Radiotherapy Robot: From Cobalt Couches to ABB Arms

A radiotherapy robot does one of two jobs: it aims the radiation beam, or it puts the patient in exactly the right place under it. Both jobs now use six-axis robot arms of the kind built for car factories. This post follows patient positioning from the cobalt-60 units of 1951 and the first linear accelerators to the CyberKnife and the industrial robots that carry patients in particle therapy centres. It then covers what Siemens Healthineers and Accuray showed at ASTRO 2026 in Boston, where an ABB arm could fit, and what still limits robots next to cancer patients.

A robotic CyberKnife and its treatment couch at St. Mary's of Michigan, 2008. Photo: St. Mary's of Michigan / Wikimedia Commons (CC BY 2.0)

How patients were positioned under the first radiation beams

In 1949 Harold Johns of the University of Saskatchewan asked Canada's National Research Council for cobalt-60, and two treatment units were built, one in Saskatoon and one in London, Ontario. The first patient was treated with cobalt-60 on 27 October 1951 at the War Memorial Children's Hospital in London, and newspapers soon nicknamed the machines "cobalt bombs". Patients lay on a flat table under a heavy source head, and therapists lined them up with the beam by hand.

A patient receiving cobalt-60 cancer therapy, 1951. Photo: National Museum of American History via National Cancer Institute and Wikimedia Commons (public domain)

Linear accelerators followed within a few years. The first patient was treated with a linac in 1953 at Hammersmith Hospital in London, on an 8 MV machine built by Metropolitan-Vickers. Stanford installed a 6 MV linac in 1954 and began treatments in 1956. In 1957 Henry Kaplan used it to treat Gordon Isaacs, a young boy with retinoblastoma in his left eye, with an electron beam. The photo of the boy sitting on the treatment table under the machine shows how simple the couch still was.

Gordon Isaacs, the first patient treated for retinoblastoma with Stanford's linear accelerator, 1957. Photo: National Cancer Institute via Wikimedia Commons (public domain)

Robots arrived in two forms. At Stanford, the surgeon John Adler began developing the CyberKnife in 1989, a small linear accelerator on a robot arm with image guidance that tracks a tumour as it moves and re-aims the beam. The first system was installed at Stanford in 1991, and the FDA cleared it for brain tumours in 1999 and for the body in 2001. Particle therapy centres used industrial robots as couches instead. At the Heidelberg Ion Beam Therapy Center, Siemens adapted floor-mounted KUKA KR 240 L210 MED robots to carry the treatment table.

A CyberKnife robot arm carrying its linear accelerator at a hospital in New Delhi, 2015. Photo: BLK CyberKnife Hospital / Wikimedia Commons (CC BY-SA 3.0)

Faster machines at ASTRO 2026 and robots in the room

The Heidelberg robots were checked carefully. A 2013 study tracked 1,018 patient setups in 2010 with a laser tracker and found the 3D error below 0.72 mm in 95% of setups in the first room, and 0.53 mm in the second room after Siemens changed how the robot approached its final position. That accuracy matters more as treatments get shorter. At ASTRO in Boston in late September, Siemens Healthineers launched Accela, which it says can deliver multi-site SBRT in as little as 60 seconds, with a gantry turning at 2.5 RPM and dose rates up to 40 Gy per minute.

Radiotherapists in Ghana position a patient on the couch of a linear accelerator, 2017. Photo: Chris Sam / Wikimedia Commons (CC BY-SA 4.0)

Accuray used the same meeting to announce an agreement with Samsung NeuroLogica to develop volumetric imaging for the CyberKnife, with the Royal Marsden as the first centre to take part. No product has been announced yet, and Accuray says the work will move in phases and remains subject to regulatory requirements. In Australia, researchers at the Australian Synchrotron built the first robotic treatment delivery system for synchrotron radiotherapy, where the beam is fixed and the patient has to move through it. Their robot is a KUKA KR 150 R2700 extra, rated for 150 kg with positional accuracy of plus or minus 0.06 mm.

A Varian TrueBeam linear accelerator with its treatment couch. Photo: Michael Goodyear / Wikimedia Commons (CC BY-SA 4.0)

ABB does not sell a radiotherapy robot, and the positioners described above use KUKA arms. Where ABB's range lines up is payload. A patient positioner carries a carbon fibre couch top plus a patient, which is why centres chose KUKA arms rated for 150 and 240 kg. ABB's IRB 6700 family carries 150 to 300 kg, and SafeMove can limit speed and keep an arm out of set zones, which a crowded treatment room needs. ABB already works on hospital automation at its healthcare research hub in Houston, covered in our post on hospital lab automation. A medical positioner would still need certification as a medical device, so this is a possibility only.

An ABB IRB 6700 lifts a solar module at dhp technology; the family carries 150 to 300 kg. Photo: ABB

What robotic radiotherapy needs next, in clinics and in factories

For patients the change is mainly time. When the beam is on for only a minute, setup and imaging take up a larger share of the session, so a robot that brings the couch to the planned position quickly and correctly shortens the whole visit. AuntMinnie also reported from ASTRO that shorter SBRT regimens improved patients' physical function. Fewer and shorter sessions mean fewer trips to the hospital, which matters most to people who live far from a cancer centre or are already weak from treatment.

An Elekta Compact linear accelerator and couch at Narayana Multispeciality Hospital, Mysore, 2015. Photo: Narenfox / Wikimedia Commons (CC BY-SA 4.0)

The open problems are safety and checking. A positioner carries a person, often immobilised, close to a moving gantry, so every path must be checked for collisions and every position confirmed by imaging before the beam turns on. The Heidelberg team measured its robots against a laser tracker, and medical physicists repeat checks like these as quality assurance. Simulation helps here too. Industrial robot programmers test reach and collisions in RobotStudio before a cell is built, and clinics model the treatment room in a similar way.

A GoFa cobot at ABB's healthcare research hub. Photo: ABB

Cost and skills decide how far these systems spread. A robotic couch adds an industrial arm, its safety systems and medical certification to a linac that is already expensive, and many hospitals worldwide still lack basic radiotherapy. Staff need training in both radiation physics and robot behaviour. On the factory side, linacs and couches are heavy precision products that robots could help build and test. We looked at how robots moved into the operating theatre in our post on surgical robot history.

ABB YuMi assembling small parts beside a lab worker. Photo: ABB

Innovation

AI solutions for effortless ABB robot control.

Automation

Robotics

ceojohntran@chatwithrobot.net

+84905311611

© 2025. All rights reserved.

qtran1215@gmail.com