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2023 Peter Mansfield Medal and Prize

Professor Emeritus Borivoj Vojnovic for pioneering and sustained contributions to the field of cancer research, through development of novel sensing, imaging and ionizing radiation technologies applied to basic translational and medical research.

Professor Emeritus Borivoj Vojnovic is a physicist who has developed, introduced and applied numerous technological innovations related to cancer research. He conducted his PhD at the Gray Laboratory in Mount Vernon Hospital, developing methods to study chemical reactions induced by ionizing radiation. These fast reactions (nanoseconds to milliseconds) involve biologically important free radicals. Their fate is a major determinant of longer-term biological consequences. He developed fast optical and conductimetric detection devices towards this.

As head of the Advanced Technology Development Group, he combined his interests in fast electronics and the physics of ionising radiation, applying them, as part of a team, to the development of the first cellular micro-irradiation installation in the UK. This could target individual cells with energetic ions, one or more at a time. The consequences of energy deposition from ionizing particles and their interactions with individual cells could be studied, making important contributions towards the understanding of radiation responses in cells and tissue models. This required him to devise and apply novel automated fluorescence microscopy approaches that could ‘find’ and irradiate tens of thousands of cells per hour.

During this time, it became clear that 3D microscopy techniques would be required for this work, as would means of identifying interactions between proteins. This was made possible by emerging time-resolved fluorescence imaging technologies. He thus set up one of the first two-photon fluorescence microscopy installations in the UK. This exploits nonlinear optical phenomena that occur when ultrashort, intense light pulses are used, making possible not only imaging in 3D but also enabling fluorescence decays at nanosecond timescales to be followed. These ‘lifetimes’ change when energy transfer between labelled proteins takes place: protein interactions can thus be visualised. Similar techniques were applied both at the Gray Institute at Mount Vernon Hospital and later at King’s College London, for in vitro and in vivo work.

After moving to the University of Oxford, Vojnovic developed a single pulse linear accelerator along with associated robotics and imaging to follow, in near real-time, the fate of DNA damage foci. The ability to generate high doses in short times has allowed this installation to also perform ‘flash’ irradiations that minimize normal tissue damage.

More recently, he has added to his interests in radiation physics by developing a novel form of intraoperative molecular fluorescence imaging, operating in the near-infrared region of the spectrum. This allows cancer tissue to be visualised in real time, thus guiding surgical resection.