HESI Radiology Exit Exam prep
Version 1 Exam Questions and
Answers Practice Questions with
Solutions Newest | Already Graded
A+
Q1: If a radiographer receives an exposure of 0.05 millisievert (mSv) at
a distance of 1.5 feet from a portable x-ray unit, what will the
exposure be at a distance of 6 feet?
Answer: 0.003 mSv.
Rationale: This is calculated using the inverse square law, which states
that the intensity of radiation is inversely proportional to the square of
the distance from the source. The formula is I1/I2 = (D2)²/(D1)².
Therefore, I2 = I1 * (D1²/D2²) = 0.05 mSv * (1.5²/6²) = 0.05 * (2.25/36)
= 0.0031 mSv .
Q2: What is the annual occupational effective dose limit for a non-
pregnant radiation worker?
Answer: 50 mSv.
Rationale: Regulatory agencies set this limit to ensure that the risk of
stochastic effects (like cancer) remains acceptably low for radiation
workers .
,Q3: Which interaction with matter contributes to the majority of
occupational exposure?
Answer: Compton scattering.
Rationale: Compton scatter occurs when an x-ray photon interacts
with an outer-shell electron, losing energy and changing direction.
These scattered photons are a primary source of exposure for
radiographers and others near the patient during an exam .
Q4: What is the primary purpose of beam filtration?
Answer: To protect the patient from low-energy x-rays.
Rationale: Low-energy x-rays (long wavelengths) are more likely to be
absorbed by the skin and superficial tissues, contributing to patient
dose without reaching the image receptor to form the image.
Filtration removes these from the beam .
Q5: Over the entire gestational period, what is the fetal exposure limit?
Answer: 5 mSv.
Rationale: The fetus is highly radiosensitive, especially during the first
trimester. This low limit is set to minimize the risk of childhood cancer
and congenital abnormalities .
Q6: Which dose may cause temporary sterility of both males and
females?
Answer: 2 Gy.
Rationale: The gonads are highly radiosensitive. A dose of
approximately 2 Gy (200 rads) can cause temporary sterility, while
higher doses can lead to permanent sterility .
Q7: What is the primary controlling factor for x-ray beam quality?
, Answer: Kilovolts peak (kVp).
Rationale: kVp determines the maximum energy and the penetrating
power (quality) of the x-ray beam. A higher kVp produces higher-
energy x-rays that are more penetrating .
Q8: What is the required amount of inherent filtration for general
purpose x-ray tubes?
Answer: 0.5 mm aluminum (Al) equivalent.
Rationale: Inherent filtration comes from the x-ray tube's glass
envelope and oil coolant. Federal standards require a minimum total
filtration of 2.5 mm Al equivalent for tubes operating above 70 kVp .
Q9: Which interaction with matter contributes to the majority of
occupational exposure?
Answer: Compton scattering.
Rationale: When an x-ray scatters, it changes direction and loses
energy. These scattered photons are the main source of exposure for
anyone standing near the patient .
Q10: Which term refers to the removal of an electron from the orbital
shell of an atom?
Answer: Ionization.
Rationale: Ionization is the fundamental event by which radiation
causes damage in biological tissue. It can lead to the formation of free
radicals and damage to DNA .
Q11: Which type of radiation is produced when an outer shell electron
fills an inner shell vacancy?
Answer: Characteristic.
, Rationale: This is a key concept for understanding x-ray production.
When a high-speed electron from the filament dislodges an inner-
shell tungsten atom, an outer-shell electron fills the vacancy, releasing
energy as a characteristic x-ray .
Q12: What is the maximum allowable tabletop intensity in high-level
control (HLC) fluoroscopic procedures?
Answer: 200 mGya/min.
Rationale: High-level control fluoroscopy is used for longer, more
complex procedures. The higher dose rate is permitted to improve
image quality but is regulated to prevent patient injury .
⚙️ Image Production & Equipment
Q13: Which part of the x-ray circuit is controlled by adjusting the
milliamperage (mA) setting?
Answer: Filament circuit.
Rationale: The mA setting controls the current that heats the filament
in the x-ray tube. A hotter filament (higher mA) releases more
electrons via thermionic emission, resulting in a higher tube current
and more x-rays produced (quantity) .
Q14: How is the process of thermionic emission described?
Answer: Electrons are released when the filament is heated.
Rationale: This is the fundamental principle of how an x-ray tube
creates an electron cloud. The heated filament "boils off" electrons,
which are then accelerated toward the anode to produce x-rays .
