Sun Nuclear MapCHECK 3 - Acquire Measurement; Preparation and Setup; Measurement Execution

10 Section 2. Operation
3 Adjust couch height until SDD (source-to-detector distance) is equal to SAD (source-to-axis-
distance). This can be done by aligning the detector plane indicator on the side of the
MapCHECK 3 to the coronal laser. See Detector Plane Marking on page 19.
4 Ad
d enough buildup to the device’s inherent buildup to create total buildup equal to the
planned dose depth. The MapCHECK 3 is capable of physically supporting up to 30 g/cm
2
of
buildup. Do not exceed this amount.
Measurement with MapPHAN Accessory
The MapPHAN accessory envelops MapCHECK 3 with 5 cm or 10 cm of water-equivalent buildup
and allows MapCHECK 3 to be used for planar QA of a rotationally delivered plan.
If the plan to be delivered has a large proportion of dose delivered with gantry at 90 or 270
degrees, stand the MapCHECK 3/MapPHAN assembly on its side such that the MapCHECK 3 array
is perpendicular to the gantry at 90 or 270 degrees.
Perform the following steps to insert MapCHECK 3 in MapPHAN
and align the assembly to
isocenter.
1 Insert
MapCHECK 3 into MapPHAN.
a. Place MapPHAN on level surface then loosen four thumbscrews.
b. Lift top plate slightly then insert MapC
HECK 3 all the way into MapPHAN cavity.
c. Gently tighten thumbscrews.
2 Place MapCHECK 3/Map
PHAN assembly on couch and set up detector plane (indicated by
coronal lines on sides of MapPHAN accessory) to isocenter plane.
3 Se
t up detector plane (indicated by the coronal lines on the sides of the MapPHAN accessory)
to isocenter plane.
4 A
lign marks on anterior surface of MapPHAN to lasers or field cross-hair to place MapCHECK
3 central detector at isocenter.
Acquire Measurement
1 Close all non-essential applications on the computer.
2 In SNC Patient toolbar:
• Click L
oad Array Calibration , select the array calibration that corresponds to the
measurement type (Standard array calibration for deliveries where beam incidence is
normal to the surface of the array, or VMAT array calibration for rotational deliveries in
MapPHAN), and then click Open.
• Click the down arrow next to Dose and select the absolute dose calibration that
corresponds to the planned energy.
3 Place
MapCHECK 3 in measurement position as described in Position MapCHECK 3 for
Measurement on page 9.
4 If
the measurement will be stored in File Manager (see Set Up File Manager on page 9), select
the appropriate Patient Plan from
the SNC Patient toolbar.
5 If t
he Background toolbar displays “No”, select Setup > Collect Background, select a
background period and then click Collect.
6 Click
Start. When status box displays ‘Waiting for beam’, deliver the plan. The status box
displays “Collecting data”. When the beam turns off, click Stop.
CAUTION: Applying the wrong array calibration or absolute dose calibration will
cause erroneous results.