@The selection of the proper type of film to be used for the x-ray examination of a particular part depends on: \D |A. the thickness of the part. |B. the material of the specimen. |C. the voltage range of the available x-ray machine. |D. all three of the above factors.
@Radiographic sensitivity, in the context of the minimum detectable flaw size, depends on: \D |A. graininess of the film. |B. the unsharpness of the flaw image in the film. |C. the contrast of the flaw image on the film. |D. all three of the above.
@Any of the body tissues may be injured by excessive exposure to X or gamma rays but particularly sensitive are: \D |A. blood. |B. lens of the eye. |C. internal organs. |D. all of the above.
@X-ray exposure may be due to: \C |A. the direct beam from the x-ray tube target. |B. scatter radiation arising from objects in the direct beam. |C. both A and B above. |D. both A and B above plus residual radiation that exists for the
first few minutes after the x-ray machine has been returned to the "off" position.
@Lead foil screens are used in radiography: \C |A. to improve the quality of the radiograph by preferentially reducing the effect of scatter radiation. |B. to reduce the exposure time. |C. both A and B are reasons for using lead foil screens.
@The purpose of fixation is: \D |A. to remove all the undeveloped silver salts of the emulsion. |B. to leave the developed silver as a permanent image. |C. to harden the gelatin. |D. all of the above.
@Unwanted inclusions in a part will appear on a radiograph as: |D. either a dark or light spot or area depending on the relative absorption ratio of the part material and the inclusion material.
@The radiation quality of a gamma-ray source is: |B. determined by the isotope involved.
@The most common material used to provide protection against X-rays is:
|D. lead. ^D. VERY GOOD! Lead is very effective, relatively inexpensive, and compact.
@A curie is the equivalent of: |B. 1,000 millicuries. ^B. YES! One thousand milli-(one thousandth) curies equal one curie.
@The exposure of personnel to X- and gamma radiation can be measured or monitored by means of: \D |A. film badges. |B. dosimeters. |C. radiation exposure survey meters. |D. all of the above. ^A. Yes, but how about exposure survey meters? ^B. Yes, but how about film badges? ^C. Yes, but how about dosimeters? ^D. RIGHT ON! Film badges, dosimeters, and radiation exposure survey meters are all used to measure or monitor the
exposure of personnel to X- and gamma radiation.
@Assuming that a good radiograph is obtained at a setting of 10 milliamperes in 40 seconds, how much time will be necessary to obtain one equivalent radiograph if the milliamperage is change to 5 milliamperes (all other conditions remain constant)? |C. 80 seconds. ^C. TRUE! The inverse square does not apply here and cutting the amount of X-rays produced would double the exposure time.
@A graph showing the relation between material thickness, kilovoltage, and exposure is called: |B. an exposure chart or technique chart.
@A graph which expresses the relationship between the
logarithm of the exposure applied to a photographic material and the resulting photographic density is called: |C. the characteristic curve. ^C. YES! The plot of this function is a characteristic curve depending on film type and the radiation source.
@Short wavelength electromagnetic radiation produced during the disintegration of nuclei of radioactive substances is called: |B. gamma radiation. ^B. CORRECT! Gamma and X- radiation of the same wavelength are identical, but are produced differently.
@A photographic image recorded by the passage of X or gamma rays through a specimen onto a film is called a: |B. Radiograph. ^B. CORRECTO MUNDO! A radiograph is the general term applied to
all X- or gamma ray photographs.
@The normal development time for manually processing X-ray film is: |D. 5 to 8 minutes in processing solutions at 68 degrees F. ^D. YES! Just right. Actual time will vary between 5 to 8 minutes depending on other factors. 68 degrees F is considered the optimum developing temperature.
@In order to achieve uniformity of development over the area of X-ray film during manual processing: |C. the film should be agitated while in the developer. ^C. YOU'RE RIGHT! Agitation is necessary to replenish depleted developer at the film's surface, whether it's mechanical or manual is of no consequence.
@When referring to a "2T" or "4T" hole in the ASTM penetrameter, the T refers to: |B. the penetrameter thickness. ^B. ALRIGHTY! 2T equals 2% and 4T equals 4% of the material's thickness.
@A sheet of lead with an opening cut in the shape of the part to be radiographed may be used to decrease the effect of scattered radiation which undercuts the specimens. Such a device is called: |A. a mask. ^A. YES INDEEDY! Because it "masks" out everything but the object being radiographed.
@Two X-ray machines operating at the same nominal kilovoltage
and milliamperage settings: |D. may give not only different intensities but also different qualities of radiation. ^D. AYE! Many other factors besides kilovoltage and milliamperage determine X-ray intensity and quality.
@Fluoroscopy differs from radiography in that: |C. the X-ray image is observed visually on a fluorescent screen rather than recorded on a film. ^C. O.K.! This is why it is called fluoroscopy.
@An advantage of the pocket dosimeter type of ionization chamber used to monitor radiation received by personnel is: |B. it provides an immediate indication of dosage. ^B. ABSOLUTELY! It is not a permanent record.
@The density difference between two selected portions of a
radiograph is known as: |B. radiographic contrast. ^B. ROGER! The selected portions should be from the lightest and darkest areas of the radiograph to measure the overall image contrast.
@One requirement for keeping fluorescent screens in good condition is that they must: |B. not be exposed to intense ultraviolet radiation. ^B. VERY GOOD! UV light depletes the screen of the available material used to intensify the X- or gamma radiograph.
@In making an isotope exposure in an unshielded area, you find the dose rate 6 feet from the source is 1200 mR/hr. What would be the dose rate at 24 feet? |A. 75 mR/hr. ^A. PRECISELY! According to the inverse square law increasing the distance by 4 results in 1/16th the exposure.
@The intensity of X- or gamma radiation is measured in: |C. roentgens per unit of time. ^C. EXACTLY! Roentgens only refer to the ionization power of the radiation for one cubic-centimeter of air.
