Before a new radiation therapy for cancer reaches patients, it is tested in the lab. For a long time that meant a crude setup: a cabinet that blasts X-rays at the whole subject, with lead shields to block what you can. This machine scans the subject in 3D, finds the tumor and aims X-ray beams as narrow as 0.5 mm at it, the way modern radiation therapy treats people.
- First 2 years
- Sole and principal engineer: owned the software, calibration and systems integration, and directed our contract manufacturer’s engineers until the machine could be built, shipped and supported.
- Later, as CTO
- Built an R&D team of electrical, mechanical and software engineers across the US, UK and Germany. Built technology-transfer and research partnerships with Johns Hopkins, Oxford, Harvard Medical School, the University of Pennsylvania and others, and co-authored two published studies with academic groups, one with Oxford and one spanning 11 institutions, including Stanford, Harvard Medical School, MD Anderson and UCLA.
- 2018
- Helped lead the company through its private-equity acquisition.
- As COO
- Ran operations for 65 people across the US, UK and Germany, serving 700+ medical and research facilities in 25+ countries.
- Research impact
- At the University of Pennsylvania alone, research on the machine had produced 50+ papers and led to 5 clinical trials by 2021.
- Flagship machine
- Sales grew to about 100 units by 2020, at a list price of about $1M, making it the market leader in its category. It is now in nearly 130 research labs worldwide and cited in 2,000+ peer-reviewed papers.
- Beyond the flagship
- 5+ other major devices shipped, with supporting software and a suite of accessories.
From a one-off prototype to a commercial product
Johns Hopkins built the first one as a research prototype. We turned it into a product any lab could buy, install and run, and the software had to change as much as the hardware: calibration, servicing and daily use had to become routine for cancer biologists, who are not radiation physicists.
| Johns Hopkins prototype | Our product | |
|---|---|---|
| Housing | Open frame on wheels behind hanging lead blankets, in a shielded room | Self-contained, lead-shielded cabinet that rolls through a set of double doors into an ordinary lab |
| X-ray arm | Turned by hand, 120° in 15° steps | Motorized, a full 360° circle |
| Scan to 3D image | 4 minutes | About a minute, reconstructed on a GPU |
| Beam calibration | Measured at 7 angles on one side | Measured at 25 angles around the full circle, corrected even while the beam sweeps |
| Built | One unit | Manufactured in volume and CE marked |
| Used by | Johns Hopkins researchers | Nearly 130 research labs worldwide |
What’s inside a $1M lab robot
The machine combines an X-ray source, an X-ray detector and a robot, under one control system.
- X-ray source
- A kilovoltage X-ray tube on a motorized gantry arm
- Detector
- A flat-panel X-ray detector, fixed opposite the source
- Robot
- A stage that moves the subject on 4 axes (3 directions of travel plus rotation), with the gantry as a fifth
- Motion control
- Galil motion controllers on every axis
- X-ray generator
- Run by its own firmware, which our software controls directly
- Software
- A C++ application that runs the whole machine
Hitting a target a quarter of a millimeter wide
The arm holding the X-ray tube sags a little differently at every angle, by 0.4 to 5.2 mm, enough to miss a tumor a few millimeters wide. A machine built in a factory also shifts when it is shipped: it weighs about 2.5 tonnes, more than most cars (most of that is lead shielding). We developed automated calibration software that corrects for both. A camera watches the beam spot while the robot steers onto it at two depths, which traces each beam’s line in the robot’s own coordinates, for 25 angles around the full circle. A least-squares fit across all 25 lines finds the center they really share, a digital version of the “star shot” physicists use, and each angle’s miss goes into an offset table. The robot stage then shifts the subject by the interpolated offset at any angle, even while the beam sweeps. A 2019 study in Medical Physics, led by the University of Victoria with Oxford, measured its targeting accuracy on a 3D-printed test object at 0.25–0.28 mm, about a quarter of a millimeter.
One flagship machine to many
Around the machine I led the development of more products, through technology transfers and research collaborations with Johns Hopkins, Oxford, the University of Pennsylvania, Harvard and others: its own 3D scan engine, planning software, motorized beam-shaping jaws, and a way to find hidden tumors by their light. Separately, we brought a clinical X-ray machine for skin cancer through FDA 510(k) clearance as a medical device.