Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
Mayneord factor compensates for a change in central axis depth
dose and includes corrections for: -
correct answer ✅inverse square law
The Dmax for a 10MV photon beam at an 100cm SSD with a 15 x 15
cm field is approximately: -
correct answer ✅2.5cm
The point of maximum electron equilibrium is referred to as: -
correct answer ✅Dmax
In a fixed SSD technique, the dose is routinely normalized: -
correct answer ✅at Dmax
Which of the following curves represents the beam possessing the
lowest energy? -
correct answer ✅Curve 1
Which of the following curves represents the beam possessing the
highest energy? -
correct answer ✅Curve 3
,Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
Calculate the equivalent square for a 10 x 15 cm rectangular field: -
correct answer ✅12cm x 12cm
Determine the equivalent square for a rectangular field with a
width of 8cm and a length of 15cm -
correct answer ✅10.4cm2
The figures below represent different quality beams at a 10.0 x 10.0
cm field size which curve possesses the lowest energy? -
correct answer ✅Curve 2
Calculate the equivalent square of a 12 x 12cm field with a 2 x 6cm
block. -
correct answer ✅11.5
A patient's treatment requires 150 MU. A tray is added with a factor
of 0.972. How many MU must the therapist now give? -
correct answer ✅154 MU
A patient received 2084cGy given dose from the anterior port of a
parallel opposed evenly weighted pair of fields. 3000cGy total
,Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
tumor dose was given. What %DD was used? -
correct answer ✅72
172 MU are required to deliver 150cGy. 200 MU were accidentally
given. How many cGy did the patient receive? -
correct answer ✅174
A rotation treatment must deliver 277 MU in a full rotation. What is
the MU/degree? -
correct answer ✅0.77
As electron energy increases, surface dose: -
correct answer ✅increases
A wedge angle is: -
correct answer ✅the angle between the 50% isodose curve and a
line perpendicular to the central axis
Which of the following is the most accurate method of taking a
patient contour? -
correct answer ✅CT scan
, Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
Depth dose increases as the: -
correct answer ✅source to skin distance increases
source to skin distance increases -
correct answer ✅110
Irregular fields dose calculations can be done using the _________
method.
1. SSD
2. Clarkson
3. TMR -
correct answer ✅2 only
The field size when using an SSD technique and a photon beam is
usually defined: -
correct answer ✅on the skin surface
If the field size indicator is set for 20 x 20 cm at 80 cm SSD, what is
the field size at 84cm? -
correct answer ✅21 X 21
Questions and Answers 2026
Mayneord factor compensates for a change in central axis depth
dose and includes corrections for: -
correct answer ✅inverse square law
The Dmax for a 10MV photon beam at an 100cm SSD with a 15 x 15
cm field is approximately: -
correct answer ✅2.5cm
The point of maximum electron equilibrium is referred to as: -
correct answer ✅Dmax
In a fixed SSD technique, the dose is routinely normalized: -
correct answer ✅at Dmax
Which of the following curves represents the beam possessing the
lowest energy? -
correct answer ✅Curve 1
Which of the following curves represents the beam possessing the
highest energy? -
correct answer ✅Curve 3
,Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
Calculate the equivalent square for a 10 x 15 cm rectangular field: -
correct answer ✅12cm x 12cm
Determine the equivalent square for a rectangular field with a
width of 8cm and a length of 15cm -
correct answer ✅10.4cm2
The figures below represent different quality beams at a 10.0 x 10.0
cm field size which curve possesses the lowest energy? -
correct answer ✅Curve 2
Calculate the equivalent square of a 12 x 12cm field with a 2 x 6cm
block. -
correct answer ✅11.5
A patient's treatment requires 150 MU. A tray is added with a factor
of 0.972. How many MU must the therapist now give? -
correct answer ✅154 MU
A patient received 2084cGy given dose from the anterior port of a
parallel opposed evenly weighted pair of fields. 3000cGy total
,Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
tumor dose was given. What %DD was used? -
correct answer ✅72
172 MU are required to deliver 150cGy. 200 MU were accidentally
given. How many cGy did the patient receive? -
correct answer ✅174
A rotation treatment must deliver 277 MU in a full rotation. What is
the MU/degree? -
correct answer ✅0.77
As electron energy increases, surface dose: -
correct answer ✅increases
A wedge angle is: -
correct answer ✅the angle between the 50% isodose curve and a
line perpendicular to the central axis
Which of the following is the most accurate method of taking a
patient contour? -
correct answer ✅CT scan
, Unit IV: Dosimetry Exam Actual
Questions and Answers 2026
Depth dose increases as the: -
correct answer ✅source to skin distance increases
source to skin distance increases -
correct answer ✅110
Irregular fields dose calculations can be done using the _________
method.
1. SSD
2. Clarkson
3. TMR -
correct answer ✅2 only
The field size when using an SSD technique and a photon beam is
usually defined: -
correct answer ✅on the skin surface
If the field size indicator is set for 20 x 20 cm at 80 cm SSD, what is
the field size at 84cm? -
correct answer ✅21 X 21
