Keamogetswe Ramonaheng – the first Black woman in South Africa in to earn a PhD in nuclear medicine – talks to Mkhululi Chimoio about her work at the first dedicated nuclear medicine research facility in Africa
For Keamogetswe Ramonaheng, physics was never just about equations – it was about clarity. “From a young age, I was attracted to mathematics and science as a way of understanding complex phenomena through a structured approach,” she says. “Physics was the area that spoke to me the most because it is the foundation for the fundamental principles that govern the natural world.”
Ramonaheng is head of medical physics and radiobiology at the Nuclear Medicine Research Infrastructure (NuMeRI) in Pretoria, South Africa, where she applies the principles of radiation science to treat cancer. NuMeRI, which opened in 2024, is the first research facility in Africa dedicated to nuclear medicine. It’s a joint venture between the Steve Biko Academic Hospital, the University of Pretoria, iThemba Laboratories for Accelerator-Based Sciences and the Nuclear Energy Corporation of South Africa.
Ramonaheng’s academic journey began at the University of the Free State (UFS), where she completed her undergraduate and honours studies before starting an internship at Universitas Academic Hospital in Bloemfontein. There she saw how a rigorous physics training can lead to tangible, clinical benefits. “The ability to comprehend and harness the interaction between radiation and matter in the human body demonstrated the power and relevance of scientific inquiry,” she recalls.
In many ways, nuclear medicine found me
Keamogetswe Ramonaheng
Thanks to a fellowship from the International Atomic Energy Agency (IAEA), Ramonaheng completed a clinical placement at Royal North Shore Hospital in Sydney, Australia. She later continued her postgraduate studies at UFS, becoming the first Black South African woman to earn a PhD in medical physics for nuclear medicine. “In many ways, nuclear medicine found me,” says Ramonaheng, who is grateful to the encouragement of various senior staff members who saw her potential and guided her into the field.
Multifaceted role
Following a spell as an independent medical physicist and manager at Universitas Academic Hospital and lecturer at UFS, Ramonaheng joined NuMeRI in 2024 and the University of Pretoria. Along with the team of scientists she leads, Ramonaheng oversees the safe and effective use of ionizing radiation at NuMeRI used to treat and diagnose disease in a safe and effective manner.
It’s a varied role, which stretches from providing patient-focused clinical services to carrying out applied research. “We integrate research with operations,” says Ramonaheng. “That requires careful planning and rigorous quality assurance, ensuring that innovation does not compromise safety.”
Among her duties, Ramonaheng carries out dosimetry calculations for innovative radiopharmaceuticals, works on new forms of quantitative imaging, and helps to develop novel radionuclide therapies, including using alpha particles to treat cancer. She also uses gamma-ray cameras equipped with highly sensitive cadmium-zinc-telluride detectors, which allow radiopharmaceuticals to be quantified and imaged more precisely.
Ramonaheng is particularly interested in “theranostics” – a form of “precision medicine” that combines therapy with diagnostics. It involves giving a patient a tumour-targeting molecule labelled with a radionuclide. This allows the tumour to be visualized using techniques such as positron emission tomography (PET) or single-photon emission computerized tomography (SPECT). The same molecule – or one similar to it – is then used to deliver a therapeutic radionuclide directly to the tumour.
Daily challenges
For Ramonaheng, a typical day is fast-paced. Mornings often begin with her overseeing radiation-safety protocols and ensuring that radiation imaging and counting equipment are working as well as possible, such that they meet quality assurance standards. Through the day, Ramonaheng also oversees all operational medical-physics activities and carries out her duties as chair of NuMeRI’s radiation protection committee.
As the day progresses, she might find herself reviewing clinical theranostics dosimetry workflows to carrying out patient-specific dose calculations or evaluating quantitative imaging metrics from SPECT/CT and PET/CT systems. Other tasks include reviewing research protocols for cancer theranostics, mentoring postgraduate students at the University of Pretoria, and examining clinical trials.
Innovation accelerates when silos are dismantled
Keamogetswe Ramonaheng
Ramonaheng works in a highly interdisciplinary environment, collaborating with radiographers, nurses, radiochemists, radiopharmacists, medical physicists and clinicians to address live issues in real time. “Innovation accelerates when silos are dismantled,” she says.
The work is not without its challenges. Funding for postgraduate training is a persistent concern. Clinical physics is also a highly specialized field, which means it can be hard to recruit people with the right skills, who might be drawn to better-paid industry jobs. In addition, NuMeRI is an operationally complex mix of advanced imaging systems, radiopharmaceuticals and clinical regulations, which requires good project-management and planning skills.
But Ramonaheng, who recently won two awards at the 8th Theranostics World Congress in Cape Town, feels the benefits outweigh the challenges. “It is very fulfilling to see the translation of research into clinical application,” she says. Just as gratifying, she adds, is watching her students move from their studies to publications and clinical applications. “You see the entire process of scientific advancement.”
A more promising future
Looking ahead, Ramonaheng envisages a growing use of artificial intelligence (AI) in her work. She also collaborates with national and international partners to automate workflows and enhance efficiency, precision and patient-centred care. Another ambition for Ramonaheng is to further strengthen NuMeRI as an Africa-wide hub for research, clinical service and training – a vision reinforced by the IAEA recently naming NuMeRI as one of 18 global “anchor centres” for its work in radiotherapy and medical imaging.
Ramonaheng believes medical physics will grow rapidly in Africa over the next 10 years, fuelled by an expansion of theranostics and precision medicine. Her hope is to guide this growth through mentorship and leadership, ensuring that Africa develops its own talent pool of medical physicists who can address the continent’s unique healthcare needs.
Africa suffers, for example, from limited access to advanced imaging and targeted therapies. Ramonaheng’s aim is to optimize personalized and precision medicine for cancer patients, ultimately improving treatment outcomes and quality of life. Eventually, she hopes, medical physics will be recognized as a profession across the continent. “We are building not only research outputs but human capital.”
Leadership is not only about the creation of paths, but the creation of paths where there were no paths previously.
Keamogetswe Ramonaheng
Being a pioneer in the field has required resilience on her part. “Competence must be coupled with confidence,” says Ramonaheng, who has had to learn the unwritten rules of a world dominated by men. As a mentor, her guiding principle is the African concept of motho ke motho ka batho babang – a person is a person only through others. “Leadership is not only about the creation of paths,” she says, “but the creation of paths where there were no paths previously.”
Her message to young physicists – particularly women and those from other underrepresented groups – is clear. “Medical physics is a dynamic and impactful field at the intersection of physics, medicine and technology,” she says. “ It allows you to see the direct translation of science to patients.” Medical physics requires resilience, curiosity and commitment, but for Ramonaheng its beauty is that equations don’t stay on paper – they become a tool for healing.
