RAD 121 Unit 1

The original technique for the exam was on a single-phase full-wave unit. The technique was 300 mA, .1 seconds, 80 kVp and a 72 inch SID that produced an exposure rate of 40 mR. The radiologist requires the film to be repeated. He wants higher contrast on the film. The only room available is a three-phase six-pulse unit. Using the 15/50% rule and compensating for the changing generators, the patient's exposure on the new film will be ______ mR. For each fill-in-the-blank question, when doing your calculations, only carry out the number to the second digit beyond the decimal point. Also when giving your answer, answer to the second digit beyond the decimal point. Ex: 2.334323 is the number you have, use 2.33 in the calculations. If this were your answer, you would answer 2.33 unless the question ask for the answer as a whole number. Then you would answer as 2. DO NOT ROUND UP OR DOWN WHEN DOING YOUR CALCULATIONS.

38.53

As the photon energy increases, _________ decreases. Select one: a. photon wavelength b. photon frequency c. target electron binding energy d. projectile electron energy

a. photon wavelength

The only portion of the anode assembly placed outside the vacuum of the envelope is the Select one: a. stator. b. rotor. c. rotating disc. d. molybdenum neck.

a. stator.

The rotating anode of the X-ray tube consists of a molybdenum disc coated with a: Select one: a. silver bromide alloy b. zinc cadmiun sulfide alloy c. tungsten rhenium alloy d. calcium tungstate alloy

c. tungsten rhenium alloy

The area under the curve of an emission spectrum at 100 mA at 70 kVp is 7.8 cm2 and the quantity of the x-rays produced is 252 mR. If the kVp was changed to 92 kVp, the quantity of x-rays produced seen with this new kVpwould be _______? For each fill-in-the-blank question, when doing your calculations, only carry out the number to the second digit beyond the decimal point. Also when giving your answer, answer to the second digit beyond the decimal point. Ex: 2.334323 is the number you have, use 2.33 in the calculations. If this were your answer, you would answer 2.33 unless the question ask for the answer as a whole number. Then you would answer as 2. DO NOT ROUND UP OR DOWN WHEN DOING YOUR CALCULATIONS. Only put in the number, not the measurement.

435.29

Filament saturation occurs when the negative charge of the electron cloud opposes the emission of additional electrons from the filament. Select one: True False

False

The electron ejected during a characteristic interaction is also known as the x-ray photon. Select one: True False

False

The entire cathode and anode assemblies are enclosed within the glass or metal envelope. Select one: True False

False

As the kinetic energy of the incident electron increases, so does the efficiency of the photon production. Select one: True False

True

In the diagnostic range, the kinetic energy of the incident electrons is high enough to eject an outer-shell electron causing ionization. Select one: True False

True

Most x-ray tubes have a dual-focus arrangement. Select one: True False

True

When the target angle is less than 45°, the effective focal spot is smaller than the actual focal spot. Select one: True False

True

If the minimum wavelength of a given x-ray is 10 angstroms (Å), it is also: Select one: a. 1 nm b. 10 nm c. 100 nm d. 1000 nm

a. 1 nm

If 85 kVp, 400 mA, and 1/8 second was used for a particular exposure using single-phase equipment, which of the following milliamperage or time values would be required, all other factors being constant, to produce a similar density using 3-phase, 12-pulse equipment? Select one: a. 200 mA b. 600 mA c. 0.125 second d. 0.25 second

a. 200 mA

A lateral chest x-ray is taken at 110 kVp with 10 mAs and results in an x-ray intensity of 32 mR. What will the intensity of the beam be if the kVp is increased to 125 kVp? Select one: a. 41.3 mR b. 32 mR c. 20.8 mR d. 10.3 mR

a. 41.3 mR

During a characteristic interaction, the dropping of a higher-energy state electron into a lower-energy state hole results in the emission of Select one: a. a photon of energy. b. a high-energy electron. c. a low-energy electron. d. more than one of the above e. all of the above

a. a photon of energy.

As the angle of the anode target decreases, the: Select one: a. effective focal spot decreases b. effective focal spot increases c. actual focal spot increases d. actual focal spot decreases

a. effective focal spot decreases

During bremsstrahlung interactions: Select one: a. electrostatic attractive forces are present b. electrostatic repulsive forces are present c. attractive and repulsive magnetic forces are present d. gravitional forces are present

a. electrostatic attractive forces are present

In bremsstrahlung x-ray production: Select one: a. the projectile electron originates in the cathode b. the target electron originates in the cathode c. the projectile electron is bound to an atom of tungsten d. the target electron exists as a free electron

a. the projectile electron originates in the cathode

As electrons impinge on the target surface, less than 1% of their kinetic energy is changed to Select one: a. x-rays. b. heat. c. gamma rays. d. recoil electrons.

a. x-rays.

