Physicist Soma took the nuclear option to harness the science of radiation to save lives in Singapore General Hospital.

Every morning at 5.30am, medical physicist S Somanesan dutifully checks in on one of his ‘children’ locked away in the basement of Singapore General Hospital (SGH) -  the hulking, silent 20-year-old giant cyclotron.

The cyclotron holds a special place in Soma’s heart. As the operation and quality assurance manager of the cyclotron and molecular radiopharmaceutical production team, he single-handedly managed the procurement of the device – from drawing up the specifications to installation - to make SGH the first medical cyclotron facility in Singapore and Southeast Asia in 2003.

Hearing ‘cyclotron’ might cause one to think of a transformer robot. You might have seen it in the recent movie ‘Oppenheimer’, where the cyclotron was developed in the background of the world’s first atomic bomb. At SGH, this massive machine manufactures a type of radioactive material called radionuclides, which in turn is incorporated in a pharmaceutical and is transformed into a radiopharmaceutical. Radiopharmaceuticals when injected in patients in small amounts can diagnose some types of cancer and other illnesses.

Soma standing in front of his favourite machine. The massive cyclotron weighs 80 tonnes and is encased by a movable shielded tank to protect against radiation exposures.

Choosing the nuclear option
“28 June 1989,” recalls Soma as his first day at SGH. “Straight out of university, with an honour’s degree in physics, I responded to an ad for Radiation Physicist. I had no idea what medical physics meant as it was so new. What caught my interest was the word ‘nuclear physics’ in the description. It was a steep learning curve. The former medical physicist had left three months earlier. So I had to learn from the doctors, engineers, nurses and radiographers. Also there wasn’t the internet at the time. So I also learnt a lot from books and journals.”

Starting a chain reaction
And he had to learn quickly as he soon found himself having to teach physics to radiography students. In those days, SGH ran the School of Radiography for Singapore located on our campus.  When the school moved to Nanyang Polytechnic, he continued teaching there. 

Fast forward 34 years later, today Soma is a master medical physicist who teaches extensively – at the National University of Singapore, Singapore Institute of Technology and soon, Nanyang Technological University, training tomorrow’s medical physicists, radiographers and nurses. Likewise, in SGH, he teaches residents of nuclear medicine and radiology and other colleagues about aspects of medical physics related to their jobs. At the same time, he has helped train diagnostic medical physicists for other institutions like Sengkang General Hospital, from all three healthcare clusters.

Soma lights up when he explains how he enjoys making physics come alive. I experienced his teaching first hand when I asked him what a medical physicist does.  He passionately launches into explaining how physics works in healthcare. And his mastery as a teacher is evident. Soma pitches the lesson at a level perfect for my understanding – one with an ‘O’ Level physics background, even whipping out his notebook to sketch how atoms interact. 

How medical physics is used to treat or diagnose
My understanding in a nutshell: 

The images are then used to determine a diagnosis and treatment plan.

High reliability medicine
Quality management is one of the most crucial aspects of Soma’s job. As Senior Principal Medical Physicist, Soma heads a team responsible for ensuring that every radiation-related equipment is safe, effective and working properly. The machines must be functioning optimally; hence, for example, a daily check on the cyclotron is crucial. The radionuclide (radioactive material) manufactured by the cyclotron must be of the purest form. Even the quality of the images captured by the scan detectors like a PET/CT scanner must be clear enough to allow an accurate diagnosis.

Working with many complex machines and devices means medical physicists also need to be familiar with engineering. When asked how many machines and types of equipment he is familiar with, Soma chuckles. “We are not challenged by any equipment. When considering whether to purchase or commission complex machines, we’ll take them as a challenge, to understand how they work and see if we can even use them optimally.”

A safety shield
Medical physicists also develop procedures to ensure the safe and effective use of radiation in medicine.  “As we harness radiation, we are also mindful of its ill effects. So we work closely with the doctors and radiographers to ensure that only the optimal dosage of radiation is administered to patients.’’  

Radiation survey of patient undergoing radiopharmaceutical therapy

“We also look after our colleagues’ safety as well. All radiographers carry a TLD (Thermoluminescent Dosimeter) at all times. The device measures the amount of radiation they are exposed to, which needs to be kept within a certain tolerance level. We also work with nurses, health attendants and couriers who come into contact with the radioactivity to ensure their radiation exposure is kept to a minimum.”

From left) Devices to keep colleagues safe from radiation exposure: A radiation safety shield, safety cabinet, a TLD 

In fact, Soma has been the SGH Radiation Safety Officer since 1999, and oversees the radiation safety in laboratories, radiology services, research units, animal facilities, nuclear medicine services on Campus, as well as emergency planning for radiological incidents and accidents.

A positive force

Soma standing by the flag post area at the Vienna International Centre during a consultancy expert meeting organised by the IAEA in October 2023.

Today Soma is internationally recognised as an expert by the International Atomic Energy Agency (IAEA). His humble demeanour hides the supernova status he has acquired in the field. He regularly consults for IAEA as an international trainer and is well known. His love for medical physics radiates when he describes his passion for his work, “The beauty of my profession is that I see the clinical application of physics I learnt back in university, as well as through continual education. It’s so fulfilling to see how the science of gamma rays and x-rays are utilised in the healthcare sector to diagnose and even save lives.” He adds, “This field is never static. It is always evolving with new discoveries and applications. This keeps me excited”.    

Soma (front, centre) with his team of medical physicists from the Division of Radiological Sciences today. When he first joined SGH, he was the only medical physicist.