RT2 Flashcards
1 . Low voltage X-ray tubes are generally fitted with windows made of:
a. plastic
b. beryllium
c. glass
d. lead
b. beryllium
- A monochromatic X-ray beam is:
a. a narrow beam used to produce high-contrast
radiographs
b. also referred to as a heterogeneous X-ray beam
c. a beam containing only characteristic X-radiation
d. a beam consisting of a single wavelength
d. a beam consisting of a single wavelength
- The general method of producing X-rays involves the sudden deceleration of high velocity electrons in a solid body called a:
a. focus cup
b. filament
c. target
d. cathode
c. target
- If it were necessary to radiograph a 18 cm (7 in.) thick steel product, which of the following gamma ray sources would most likely be used?
a. Co-60
b. Tm-170
c. lr-192
d. Cs-137
a. Co-60
- A Co-60 gamma ray source has an approximate practical thickness limit of:
a. 63 mm (2.5 in.) of steel or its equivalent
b. 102 mm ( 4 in.) of steel or its equivalent
c. 23 cm (9 in.) of steel or its equivalent
d. 28 cm (11 in.) of steel or its equivalent
c. 23 cm (9 in.) of steel or its equivalent
- The absorption of gamma rays from a given source when passing through matter depends on the:
a. atomic number, density, and thickness of the
matter
b. Young’s modulus value of the matter
c. Poisson’s ratio value ofthe matter
d. specific activity value of the source
a. atomic number, density, and thickness of the
matter
- The fact that gases, when bombarded by radiation, ionize and become electrical conductors make them useful in:
a. X-ray transformers
b. X-ray tubes
c. masks
d. radiation detection equipment
d. radiation detection equipment
- The velocity of electrons striking the target in an X-ray tube is a function of the:
a. atomic number of the cathode material
b. atomic number of the filament material
c. voltage difference between the cathode and anode
d. current flow in the rectifier circuit
c. voltage difference between the cathode and anode
- The uneven distribution of developed grains within the emulsion of a processed X-ray film causes the subjective impression of:
a. graininess
b. streaks
c. spots
d. white scum
a. graininess
- Co-60 is reported to have a half-life of 5.3 years. By how much should exposure time be increased (over that used initially to produce excellent radiographs when the Co-60 source was new) when the source is two years old?
a. no change in exposure time is needed
b. exposure time should be about 11 percent longer
c. exposure time should be about 31 percent longer
d. exposure time should be about 62 to 100 percent longer
c. exposure time should be about 31 percent longer
- A source of Ir-192, whose half-life is 75 days,
provides an optimum exposure of a given test object today in a period of 20 minutes. Five months from now, what exposure time would be required for the same radiographic density, under similar exposure conditions?
a. 10 minutes
b. 20 minutes
c. 1 hour and 20 minutes
d. 6 hours
c. 1 hour and 20 minutes
- Of the following, the source providing the most penetrating radiation is:
a. Co-60
b. 220 kVp X-ray tube
c. 15 Me V X-ray betatron
d electrons from Ir-192
c. 15 Me V X-ray betatron
- The gamma ray intensity at 30 cm (1 ft) from a 37 GBq (1 Ci) source of radioactive Co-60 is nearest to:
a. 15 roentgens per hour
b. 1 000 roentgens per hour
c. 1 roentgen per minute
d. 10 milliroentgens per day
a. 15 roentgens per hour
- The focal spot in an X-ray tube:
a. is inclined at an angle of 30º from the normal to the tube axis
b. is maintained at a high negative voltage during operations
c. should be as large as possible to ensure a narrow beam of primary radiation
d. should be as small as possible without unduly shortening the life of the tube
d. should be as small as possible without unduly shortening the life of the tube
- In an X-ray tube, the filament and focusing cup are the two essential parts of the:
a. anode
b. cathode
c. rectifier
d. X-ray transformer
b. cathode
- The quantity of radiation which will produce, by means of ionization, one electrostatic unit of electricity in 0.001293 g of dry air is known as a:
a. millicurie
b. gamma
c. roentgen
d. curie
c. roentgen
- The specific activity of an isotopic source is usually measured in:
a. million electron volts (Me V)
b. curies per gram (Ci/g)
c. roentgens per hour (R/h)
d. counts per minute (cpm)
b. curies per gram (Ci/g)
- Which of the following isotopes has the longest half-life?