@When producing radiographs, if the kilovoltage is increased: |A. the subject contrast decreases. ^A. OF COURSE! An increase in kilovoltage produces shorter wavelength X-rays which are less photo-reactive at the film.
@The accidental movement of the specimen or film during exposure or the use of a focus-film distance that is too small will: |C. result in unsharpness of the radiograph. ^C. YOU BET! Just as in conventional photography movement blurs the image and reduces its sharpness.
@A properly exposed radiograph that is developed in a
developer solution at a temperature of 58 degrees F for 5 minutes will probably be: |B. underdeveloped. ^B. YEA! 58 degrees F is too cool and five minutes is barely enough developing time for 68 degrees F. The combination of the two results in an underdeveloped radiograph.
@A good radiograph is obtained using a milliamperage of 15 milliamperes and an exposure time of 1/2 minute. What exposure time will be necessary to produce an equivalent radiograph if the milliamperage is change to 5 milliamperes and all other conditions remain the same? |B. 1 1/2 minutes. ^B. GOOD! One-third the X-rays means the exposure time must be tripled.
@Lead screens in contact with the film during exposure: |A. increase the photographic action on the film largely by reason
of the electron emission and partly by the secondary X-rays generated in the lead. ^A. TRUE! THey also reduce fogging due to scattered radiation.
@The sharpness of the outline in the image of the radiograph is a measure of: |B. radiographic definition. ^B. SURE! Sharpness is a measure of how well an object is defined against its background.
@An unshielded isotope source gives a dosage rate of 900 mR per hour at 10 feet. What would the unshielded dosage rate be at 30 feet? |C. 100 mR/hr. ^C. YOU'RE RIGHT! According to the inverse square law the distance is 3 times as much and 3 squared is 9. Therefore, the output is 1/9 of 900.
@Which has the shortest wavelengths? |C. 100 kilovolt peak X-rays ^C. CORRECT! These are the shortest. Would 400 kilovolt X-rays be shorter or longer than 100 kilovolt X-rays?
@Beta particles are: |C. electrons. ^C. ALRIGHTY! Electrons ejected from an atom's nucleus are known as Beta particles.
@A radioactive source with an activity of one curie has: |D. 370,000,000,000 disintegrations per second taking place. ^D. YESIRREEBOB! This is a tremendous number of disintegrations, but remember the total number of atoms in a gram of Cobalt-60 equals approximately 1021 atoms.
@The formula for determining permissible accumulated personnel dose is: |C. 5 (N-18)
@The metal that forms the image on an x-ray film is: |B. silver. ^B. AYE! Silver bromide is a light sensitive compound that reduces to black metallic silver after it is exposed to radiation or light and then developed.
@Unexposed boxes of x-ray film should be stored: |B. on edge or end. ^B. CORRECTO MUNDO! Storing film in a vertical position greatly reduces the chances of pressure damage due to stacking.
@The lead symbol "B" is attached to the back of the film holder to determine: |B. whether excessive backscatter is present. ^B. RIGHT ON! The resolution of the lead B on the resulting radiograph indicates the amount of backscatter present
during exposure.
@Penetrameters for _____ are considered Group 1 Materials and need not have an identification notch. |C. Stainless steel.
@The purpose of a dated decay curve is to: |C. determine the source strength (activity) at any time. ^C. AFFIRMATIVE! This is the logical choice because size and shielding are set, and atomic decay is not recorded on a film log.
@Why is cobalt-60 used as a radiation source for medium-weight metals of thickness ranges form 1.5 to 9 inches? |C. Because of its penetrating ability. ^C. O.K.! Cobalt-60 emits highly penetrating X-rays of 1.17 and 1.33 MeV.
@The cause for poor image definition could be: \D |A. too short source-to-film distance. |B. screens and film not in close contact. |C. film graininess. |D. all of the above. ^A. Yes, but what about film graininess? ^B. Yes, but what about too short a source-to-film distance? ^C. Yes, but what about not having your screen and film in close contact? ^D. ABSOLUTELY! All these factors will contribute to poor image definition.
@During manual film processing, the purpose of the stop bath is to: |B. neutralize the developer and stop the developing process. ^B. ROGER! The stop bath contains a weak acid that "stops" the
developing action.
@A thin metallic sheet (brass, copper, aluminum, etc.) placed at the source to reduce effects of softer radiation is known as: |B. a filter. ^B. VERY GOOD! By reducing the effect of the soft X-rays the resulting radiograph will be less foggy.
@The reason a "shim" is used in radiographic setup is to: |C. simulate weld reinforcement. ^C. PRECISELY! This is used to check and calibrate the radiographic equipment.
@The focal spot size of an x-ray machine must be known in order to determine: |A. the geometric unsharpness value. ^A. EXACTLY! The exact size must be known. This usually is
measured in hundredths or thousandths of an inch.
@A section with a significant increases in thickness, variation is required to be shown on a single radiograph within a desired film density range. This may be accomplished by: |A. increasing kilovoltage. ^A. OF COURSE! By increasing the kilovoltage shorter more penetrating X-rays are produced, thus enabling a radiograph of equal contrast to be made of the thicker area.
@The density of a radiograph image refers to: |D. the degree of film blackening. ^D. YEA! The blackening is a result of clumps of black metallic silver.
@A beam of radiation consisting of a single wavelength is known as: |C. monochromatic radiation.
^C. GOOD! Monochromatic literally mans one (mono) color (chromatic). Generally light and thus radiation are thought of as having a color (wavelength).
@The image of the required penetrameter and hole on the radiograph indicates that the radiograph has the required: |C. sensitivity. ^C. TRUE! Even if the latitude of the radiograph is wide or narrow, or the contrast and definition shoddy the imaging of the penetrameter hole is a measure of radiographic sensitivity.
@The primary parts of an atom are: |D. proton, electron, neutron. ^D. YOU BET! These are the primary atomic parts there are many others which are very small, but do not concern us here.
