CyberKnife S7 in Melbourne and the Precision of Robotic Prostate Radiotherapy

A Different Approach to Precision Radiotherapy

CyberKnife is an advanced robotic radiotherapy system designed to deliver highly focused stereotactic radiation with exceptional accuracy. Despite the name, there is no knife, incision or surgery involved.

What distinguishes CyberKnife is the combination of a compact linear accelerator mounted on a six-axis robotic arm, highly flexible non-coplanar beam delivery and integrated imaging that allows selected targets to be monitored throughout treatment. The newer CyberKnife S7 system brings these technologies together in a platform capable of delivering stereotactic treatment with sub-millimetre precision.

For prostate cancer, this is particularly relevant because the prostate sits immediately beside the rectum and bladder, with the urethra running directly through it. It can also move during an individual treatment session. Precision therefore means more than creating an accurate treatment plan. It also means knowing where the prostate is while that plan is actually being delivered.

Robotic Radiation Delivery

Most modern radiotherapy machines are built around a large rotating gantry. CyberKnife takes a different approach, with the radiation source mounted on a highly manoeuvrable robotic arm.

This allows radiation to be delivered from a large number of directions around the patient, including angles that do not all sit within the same plane. These are known as non-coplanar beams.

By combining many carefully selected beam directions, the treatment can be shaped closely around the intended target while distributing the paths of individual beams through the surrounding tissues. This helps create the steep dose gradients that are central to stereotactic radiotherapy, where we want a high dose within the treatment volume followed by a rapid fall in dose immediately outside it.

The advantage is not simply that the robot can move in many directions. It is that this flexibility can be used to create highly conformal treatment around complex anatomy.

Tracking the Prostate During Treatment

The prostate does not remain perfectly still.

Changes in bladder filling, rectal filling and bowel gas can cause its position to shift during treatment. Even movements of only a few millimetres can become important when high-dose stereotactic radiation is being delivered close to sensitive normal structures.

For CyberKnife prostate treatment, small fiducial markers are placed within the prostate before radiotherapy. During each treatment, paired X-ray images repeatedly identify the position of these markers and therefore the position of the prostate.

If the prostate moves, the CyberKnife system detects that change and the robotic treatment arm can correct where the radiation beam is directed.

This is known as intrafraction tracking because the prostate is monitored during the treatment fraction itself rather than simply being positioned correctly at the beginning.

It is one of the defining features of CyberKnife prostate radiotherapy.

Five-Treatment SABR for Localised Prostate Cancer

For appropriately selected men with localised prostate cancer, stereotactic ablative body radiotherapy, or SABR, allows an entire radiation treatment course to be delivered in just five sessions.

The international PACE-B phase III trial provides strong evidence for this approach. At five years, 95.8% of men treated with SABR were free from biochemical or clinical failure, compared with 94.6% of men receiving longer conventional or moderately hypofractionated radiotherapy schedules.

PACE-B demonstrated that five-treatment SABR was non-inferior to these longer radiation schedules in the population studied.

CyberKnife was one of the principal technologies used to deliver SABR within the trial, giving researchers an opportunity to examine whether outcomes differed according to the treatment platform used.

The CyberKnife Finding in PACE-B

Among 414 patients who received SABR in the treatment-platform analysis, 169 were treated with CyberKnife and 245 with conventional linear accelerator-based SABR.

At two years, grade 2 or greater urinary toxicity was reported in approximately 6% of men treated with CyberKnife compared with 17% of men treated using conventional linac SABR. Significant bowel toxicity was low with both approaches.

This is an interesting finding, particularly given CyberKnife’s ability to monitor and correct for prostate motion throughout treatment.

However, the comparison needs to be interpreted carefully. Patients were not randomly assigned between CyberKnife and conventional linac treatment. They received the technology available at their participating centre, so differences between patients, centres and treatment techniques may also have contributed.

PACE-B therefore does not prove that CyberKnife itself was responsible for the lower urinary toxicity. It does, however, provide an important clinical observation alongside the technological rationale for real-time prostate tracking.

A Non-Surgical Option for Localised Prostate Cancer

Men with localised prostate cancer may have several appropriate management options depending on the characteristics of their cancer, age, general health and personal priorities.

For selected men requiring treatment, CyberKnife SABR provides a non-surgical option delivered over five outpatient treatment sessions. This may be particularly relevant for men who are not suitable for surgery or who, after considering their options, prefer to avoid an operation.

There is no incision and the prostate is not removed. The radiation itself cannot be seen or felt, and patients can leave the treatment centre afterwards.

The decision between surgery, radiation therapy and other management approaches remains individual. CyberKnife is therefore best viewed not simply as an impressive piece of technology, but as one highly precise way of delivering an established prostate cancer treatment.

Beyond Prostate Cancer

The same capabilities that make CyberKnife attractive for prostate SABR can also be useful elsewhere in the body.

Selected tumours in the brain, spine, lung, liver, kidney, lymph nodes and bone can be treated using CyberKnife, depending on the clinical situation.

For lung and liver tumours, respiratory movement presents a different challenge. CyberKnife’s Synchrony technology can track selected tumours as they move with breathing and adapt beam delivery to that motion while the patient continues to breathe normally.

For brain and spinal targets, robotic non-coplanar beam delivery can help create highly conformal treatment around small targets close to sensitive neurological structures.

Different cancers therefore make use of different aspects of the same technology.

CyberKnife S7 in Melbourne

Victoria’s first CyberKnife centre opened at 5D Clinics Melbourne in Cremorne in July 2025, through a collaboration between 5D Clinics and Icon Cancer Centre. It is also the first CyberKnife service on Australia’s east coast.

The centre is equipped with the newer CyberKnife S7 system.

The first patient with prostate cancer to receive CyberKnife treatment in Melbourne was treated under the care of Radiation Oncologist Dr Paul Conway, who completed dedicated CyberKnife training and credentialing before the service opened.

For Victorian patients, access to robotic stereotactic radiotherapy with real-time target tracking is now available locally rather than requiring travel interstate.

CyberKnife at Pinpoint Radiotherapy

Dr Paul Conway provides CyberKnife treatment through 5D Clinics Melbourne as part of his radiation oncology practice, with particular clinical interests in prostate cancer, stereotactic radiotherapy and oligometastatic disease.

For men with localised prostate cancer, the first question is whether five-treatment SABR is an appropriate option for their particular disease.

When it is, CyberKnife offers a distinctive way of delivering that treatment. The robotic arm provides highly flexible non-coplanar beam delivery, the treatment plan can create steep dose gradients around the prostate, and integrated imaging allows the prostate to be tracked and its movement accounted for during treatment.

The technology is sophisticated, but the goal is straightforward.

Deliver the intended radiation dose accurately to the prostate while limiting unnecessary radiation to the normal tissues immediately around it.

For selected men with localised prostate cancer, CyberKnife SABR now provides an evidence-based, non-surgical treatment option available here in Melbourne.