Although two cancer patients might receive the same amount of radioactive drug, their bodies are capable of absorbing completely different doses of radiation. Nuclear medicine researchers from the University of Pretoria (UP) believe that resolving this discrepancy is the next major direction in the field of precision cancer treatment.
In a recently published paper, Professor Mike Sathheke and Dr. Kamo Ramonaheng advocate for the widespread implementation of patient-specific dosimetry. Currently, radiopharmaceutical therapy, which uses radioactive substances to locate and destroy cancer cells, often relies on standard levels of radioactivity, which are sometimes adjusted based on factors such as body weight.
However, the researchers emphasize that knowing the administered dose does not mean knowing the actual dose received by the cancer cells. Sathheke, head of the Department of Nuclear Medicine at UP and Steve Biko Hospital, and CEO of the Nuclear Medicine Research Infrastructure (NuMeRI), explains: 'Two patients can receive the same treatment, but their bodies can handle it very differently.'
He continues that 'Precision medicine must ultimately mean accuracy for the individual patient. If we can measure how much radiation reaches the cancer and how much reaches healthy tissues, we will have much more complete information to guide treatment.'
Nuclear Medicine
Dosimetry measures the actual absorbed radiation in both tumors and healthy organs. The researchers propose a practical initial step: measuring this absorption after treatment completion. This data allows doctors to ensure that the tumor has received a sufficient dose while protecting healthy tissues from unnecessary exposure.
For patients undergoing multiple treatment cycles, data from the first cycle can determine whether subsequent therapies should be adjusted or if continuing treatment is likely to benefit the patient. This is particularly important because treatment is prescribed at early stages of cancer fighting, making the reduction of long-term side effects vital for patients who may live many years after treatment.
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Ramonaheng clarifies that 'The question should not only be: 'How much did we give the patient?', but also: 'How much did this patient actually receive where it mattered?' Dosimetry brings us closer to answering this question.'
Progress in medical imaging and artificial intelligence is accelerating this transition to personalized care. Highly sensitive scanners now provide more accurate data on where radioactive drugs move in the body, while AI promises faster image analysis and the ability to predict individual patient responses.
Nevertheless, the researchers warn that these tools require thorough testing before routine clinical integration. Ultimately, preoperative imaging can predict radiation distribution, allowing doctors to plan treatment with high accuracy even before therapy begins.
Much of the necessary infrastructure to study these approaches is already operational at NuMeRI, located at Steve Biko Hospital. This national center combines advanced PET and SPECT imaging, radiopharmaceutical development, medical physics, radiobiology, and clinical trials to translate laboratory discoveries into patient care.
Dr. Ramonaheng, head of the Department of Medical Physics and Radiobiology at NuMeRI and a recipient of the prestigious Saul Hertz Award at the World Congress of Theranostics in 2026, has focused her research on patient-specific dosimetry. Professor Sathheke explains: 'NuMeRI provides us with a place where we can develop science, test it, visualize patients, and accumulate the evidence needed to improve treatment.'
He adds: 'This is important for dosimetry because personalized treatment depends not only on the idea but also on having the technology, expertise, and clinical environment to make it possible.'
Despite these technological advancements, the researchers caution that technology alone is not enough. The widespread adoption of personalized dosimetry requires trained specialists, standardized protocols, adequate funding, and robust clinical evidence.
Describing dosimetry as a 'compass' that can guide radiopharmaceutical therapy toward truly individualized care, the researchers have outlined a clear trajectory for the future of oncology. For Professor Sathheke, the ultimate goal is clear: 'We want to get close to giving the right treatment, in the right radiation dose, to the right patient at the right time.'