Acrylic Cube 0ne 2mm Titanium Marker

This Cube can be used to do a modified Winston-Lutz test for IGRT accuracy. The phantom will provide a means to test the isocenter coincidence from CT scan to treatment planning system to treatment delivery.

The accuracy of radiation isocenter relative alignment and couch shift process is of fundamental importance in the accuracy of delivered dose in image Guided Radiation Therapy (IGRT). Item 710-032, the 73mm Cube, has one (1) Central axis titanium marker for the testing and verification of predetermined measurable couch shifts. This phantom can be used to test the accuracy of CBCT alignment and couch shift in a simple and efficient manner. Images can be transferred to the treatment planning system to check coincidence of treatment planning system to couch shifts.

It is, therefore, critical to ensure the coincidence of these two coordinate systems for different clinical needs of image-guided radiation therapy procedures. The QA item “imaging and treatment coordinate coincidence” is aimed to test this coincidence and is applicable for each of the imaging systems considered. In addition, each system performing patient positioning and/or repositioning based on in-room imaging systems, either 2D or 3D, relies upon vendor software that compares and registers on-board images and reference images. Quality assurance of this process could be easily done by a phantom study with known shifts and is recommended for each system used clinically. The accuracy of this process should be tested on the daily basis, especially for SRS/SBRT.

Like the original Winston-Lutz test, the isocenter coincidence test is an end-to-end QA procedure in that it must start with the planning imaging process and end with the treatment step. In this case the last step is the use of the treatment beam to both irradiate and image markers using the treatment beam.

The 73mm Cube is made of Acrylic with three (3) sides each having a white vinyl label with the alignment markings as seen above. The titanium marker can be seen on the other three (3) sides.