Double-focus x-ray tubes have two 1. focal spots. 2. filaments. 3. anodes. Select one: a. 1 only b. 1 and 2 only c. 1 and 3 only d. 2 and 3 only

b. 1 and 2 only

Which of the following can impact the visibility of the anode heel effect? 1. SID 2. Image recorder size 3. Screen speed Select one: a. 1 only b. 1 and 2 only c. 2 and 3 only d. 1, 2, and 3

b. 1 and 2 only

The area under the curve of an emission spectrum at 100 mA at 70 kVp is 4.2 cm2 and the quantity of the x-rays produced is 325 mR. If the mA station is changed to 400 mA, what would be the quantity of x-rays produced seen with this new mA station? Select one: a. 81.25 mR b. 1300 mR c. 1.05 mR d. 16.8 mR

b. 1300 mR

Electron kinetic energy in an x-ray tube is increased by raising: 1. mass 2. acceleration 3. kVp Select one: a. 1 only b. 3 only c. 1 and 2 only d. 1 and 3 only e. 1, 2, and 3

b. 3 only

The intensity of radiation is 3 mR at 30 mAs. If the mAs is increased from 30 to 60, the new intensity is: Select one: a. 1.5 mR b. 6.0 mR c. 9.0 mR d. 12.0 mR

b. 6.0 mR

Which of the following occurs during Bremsstrahlung radiation production? Select one: a. An electron makes a transition from an outer to an inner electron shell b. An electron approaching a positive nuclear charge changes direction and loses energy. c. A high-energy photon ejects and outer-shell electron. d. A low-energy photon ejects an inner-shell electron

b. An electron approaching a positive nuclear charge changes direction and loses energy.

One of the functions of the vacuum created by the glass envelope surrounding the working components of the X-ray tube is to: Select one: a. decrease the risk of electrical shock b. allow free flow of electrons from cathode to anode c. decrease the amount of leakage radiation leaving the tube d. eliminate the buildup of heat units inside the tube

b. allow free flow of electrons from cathode to anode

The component of the X-ray tube that is responsible for providing a source of electrons through thermionic emission is the: Select one: a. anode b. cathode c. focusing cup d. rotor

b. cathode

As the angle of the anode target increases, the: Select one: a. effective focal spot decreases b. effective focal spot increases c. actual focal spot increases d. actual focal spot decreases

b. effective focal spot increases

During a characteristic interaction, the energy of the incident electron must be ____ the electron it knocks from its orbit. Select one: a. less than that of b. greater than that of c. proportional to that of d. characteristic of

b. greater than that of

An increase in mAs will: Select one: a. increase the energy of bremsstrahlung x-rays b. increase the number of bremsstrahlung x-rays c. increase both the efficiency and number of bremsstrahlung x-rays d. does not affect bremsstrahlung production

b. increase the number of bremsstrahlung x-rays

The function of the stator and rotor assembly is to Select one: a. create a vacuum. b. rotate the anode. c. insulate the anode. d. disrupt the electromagnets of the induction motor.

b. rotate the anode.

How would the emission spectrum be affected by the addition of 2 mm Al filtration? The relative position of the spectrum would: Select one: a. shift to the left, and the amplitude would be lower b. shift to the right, and the amplitude would be lower c. remain the same, but the amplitude would increase d. remain the same, but the amplitude would decrease

b. shift to the right, and the amplitude would be lower

The variation in photon distribution between the anode and cathode ends of the x-ray tube is known as Select one: a. the line focus principle. b. the anode heel effect. c. the inverse square law. d. Bohr's theory.

b. the anode heel effect.

Which of the following will occur as a result of a decrease in the anode target angle? 1. Less pronounced anode heel effect 2. Decreased effective focal spot size 3. Greater photon intensity toward the cathode side of the x-ray tube Select one: a. 1 only b. 1 and 2 only c. 2 and 3 only d. 1, 2, and 3

c. 2 and 3 only

The anode is: Select one: a. Always the negative side of the tube b. Always on the right side when facing the tube c. Always on the side connected to the high-voltage circuit d. Not responsible for the anode heel effect

c. Always on the side connected to the high-voltage circuit

Although the stated focal spot size is measured directly under the actual focal spot, focal spot size really varies along the length of the x-ray beam. At which portion of the x-ray beam is the effective focal spot the largest? Select one: a. At its outer edge b. Along the path of the central ray c. At the cathode end d. At the anode end

c. At the cathode end

The material of choice for the construction of the focusing cup is: Select one: a. Lead b. Tungsten c. Nickel d. Aluminum

c. Nickel

When electrons are ejected from the surface of the filament, what holds them in a tight cloud and prevents them from dissipating? Select one: a. The vacuum of the x-ray tube. b. A grid bias tube prevents this from happening c. The focusing cup d. The positive charge of the focusing cup

c. The focusing cup

The collection of all different energies (wavelengths) of x-rays is called the: Select one: a. X-ray rainbow b. X-ray homogeneous beam c. X-ray emission spectrum d. Peak electron energy

c. X-ray emission spectrum

In a tungsten-targeted x-ray tube operated at 75 kVp, the most abundant x-ray would be: Select one: a. a 10 keV bremssthralung x-ray b. a 57 keV characteristic x-ray c. a 25 keV bremssthralung x-ray d. a 69 keV characteristic x-ray

c. a 25 keV bremssthralung x-ray

Double focus x-ray tubes have two: Select one: a. port windows b. anodes c. filaments d. rectifiers

c. filaments

Molybdenum has a lower atomic number than tungsten; therefore the molybdenum emission spectrum will: Select one: a. have a higher amplitude b. extend to higher energies c. have a lower amplitude d. extend to lower energies

c. have a lower amplitude

An increase in kVp will: Select one: a. increase the energy of bremsstrahlung x-rays b. increase the number of bremsstrahlung x-rays c. increase both the efficiency and number of bremsstrahlung x-rays d. does not affect bremsstrahlung production

c. increase both the efficiency and number of bremsstrahlung x-rays

Bremsstrahlung interactions may occur only when the incident electron interacts with Select one: a. an inner-shell electron. b. an outer-shell electron. c. the force field of the nucleus. d. none of the above

c. the force field of the nucleus.

