With Micromate™, Interventional Systems develops a robotic and navigation solution for minimally invasive procedures. The accuracy of the system is anchored to five titanium landmarks in the end-effector assembly. Using industrial CT, Microvista provides traceable proof that each one lies within the drawing tolerance, as an end-of-line control.
| At a glance | |
|---|---|
| Customer | Interventional Systems (iSYS Medizintechnik GmbH), specialist in robot-assisted systems for minimally invasive interventions, manufacturer of the Micromate™ system |
| Industry | Medical robotics |
| Field of application | Interventional radiology and related disciplines, CT- and fluoroscopy-guided procedures |
| Task | Non-destructive measurement of five titanium landmarks in the end effector assembly |
| Method | Industrial computed tomography as an end-of-line inspection |
| System | Several CT systems with flat-panel detectors, plus the matching analysis software |
| Parameters | 225 kV · 480 µA · 500 ms · 2,880 projections · 103 µm voxel size |
| Result | Traceable proof for each assembly that every landmark lies within the drawing tolerance, completely non-destructive |
| Benefit | A reliable basis for automatic sphere detection in the clinical CT and the subsequent optical navigation |
The customer
Interventional Systems (iSYS Medizintechnik GmbH) is a medical technology company specializing in robot-assisted systems for minimally invasive interventions. With Micromate™, the company develops and markets a precise navigation and robotic solution for CT- and fluoroscopy-guided procedures. The goals are clearly defined: to make needle placements more accurate, to reduce radiation exposure for patients and medical staff, and to make clinical workflows more efficient. The solutions are used internationally in interventional radiology and related disciplines.
Micromate is mounted directly to the patient table. For spatial orientation, five titanium spheres in the end-effector assembly serve as landmarks. They are detected automatically in the CT image, from which the robot determines its position relative to the patient. If the spheres sit accurately, this determination is precise enough for the navigation to continue purely optically, without further CT scans of the patient. The manufacturing accuracy of the spheres therefore feeds directly into the company’s goals, because every scan saved means less radiation exposure and a faster workflow.
The challenge
For this to hold, the spheres must sit exactly where the design specifies, within tight tolerances. If one deviates, it distorts the automatic detection in the CT image and therefore the registration to the patient. The spheres, however, sit hidden inside the assembly. Tactile and optical measuring methods cannot reach them, and taking the part apart is out of the question because it would destroy the very positional relationships to be checked. What was needed, then, was a proof that inspects every assembly without touching it.
Die The solution
Microvista digitizes the assembly completely using industrial computed tomography. This scan takes place once during manufacturing and should not be confused with the imaging used during the procedure. The part is X-rayed from many directions and reconstructed into a complete three-dimensional volume, inside and out, in a single scan.
A reliable result starts with the right acquisition parameters. For the metallic end-effector assembly the following values were used:
| Parameter | Value | Purpose |
|---|---|---|
| Tube voltage | 225 kV | enough energy to penetrate the metal |
| Tube current | 480 µA | sufficient signal for high-contrast images |
| Integration time | 500 ms | low-noise individual projections |
| Projections | 2,880 | dense sampling for a low-artifact volume |
| Voxel size | 103 µm | fine resolution for reliable determination of the sphere centers |
Each titanium sphere is reconstructed as a complete volumetric body. From thousands of surface points we calculate the geometric center. Titanium stands out clearly from the surrounding material. The center of each sphere is then determined as a best-fit sphere and compared against the drawing in a nominal-actual comparison, for each axis individually and as a spatial overall value. This yields a clear statement for every sphere: within tolerance or not. The whole process is implemented as an end-of-line control; the technical drawing with the specifications was all it took as a basis.
The result
For every assembly it is documented in a traceable way whether each of the five landmarks lies within the drawing tolerance, fully non-destructively. This ensures that the automatic sphere detection in the CT image builds on a geometrically sound assembly and that the optical navigation works without further CT scans of the patient. On request, the complete 3D data set can be archived. Microvista was able to deliver the required positioning data after a first trial.
The fact that Interventional Systems has firmly established this end-of-line control shows how consistently the team prioritizes precision and patient safety.
“
We approached Microvista to implement an end-of-line CT control method for our end-effector assembly, which had quite tight tolerance requirements. All it took was a technical drawing with specifications, and they were able to provide us with the necessary landmark positioning data after a first trial. Overall, it was a very smooth process with great results.
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– Pedro Pinto, Head of Development, Interventional Systems –
About Microvista
Microvista has been providing industrial computed tomography as a service since 2008, for customers in medical technology, the automotive and aerospace industry, battery technology, additive manufacturing, archaeology and the foundry sector. Several CT systems are available for different part sizes and inspection tasks, together with the matching evaluation software.
Would you like to reliably prove the position of your landmarks? Talk to our CT experts and request your individual quote.