X-RAY TECHNICIAN CERTIFICATION
EXAMINATION
100 PRACTICE QUESTIONS WITH ANSWERS AND
RATIONALES
2026–2027 TESTING CYCLE
SECTION 1: RADIATION PHYSICS AND EQUIPMENT (Questions 1–20)
Question 1: X-rays were discovered by:
Answer: Wilhelm Roentgen in 1895 in Germany.
Rationale: Wilhelm Conrad Roentgen discovered X-rays on November 8, 1895, while
experimenting with cathode rays. He observed that a fluorescent screen glowed even when
shielded from the cathode rays and called the mysterious new rays "X-rays," with "X"
representing the unknown. This discovery revolutionized medicine and earned Roentgen the first
Nobel Prize in Physics in 1901.
Question 2: What type of radiation is primarily produced when high-speed electrons are
decelerated by the tungsten target in an X-ray tube?
Answer: Bremsstrahlung radiation.
,Rationale: Bremsstrahlung ("braking") radiation is produced when high-speed electrons from
the cathode are decelerated or "braked" by the strong electric fields of the tungsten target nuclei.
This interaction produces a broad spectrum of X-ray energies. Characteristic radiation is also
produced but represents a smaller portion of the X-ray beam.
Question 3: The source of X-rays is the:
Answer: X-ray tube.
Rationale: The X-ray tube is the source of X-rays. It consists of a cathode (negative electrode)
that emits electrons and an anode (positive electrode) that serves as the target where X-rays are
produced. The electrons are accelerated from the cathode to the anode by a high voltage, and
upon impact, X-rays are generated.
Question 4: The primary function of a step-up transformer in an X-ray circuit is to:
Answer: Increase voltage for X-ray production.
Rationale: The step-up transformer is used in the X-ray circuit to increase the incoming line
voltage to the high kilovoltage (kVp) levels needed for X-ray production. Typical kVp ranges
from 40 to 150 kV. The step-down transformer, in contrast, reduces voltage to heat the filament
in the cathode.
,Question 5: Which subatomic particle determines the atomic number of an element?
Answer: Proton.
Rationale: The atomic number (Z) is determined by the number of protons in the nucleus of an
atom. Each element has a unique number of protons. Neutrons contribute to the atomic mass but
do not change the atomic number. Electrons orbit the nucleus in shells and determine chemical
properties but do not define the atomic number.
Question 6: What is the primary mode of heat transfer in a rotating anode X-ray tube?
Answer: Radiation.
Rationale: The primary mode of heat transfer in a rotating anode X-ray tube is radiation. The
anode, which can reach temperatures exceeding 2,000°C, dissipates heat primarily through
radiation to the surrounding oil and tube housing. Conduction and convection also occur but are
secondary mechanisms.
Question 7: The device that restricts the size of the X-ray beam to the area of interest is the:
Answer: Collimator.
Rationale: Collimators are devices used to restrict the size and shape of the X-ray beam to the
area of clinical interest. This reduces patient dose by limiting the volume of tissue irradiated and
also reduces the amount of scatter radiation produced, which improves image quality.
, Question 8: The central ray (CR) of an X-ray beam is defined as:
Answer: The imaginary middle ray of the beam as it comes from the tube.
Rationale: The central ray is the imaginary line that passes through the center of the X-ray beam
and is perpendicular to the long axis of the X-ray tube. It is the reference point for centering the
X-ray beam to the image receptor and the anatomical area of interest.
Question 9: The device in the X-ray tube that provides a stop in a specific location is called a:
Answer: Detent.
Rationale: A detent is a mechanical mechanism on the X-ray tube that provides a positive stop,
allowing the operator to lock the tube in a specific position. This ensures consistent and
reproducible positioning for radiographic examinations.
Question 10: Which component is a movable grid under the tabletop that may or may not be
present in the wall receptor?
Answer: Bucky.
