TEXAS INDUSTRIAL RADIOGRAPHER
CERTIFICATION PRACTICE EXAM
Section 1: Fundamentals of Radiation (Questions 1-15)
1. A radiographer is using Iridium-192. What is the primary type of radiation emitted during its decay?
A) Alpha particles
B) Beta particles only
C) Gamma rays
D) Neutrons
Correct Answer: C) Gamma rays
*Rationale: Iridium-192 decays by beta emission followed by gamma emission. For industrial
radiography, the penetrating gamma rays are used for imaging. Beta particles are absorbed by the
source capsule wall.*
2. The half-life of Iridium-192 is approximately 74 days. If a source has an activity of 100 Ci today,
what will the approximate activity be in 148 days?
A) 50 Ci
B) 33 Ci
C) 25 Ci
D) 0 Ci
Correct Answer: C) 25 Ci
*Rationale: Half-life is the time for activity to reduce by half. 148 days equals two half-lives (74 + 74).
100 Ci -> 50 Ci (1st half-life) -> 25 Ci (2nd half-life).*
3. Which of the following describes the "Inverse Square Law"?
A) Intensity is directly proportional to the square of the distance.
B) Intensity is inversely proportional to the square of the distance.
C) Intensity doubles as the distance doubles.
D) Intensity is unaffected by distance.
Correct Answer: B) Intensity is inversely proportional to the square of the distance.
*Rationale: The Inverse Square Law states that if you double the distance from the source, the exposure
rate decreases to one-quarter of the original value (I1/I2 = D2^2/D1^2).*
,4. What is the primary function of a "collimator" on a radiographic exposure device?
A) To increase the energy of the source.
B) To restrict the size of the radiation beam.
C) To secure the source in the shielded position.
D) To measure the exposure time.
Correct Answer: B) To restrict the size of the radiation beam.
Rationale: Collimators are adjustable apertures placed on the source tube or head to limit the area of
radiation exposure, reducing scatter radiation and improving image quality while minimizing the hazard
area.
5. What does the "Specific Gamma-Ray Constant" (Gamma Factor) allow a radiographer to calculate?
A) The energy level of the source in MeV.
B) The exposure rate at a specific distance from a known quantity of radioactive material.
C) The remaining half-life of the source.
D) The thickness of lead required for shielding.
Correct Answer: B) The exposure rate at a specific distance from a known quantity of
radioactive material.
*Rationale: The Gamma Factor (e.g., 0.48 R/hr per Ci at 1 meter for Ir-192) is used to calculate exposure
rates for shielding and boundary calculations.*
6. According to Texas regulations, what is the Annual Occupational Dose Limit for the lens of the eye?
A) 5 rem (0.05 Sv)
B) 15 rem (0.15 Sv)
C) 50 rem (0.5 Sv)
D) 500 rem (5 Sv)
Correct Answer: B) 15 rem (0.15 Sv)
*Rationale: Texas DSHS adopts the NRC limits: Total Effective Dose Equivalent (TEDE) 5 rem, Lens of the
eye 15 rem, Skin/extremities 50 rem.*
7. Which of the following materials is most effective for shielding Gamma radiation from Cobalt-60?
A) Plastic
B) Aluminum
C) Lead
D) Depleted Uranium (or high-density lead)
Correct Answer: D) Depleted Uranium (or high-density lead)
*Rationale: While lead is common, Cobalt-60 has high-energy gamma rays (~1.17 and 1.33 MeV). Dense
materials like lead, tungsten, or depleted uranium are required. Depleted uranium is often used in S-
, tubes due to its high density and self-sharpening properties, though lead is acceptable for transport
containers.*
8. What is the purpose of a "pocket dosimeter" (pen dosimeter)?
A) To record the dose for permanent legal records.
B) To provide an immediate, real-time reading of accumulated exposure.
C) To prevent exposure by alarming when radiation is present.
D) To measure the energy of the gamma rays.
Correct Answer: B) To provide an immediate, real-time reading of accumulated exposure.
Rationale: Pocket dosimeters (direct-read) allow the radiographer to check their current exposure at any
time. They must be supplemented with an official dosimeter (TLD/OSL) for legal record keeping.
9. A source is stuck in the "exposed" position. What is the FIRST thing the radiographer should do?
A) Crank harder to retract the source.
B) Evacuate the restricted area and secure it.
C) Call the RSO immediately.
D) Approach the projector to manually crank.
Correct Answer: B) Evacuate the restricted area and secure it.
Rationale: Life safety is paramount. The first step is to ensure no one is being exposed by securing the
boundaries. After ensuring safety, attempt retrieval per emergency procedures or call the RSO.
10. What is the definition of a "Restricted Area"?
A) An area where radiation levels are less than 2 mrem/hr.
B) An area where radiation levels are greater than 5 mrem/hr.
C) An area where access is controlled to protect individuals from exposure to radiation.
D) The area inside the transport vehicle.
Correct Answer: C) An area where access is controlled to protect individuals from exposure to
radiation.
