Owandy Radiology i-max touch 3D, Руководство пользователя

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User Manual
– Quality assurance program
NIMXEN020I
Owandy Radiology SAS 55
8.5.9 Homogeneity
Click on "Next measure" button (6 - Figure 11) to proceed with the "Homogeneity" test which gives
information about the uniformity of the reconstruction. The image will be loaded automatically:
verify that the displayed image looks like the following:
Figure 16
The measurement will be performed automatically. The Homogeneity value must be greater or
equal to 5.
Report these values in the "Homogeneity" cell of the QC log book at paragraph 8.5.12.
8.5.10 Dose at the isocenter
Note
Perform this test only if required by local regulation.
For this analysis three dose measurements are required. The dose measures must be taken in
free air, with the dosimeter as close as possible to the image receptor plane and the exposure
parameters set to Full Dentition 3D, Adult patient, Medium size. The dose values should be
expressed in mGy.
Two values are computed starting from the three dose measures:
•
dose at the isocentre
–dose computed in the center of rotation, where the patient is,
according to the geometry of the machine
•
dose maximum aberration
–index of the dose reproducibility, expressed as percentage
deviation from the mean value.
8.5.11 Acceptance index
In the last section an index is displayed summarizing the quality of the 3D image with respect to
the given dose.
It is computed starting from the quality parameters previously measured: Contrast to Noise Ratio,
MTF
50%
and Dose at the isocentre. The index is expressed in 1/(mGy•cm
2
).