a. Tm-170
b. Co-60
c. Ir-192
d. Cs-137
d. Cs-137
- The primary form of energy conversion when electrons strike a target in an X-ray tube results in the production of:
a. primary X-rays
b. secondary X-rays
c. short wavelength X-rays
d. heat
d. heat
- The slope of a straight line joining two points of specified densities on a characteristic curve of a film is known as the:
a. speed of the curve
b. latitude
c. average gradient
d. density
c. average gradient
- An X-ray film having wide latitude also has, by definition:
a. poor definition
b. low contrast
c. high speed
d. none of the above
b. low contrast
- The purpose for circulating oíl in some types of X-ray tubes is to:
a. lubricate moving parts
b. absorb secondary radiation
c. decrease the need for high current
d. dissipate heat
d. dissipate heat
- An X-ray tube with a small focal spot is considered better than one with a large focal spot when it is desired to obtain:
a. greater penetrating power
b. better definition
c. less contrast
d. greater film density
b. better definition
- One method of reducing radiographic contrast is to:
a. increase the distance between the radiation source and the object
b. decrease the distance between the object and the film
c. decrease the wavelength of the radiation used
d. increase development time within manufacturer’s recommendations
c. decrease the wavelength of the radiation used
- Thin sheets of lead foil in intimate contact with X-ray film during exposure increase film density because they:
a. fluoresce and emit visible light which helps expose the film
b. absorb the scattered radiation
c. prevent backscattered radiation from fogging the film
d. emit electrons when exposed to X-and gamma radiation which help darken the film
d. emit electrons when exposed to X-and gamma radiation which help darken the film
- X-ray tubes are often enclosed in a shockproof casing in order to:
a. dissipate heat
b. protect the operator from high-voltage shock
c. shield the tube from secondary radiation
d. increase the efficiency of the rectifier
b. protect the operator from high-voltage shock
- An X-ray tube is rated for a maximum of 250 kVp. This tube may be operated at a maximum of:
a. 250 000 V peak voltage
b. 250 kV effective voltage
c. 250 000 000 V rms voltage
d. 250 kV average voltage
a. 250 000 V peak voltage
- A voltage selector consisting of an iron core
transformer with a single winding having a series of taps at various points on the winding is called:
a. a high-voltage transformer
b. a filament transformer
c. an autotransformer
d. a power transformer
c. an autotransformer
- In X-ray radiography, alternating current must be changed to pulsating direct current in order to satisfy the need for unidirectional current. This change may be accomplished by:
a. transformers
b. rectifiers
c. anodes
d. cathodes
b. rectifiers
- When radiographing to the 2-2T quality level, an ASTM penetrameter for 63 mm (2.5 in.) steel has a thickness of:
a. 13 mm (0.5 in.)
b. 64 μm (2.5 mils)
c. 127 μm (5 mils)
d. 1270 μm (50 mils)
d. 1270 μm (50 mils)
- Valve tubes are used in X-ray equipment to:
a. provide necessary rectification
b. activate and deactivate the X-ray tube
c. heat the filaments in the X-ray tube
d. adjust the size of the target
a. provide necessary rectification
- A good Co-60 radiograph is made on a 76 mm (3 in.) steel casting using an exposure time of 10 minutes and a source-to-film distance of 91 cm (36 in.). If it is necessary to change the source-to-film distance to 61 cm (24 in.), what exposure time would produce a similar radiograph if all other conditions remain the same?
a. 1.6 minutes
b. 4.4 minutes
c. 6.4 minutes
d. 8.8 minutes
b. 4.4 minutes
- When sharp, black, bird-foot shaped marks which are known not to correspond with any discontinuities appear at random on radiographs, they are probably caused by:
a. prolonged development in old developer
b. exposure of the film by natural cosmic ray showers during storage
c. static charges caused by friction
d. inadequate rinsing after fixing
c. static charges caused by friction
- The adjustment of tube current in conventional X-ray tube circuits is made by:
a. adjusting the filament heating current
b. adjusting the target-to-cathode distance
c. inserting resistance in the anode lead
d. opening the shutter on the X-ray tube port
a. adjusting the filament heating current
- In comparison with lower-voltage radiographs, high-energy radiographs show:
a. greater contrast
b. greater latitude
c. greater amounts of scatter radiation relative to primary beam intensity
d. none of the above
b. greater latitude
- Filters used at the port of the X-ray tube:
a. intensify the X-ray beam by contributing secondary radiation
b. filter short wavelength X-ray beams to provide “softer” radiation
c. provide the most readily adjusted means of modifying X-ray intensity
d. filter out “soft” radiation to provide a more homogeneous X-ray beam
d. filter out “soft” radiation to provide a more homogeneous X-ray beam
- An ASTM penetrameter for use when inspecting a 13 mm (0.5 in.) thick steel plate to the 2-2T quality level using a 41 cm (16 in.) source-to-film distance would be made of:
a. 127 μm (5 mil) thick aluminum
b. 1270 μm (50 mil) thick aluminum or steel
c. 254 μm (10 mil) thick steel
d. 51 μm (2 mil) strip of any metallic material
c. 254 μm (10 mil) thick steel
- Filters placed between the X-ray tube and specimen tend to reduce scatter radiation undercutting the specimen by:
a. absorbing the longer wavelength components of the primary beam
b. absorbing the shorter wavelength components of the primary beam
c. absorbing backscatter radiation
d. decreasing the intensity of the beam
a. absorbing the longer wavelength components of the primary beam
- Besides serving as a filter, screens of high atomic numbers, such as lead and lead antimony, also:
a. decrease the source-to-film distance needed for a proper radiograph
b. provide some image intensifying action
c. permit the use of higher speed film