*Rationale: By definition, a restricted area is one where access is controlled to limit exposure to
radiation. The "Caution: Radiation Area" is typically defined as >5 mrem/hr at 30 cm, but the definition
of Restricted Area is broader (access control).*
11. Which of the following sources emits the highest energy gamma photons?
A) Iridium-192
B) Selenium-75
C) Ytterbium-169
D) Cobalt-60
CERTIFICATION PRACTICE EXAM
Section 1: Fundamentals of Radiation (Questions 1-15)
1. A radiographer is using Iridium-192. What is the primary type of radiation emitted during its decay?
A) Alpha particles
B) Beta particles only
C) Gamma rays
D) Neutrons
Correct Answer: C) Gamma rays
*Rationale: Iridium-192 decays by beta emission followed by gamma emission. For industrial
radiography, the penetrating gamma rays are used for imaging. Beta particles are absorbed by the
source capsule wall.*
2. The half-life of Iridium-192 is approximately 74 days. If a source has an activity of 100 Ci today,
what will the approximate activity be in 148 days?
A) 50 Ci
B) 33 Ci
C) 25 Ci
D) 0 Ci
Correct Answer: C) 25 Ci
*Rationale: Half-life is the time for activity to reduce by half. 148 days equals two half-lives (74 + 74).
100 Ci -> 50 Ci (1st half-life) -> 25 Ci (2nd half-life).*
3. Which of the following describes the "Inverse Square Law"?
A) Intensity is directly proportional to the square of the distance.
B) Intensity is inversely proportional to the square of the distance.
C) Intensity doubles as the distance doubles.
D) Intensity is unaffected by distance.
Correct Answer: B) Intensity is inversely proportional to the square of the distance.
*Rationale: The Inverse Square Law states that if you double the distance from the source, the exposure
rate decreases to one-quarter of the original value (I1/I2 = D2^2/D1^2).*
,4. What is the primary function of a "collimator" on a radiographic exposure device?
A) To increase the energy of the source.
B) To restrict the size of the radiation beam.
C) To secure the source in the shielded position.
D) To measure the exposure time.
Correct Answer: B) To restrict the size of the radiation beam.
Rationale: Collimators are adjustable apertures placed on the source tube or head to limit the area of
radiation exposure, reducing scatter radiation and improving image quality while minimizing the hazard
area.
5. What does the "Specific Gamma-Ray Constant" (Gamma Factor) allow a radiographer to calculate?
A) The energy level of the source in MeV.
B) The exposure rate at a specific distance from a known quantity of radioactive material.
C) The remaining half-life of the source.
D) The thickness of lead required for shielding.
Correct Answer: B) The exposure rate at a specific distance from a known quantity of
radioactive material.
*Rationale: The Gamma Factor (e.g., 0.48 R/hr per Ci at 1 meter for Ir-192) is used to calculate exposure
rates for shielding and boundary calculations.*
6. According to Texas regulations, what is the Annual Occupational Dose Limit for the lens of the eye?
A) 5 rem (0.05 Sv)
B) 15 rem (0.15 Sv)
C) 50 rem (0.5 Sv)
D) 500 rem (5 Sv)
Correct Answer: B) 15 rem (0.15 Sv)
*Rationale: Texas DSHS adopts the NRC limits: Total Effective Dose Equivalent (TEDE) 5 rem, Lens of the
eye 15 rem, Skin/extremities 50 rem.*
7. Which of the following materials is most effective for shielding Gamma radiation from Cobalt-60?
A) Plastic
B) Aluminum
C) Lead
D) Depleted Uranium (or high-density lead)
Correct Answer: D) Depleted Uranium (or high-density lead)
*Rationale: While lead is common, Cobalt-60 has high-energy gamma rays (~1.17 and 1.33 MeV). Dense
materials like lead, tungsten, or depleted uranium are required. Depleted uranium is often used in S-
, tubes due to its high density and self-sharpening properties, though lead is acceptable for transport
containers.*
8. What is the purpose of a "pocket dosimeter" (pen dosimeter)?
A) To record the dose for permanent legal records.
B) To provide an immediate, real-time reading of accumulated exposure.
C) To prevent exposure by alarming when radiation is present.
D) To measure the energy of the gamma rays.
Correct Answer: B) To provide an immediate, real-time reading of accumulated exposure.
Rationale: Pocket dosimeters (direct-read) allow the radiographer to check their current exposure at any
time. They must be supplemented with an official dosimeter (TLD/OSL) for legal record keeping.
9. A source is stuck in the "exposed" position. What is the FIRST thing the radiographer should do?
A) Crank harder to retract the source.
B) Evacuate the restricted area and secure it.
C) Call the RSO immediately.
D) Approach the projector to manually crank.
Correct Answer: B) Evacuate the restricted area and secure it.
Rationale: Life safety is paramount. The first step is to ensure no one is being exposed by securing the
boundaries. After ensuring safety, attempt retrieval per emergency procedures or call the RSO.
10. What is the definition of a "Restricted Area"?
A) An area where radiation levels are less than 2 mrem/hr.
B) An area where radiation levels are greater than 5 mrem/hr.
C) An area where access is controlled to protect individuals from exposure to radiation.
D) The area inside the transport vehicle.
Correct Answer: C) An area where access is controlled to protect individuals from exposure to
radiation.
*Rationale: By definition, a restricted area is one where access is controlled to limit exposure to
radiation. The "Caution: Radiation Area" is typically defined as >5 mrem/hr at 30 cm, but the definition
of Restricted Area is broader (access control).*
11. Which of the following sources emits the highest energy gamma photons?
A) Iridium-192
B) Selenium-75
C) Ytterbium-169
D) Cobalt-60