@X-rays and gamma rays always travel: |C. straight lines. ^C. SURE! According to Sir Isaac Newton they will continue traveling in a straight line forever, until a collision or gravity affects their course.
@A large source size can be compensated for by: |A. increasing the source-to-specimen distance. ^A. YEP! By using the inverse square law doubling the distance decreases the radiation by 2 squared (2x2) or a factor of 4.
@Radiation arising directly from the target of an x-ray tube or an accelerator, or from a radioactive source, is usually referred to as: |B. primary radiation. ^B. YOU'RE RIGHT! They are also known as Bremsstrahlung (German for braking.) X-rays.
@To produce X-rays, electrons are accelerated to a high velocity by an electrical field and then suddenly stopped by a collision with a solid body. This body is called: |C. target. ^C. CORRECT! A target material at the anode then emits a spectrum of X-rays whose minimum wavelength is controlled by the kilovoltage.
@The best x-ray efficiency is produced when the target material has: |B. a high atomic number. ^B. ALRIGHTY! elements with high atomic numbers are the heavier, more dense elements and make excellent X-ray emitters.
@What is sometimes used to change the alternating current from the high voltage transformer to direct current for the purpose of
increasing the X-ray machine output? |A. Rectifier.
@In a fluoroscopic inspection system using a 15 inch source-to-material distance and 2 inch material-to-screen distance, transverse vibration of which item will cause the most image blurring? |C. Material vibration. ^C. AYE! The source and screen are in a fixed position and should not vibrate; however their vibrating does not create the most image blurring.
@If a fluorescent screen is accidentally exposed to unattenuated x-rays, which of the following occurs? |C. The screen is essentially undamaged. ^C. RIGHT ON! If the screen were greatly effected by attenuated or unattenuated X-rays their repeated use would be severely limited and this is not the case.
@Which of the following is an advantage of a fluoroscopic system when compared to a radiographic system? |B. Live image presentation for immediate viewing. ^B. CORRECTO MUNDO! A "real-time" radiographic system has many advantages including eliminating on going film and development cost, but lacks the sensitivity of film.
@A fluoroscopic installation utilizing fluorescent screen requires: |B. Lead glass, mirrors, or other means for transmitting the fluorescent image without subjecting the operator to x-radiation. ^B. YES INDEEDY! These are needed to shield andprotect the operator from nonconverted X-rays passing through the screen.
@In performing fluoroscopic examination of a part, it is
important to control: |A. geometry. |B. scatter radiation. |C. source kilovoltage and milliamperage. |D. all of the above. ^A. What about scatter radiation? ^B. What about kilovoltage and milliamperage? ^C. What about geometry. ^D. O.K.! Geometry, scatter radiation, kilovoltage, and milliamperage are all important control factors in fluoroscopy.
@In X-radiography, the ability to penetrate the test object is governed by: |C. kilovoltage. ^C. AFFIRMATIVE! Kilovoltage determines the minimum wavelength of the spectrum of X-rays produced. Increasing kilovoltage produces short wavelength more penetrating X-radiation.
@Which of the following types of radiation is emitted by
cobalt-60 and used in nondestructive testing? |B. Gamma rays. ^B. ABSOLUTELY! Gamma rays are the result of the atomic disintegrations occurring in Cobalt-60.
@The term used to describe the loss of excess energy by the nucleus of radioactive atoms is called: |A. decay (disintegration). ^A. ROGER! It is the atomic decay (disintegration) that creates gamma rays which is energy lost by the material in the form of radiation.
@X-rays, gamma rays, and alpha particles all have one thing in common-they are all: |D. ionizing radiations. ^D. VERY GOOD! All three are capable of ionizing (creating negative or positive ions) elements or compounds.
@The term used to express the number of curies of radioactivity per gram or ounce of source weight is: |C. specific activity. ^C. PRECISELY! The specific activity is the curies per gram or ounce of material. One curie equals 3.7 x 1010 atomic disintegrations per second.
@Atoms, molecules, and various subatomic particles which carry either a positive or negative electrical charge are called: |C. ions. ^C. EXACTLY! Compounds are composed of only molecules, all electrons are negative, and all protons are positive.
@Gamma and X-radiation interact with matter and may be absorbed by: \D |A. photoelectric absorption. |B. Compton scattering. |C. pair production. |D. all of the above. ^A. What about positron-electron pair production?
^B. What about photoelectric absorption? ^C. What about Compton scattering? ^D. OF COURSE! These are the only three absorption phenomena known.
@Approximately what percent of the original radioactivity is left after six half-lives? |D. 2 ^D. YEA! This is an approximation it is actually one 64th or 1.56 percent.
@The velocity of all electromagnet radiation is: |A. 186,000 miles per second.
@The radiation intensity of a radioisotope: |B. decreases with time. ^B. GOOD! The half-life is a measure of this decrease.
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RADIOGRAPHY TESTING LEVEL II
@Low voltage X-ray tubes are generally fitted with windows made of: |B. beryllium. ^B Correct! Beryllium allows all but the longtest wavelength xrays to pass through it.
@A monochromatic X-ray beam: |D. is a beam consisting of a single wavelength. ^D. YOU'RE RIGHT! Mono means one or single and chromatic refers to the color or wavelength.
@The general method of producing X-rays involves the sudden
deceleration of high velocity electrons in a solid body called a: |C. target. ^C. CORRECT! The focusing cup, filament, and cathode produce and direct the electron beam.
@If it were necessary to radiograph a 7-inch thick steel product, which of the following gamma-ray sources would most likely be used? |A. Cobalt-60 ^A. ALRIGHT! Cobalt is suitable for radiographing steel above 3-4 inches thick and has a rated penetrating power of 1.17 and 1.33 MeV respectively.
@A Cobalt-60 gamma ray source has an approximate practical thickness limit of: |C. 9 inches of steel or its equivalent.
@The absorption of gamma rays from a given source when passing
through matter depends on:
|A. the atomic number, density, and thickness of the matter. ^A. YES! The thickness, atomic number, and material density all effect the absorption of both gamma and X-rays.
