Go to Meet the Expert interview series
Learn more about Prof. Yimin Hu
Transcript
[ Disclaimer: abridged/summarised transcript; All the views and thoughts expressed in this interview are the personal opinion of the interviewee only and not necessarily that of AFOMP ]
Xiance Jin: Hello, Prof Hu! Congratulations on winning the 2022 AFOMP Lifetime Achievement Award. Can you tell us something about the history of AFOMP?
Yimin Hu: AFOMP was founded at the North American Radiology Conference in 2000. At that time, the main sponsors were Japan, China (including Hong Kong, China), Malaysia, Thailand, Indonesia and so on. But before the establishment of AFOMP, there was an organization called SEAFOMP, which was set up by several countries in Southeast Asia. As SEAFOMP only covered a few countries, South Korea, Japan, and China (Hong Kong, and Taipei) proposed to establish a federation of medical physics organizations in the Asia-Pacific region. AFOMP was established with the approval of IOMP. The first president of AFOMP was Dr. Kin-YinCheung, and the second chairman was Dr. Barry Allen. He held the international joint conference on medical physics and biomedical engineering for the first time in the Asia-Pacific region, and stressed the need to strengthen the links of medical physics in the Asia-Pacific region. They are two major contributors to AFOMP.
Since the establishment of AFOMP, several meetings have been held in Malaysia, Thailand and China, etc. The first meeting in China was in 2007in Huangshan. Many manufacturers from China participated in that meeting and the scale of the meeting was huge. The response was really good. The second AFOMP annual meeting in China was in 2015 in Xi’an.
When AFOMP was founded in 2000, the number of medical physicists in China (including Hong Kong and Taipei) was relatively small, which was around 1000. Now the number of registered medical physicists is over 4000, which is far more than that in Europe. The American Association of Medical physicists (AAPM) has 15000 to 20000 medical physicists, of which more than 2/3 is in the field of radiotherapy and the remaining 1/3 is in nuclear medicine and imaging. However, in China, more than 90% of the medical physicists are concentrated in the field of radiotherapy. So China’s strength in nuclear medicine and imaging is relatively weak with a relative small number of medical physicists. Therefore, this is a focus of the future development of the Chinese Society of Medical Physics.
Xiance Jin: As a lead medical physicist in China, how did you embark on the path of medical physics?
Yimin Hu: I would like to share my personal experience. In 1964, Chinese government at first assigned four students graduated from physics major to work in the physics department in Hospital. Fortunately, I was one of the four students. So, I started my career in the physics department in Cancer Hospital of the Chinese Academy of Medical Sciences in 1964. At that time, radiology, imaging, and radiotherapy were all in one department, called radiation oncology. But after 1965, the department was divided into three parts: radiotherapy, imaging and nuclear medicine. Since then, I focused on the field of radiotherapy physics. I went to England for further study in 1977, 1979 and 1982, respectively. In 1977, I went to England for a three-week training in accelerator. In 1979, China decided to build own CT machine, so I was sent to United Kingdom (UK) again to study CT with other colleagues.
Xiance Jin: How the medical physics developed in China in the past 60 years? What are the problems?
Yimin Hu: The history of medical physics in China began in 1964, when graduate students with physics major were assigned to work in various hospitals (mainly in Beijing, Shanghai and Guangzhou). Medical physics in China developed rapidly from 1968 to 1982. During that 14-year period, the number of medical physicists increased quickly, and it was also during that period that the research and application of clinical medical physics developed greatly. Many new technologies of radiotherapy were developed independently in China.
Xiance Jin: Could you please tell us more about the new technologies developed at that time?
Yimin Hu: One of the major technologies developed by Chinese medical physicists in the 1960s was the manual multi-leaf collimator. At that time, I worked as a technician and physicist for a cobalt-60 machine. My duty included positioning, dose measurement, cobalt source replacement and machine maintenance. I found that the fixed collimator of Cobalt-60 machine was very heavy. We had to turn the gantry to 180° to install the collimator, so the operation was very troublesome. And the lead block must be placed on the patient body. So I proposed a new style manual multi-leaf collimator to replace the old one.
Xiance Jin: What was the first high-end equipment introduced into China at that time? Were there any other advanced machines later?
Yimin Hu: In1967, our department imported the first Betatron from Switzerland. However, due to the information blockade on China by United States, Chinese medical physicists could only get new technology information from Europe at that time. After the launch of Betatron, medical physicists and technicians in our hospital and other Hospitals in China, together with some returned talents in the Chinese Academy of Electrical Sciences, developed a 25MeV accelerator. This accelerator took less than a year from design to completion. A total of three new machines were build. The first one was installed in our hospital, the second one was installed in the Second Hospital of Baoding and the third on was in Zhejiang province. In 1978, we imported a SL75-10 accelerator from British. Chinese medical physicists realized that the therapeutic effect of linear accelerator is better than that of Betatron with a higher efficiency and better energy spectrum of linear accelerator.
In 1978, with the designed new accelerators by Chinese medical physicists. Chinese medical physicist developed the isocenter therapy technology, which replaced the conventional standard source-distance (SSD) positioning technique. Later, conformal radiotherapy and intensity modulation technology (IMRT) was adapted in clinical practice in China. I was the first person to translate conformal radiotherapy into “适形放疗 in Chinese, which I think is very appropriate for the meaning of the conformal radiotherapy technology itself. I hope you and young generation can pursue the accuracy of translation when translating professional terms into Chinese in the future.
Xiance Jin: What do you think is the biggest difficulty or problem during the development of medical physics in China?
Yimin Hu: I think the biggest problem in the development of medical physics in China was the lack of talents. In that time, there were few undergraduate students graduated with physics major joined in the radiotherapy. Most of the graduated students went to work in the department of machine maintenance. Only after the new Millennium, with more young people of your generation joined the team, the Chinese medical physics community was expanded. Some of the young medical physicists are engaged in medical physics research. Today’s medical physics in China belongs to your and younger generation.
Xiance Jin: What areas of research should young medical physicists focus on now?
Yimin Hu: Positioning uncertainty in radiotherapy is the first problem need to be resolved. Imaging guided radiotherapy and dosimetry guided radiotherapy are still the main research topics in the near future. Although, positioning technologies has been dramatically improved with the introduction of CT,MR and even PET-CT into radiotherapy. During the treatment, the geometric and dosimetric variations are still big concerns for medical physicists and radiation oncologists. In the next decade, advanced research on adaptive radiotherapy is still one of the main topics.
Xiance Jin: What’s message do you want to say to young medical physicists?
Yimin Hu: I think our young medical physicists should firstly pay attention to the application of AI technologies into radiotherapy, such as solving the problem of accurate target delineation. The second is to know exactly what happened during radiotherapy, which is also a fundamental problem. If this problem is not solved, adaptive radiotherapy will not be achieved. The third one is to combine radiation therapy with multiple techniques, such as the combination of CT with accelerator, PET and magnetic resonance with accelerator. At present, medical physicists have partially achieved in the combination, but there are still rooms for further improvement.
