Dosimetry / Radiation Therapy Terms
Exam Actual Questions and Answers
2026
DRR - Digital Reconstructed Radiograph -
correct answer ✅Based on acquired CT information, these are
images that render a beam's eye view display of the treatment field
anatomy and ares of treatment interest (W/L pg #993)
Attenuation -
correct answer ✅Removal of photons and electronsfrom a
radiation beam by scatter or absorption as it travels through a
medium, typically tissue or tissue equivalent materials (W/L #940)
Beam Hardening -
correct answer ✅The process of increasing the average energy
level of an x-ray beam by filtering out the low-energy photons.
(Mosby's Medical Dictionary, 8th edition. © 2009, Elsevier.)
CT window and leveling -
correct answer ✅Demonstrates various structures based on their
ability to attenuate and prevent transmission of the incident X-ray
beam, determines the center CT number value displayed by the
gray scale range.
, Dosimetry / Radiation Therapy Terms
Exam Actual Questions and Answers
2026
Dmax -
correct answer ✅Depth at which electronic equilibrium occurs for
photon beams; the point where dose reaches its maximum value
Tomotherapy -
correct answer ✅Radiation therapy in which the radiation is
delivered slice-by-slice
Effective Field -
correct answer ✅Open or treated area within the collimator field
dimensions when blocks are used to customize the shape of the
treatment area
Equivalent Square -
correct answer ✅Rectangular field size that demonstrate the same
measurable scattering and attenuation characteristics of a square
field size
Given Dose -
correct answer ✅Delivered dose measured at a specific point in a
medium and refers to the energy deposited at that point (Dmax)
Exam Actual Questions and Answers
2026
DRR - Digital Reconstructed Radiograph -
correct answer ✅Based on acquired CT information, these are
images that render a beam's eye view display of the treatment field
anatomy and ares of treatment interest (W/L pg #993)
Attenuation -
correct answer ✅Removal of photons and electronsfrom a
radiation beam by scatter or absorption as it travels through a
medium, typically tissue or tissue equivalent materials (W/L #940)
Beam Hardening -
correct answer ✅The process of increasing the average energy
level of an x-ray beam by filtering out the low-energy photons.
(Mosby's Medical Dictionary, 8th edition. © 2009, Elsevier.)
CT window and leveling -
correct answer ✅Demonstrates various structures based on their
ability to attenuate and prevent transmission of the incident X-ray
beam, determines the center CT number value displayed by the
gray scale range.
, Dosimetry / Radiation Therapy Terms
Exam Actual Questions and Answers
2026
Dmax -
correct answer ✅Depth at which electronic equilibrium occurs for
photon beams; the point where dose reaches its maximum value
Tomotherapy -
correct answer ✅Radiation therapy in which the radiation is
delivered slice-by-slice
Effective Field -
correct answer ✅Open or treated area within the collimator field
dimensions when blocks are used to customize the shape of the
treatment area
Equivalent Square -
correct answer ✅Rectangular field size that demonstrate the same
measurable scattering and attenuation characteristics of a square
field size
Given Dose -
correct answer ✅Delivered dose measured at a specific point in a
medium and refers to the energy deposited at that point (Dmax)
