How to configure the CT scan of the MatriXX Resolution in the TPS in order to use it in myQA Patients?
This article is about the MatriXX Resolution and miniPhantom R.
If you are searching for the workflow for the MatriXX Evolution and miniPhantom please refer to this article: How to configure the CT scan of the MatriXX Evolution in the TPS in order to use it in myQA Patients?
Step 1: Acquire CT Image of MatriXX Resolution and miniPhantom R assembly
Place the MatriXX Resolution in the miniPhantom R and position it in the CT scanner using the alignment lasers: The CT origin can be aligned with the isocenter markings. The device is positioned in the CT scanner so that the central point of the measurement is positioned at the CT origin.
Scan the entire phantom, taking care to not scan the electronics area.
A CT scan resolution of 2.5 mm and below should be used with standard departmental scanning protocol for soft tissue (pelvis, abdomen) imaging.
Step 2: Contour and edit the structures in the TPS
Import the CT scan into the TPS.
Create an external contour of miniPhantom R (1), MatriXX Resolution housing/build-up (2), and detector (3). If required, add a support (couch) to the CT scan:
Perform the necessary mass density override:
- miniPhantom R (RW3): 1.045 g/cm3
- MatriXX Resolution (ABS): 1.04 g/cm3
- Detector area: it can be substituted with a homogeneous material such as water
Verify the structures against the dimensions of MatriXX Resolution and miniPhantom R.
MatriXX Resolution (vertical profile):
miniPhantom R (dimensions in mm):
Step 3: Calculate the isocenter point dose in the TPS
On the MatriXX Resolution images, set a point on the plane corresponding to the LINAC isocenter alignment marks on phantom surface and shown on both coronal and transverse views. Label it.
For the MatriXX Resolution, the effective point of measurement is 1/3 height of the chamber. For beams from 0° angle, it coincides with the Isocenter.
Create an open reference field (recommended: 10x10 cm² open field, 100 MU) at 0° and have the system calculate the dose using a grid size of 2.5 mm or lower.
Find the isocenter plane and export this dose plane that will used for the verification in myQA Patients. The isocenter is set up geometrically based on the depth and central pixel position in the TPS image.
Step 4 (optional): Cross-checking
Export the isocenter dose as the TPS reference dose.
Insert a chamber into the phantom and measure the dose with the same field size and the same number of MUs as in the TPS.
Compare the TPS reference dose with the measured reference dose.