It is quite common for nuclear medicine to be mistakenly categorised as radiology or oncology by the layman when it is, in fact, a distinct medical discipline on its own.
The confusion likely occurs as this specialised branch of medicine combines imaging with targeted treatment to diagnose, stage and treat disease.
While radiology uses external imaging techniques, such as X-rays, magnetic resonance imaging (MRI) and computed tomography (CT), to diagnose structural abnormalities, radiation oncology – a branch of oncology – uses high-energy, precisely targeted radiation to treat cancer.
In contrast, nuclear medicine uses small, carefully-controlled amounts of radioactive substances to assess how organs and tissues function, as well as to both diagnose and treat disease.
These substances contain radioactive isotopes, i.e. unstable forms of elements that release energy as alpha, beta or gamma radiation as they become stable.
“Nuclear medicine allows us to use radioactive isotopes, which differentiates our work from that of oncologists and radiologists,” says consultant nuclear medicine physician Assoc Prof Dr Tan Teik Hin.
While some nuclear medicine services are administratively placed under radiology or oncology departments, the discipline itself remains distinct.
Centres focused on imaging may sit within radiology, while those offering both imaging and therapy are sometimes grouped under oncology.
What sets it apart?
One of the key strengths of nuclear medicine is its ability to precisely locate and treat disease using targeted radioactive substances.
According to Assoc Prof Tan, the process begins with the injection of a tracer into the patient’s body.
These tracers are specially- designed molecules that seek out specific disease cells, which are linked to a radioisotope.
“For example, in cancer, we use tracers that target tumours, such as those found in prostate cancer,” he explains.
Once administered, the tracer binds to the targeted cells while emitting radiation as a signal.
Specialised imaging devices, such as gamma cameras or PET (positron emission tomography) scanners, then detect this radiation, allowing doctors to pinpoint the tumour’s exact location.
After identifying the tumour, doctors can use a higher-energy therapeutic isotope to deliver targeted radiation and destroy the cancer cells.
This dual approach – using the same tracer for both diagnosis and treatment – is known as theranostics, combining therapy and diagnostics in a single strategy.
Assoc Prof Tan says the field has advanced rapidly in recent years, particularly with the development of radiopharmaceuticals, i.e. specialised drugs that contain radioactive isotopes.
“New tracers are being developed to detect different types of cancer,” he says.
One example is prostate-specific membrane antigen (PSMA) – a receptor found on prostate cancer cells.
A PSMA PET scan enables doctors to detect the cancer with high precision.
“If the disease is identified, a higher-energy radioisotope can then be used to deliver targeted treatment directly to kill the tumour,” he explains.
Similar approaches are being explored for other cancers, including neuroendocrine tumours and certain bone cancers.
These advances offer a more comprehensive view of tumour behaviour, compared with conventional methods.
In standard cancer care, doctors often rely on blood tests or tissue biopsies to identify specific markers, such as programmed cell death ligand 1 (PD-L1), to guide treatment decisions.
“If it’s positive, we can use targeted therapy for that patient,” says Assoc Prof Tan.
However, a biopsy samples only a small part of the tumour and may miss important areas.
“With nuclear medicine, we inject a tracer that maps the tumour throughout the body,” he explains.
“This allows us to see which parts express specific targets and which do not.”
This whole-body view enables more precise, personalised treatment.
Areas that express certain targets can be treated accordingly, while others may require a different approach, helping doctors design more effective, tailored treatment strategies.
A centralised platform
For nearly 60 years, nuclear medicine has played an important role in Malaysia’s healthcare system.
While the number of nuclear medicine centres has grown significantly over the past few decades, a key challenge remains the limited number of trained specialists.
Tun Abdullah Ahmad Badawi Cancer Centre consultant nuclear medicine physician Dr Mahayuddin Abdul Manap, who is involv-ed in training nuclear medicine physicians in Malaysia, notes that: “Since the early 2000s until now, we’ve had only 69 trained nuclear medicine physicians serving a population of 33 million.
“By ratio, that number is quite small.”
This shortage means that nuclear medicine services re- main regionally concentrated – mainly in Penang, the Klang Valley, Johor Baru, Kota Kinabalu and Kuching.
The Health Ministry operates six facilities, while the Higher Education Ministry oversees four centres.
A significant proportion of services is also delivered by private healthcare providers.
“People often ask where they can get a PET scan, a kidney scan or a paediatric scan,” says Assoc Prof Tan.
“Whenever someone mentions a ‘scan’, it is often related to nuclear medicine.
“However, due to limited availability, five states in Malaysia still do not have a nuclear medicine centre.”
To address this gap, Dr Mahayuddin – who is also president of the Malaysian Society of Nuclear Medicine and Molecular Imaging (MSNMMI) – has collaborated with the Health Ministry, with support from Novartis Malaysia, to develop the Malaysian Nuclear Medicine Care Locator Education and Resources (MyNuCLEaR) website.
MyNuCLEaR is Malaysia’s first integrated nuclear medicine resource platform, linking patients, specialists and researchers online nationwide.
It consolidates key information and helps users locate hospitals and centres offering nuclear medicine in two ways.
“First, you can use a keyword search by location, selecting your state to narrow down the options,” Dr Mahayuddin explains.
“Second, you can search by services offered, such as specific radiopharmaceuticals or disease types.
“When you select a result, it highlights the relevant centre on a map, with additional details on its services.”
This system makes it easier for users to find and access appropriate care.
“Nuclear medicine services in Malaysia are regionally dispersed, and with an integrated platform, we hope to connect centres across the country,” he says.
He also points out that not all centres provide the same services.
“Some may not have PET scanners, while others may not offer certain treatments.”
The platform helps patients understand these differences and identify facilities that meet their needs.
“For example, if a patient urgently needs a PET scan, but appointments at their usual hospital are full, the platform can help them find other available centres,” says Assoc Prof Tan.
Beyond improving access, the platform is entering its second phase, which focuses on advancing nuclear medicine development.
This includes organising training programmes to strengthen expertise and establish a network of training centres.
“We are also working on providing a standardised way to refer cases,” Dr Mahayuddin says.
“The goal is to develop a referral system adopted by all centres, making it easier for practitioners and patients to navigate the healthcare system.”
It will also support collaboration at both local and global levels, while plans are underway to link with accreditation bodies to ensure high standards of care across Malaysia.
