Planmeca ProMax X-ray Instruction Manual page 118

Chapter E - C-ARM AND IMAGING ARM
NOTE Before you can measure the true distance between the balls, you have to define a refer-
ence distance as follows:
Click the CAL button in the Toogle Measurement Toolbar and then draw a long horizon-
tal line to the image by clicking the start point, releasing the mouse button and clicking
the end point. The Reference distance window appears.
Calculate the line length using the formula A x 0.x mm = B, where A is the distance in
pixels and B is distance in millimetres. Value x depends on the used resolution: x =
0.066 (high resolution), x = 0.099 (enhanced resolution) and x = 0.132 (normal resolu-
tion)
Enter the value B (line length in millimetres) to the Reference distance window and
click OK.
The distance from the center of the middle ball to the center of the tenth ball to the left
and the tenth ball to the right can now be measured.
The images of 23 balls should appear on the image (Fig. 58). They should be round, all the
same size, and evenly spaced. Note that they will not necessarily be at the same vertical
height. The outermost balls on the left and right sides should appear symmetrically.
The distance from the center of the middle ball to the center of the tenth ball must be 118 ±
2mm. The difference in distances must be less than 2mm. If the distances are not correct,
you will have to check the position of the patient positioning mechanism and the calibration of
the angle sensors, refer to sections 1.10 "Patient positioning mechanism adjustment" on page
E-33 and 2.1 "Calibration of angle sensors" on page E-56.
R
Figure 58
The distance from the center of the middle ball to the center of the rear middle ball should be
less than 2mm. If the distance is not correct you will have to readjust the position of the
patient positioning mechanism, refer to section 1.10 "Patient positioning mechanism adjust-
ment" on page E-33.
E-32 ProMax X-ray unit with Dimax3
118 ± 2mm
X
PANORAMIC BEAM AND PATIENT POSITIONING MECH-
118 ± 2mm
Y = X ± 2mm
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Technical Manual