Anode angle will have an effect on the 1. severity of the heel effect. 2. focal spot size. 3. heat load capacity. Select one: a. 1 only b. 2 only c. 1 and 2 only d. 1, 2, and 3

d. 1, 2, and 3

Excessive anode heating can cause vaporized tungsten to be deposited on the port window. This can result in 1. decreased tube output. 2. tube failure. 3. electrical sparking. Select one: a. 1 only b. 2 only c. 1 and 2 only d. 1, 2, and 3

d. 1, 2, and 3

Target angle will have an effect on the: 1. severity of the heel effect 2. focal spot size 3. heat load capacity Select one: a. 1 only b. 2 only c. 1 and 2 only d. 1, 2, and 3

d. 1, 2, and 3

To cover a 14 in. x 17 in. field at 40 inches, a ____-degree target angle is required Select one: a. 3 b. 5 c. 7 d. 12

d. 12

An L-shell electron (binding energy of 26 keV) is removed from an atom that has an M-shell binding energy of 4 keV and an N-shell binding energy of 1 keV. If a free electron fills the vacancy in the L-shell, the characteristic x-rays produced will have an energy of: Select one: a. 4 keV b. 22 keV c. 25 keV d. 26 keV

d. 26 keV

The area under the curve of an emission spectrum at 100 mA at 70 kVp is 4.2 cm2 and the quantity of the x-rays produced is 325 mR. If the kVp was changed to 80 kVp, what would be the quantity of x-rays produced seen with this new kVp? Select one: a. 1.3 mR b. 5.46 mR c. 250 mR d. 424.5 mR

d. 424.5 mR

Gold is sometimes used as target material in special types of radiation-producing machines. Its electron binding energies are as follows: K shell 81 keV; L shell 14 keV; M shell 3 keV; N shell 1 keV. Which of the following characteristic x-rays will be produced with operation of 90 kVp? Select one: a. 90 keV b. 87 keV c. 76 keV d. 67 keV

d. 67 keV

A projectile electron interacts violently with an electron in the K-shell of an atom. When the K-shell electron is subsequently ionized, which of the following responses occur: Select one: a. A low-energy excitation occurs in the nucleus b. Outer-shell electrons are raised to an excited level c. An M-shell electron s displacement makes the shell impenetrable by any other projectile electron. d. An outer-shell electron fills the vacancy in the K shell

d. An outer-shell electron fills the vacancy in the K shell

The cathode boils electrons off the filament s surface through a process called thermionic emission. This process occurs during what stage of x-ray production? Select one: a. At the time of exposure b. Immediately after the exposure c. During the preparation stage after the application of the kVp d. During the preparation stage prior to the application of the kVp.

d. During the preparation stage prior to the application of the kVp.

Less than 1% of electrical energy is converted into photon energy. What happens to the rest of the electrical energy in the x-ray tube? Select one: a. It remains electrical energy to complete the circuit. b. It is converted to x-ray energy c. It is converted to ionic energy d. It is converted to heat energy

d. It is converted to heat energy

Which of the following statements apply to the x-ray emission spectrum? Select one: a. Adding filtration affects minimum wavelength energy b. Adding filtration affects the position of the characteristic x-ray emission spectrum c. The target material affects the minimum wavelength d. The target material affects the amplitude of the bremsstrahlumg emission spectrum

d. The target material affects the amplitude of the bremsstrahlumg emission spectrum

Driving the thermionic cloud from the cathode to the anode requires Select one: a. a large potential difference. b. a small voltage. c. a large amperage. d. a small amperage.

d. a small amperage.

Which of the following would affect the production of a thermionic cloud? Select one: a. filament diameter b. filament length c. filament temperature d. all of the above

d. all of the above

All x-ray tubes must be contained within a protective housing which reduces: Select one: a. high-intensity radiation to less than 100 mR/hr at a distance of 1 meter from the housing b. gamma radiation to less than 100 mR/hr at a distance of 1 meter from the housing c. beta radiation to less than 100 mR/hr at a distance of 1 meter from the housing d. leakage radiation to less than 100 mR/hr at a distance of 1 meter from the housing

d. leakage radiation to less than 100 mR/hr at a distance of 1 meter from the housing

In a x-ray machine, the induction motor is used to: Select one: a. heat the filament of the cathode b. drive the portable machine c. operate the autotransformer d. rotate the rotor of the anode

d. rotate the rotor of the anode