Engineering 101

Next-Generation Cancer Treatment With Precision Motion Control

Leo Cancer Care is relying on precision motion control products from R.A. Rodriguez for its new Marie Proton Therapy compatible solution. In order to rotate and position patients in an upright orientation, Marie uses a meticulously engineered system which includes a number of R.A. Rodriguez-supplied components that include slewing rings, ballscrews and LinearChain.

Leo Cancer Care is built on global research which suggests that vital organs move less in the upright orientation due to gravity. When targeting a cancerous tumour, this reduction in motion allows Particle Therapy solutions to be more accurate. By combining upright positioning with a shift to patient – not machine – rotation, the company is set to change the face of cancer treatment forever.

The basis of the company’s foundation was to reduce the cost involved in producing conventional radiation therapy systems, whereby a machine that sometimes weighs up to 600 tons rotates around a horizontal patient to fire radiation beams at a tumour from different angles.

“Research revealed it was way more cost-effective to rotate a 100kg upright patient in front of a fixed radiation source, reducing overall machine size by a factor of 16 and simplifying use, service and maintenance,” explained Stephen Towe, CEO of Leo Cancer Care.

The development and manufacture of patient positioning systems takes place at Leo Cancer Care’s headquarters.  Another facility in Wisconsin, USA focusses on CT imaging technology. Today, the company has 22 employees.

Leo Cancer Care worked closely with R.A. Rodriguez on Marie to provide solutions capable of delivering patient positioning to less than 1 mm. Not only does the chair rotate, but the system can lift and lower the patient, and tilt them left to right and front to back. This capability facilitates the imaging and treating of all Particle Therapy-specific anatomical sites in the upright orientation.

“The other major component of Marie is the imaging system, which images the patient just before treatment,” said Towe. “Here, R.A. Rodriguez supplies a bearing and slip-ring interface where we spin a large ring at 60 rpm to collect lots of images. The ring also has to travel up and down, and we have to tilt the arms upon which the ring moves. Ultimately, the system provides flexibility through many independent motion axes.”

Leo Cancer Care has an experienced mechanical engineering team in place, some of whom had used R.A. Rodriguez components successfully on other projects.

 “If we could source tried, tested and reliable solutions off the shelf, then it made sense to take that advantage,” stated Towe. “There are not many places you can go for super-high precision solutions – matched by high reliability and performance – but R.A. Rodriguez is certainly one. In the development of Marie, it was a collaborative effort between ourselves and R.A. Rodriguez with combined expertise and many high quality, off-the-shelf parts.”

Another major factor in selecting R.A. Rodriguez was the potential for single-source supply. “Supply chain management is always important, particularly for a small business,” said Towe.

Among ten different products supplied by R.A. Rodriguez for Marie are slewing rings, ballscrews, linear guides, Grob LinearChains, gears and bearings. A large bearing facilitates rotation of the sophisticated patient positioning system, while another interesting application involves a Grob LinearChain.

“LinearChain is really clever technology,” added Towe. “One of our design constraints on Marie is that we are trying to introduce 700 mm of vertical translation, and when the unit is completely compressed it has to fit inside a space that is only 500 mm deep. The Grob LinearChain is a ‘push’ chain, so unlike a traditional chain it can push and pull. However, the other neat trick is that it folds up into a very compact space. It would have been challenging to design another solution if LinearChain did not exist.”

Marie is already through prototyping and the company is currently placing its first production-representative system with a potential customer under a research agreement. In full production, Leo Cancer Care anticipates the sale of hundreds of Marie systems per annum.

“The market opportunity for Marie is vast across the areas of Particle Therapy, conventional X-ray radiotherapy and radiology,” concluded Towe.

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