Question:
How can I perform CBCT tests in myQA Machines with scans not containing the whole phantom?
Answer:
The myQA CBCT Plugin only allows to import one image. If the image doesn't contain all ROIs defined in the myQA CBCT Plugin (e.g. several set of images), the results will look as follows:
You will see in the status column "Undefined" and "Failed" results. The reason is that the image might not contain all parts that are needed for analysis. To avoid that, the tests could be splitted in order to match each set of images of the CBCT study with its corresponding test.
To do so, one could add a new CBCT test in myQA Machines, add a new phantom and the module you would like to add in Test setup, e.g. like shown in the image below:
Afterwards, the ROIs have to be defined manually. Click on the edit button as shown here:
Add the ROIs needed for the evaluation and define the properties. The table below shows the default values taken from the CBCT plugin for the CatPhan 503.
| Test | ROI | X coordinates (mm) | Y coordinates (mm) | ROI type | Radius | Reference value | Material |
| Contrast and CNR | 1 | -29 | -50,50 | circle | 4 | Reference HU: -45 | Polystyrene |
| Contrast and CNR | 2 | -58,50 | 0 | circle | 4 | -102 | LDPE |
| Test | ROI | X coordinates (mm) | Y coordinates (mm) | ROI type | Reference value |
| Geometric distortion | 1 | -10 | 68 | rectangle | Reference HU: -1000 |
| 1 | 10 | 68 | |||
| 1 | 10 | 48 | |||
| 1 | -10 | 48 | |||
| Geometric distortion | 2 | -10 | -48 | rectangle | Reference HU: -1000 |
| 2 | 10 | -48 | |||
| 2 | 10 | -68 | |||
| 2 | -10 | -68 | |||
| Geometric distortion | 3 | -68 | 10 | rectangle | Reference HU: -102 |
| 3 | -48 | 10 | |||
| 3 | -48 | -10 | |||
| 3 | -68 | -10 | |||
| Geometric distortion | 4 | 48 | 10 | rectangle | Reference HU: 365 |
| 4 | 68 | 10 | |||
| 4 | 68 | -10 | |||
| 4 | 48 | -10 |
| Test | ROI | X coordinates (mm) | Y coordinates (mm) | ROI type | Radius | Reference value | Material |
| HU Constancy | 1 | 58.50 | 0 | circle | 4 | Reference HU: 365 | N/A |
| HU Constancy | 2 | 47 | -30 | circle | 4 | Reference HU: 100 | N/A |
| HU Constancy | 3 | 29 | -50,50 | circle | 4 | Reference HU: 120 | Acrylic |
| HU Constancy | 4 | 0 | -58,50 | circle | 4 | Reference HU: -1000 | Air |
| HU Constancy | 5 | -29 | 50,50 | circle | 4 | Reference HU: -200 | PMP |
| HU Constancy | 6 | 29 | 50,50 | circle | 4 | Reference HU: 990 | Teflon |
| HU Constancy | 7 | 0 | 0 | circle | 4 | Reference HU: 100 | CTP404 |
| Test | ROI | X coordinates (mm) | Y coordinates (mm) | ROI type | Radius |
| Uniformity | 1 | 0 | 0 | circle | 10 |
| Uniformity | 2 | 0 | -55 | circle | 10 |
| Uniformity | 3 | 55 | 0 | circle | 10 |
| Uniformity | 4 | 0 | 55 | circle | 10 |
| Uniformity | 5 | -55 | 0 | circle | 10 |
| test | ROI | X coordinates (mm) | Y coordinates (mm) | ROI type | Reference value |
| Spatial resolution | 1 | 42,09 | -14,42 | rectangle | Line pairs/mm: 0,10 |
| 1 | 46,42 | -16,62 | |||
| 1 | 40,53 | -28,20 | |||
| 1 | 36,90 | -25,99 | |||
| Spatial resolution | 2 | 23,49 | -37,57 | rectangle | Line pairs/mm: 0,20 |
| 2 | 32,12 | -30,79 | |||
| 2 | 35,24 | -34,76 | |||
| 2 | 26,62 | -41,55 | |||
| Spatial resolution | 3 | 6,05 | -43,72 | rectangle | Line pairs/mm: 0,30 |
| 3 | 16,47 | -41,07 | |||
| 3 | 17,77 | -46,16 | |||
| 3 | 7,35 | -48,81 | |||
| Spatial resolution | 4 | -6,89 | -44,13 | rectangle | Line pairs/mm: 0,40 |
| 4 | 0,99 | -44,96 | |||
| 4 | 0,56 | -49,06 | |||
| 4 | -7,32 | -48,23 | |||
| Spatial resolution | 5 | -19,82 | -40,39 | rectangle | Line pairs/mm: 0,50 |
| -13,28 | -43,05 | ||||
| -14,71 | -46,56 | ||||
| -21,25 | -43,89 | ||||
| Spatial resolution | 6 | -32,38 | -31,26 | rectangle | Line pairs/mm: 0,60 |
| -26,43 | -36,34 | ||||
| -28,98 | -39,33 | ||||
| -34,93 | -34,24 | ||||
| Spatial resolution | 7 | -32,60 | -22,96 | rectangle | Line pairs/mm: 0,70 |
| -39,63 | -21,13 | ||||
| -36,44 | -26,30 | ||||
| -39,41 | -28,13 | ||||
| Spatial resolution | 8 | -46,90 | -9,65 | rectangle | Line pairs/mm: 0,80 |
| -43,38 | -8,94 | ||||
| -42,36 | -14,04 | ||||
| -45,88 | -14,74 | ||||
| Spatial resolution | 9 | -48,09 | 2,21 | rectangle | Line pairs/mm: 0,90 |
| -44,59 | 2,33 | ||||
| -44,41 | -2,67 | ||||
| -47,91 | -2,79 |
If you now run a test in myQA Machines, the results will only contain the relevant information that you would like to extract from your image. Below is an example for geometric distortion: