography

C. chest radiographs


E. better than all of the above








The signal-to-noise ratio (SNR) can be improved in MRI studies by using:


A.  thinner slice thicknesses

B. smaller pixel sizes

C. more NEX

D. short TR times

E. low magnetic field strengths







D54. Although MRI units do not use ionizing radiation, safety concerns for MRI units include all of the

following factors except:

A. fringe magnetic field interference

B. electrical potential induction in neurons

C. RF beating effects

D. ferromagnetic surgical clips in patients

E. flying metallic oijects

D55. If the count rate of a radioactive sample is 3330 cpm and measured background 10 cpm, to achieve a

measuring accuracy of 1% the sample should be counted for:


B. lOmin

C. 20 mm

D. 3Omin


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D56. If the X-Y distances in an MRJ image are distorted, the most likely source of the problem is due to:

A. RF transmitter

B. RF shielding leaks

C. gradient field non-linearities

D. eddy currents

E. shim coils adjustments

D57. Which of these pulse sequences results in a Ti weighted image:


B. '1R600 s,Th60Os



E. Th20 5, TR40s

D58. A 1.0 T-MRI system is operated at the water proton resonant frequency of 42.6 MHz. If it uses an xgradient of 0.1 mT/cm, what will be the frequency difference of the signals from two vials of water placed

4 cm apart on the x-axis?

A. 11 kHz

B. 17kHz


D. 43 kHz

E. 82 kHz

D59. A 3 T-MRI machine is used for proton spectroscopy and operates at 128 MHz. If two peaks in the spectrum

are separated by 8 ppm, what is their separation in frequency units?

A. 1.024 Hz

B. 1024Hz

C. 1024 kHz


E. 128kHz

1)60. The thyroid burden of'3 'I can be efficiently measured with:

A. ionization chamber

B. geiger counter

C. Nal (11) scintillation probe

D. liquid scintillation counter

E. all of the above

1)61. For patient studies, CT image quality can be improved by all factors listed below except:

A. short scan times

B. optimized reconstru~ion algorithms

C. smaller pixel sizes

D. lower kVps

E. administration of contrast media

1)62. All the following factors influence CT spatial resolution except:

A. focal spot size

B. scanning geometry

C. detector size

D. slice thickness

E. pixel size



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1)63. The two materials used to calibrale the CT number scale of CT scanners are:

A. tissue and bone

B. water and bone

C. water and acrylic

D. air and acrylic

E. air and water

1)4. The percent low contrast discrimination for large object sizes is _______ for CT scanners as compared to

film-screen chest radiography.

A. 20 times greater

B. 5 times greater

C. the same

D. 5 times smaller

E. 10 times smaller

1)65. One of the disadvantages of helical (spiral) CT scans over axial CT slices of the same tissue volume is:

A. increased slice profiles

B. increased radintion dose

C. increased scatter radiation

D. longer scan times

E. higher kYps

1)66. The typical x-ray tube heat load from a series of 40 helical (spiral) CT slices is about to _____ of the

anode heat capacity.


C. 10%, 20%

D. 25%, 50%


1)67. Non-erasable optical disk storage represents a category of memory units called:






1)68. Software that has multiple complex processing sections requires a large:


B. hard disk



E. modem

1)69. In order to transmit data over telephone lines to another computer, a computer system must have:

A. icon

B. parallel processing

C. ethernet

D. modem





RAPHEX 1996 0 Diagnostic Questions 0 Page 23

D70. The number of binary bits that are required to represent all CT numbers from -1024 to +3096 Hounsfield

units~is _____bits.



C. 10

D. 11

E. 12

D71. An ultrasound transducer which utilizes a series of elements that transmit sequential sound waves in order

to form a rectangular image is called:

A. annual array

B. phased array

C. linear array

D. sector scanner

E. variable focus scanner

D72. The speed of an ultrasound wave in a body tissue depends upon the and the

A. frequency, viscosity

B. atomic number, wavelength

C. density, compressibility

D. refraction, diffraction

E. none of the above

D73. Modern ultrasound units have spatial resolution limits of about in both axial and lateral directions.