@The fact that gases, when bombarded by radiation, ionize and become electrical conductors make them useful in: |D. radiation detection equipment.
@The velocity of electrons striking the target in an X-ray tube is a function of: |C. the voltage difference between the cathode and anode. ^C. RIGHT ON! The voltage potential between the cathode and anode is responsible for electron velocity.
@The uneven distribution of developed grains within the emulsion of a processed X-ray film causes the subjective impression of:
|A. graininess. ^A. CORRECT! Also note the faster the film the larger the individual silver salts (grains). Thus fast film tends to be grainier.
@Of the following, the source providing the most penetrating radiation is: |C. 15 MeV x-ray betatron. ^C. YES! A 15MeV X-ray betatron is a linear accelerator whose beam strength is 12 times that of Cobalt the next most penetrating source on this list.
@The gamma-ray intensity at one foot from a one curie source of radioactive cobalt-60 is nearest: |A. 15 roentgens per hour.
@The focal spot in an X-ray tube: |D. should be as small as possible without unduly shortening the
life of the tube. ^D. O.K.! A smaller focal spot creates a narrower beam of Xradiation and raises the definition of the radiograph.
@In an X-ray tube, the filament and focusing cup are the two essential parts of the: |B. cathode. ^B. ABSOLUTELY! The filament is the source of the electrons and the focusing cup aims them onto the target anode.
@The quantity of radiation which will produce, by means of ionization, one electrostatic unit of electricity in 0.001293 grams of dry air is known as: |C. a roentgen. ^C. CORRECT! 0.001293 grams of dry air is equivalent to one cubic centimeter of dry air at sea level.
@The specific activity of an isotopic source is usually measured
in: B. curies per gram. ^B. VERY GOOD! The curies per gram is the measure of specific activity. One curie equals 37,000,000 disintegrations per second.
@Which of the following isotopes has the longest half-life? |D. Cesium-137 ^D. PRECISELY! Cesium-137 with a half-life of 30 years in the longest of this group.
@The primary form of energy conversion when electrons strike a
target in an X-ray tube results in the production of: |D. heat. ^D. EXACTLY! For example: only 3% of a 300 keV X-ray tube's total energy is converted to X-rays. The other 97% is released as heat.
@The slope of a straight line joining two points of specified
densities on a characteristic curve of a film is known as the:
|C. average gradient.
@An X-ray film having wide latitude also has, by definition: |B. low contrast. ^B. YES! X-ray films with a narrow latitude by definitions are
high contrast.
@The purpose for circulating oil in some types of X-ray tubes is: |D. to dissipate heat. ^D. GOOD! Because 97% or more of the energy of an X-ray tube is given off as heat circulating oil is used for cooling.
@An X-ray tube with a small focal spot is considered better than one with a large focal spot when it is defined to obtain:
|B. better definition. ^B. TRUE! The smaller the focal spot the better the definition.
@One method of reducing radiographic contrast is to: |C. decrease the wavelength of the radiation used. ^C. YOU BET! Shorter wavelength X-rays are more penetrating , but less photographically active and produce high contrast radiographs.
@Thin sheets of lead foil in intimate contact with X-ray film during exposure increase film density because: |D. they emit electrons when exposed to X- and gamma radiation
which help darken the film. ^D. CORRECT! These electrons are photographically active and intensify the exposure and increase the darkening of the film.
@X-ray tubes are often enclosed in a shockproof casing in
order to: |B. protect the operator from high-voltage shock. ^B. YOU'RE RIGHT! Do to the high voltages involved an electrically insulated casing is required to protect the operator.
@An X-ray tube is rated for a maximum of 250 kVp. This tube may be operated at a maximum of: |A. 250,000 volts peak voltage. ^B. Effective voltage! Not conventional radiographic term. What does the "p" stand for?
@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: |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: |B. rectifiers. ^B. YES! The half wave rectifier converts the ac to pulsing dc
current.
@When radiographing to the 2-2T quality level, an ASTM penetrameter for 2.5 inch steel has a thickness of: |D. 50 mils. ^D. CORRECT! 50 mils. equals .05 inches or 2 percent of 2.5 inches, computed as 2.5 x .05 or 50 mils., or 50 thousandths of an inch.
@Valve tubes are used in X-ray equipment to: |A. provide necessary rectification. ^A. Correct! yes the valve tubes are used to convert ac to pulsing dc current.
@A good cobalt-60 radiograph is made on a 3 inch steel casting using an exposure time of 10 minutes and a source-to-film distance of 36 inches. It is necessary to change the source-to-film distance to 24 inches, what exposure time would produce a similar radiograph if all other conditions remain the same? |B. 4.4 minutes. ^B. Yes! 3 ft. squared equals 9, and 2 ft squared equals 4. 4 /9 = 4/9 x 10 = 4.444...
@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: |C. static charges caused by friction. ^C. Yes! The electrical discharge of static electricity exposes crystals.
@The adjustment of tube current in conventional X-ray tube circuits is made by: |A. adjusting the filament heating current. ^A. CORRECT! This increases the number of electrons produced and is a function of amperage.
@In comparison with lower-voltage radiographs, high-energy radiographs show: |B. greater latitude. ^B. CORRECT! High penetrating short wavelength X-rays are less
photographically active.
@Filters used at the port of the X-ray tube: |D. filter out "soft" radiation to provide a more homogeneous X-ray beam. ^D. Yes! The short wavelengths pass through with minimal attenuation. The longer wavelengths "softer" X-rays create scatter radiation and film fog.
@An ASTM penetrameter for use when inspecting a one-half inch
thick steel plate to the 2-2T quality level using a 15 inch source-to-film distance would be made of: |C. 10 mil thick steel. ^C. VERY GOOD! 10 mils. is the equivalent to .01 inches or 2 percent of .5 inches.