Version 1 Exam Questions and
Answers Practice Questions with
Solutions Newest | Already Graded
A+
Q1: If a radiographer receives an exposure of 0.05 millisievert (mSv) at
a distance of 1.5 feet from a portable x-ray unit, what will the
exposure be at a distance of 6 feet?
Answer: 0.003 mSv.
Rationale: This is calculated using the inverse square law, which states
that the intensity of radiation is inversely proportional to the square of
the distance from the source. The formula is I1/I2 = (D2)²/(D1)².
Therefore, I2 = I1 * (D1²/D2²) = 0.05 mSv * (1.5²/6²) = 0.05 * (2.25/36)
= 0.0031 mSv .
Q2: What is the annual occupational effective dose limit for a non-
pregnant radiation worker?
Answer: 50 mSv.
Rationale: Regulatory agencies set this limit to ensure that the risk of
stochastic effects (like cancer) remains acceptably low for radiation
workers .
,Q3: Which interaction with matter contributes to the majority of
occupational exposure?
Answer: Compton scattering.
Rationale: Compton scatter occurs when an x-ray photon interacts
with an outer-shell electron, losing energy and changing direction.
These scattered photons are a primary source of exposure for
radiographers and others near the patient during an exam .
Q4: What is the primary purpose of beam filtration?
Answer: To protect the patient from low-energy x-rays.
Rationale: Low-energy x-rays (long wavelengths) are more likely to be
absorbed by the skin and superficial tissues, contributing to patient
dose without reaching the image receptor to form the image.
Filtration removes these from the beam .
Q5: Over the entire gestational period, what is the fetal exposure limit?
Answer: 5 mSv.
Rationale: The fetus is highly radiosensitive, especially during the first
trimester. This low limit is set to minimize the risk of childhood cancer
and congenital abnormalities .
Q6: Which dose may cause temporary sterility of both males and
females?
Answer: 2 Gy.
Rationale: The gonads are highly radiosensitive. A dose of
approximately 2 Gy (200 rads) can cause temporary sterility, while
higher doses can lead to permanent sterility .
Q7: What is the primary controlling factor for x-ray beam quality?
, Answer: Kilovolts peak (kVp).
Rationale: kVp determines the maximum energy and the penetrating
power (quality) of the x-ray beam. A higher kVp produces higher-
energy x-rays that are more penetrating .
Q8: What is the required amount of inherent filtration for general
purpose x-ray tubes?
Answer: 0.5 mm aluminum (Al) equivalent.
Rationale: Inherent filtration comes from the x-ray tube's glass
envelope and oil coolant. Federal standards require a minimum total
filtration of 2.5 mm Al equivalent for tubes operating above 70 kVp .
Q9: Which interaction with matter contributes to the majority of
occupational exposure?
Answer: Compton scattering.
Rationale: When an x-ray scatters, it changes direction and loses
energy. These scattered photons are the main source of exposure for
anyone standing near the patient .
Q10: Which term refers to the removal of an electron from the orbital
shell of an atom?
Answer: Ionization.
Rationale: Ionization is the fundamental event by which radiation
causes damage in biological tissue. It can lead to the formation of free
radicals and damage to DNA .
Q11: Which type of radiation is produced when an outer shell electron
fills an inner shell vacancy?
Answer: Characteristic.
, Rationale: This is a key concept for understanding x-ray production.
When a high-speed electron from the filament dislodges an inner-
shell tungsten atom, an outer-shell electron fills the vacancy, releasing
energy as a characteristic x-ray .
Q12: What is the maximum allowable tabletop intensity in high-level
control (HLC) fluoroscopic procedures?
Answer: 200 mGya/min.
Rationale: High-level control fluoroscopy is used for longer, more
complex procedures. The higher dose rate is permitted to improve
image quality but is regulated to prevent patient injury .
⚙️ Image Production & Equipment
Q13: Which part of the x-ray circuit is controlled by adjusting the
milliamperage (mA) setting?
Answer: Filament circuit.
Rationale: The mA setting controls the current that heats the filament
in the x-ray tube. A hotter filament (higher mA) releases more
electrons via thermionic emission, resulting in a higher tube current
and more x-rays produced (quantity) .
Q14: How is the process of thermionic emission described?
Answer: Electrons are released when the filament is heated.
Rationale: This is the fundamental principle of how an x-ray tube
creates an electron cloud. The heated filament "boils off" electrons,
which are then accelerated toward the anode to produce x-rays .
