Field gaps or abutting junctions are often shifted (feathered) a few times during the
course or treatment in order to:
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reduce the risk of overdosing critical structures
When treating adjacent, multiple fields on a patient:
A. Patient position should remain the same for all fields
.B. Field borders should abut on the patient's skin.
C. Fields should be treated on alternate days.
D. Patients should be positioned supine.
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, A. Patient position should remain the same for all fields
In order to make custom Cerrobend blocks, the following information is needed:
1. target-to-film distance
2. beam energy
3. patient thickness
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1. target-to-film distance
2. beam energy
Rotational arc therapy is elected for treatment to the pituitary gland. The arc is 240
degrees and the calculated monitor units are 196 MU. The MU/degree setting will be:
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0.817
MU/degree: 196/240
While treating lateral fields in the treatment of the craniospinal axis, to avoid having
the caudal margin of the lateral fields diverge into the posterior spine field, the couch
should be rotated:
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, toward the collimator
A dose of 55 Gy will be given through anterior and lateral ports to the maxillary sinus.
The lens is included in the treatment fields. The therapeutic ratio is approximately:
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0.18
*therapeutic ratio formula: 1000/5500 = 0.18.
The best position for treating the vertex field is:
A. chin extended as much as possible
B. chin flexed
C. chin turned to one side
D. chin extension at 12 cm
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B. chin flexed
Tissue inhomogeneites that may alter dose distribution would include:
1. air cavities
2. lung
3. fat
4. bone
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, 1, 2, 3, 4
An entire spine is treated by matching two fields both treated at 100 cm SSD. Field
number 1 measures 8 x 20 and field number 2 measures 8 x 25. In order to match
these fields at a depth of 5 cm, a_______cm skin gap would be required.
A. 1.1 cm
B. 2.0 cm
C. 5.0 cm
D. 3.2 cm
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A. 1.1 cm
. *L/2(d/SSD) + L/2 (d/SSD) = skin gap20/2 (5/100) + 25/2 (5/100) = 1.1 cm.
In preparation for Fletcher's suite brachytherapy, an orthogonal set of films was
acquired on the conventional simulator. The hinge angle for the set of films was:
A. 45 degrees
B. 90 degrees
C. 180 degrees
D. not enough information given
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B. 90 degrees
The physical size of the treatment field is defined at the interception of the central
axis at the specific isocentric distance and which isodose line?
A. 10%
course or treatment in order to:
Give this one a try later!
reduce the risk of overdosing critical structures
When treating adjacent, multiple fields on a patient:
A. Patient position should remain the same for all fields
.B. Field borders should abut on the patient's skin.
C. Fields should be treated on alternate days.
D. Patients should be positioned supine.
Give this one a try later!
, A. Patient position should remain the same for all fields
In order to make custom Cerrobend blocks, the following information is needed:
1. target-to-film distance
2. beam energy
3. patient thickness
Give this one a try later!
1. target-to-film distance
2. beam energy
Rotational arc therapy is elected for treatment to the pituitary gland. The arc is 240
degrees and the calculated monitor units are 196 MU. The MU/degree setting will be:
Give this one a try later!
0.817
MU/degree: 196/240
While treating lateral fields in the treatment of the craniospinal axis, to avoid having
the caudal margin of the lateral fields diverge into the posterior spine field, the couch
should be rotated:
Give this one a try later!
, toward the collimator
A dose of 55 Gy will be given through anterior and lateral ports to the maxillary sinus.
The lens is included in the treatment fields. The therapeutic ratio is approximately:
Give this one a try later!
0.18
*therapeutic ratio formula: 1000/5500 = 0.18.
The best position for treating the vertex field is:
A. chin extended as much as possible
B. chin flexed
C. chin turned to one side
D. chin extension at 12 cm
Give this one a try later!
B. chin flexed
Tissue inhomogeneites that may alter dose distribution would include:
1. air cavities
2. lung
3. fat
4. bone
Give this one a try later!
, 1, 2, 3, 4
An entire spine is treated by matching two fields both treated at 100 cm SSD. Field
number 1 measures 8 x 20 and field number 2 measures 8 x 25. In order to match
these fields at a depth of 5 cm, a_______cm skin gap would be required.
A. 1.1 cm
B. 2.0 cm
C. 5.0 cm
D. 3.2 cm
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A. 1.1 cm
. *L/2(d/SSD) + L/2 (d/SSD) = skin gap20/2 (5/100) + 25/2 (5/100) = 1.1 cm.
In preparation for Fletcher's suite brachytherapy, an orthogonal set of films was
acquired on the conventional simulator. The hinge angle for the set of films was:
A. 45 degrees
B. 90 degrees
C. 180 degrees
D. not enough information given
Give this one a try later!
B. 90 degrees
The physical size of the treatment field is defined at the interception of the central
axis at the specific isocentric distance and which isodose line?
A. 10%