@The kilovoltage applied to an x-ray tube affects: \C |A. the quality of the beam. |B. the intensity of the beam. |C. both A and B above. |D. neither A nor B above. ^A. What about the intensity of the beam? ^B. What about the quality of the X-rays produced? ^C. PRECISELY! Kilovoltage controls the wavelength of the X-rays produced which affects both the quality and intensity or penetrating power. ^D. At least one is correct. Remember, kilovoltage controls the minimum wavelength of the X-ray spectrum produced. @Filters placed between the x-ray tube and specimen tend to reduce scatter radiation undercutting the specimen: |A. by absorbing the longer wavelength components of the primary beam.
^A. EXACTLY! The longer wavelength "soft" X-rays increase scatter radiation and can fog the resulting radiograph.
@Besides serving as a filter, screens of high atomic number, such as lead and lead antimony, also: |B. provide some image intensifying action. ^B. OF COURSE! By releasing electrons that photographly react with the film.
@The range of thickness over which densities are obtained that
are satisfactory for interpretation is a measure of the: |C. latitude of a radiograph. ^C. GOOD! The range of thickness over which densities are satisfactory for interpretation is known as latitude.
@Almost all gamma radiography is performed with: |B. iridium-192 or cobalt-60. ^B. TRUE! Thulium-170 and radium are rarely used.
@The amount of unsharpness or blurring of a radiograph is: |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: |B. the thickness of the specimen increases. ^B. SURE! The increase in material between the discontinuity and the film reduces the definition.
@The inherent filtration of an x-ray tube is a function of: |A. the thickness and composition of the x-ray tube port.
@X-ray films with large 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 250kV: |A. film graininess increases.
@The specific activity of cobalt-60 depends on:
|A. the time the material has been in the reactor. ^A. YES! More Cobalt-59 is converted to Cobalt-60.
@The most commonly used target material in an x-ray tube is: |D. tungsten. ^D. RIGHT! Tungsten is commonly used because of its density and high melting point.
@The purpose for including a disc-shaped target that rotates rapidly during operation in some x-ray tubes is to: |C. increase the permissible load. ^C. CORRECT! By cooling the target anode rotation allows higher voltages or loads to be used without over heating and melting the target.
@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: |C. betatron.
@Two isotopic sources of a given strength have two different specific activity values. The source with the higher specific activity value will: |A. be of smaller physical size than the source with a lower specific activity. ^A. CORRECT! Specific activity is measured by curies per gram,
thus, if source strength is equal the higher specific activity source will be smaller and weigh less.
@A gas-filled region located in an electrical field created by
electrodes across which a potential difference is applied forms the major portion of: |D. an ionization chamber. ^D. ABSOLUTELY RIGHT! X-ray tubes contain a vacuum.
@Two serious obstacles to high-sensitivity fluoroscopy are: |B. the limited brightness and large grain size of fluoroscopic screens.
^B. CORRECT! The limited brightness and grainy image make fluoroscopy less sensitive.
@In general, the quality of fluoroscopic equipment is best determined by: |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. |C. Image amplifier or intensifier.
@A general rule governing the application of the geometric principles of shadow formation states that: |D. the central ray should be as nearly perpendicular to the film as possible, to preserve spatial relationships. ^D. CORRECT! Any other angle increases the geometric distortion of the object being radiographed.
@In order to utilize the principles of geometric enlargement (placing the film at a distance from the specimen): |B. the source of radiation must be extremely small. ^B. CORRECT! This would increase definition.
@The x-ray absorption of a specimen depends on: \C |A. the thickness and density of the material. |B. the atomic number of the material. |C. both A and B above. |D. neither A nor B. ^A. Yes, but what about the atomic number of the material? ^B. Yes, but what about the thickness and density of the material? ^C. CORRECT! ^D. There is at least one correct answer.
@The radiographic absorption of a material will tend to become
less dependent upon the composition of the material when: |A. the kilovoltage is increased. ^A. CORRECT! Shorter wavelength X-rays are produced and their alternation is more dependent upon material thickness.
@The formula (milliamperes X times)/(distance squared is: |D. the exposure factor.
@The load that can be handled by an x-ray tube focal spot is governed by: |B. the size of the focal spot and the efficiency of the cooling system of the anode.
@X-ray exposure holders and cassettes often incorporate a sheet of lead foil in the back which is not in intimate contact with the film. The purpose of this sheet of lead foil is: |B. to protect the film from backscatter.
@A lead sheet containing a pinhole may be placed halfway between the X-ray tube and the film in order to: |A. determine the approximate size of the focal spot.
@The most common way of cooling the anode of a high-power X-ray
tube is: |C. cooling by circulation of water or oil in the anode.
@In certain cases, it may be advantageous to pack lead shot around a specimen. The purpose for doing this is: |D. to decrease the effect of scattered radiation undercuttin the specimen.
@The mottling caused by diffraction when radiographing fairly large-grained metallic specimens can be reduced and in some cases eliminated by: |C. raising the kilovoltage and using lead foil screens. ^C. CORRECT! Raising KV produces shorter wavelength X-rays and
the lead screens filter out the less penetrating shorter wavelengths.
@When radiographing steel with a thickness less than one inch:
|B. a 250 kV X-ray machine would give greater radiographic sensitivity than cobalt-60.
@A radiograph made with an exposure of 12mA per minute has a
density of 0.8 in the region of maximum interest. It is desired to increase the density to 2.0 in this area. By reference to a
characteristic curve of the film, it is found that the difference in log E between a density of 0.8 and 2.0 is 0.76. The antilogarithm of log 0.76 is 5.8. What must the new exposure time be to produce a radiograph with a density of 2.0? |C. 69.6 mA per minute
@The absorption of radiation by a material varies: |D. in an approximately exponential manner with the thickness of the material.
@In the microradiographic technique: \D |A. soft X rays are usually employed. |B. a kilovoltage range of 5 to 50 kV is usually employed. |C. the photographic material is often finer grained than an ordinary X-ray film. |D. all three of the above choices are correct. ^A. Yes, but what about a KV range of 5 to 50 KV? ^B. Yes, but what about the primary use of soft X-rays?