Rationale: The Bucky (or Bucky diaphragm) is a moving grid assembly located under the
tabletop. Its purpose is to reduce scatter radiation reaching the image receptor by moving
EXAMINATION
100 PRACTICE QUESTIONS WITH ANSWERS AND
RATIONALES
2026–2027 TESTING CYCLE
SECTION 1: RADIATION PHYSICS AND EQUIPMENT (Questions 1–20)
Question 1: X-rays were discovered by:
Answer: Wilhelm Roentgen in 1895 in Germany.
Rationale: Wilhelm Conrad Roentgen discovered X-rays on November 8, 1895, while
experimenting with cathode rays. He observed that a fluorescent screen glowed even when
shielded from the cathode rays and called the mysterious new rays "X-rays," with "X"
representing the unknown. This discovery revolutionized medicine and earned Roentgen the first
Nobel Prize in Physics in 1901.
Question 2: What type of radiation is primarily produced when high-speed electrons are
decelerated by the tungsten target in an X-ray tube?
Answer: Bremsstrahlung radiation.
,Rationale: Bremsstrahlung ("braking") radiation is produced when high-speed electrons from
the cathode are decelerated or "braked" by the strong electric fields of the tungsten target nuclei.
This interaction produces a broad spectrum of X-ray energies. Characteristic radiation is also
produced but represents a smaller portion of the X-ray beam.
Question 3: The source of X-rays is the:
Answer: X-ray tube.
Rationale: The X-ray tube is the source of X-rays. It consists of a cathode (negative electrode)
that emits electrons and an anode (positive electrode) that serves as the target where X-rays are
produced. The electrons are accelerated from the cathode to the anode by a high voltage, and
upon impact, X-rays are generated.
Question 4: The primary function of a step-up transformer in an X-ray circuit is to:
Answer: Increase voltage for X-ray production.
Rationale: The step-up transformer is used in the X-ray circuit to increase the incoming line
voltage to the high kilovoltage (kVp) levels needed for X-ray production. Typical kVp ranges
from 40 to 150 kV. The step-down transformer, in contrast, reduces voltage to heat the filament
in the cathode.
,Question 5: Which subatomic particle determines the atomic number of an element?
Answer: Proton.
Rationale: The atomic number (Z) is determined by the number of protons in the nucleus of an
atom. Each element has a unique number of protons. Neutrons contribute to the atomic mass but
do not change the atomic number. Electrons orbit the nucleus in shells and determine chemical
properties but do not define the atomic number.
Question 6: What is the primary mode of heat transfer in a rotating anode X-ray tube?
Answer: Radiation.
Rationale: The primary mode of heat transfer in a rotating anode X-ray tube is radiation. The
anode, which can reach temperatures exceeding 2,000°C, dissipates heat primarily through
radiation to the surrounding oil and tube housing. Conduction and convection also occur but are
secondary mechanisms.
Question 7: The device that restricts the size of the X-ray beam to the area of interest is the:
Answer: Collimator.
Rationale: Collimators are devices used to restrict the size and shape of the X-ray beam to the
area of clinical interest. This reduces patient dose by limiting the volume of tissue irradiated and
also reduces the amount of scatter radiation produced, which improves image quality.
, Question 8: The central ray (CR) of an X-ray beam is defined as:
Answer: The imaginary middle ray of the beam as it comes from the tube.
Rationale: The central ray is the imaginary line that passes through the center of the X-ray beam
and is perpendicular to the long axis of the X-ray tube. It is the reference point for centering the
X-ray beam to the image receptor and the anatomical area of interest.
Question 9: The device in the X-ray tube that provides a stop in a specific location is called a:
Answer: Detent.
Rationale: A detent is a mechanical mechanism on the X-ray tube that provides a positive stop,
allowing the operator to lock the tube in a specific position. This ensures consistent and
reproducible positioning for radiographic examinations.
Question 10: Which component is a movable grid under the tabletop that may or may not be
present in the wall receptor?
Answer: Bucky.
Rationale: The Bucky (or Bucky diaphragm) is a moving grid assembly located under the
tabletop. Its purpose is to reduce scatter radiation reaching the image receptor by moving