d. decrease the graininess in a radiograph
b. provide some image intensifying action
- The range of thickness over which densities are obtained that are satisfactory for interpretation is a measure of the:
a. subject contrast of a radiograph
b. sensitivity of a radiograph
c. latitude of a radiograph
d. definition of a radiograph
c. latitude of a radiograph
- Almost all gamma radiography is performed with:
a. natural isotopes
b. Ir-192 or Co-60
c. radium
d. Tm-170
b. Ir-192 or Co-60
- The amount of unsharpness or blurring of a radiograph is:
a. directly proportional to the object-to-film distance and inversely proportional to the size of the focal spot
b. directly proportional to the size of the focal spot and inversely proportional to the source-to-object distance
c. inversely proportional to the object-to-film distance and directly proportional to the source-to-object distance
d. inversely proportional to the size of the focal spot and the object-to-film distance
b. directly proportional to the size of the focal spot and inversely proportional to the source-to-object distance
- Images of discontinuities close to the source side of the specimen become less clearly defined as:
a. source-to-object distance increases
b. the thickness of the specimen increases
c. the size of the focal spot decreases
d. the thickness of the specimen decreases
b. the thickness of the specimen increases
- The inherent filtration of an X-ray tube is a function of the:
a. thickness and composition of the X-ray tube port
b. voltage setting of the instrument
c. source-to-object distance
d. material used as a target
a. thickness and composition of the X-ray tube port
- X-ray films with large grain size:
a. will produce radiographs with better definition than film with small grain size
b. have slower speeds than those with a relatively small grain size
c. have higher speeds than those with a relatively small grain size
d. will take longer to expose properly than film with relatively small grain size
c. have higher speeds than those with a relatively small grain size
- As the effective energy of the radiation increases up to about 250 kV:
a. film graininess increases
b. film graininess decreases
c. radiographic definition increases
d. film speed decreases
a. film graininess increases
- The specific activity of Co-60 depends on the:
a. time the material has been in the reactor
b. atomic number of the material
c. gamma ray flux to which it was exposed
d. Young’ s modulus value of the material
a. time the material has been in the reactor
- The most commonly used target material in an X-ray are:
tube is:
a. copper
b. carbon
c. carbide
d. tungsten
d. tungsten
- The purpose for including a disc-shaped target that rotates rapidly during operation in some X-ray tubes is to:
a. increase the intensity of X-radiation
b. decrease the voltage needed for a specific quality of radiation
c. increase the permissible load
d. none of the above
c. increase the permissible load
- A device which is basically a combination of magnet and transformer designed to guide and accelerate electrons in a circular orbit to very high energies is called a:
a. electrostatic belt generator
b. linear accelerator
c. betatron
d. toroidal electromagnetic type X-ray tube
c. betatron
- Two isotropic sources of a given strength have two different specific activity values. The source with the higher specific activity value will:
a. have a smaller physical size than the source with a
lower specific activity
b. have a shorter half-life than the source with a
lower specific activity
c. produce harder gamma rays than the source with a
lower specific activity
d. have a larger physical size than the source with the
lower specific activity
a. have a smaller physical size than the source with a
lower specific activity
- A gas-filled region located in an electrical field
created by electrodes across which a potential
difference is applied forms the major portion of:
a. a low voltage X-ray tube
b. a megger
c. a hot cathode X-ray tube
d. an ionization chamber
d. an ionization chamber
- Two serious obstacles to high-intensity fluoroscopy are:
a. the inability to reproduce results and the need for
periodic replacement of screens
b. the limited brightness and large grain size of
fluoroscopic screens
c. cost and slow speed
d. the need for using long wavelength X-rays and the
lack of X-ray intensity associated with this method
b. the limited brightness and large grain size of fluoroscopic screens
- In general, the quality of fluoroscopic equipment is
best determined by:
a. densitometer readings
b. penetrameter sensitivity measurements
c. discontinuity area measurements
d. reference standards
b. penetrameter sensitivity measurements
- In fluoroscopic testing, a fundamental difficulty is the relative low brightness level of the images. One method for increasing brightness utilizes one of the following which converts light energy from the initial phosphor surface to electrons which are accelerated and focused onto a smaller fluorescent screen.
a. betatron
b. electron amplifier
c. image amplifier or intensifier
d. electrostatic belt generator
c. image amplifier or intensifier
- A general rule governing the application of the geometric principies of shadow formation states that the:
a. X-rays should proceed from as large a focal spot as
other considerations will allow
b. distance between the radiation source and the
material examined should be as small as practical
c. film should be as far as possible from the object
being radiographed
d. central ray should be as nearly perpendicular to the
film as possible to preserve spatial relationships
d. central ray should be as nearly perpendicular to the
film as possible to preserve spatial relationships
- The radiographic absorption of a material will tend to become less dependent upon the composition of the material when:
a. the kilovoltage is increased
b. the source-to-film distance is decreased
c. the kilovoltage is decreased
d. a filter is used
a. the kilovoltage is increased