^C. Yes, But what about the kilovoltage range? ^D. CORRECT! @In order for a radiograph to have a penetrameter sensitivity of 2-2T or better: |B. the radiographic procedure must be able to define the 2T hole in a penetrameter which is 2 percent of the thickness of the specimen.
@For practical purposes, the shape of the characteristic curve of an X-ray film: |B. is independent of the quality of X- or gamma radiation.
@The term which describes the total absorption of the useful beam caused by the X-ray tube wall, the wall of the tube housing, and any material between the tube and housing is: |D. inherent filtration.
@The interval between the time a film is placed in a fixer solution and the time when the original diffuse, yellow milkiness disappears is known as:
|A. clearing time. ^A. CORRECT! This is followed by an equal amount of time for hardening.
@Excessive subject contrast caused when the thickness range in
the test specimen is too great for the radiation quality used may be corrected by: \C |A. increasing the kilovoltage. |B. using a filter at the X-ray tube and increasing the exposure time. |C. both A and B are methods for correcting excessive subject contrast. |D. decrease the exposure time. ^A. Yes, but what about using a filter? ^B. Yes, but what about increasing the voltage? ^C. CORRECT! ^D. No, you need to increase the exposure time.
@Improper geometric factors, poor contact between film and lead
foil screens, and graininess of film are possible causes of: |B. poor definition.
@In fluoroscopy the most common means for minimizing operator fatigue is to: |D. change operators periodically.
@Which of the following X-ray generators would produce the narrowest cone of X-radiation? |C. 25MeV
@A radiograph is taken at a voltage of 500 kV. If the voltage is increased with a resultant increase in the energy of radiation
while all other conditions remain the same: |D. there will be little significant change in the graininess of the film.
@A radiograph of a steel weldment is made using a 15 MeV betatron. When the radiograph is developed, there is an overall
film mottling. A possible cause for such mottling is: |C. failure to use a lead screen during exposure.
@A basic difference between a radiograph and a fluoroscopic images is: |B. the fluoroscopic image is a positive whereas the radiograph is a negative transparency. ^B. CORRECT! It is also less sensitive.
@The quantity of radiation striking a unit area of film: |A. is the product of radiation intensity and time.
@Which of the following factors will not materially influence the image density of a radiograph? |B. The size of the film ^B. CORRECT! The size of the film is not a factor influencing film density.
@A 1,000 kVp X-ray machine used in conjunction with a lead foil screen has an approximate practical thickness limit of: |C. 5 inches of steel or its equivalent.
@Because of geometrical factors such as source size, source-to-specimen distance and specimen-to-film distance, there can be a lack of perfect sharpness at the edges of indications. The unsharpness caused by geometrical factors may be referred to as the: |B. penumbral shadow.
@Two factors which greatly affect the suitability of the target material in an X-ray tube are: |D. atomic number and melting point. ^D. CORRECT! Targets made from elements with high atonic numbers are more efficient and high operating temperatures require a high melting point.
@The reason the exposure time must be increased by a factor of
four when the source-to-film distance is doubled is: |C. the intensity of radiation is inversely proportional to the square of the distance from the source to the film. ^C. CORRECT! This is known as the inverse square law.
@The approximate radiographic equivalence factors for steel and copper at 220kV are 1.0 and 1.4 respectively. If it is desirable to radiograph a 0.5-inch plate of copper, what thickness of steel would require about the same exposure characteristics? |A. 0.7 inches of steel ^A. CORRECT! Or .5 x 1.4 x 1.0
@Which of the following technique variables is most commonly used
to adjust subject contrast? |C. Kilovoltage ^C. CORRECT! Adjusting the KV increases or decreases the penetrating power of the X-rays produced and thus the resulting image contrast.
@Films that are left between lead screens too long in a high-temperature and high-humidity atmosphere may: |B. become fogged. ^B. CORRECT! Fogging occurs because of a chemical change in the silver bromide crystals.
@The quantitative measure of film blackening is referred to as: |B. photographic density. ^B. CORRECT! The instrument used to measure film density is called a densitometer.
@A curve relating density with the logarithm of exposure or of
relative exposure is called: |C. an H & D curve.
@Subject contrast is affected by: \D |A. thickness differences in specimen. |B. radiation quality. |C. scattered radiation. |D. all of the above. ^A. How about scattered radiation and its fogging effect? ^B. What about the thickness of the specimen being radiographed? ^C. What about radiation quality? ^D. CORRECT! @The Code of Federal Regulations requires that all shipping containers for radioisotopes: |B. be fire resistant.
@Which of the following instruments would exhibit the best sensitivity and most likely be used to detect small leaks in a
radiation barrier? |C. A Geiger counter ^C. CORRECT! A geiger counter is more sensitive and gives an immediate indication of radiation.
@At voltages above 400 kV, the use of lead to provide protection may present serious problems. If this should be a serious problem, which of the following materials would most likely be
used as a substitute? |B. Concrete ^B. CORRECT! Concrete is not only effective, but inexpensive as well.
@A qualitative term often used to indicate the size of the smallest detail which can be seen in a radiograph is: |A. radiographic sensitivity.
@The slope (steepness) of a characteristic curve is a measure of: |D. film contrast.
@A special radiographic method requiring two radiographs taken
during separate exposures from two different positions to give
the visual impression of a three-dimensional display when viewed in an optical device simultaneously is referred to as: |C. stereoradiography. ^C. CORRECT! Stereo means two.
@The depth of a discontinuity may be estimated by making two exposures on a single film from two different positions of the
X-ray tube. The depth of the discontinuity is computed from the shift in the shadow of the discontinuity with respect to the images of fixed markers on the front and back of the specimen.
The method is referred to as: |D. the parallax method of depth location.