A. 0.5 cm


C. 0.05 cm

D. 0.01 cm

E. 90.005 cm

D74. Possible adverse biological effects from ultrasound procedures include:

k cavitation

B. genetic transmutation

C. ionization

D. production of radicals

E. none of the above

D75. All of the following types of radiation are possible from isomeric transitions excep::

~ photons

B. neutrinos

C. internal conversiQn electrons

D. Auger electrons

E. fluorescent x-rays

D76. If a TC-99m generator eluant contains 100 mCi of Tc-99m and 5 ~Ci of Mo-99, the amount of activity after

33.5 hours is mCi of Tc-99m and ~Ci of Mo-99.

A 25,4.8

B. 6.5,43

C. 3.7,4.0

D. 2.1, 3.5

K 1.Z 1.5



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D77-81. In nuclear medicine imaging, match the following quality control procedures with the relevant choice


A. gamma camera resolution

B. gamma camera field uniformily

C. photopeak window of the gasnma camera pulse height analyzer

D. dose calibrator linearity

E. dose calibrator constancy

D77. Is checked daily by placing a uniform flood source in front of the came~

D78. Is checked daily by measuring two standardized long half-life sources.

D79. Is checked quarterly by measuring the decay of Tc-99m over 72 hours or more.

DSO. Is checked daily by placing a small amount of known source of radioactivity in front of the came~

DSl. Is checked weekly using a bar phantom without a collimator.

D82. For a 256 x 256 matrix with an liAnch diameter crystal, the lirniting spatial resolution of a scintillation

camera study with Tc-99m is dominated by:

A. septal penetration

B. collimator hole size

C. Compton scattered photons

D. pixel size

E. inherent camera limitS

D83. Factors which complicate SPECT studies include all of the following items except:

A. attenuation corrections

B. detector non-uniformities

C. positron range

D. Compton scauer photons

E. tissue inhomogeneities

D84. In nuclear medicine studies, the critical organ dose is usually limited to less than _____ CGy.

A. 1



D. 10

E. no limit: use risk verses benefit ratio

D85. The typical thyroid ablation procedure involves the administration of MBq of 1311 which delivers a

radiation dose to the thyroid of Gy.

A. 1.5; 1.5

B. lO;20

C. 300; 300

D. 4,000; 4,000

E. 50,000; 50,000

D86. An apron which contains 0.5 mm of lead equivalent attenuates about 95% of the scattered diagnostic xrays. Regulations only require 0.25 mm of lead equivalence in protective appareL These leaded aprons would be expected to attenuate about % of the scattered x-rays.



C. 82


E. 74

RAPHEX 1996 0 Diagnostic Questions 0 Page 25

D87. Regulations limit the radiation dose equivalent to patients undergoing radiological procedures to


A. 500

B. 50

C. 5

D. 1

E. none of the above

D88. The radiation dose equivalent to the fetus of a pregnant patient is not considered to pose a significant risk

until it exceeds mSv.

A. itoS


C. 25 to 50

D. 50 to 100


D89. If a radiation badge placed outside a leaded apron at the collar level measures 1500 ~Sv per month, the

effective dose equivalent would be computed as _____ USv per month.

A. 1200

B. 1000

C. 500

D. 250

E. 50

[)90. The radiation shielding required in the walls of a diagnostic x-ray room to protect only against scattered xrays is related to all of the following factors except:

A. distances

B. workload

C. use factor

D. occupancy factor

E. tube potential (kYp)

~l-95. Match the following exposure conditions with the appropriate dose.

A. 1 mSv (100 mrem)

B. 0.1 mSv (10 mrem)

C. 2 mSv (200 mrem)

D. 2 ~Gy (0.2 mrad)

E. 50 mGy (5 rads)

~1. The approximate gonadal dose from a PA chest radiograph at 120 kVp.

D92. The approximate detection linut of a thermoluminescent dosimetry system.

~3. The maximum organ dose for patients undergoing nuclear medicine procedures.

~4. The regulatory weekly dose limit in controlled areas.

~5. The approximate typical annual effective dose equivalent for a nuclear medicine technologist.










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