@Constant agitation of the developer during the development process by means of mechanical stirrers or circulating pumps may: |C. cause undesirable, preferential flow of developer along certain paths.
@The activity of the fixer diminishes after being used for a period of time because: |C. the fixer solution accumulates soluble silver salts. ^C. CORRECT! This contamination results in the diminishing activity of the solution.
@In processing radiographs, the hourly flow of water in the wash tank should be: |B. four to eight times the volume to of the tank.
@Attenuation of gamma rays in the energy range commonly used for testing takes place through: \C |A. photoelectric absorption. |B. Compton absorption. |C. both A and B. |D. neither A nor B. ^A. What about Compton absorption?
^B. Photoelectric absorption is also possible. ^C. CORRECT! ^D. At least one is correct.
@A zinc cadmium sulfide fluoroscopic screen which is continually exposed to bright daylight, sunlight, or other sources of ultraviolet radiation will: |B. become discolored and lose some of its brilliance.
@Increasing the X-ray or gamma-ray energy will: |D. have little effect on the shape of a characteristic curve.
@As the development time increases: |A. the characteristic curve grows steeper and moves to the left.
@A distinctive characteristic of high-voltage radiography is: |C. it is applicable to comparatively thick or highly absorbing specimens. ^C. CORRECT! High voltages are necessary to accelerate the electrons fast enough in order to produce the shortest
wavelength most penetrating X-ray possible.
@Lead screens are used for almost all exposures when using: |C. high-voltage radiography. ^C. CORRECT! This eliminates most of the shorter less penetrating wavelengths that are produced when using high-kilovoltage.
@The fact that each solid crystalline substance produces its own characteristic X-ray pattern is the basis for: |D. X-ray powder diffraction examination.
@Which of the following glasses would most likely be used as an X-ray barrier window on fluoroscopic equipment? |B. Lead glass ^B. CORRECT! The attenuation properties of lead give the glass
shielding features.
@The maximum practical speed of scanning a test object for conventional fluoroscopic inspection has been estimated to be:
|D. about 3 inches per second.
@When other operating conditions are held constant, a change in tube current causes a change in radiation intensity emitted from an X-ray tube, the intensity being approximately proportional to tube current. What is the primary factor that prevents this from being exactly proportional? |A. The voltage and voltage waveform of an X-ray machine transformer varies with load.
@When viewing a radiograph, an image of the back of the cassette superimposed on the image of the specimen is noted. This is most likely due to: |D. Backscatter. ^D. CORRECT! Radiation scattered onto the back of the film
cassette causes this, a lead "B" is placed on the back of the film to measure back scatter radiation.
@A special form of scatter due to X-ray diffraction effects in a specimen with large grains will result in: |B. a radiograph of mottled appearance.
@The half-value layer of lead for cobalt-60 is approximately 0.5 inch. If the radiation level on the source side of a 1.5 inch lead plate is 64 R/hr, the radiation level on the opposite side is: |A. 8 R/hr. ^A. CORRECT! Calculated as 64 x 1/2 x 1/2 x 1/2 = 8
@Which of the following is not a factor in determining subject contrast? |C. Type of film used
^C. CORRECT! The type of film used has inherent contrast qualities known as "film contrast" which has no relation to subject contrast.
@If an exposure time of 60 seconds and a source-to-film distance of 4 feet is necessary for a particular exposure, what exposure time would be needed for an equivalent exposure if the source-to -film distance is changed to 5 feet? |B. 94 seconds ^B. CORRECT! According to the inverse square law 5 squared/4 squared = 1.5625 x 60 = 93.75 or 94 seconds.
@In order to increase latitude so that thick and thin portions may be radiographed at reasonable viewing densitiesNsimultaneously: |C. the film cassette may be loaded with two films of different speeds. ^C. CORRECT! Since latitude is an inherent property, as is
film contrast, the only way to increase it is to use two films with different speeds.
@Developer solution should be discarded when the quantity of replenisher added equals: |B. two to three times the original quantity of developer. ^B. CORRECT! Once two or three replenisher supplements have exhausted the developer it becomes too contaminated to revive.
@If a specimen were radiographed at 40 kV and again at 50 kV with time compensation to give the radiographs the same density, which of the following statements would be true? |C. The 50 kV exposure would have a lower contrast and a greater latitude than the 40 kV exposure ^C. CORRECT! Because the kV X-rays are harder and have less
photoactive capabilities.
@A 250 kVp X-ray machine used in conjunction with a lead foil screen has an approximate practical thickness limit of: |B. 2 inches of steel or its equivalent.
@The degree of concentration of the radioactive material in a gamma-ray source is referred to as: |A. the specific activity of the source. ^A. CORRECT! And it's measured as curies per gram.
@In million-volt radiography, filtration at the tube: |D. offers no improvement in radiographic quality. ^D. CORRECT! Filtration of such a powerful X-ray beam at the tube offers no improvement in the radiographic quality.
@The energy of gamma rays is expressed by which of the
following units of measurement? |D. Kiloelectron volt (keV) or million electron volt (MeV) ^D. CORRECT! KeV and MeV are measurements of gamma ray energy.
@Film selection for an X-ray exposure depends on: \D |A. thickness of the part. |B. the material of the specimen. |C. the voltage range of the X-ray machine. |D. all of the above. ^A. What about the material density of a specimen? ^B. What about the voltage range of the machine? ^C. What about the thickness of the material? ^D. CORRECT! Part thickness, material, and voltage range of the X-ray machine all influence film selection.
@While using an X-ray tube for radiography, the operator wishes to increase the radiation intensity. To do so, the: |B. tube current should be increased.
^B. CORRECT! Raising tube current or milliamperage increases Xray intensity.
@Lead screens are put in direct contact with the film to: \D |A. increase the photographic action on the film. |B. absorb the longer wavelength scattered radiation. |C. intensify the photographic effect of the primary more than
the scattered radiation. |D. all of the above. ^A. What about absorbing longer wavelength radiation? ^B. What about intensifying the photographic effect of the primary more than the scattered radiation? ^C. What about increasing the photographic action on the film?
^D. CORRECT!
@Mottling due to diffraction can be reduced and in some cases eliminated by: \C |A. raising the kilovoltage. |B. using lead foil screens.
|C. both of the above. |D. none of the above. ^A. This will reduce mottling, but if kilovoltage is already at its peak, using lead foil screens will also reduce mottling. ^B. Raising the kilovoltage and increasing X-ray penetration power will also reduce mottling. ^C. CORRECT! Both will reduce mottling by decreasing the amount of diffraction. ^D. At least one is correct. Mottling is caused by the defraction of less penetrating longer wavelength X-rays.
@Because of geometrical factors such as source size, source-to-specimen distance, and specimen-to-film distance, there can be a lack of perfect sharpness at the edges of indications. The unsharpness caused by these factors may be referred to a the: |B. penumbral shadow. ^B. CORRECT! By controlling these factors the penumbral shadow can be reduced and sharpness increased.
@The main purpose of the X-ray generator controls on the equipment is: |B. to enable the operator to obtain the intensity, quality, and duration of exposure desired. ^B. CORRECT! Intensity is controlled by milliamperage, quality by kilovoltage, and exposure duration by a timer or switch.
@Fluoroscopic screens, as mounted and used, are easily damaged by which of the following? |B. Exposure to ultraviolet radiation or sunlight ^B. CORRECT! Sunlight and ultraviolet light drain the amount of fluorescent material available for visible light production during radiography.
@When X rays, gamma rays, light, or electrons strike the photographic emulsion, a change takes place in the silver halide crystals. This change is referred to as:
|C. latent image. ^C. CORRECT! This is a chemical change which is not apparent until the film is processed.
@If one curie of iridium-192 produces a dose rate of 5900 mR per hour at one foot, how may mR will ten curies produce at the same distance? |D. 59,000 ^D. CORRECT! Since the distance is equal a ten curie source is exactly ten times as intense as a one curie source.
@With respect to quality, what three factors must be considered in selecting a source-to-film distance? |D. Source size, specimen thickness, geometric unsharpness ^D. CORRECT! All three are important quality factors.
@On a radiograph of a pipe weld there is a very light irregularly-shaped small image in the weld. This image would most likely be due to the presence of: |C. tungsten inclusion. ^C. CORRECT! Tungsten is more dense and attenautes the beam more than the surrounding material resulting in a very light image, and is irregular in shape.
@A larger physical size source may produce an equivalent quality radiograph if: |A. the source-to-film distance is increased. ^A. CORRECT! This in essence reduces its physical size as it appears from the viewpoint of the specimen.
@A light image of a backing "B" on a processed radiograph is probably caused by: |B. backscatter.
^B. CORRECT! A lead backscatter is attached to the back of the film to measure backscatter and when exposed results in a light image.
@Cobalt-59 becomes cobalt-60 when it is placed in a nuclear reactor where it captures: |B. a neutron. ^B. CORRECT! And thus increases the atomic weight by one.
@When a faster speed film is substituted for a slower one to improve the economics of the exposure, which of the following conditions occur? |C. The image resolution will be reduced ^C. CORRECT! The resulting image is grainier.
@For a given change in the radiation exposure, film contrast is the inherent ability to show: |A. a difference in density.
^A. CORRECT! It has nothing to do with graininess although faster (large grain) films usually have lower contrast than slower (fine grain) films.
@The ability of a material to block or partially block the passage of X rays and gamma rays is referred to as: |C. absorption. ^C. CORRECT! Also referred to as attenuation.
@Source size, specimen thickness, and source-to-specimen distance are the three factors that determine the: |D. unsharpness recorded on the radiograph. ^D. CORRECT! All three are factors directly related to image sharpness.
@The range of specimen thicknesses that can be adequately recorded on the radiograph is referred to as the:
|B. latitude of the radiograph. ^B. CORRECT! Latitude is the range of thicknesses that can be adequately recorded on the radiograph.
@Approximately how long would it take for a 10 curie cobalt-60 source to decay to 2 1/2 curies? |C. 10.6 years ^C. CORRECT! Since the half-life of Cobalt-600 is 5.3 years it would take two half lives to reduce a 10 curies source to a 2.5 curie source.
@The "photoelectric" effect involves: |C. complete absorption of a photon. ^C. CORRECT! Part of the photon energy is used in ejecting an electron and the remainder imparts velocity to the ejected electron.
@Radiographic undercutting is caused by: |A. side scatter. ^A. CORRECT! It is also caused by internal scatter and can
present problems when radiographing irregularly shaped objects.
@The developer solution is: |B. alkaline. ^B. CORRECT! The stop bath is acid.
@A general rule governing the application of the geometric principles of shadow formation states that: |D. the central ray should be a nearly perpendicular to the film as possible, to preserve spatial relationships. ^D. CORRECT! Any angel other than 90 degrees increases geometric distortion of the images on the radiograph.
@An X-ray film having wide latitude also has, by definition: |B. low contrast. ^B. CORRECT! Narrow latitude films have high contrast.
@The projected area of the target of an X-ray tube is called:
|C. effective focal spot. ^C. CORRECT! The effective focal spot is either equal to or less than the actual focal spot.
@The slope of the H & D curve of a radiographic film is called: |C. gamma or gradient.
|B. fluorescent screen exposures. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
@The half-life of radioactive cesium-137 is nearest: |C. 30 years. ^C. CORRECT! Its rays have an average penetration power of 664 keV.
@An iridium-192 gamma-ray source has an approximate practical thickness limit of: |A. 3 inches of steel or its equivalent.
@The half-life of radioactive cesium-137 is nearest: |C. 30 years. ^C. CORRECT! Its rays have an average penetration power of 664 keV.
@An iridium-192 gamma-ray source has an approximate practical thickness limit of: |A. 3 inches of steel or its equivalent.
