History

A Brief History of Medical Physics in Hong Kong

Geoffrey Mauldon, February 2013

It is indeed an honour to be asked to write a few lines about the early days, as I remember them, of the development of Medical Physics in Hong Kong. I thank those concerned for the honour.

Medical Physics really started with the accidental discovery of X-rays in 1895 by Wilhelm Conrad Röntgen (often written as Roentgen) in Germany when photographic plates he had safely wrapped against light intrusion, but accidentally placed near to glass tubes containing a near vacuum with which he was experimenting, became fogged showing some shadowing of the wrapping produced by a strange kind of ray and thereafter called “X” rays, where “X” was the unknown.

It was quickly demonstrated that these rays could penetrate human flesh to reveal shadow images of the bones within and there is still a photo of his wife’s hand with a finger ring to demonstrate this mysterious ability. One year later, in 1896, Antoine Henri Bequerel discovered “radioactivity” and that too led to an interest in their medical use. Marie and Pierre Curie also experimented with pitchblende, a radioactive stone from which they extracted the element “radium” which was highly radioactive.

Early X-ray tubes were of the vacuum type using high voltages often obtained by the use of “Spark Coils” similar to those in use today in cars to operate “spark plugs”. In 1913 William David Coolidge developed and patented the use of electrically heated cathodes in such tubes to provide a greater and controlled emission of electrons. X-ray tubes then became more efficient and controllable, and had a longer tube life. Incidentally W.D. Coolidge also had an extended life for, unlike many physicists, he died over the century at 101. I would suggest that it is well worth while to look up on the internet the discoveries made by those mentioned above.

Mr Andrew Tsui with the G E Maximar 400 at Queen Mary Hospital

The earliest record I have been able to find for the use of X-ray tubes or machines in Hong Kong is from a book by Dr. E.H. Paterson on a history of the development of the Nethersole Alice Mui Ling Hospital which was located at the corner of Bonham Road and Breezy Path on Hong Kong Island. In that book it is recorded: “As early as 1904 Dr. Gibson had been very keen to obtain a ‘Roentgen Ray Apparatus’ (which today we would call an X-ray machine), for which the estimated cost was 120 Pounds. But contributions came in slowly, and it was not until 1910 that the long-promised machine actually arrived. On May 16th of that year a missionary colleague wrote ‘Through the efforts of Dr. Gibson and some friends at home he has been able to install a fine X-ray apparatus in the Hospital, and the gathering was to witness a demonstration of the Rays.’ At the end of the same year in his Annual Report, Dr. Gibson refers briefly to the same occasion, writing, ‘Early in the year a Roentgen Ray Apparatus, 16 inch spark coil, was installed, and proved satisfactory. We wish to record our thanks to Mr. B.L. Frost for assistance in selecting and setting up the apparatus and kindness in giving a demonstration to gentlemen interested in the Hospitals.’ The importance of the X-rays was said to be in the diagnosis and treatment of fractures, and of tuberculosis of the bones. No mention was made of chest X-rays which perhaps were still too indistinct to be of value.”

The first known deep therapy X-ray machine in Hong Kong was the installation of a 400 KVp General Electric (G.E.) Maximar at the Queen Mary Hospital in 1939 by the hospital engineer Mr. Hon Bing Yuen and the manufacturer’s representative Mr. Raymond Huang just prior to the opening of the Queen Mary Hospital and shortly before the outbreak of the second World War. Before that the General Civil Hospital served the Hong Kong people. This later became the Sai Ying Pun Hospital. During the Japanese occupation, the Japanese tried to have the Maximar shipped to Japan but the workshop staff stalled the effort, suffering accordingly, and the radiotherapy X-ray machine thus remained in Hong Kong. Prior to WW 2 the diagnostic and radiotherapy facilities were quite unsophisticated with a limited amount of radium tubes, needles and plaques, some in private hands, and personnel protection was rather primitive. Following WW2 while Hong Kong was getting back on its feet, some “medical physics” was undertaken by the radiographers at the Queen Mary Hospital and Kowloon Hospital such as calibration of the radiotherapy X-ray machine by means of a small portable Victoreen electrometer and electrostatic ionization chambers.

Medical Physics in Hong Kong started in a very simple way on 8th October 1956 when I arrived in Hong Kong by sea on a two year loan from the Cancer Institute Board, Peter MacCallum Clinic in Melbourne, Australia. It took over a month to get to Hong Kong aboard the MV Changsha as I left Melbourne on 5 September. This “loan” arrangement was made between the Medical and Health Department of the Hong Kong Government and the Cancer Institute Board, and was brought about by the insistence of Dr. Ho Hung Chiu, the Consultant Radiologist of the Radiology Department at Queen Mary Hospital for the urgent need of Physicist services for Radiotherapy.

At that time Diagnostic Radiology and Radiotherapy were the one Department. The two year period was extended by three months and then I returned to the Peter MacCallum Clinic in Melbourne by sea, returning at Dr. Ho’s persuasion to Hong Kong by air six months later and then, in retrospect, on permanent establishment. I must confess to feeling totally inadequate for the task, my first time outside of Australia.

Mr. Lam Chin Man from the Physics Department of the University of Hong Kong joined me in 1957 and was sent for two years to the Middlesex Hospital in London to study Medical Physics, and while there obtained his M.Sc. in the field. Mr. C.Y. Woo, Mr. S.M. Kwei and Mr. Richard Abesser joined the Department in 1957 with Mr. C.K. Lo joining in 1958 and Mr. C.M. Shen in 1962. These gentlemen formed the vital team of Medical Physicists, formerly known as Hospital Physicists, which set the future course for Medical Physics in Hong Kong.

The initial period was rather slow and primitive by today’s standards, with office space being provided at the Queen Mary Hospital, for it involved the purchase of equipment, the routine calibration of the two deep radiotherapy machines in routine use, the setting up of a laboratory and the provision of benches with inbuilt viewing boxes for the production of patient isodose treatment plan distributions once the basic isodose curves were obtained. Such isodose treatment planning for patients was taken over by Radiographers dedicated to the work. The two deep radiotherapy treatment machines were a 400 kVp Maximar X-ray machine and a Bryant Simmons short source-skin distance (SSD) Cobalt-60 teletherapy machine, both located in the Diagnostic X-ray Department, the Maximar close by the Diagnostic equipment and the Cobalt-60 unit on the floor directly below and accessible by a small spiral iron staircase from the Diagnostic floor. Patients had access on the ground floor. In 1958 a Maxitron 250kVp X-ray therapy machine as installed opposite to the Cobalt-60 unit, in a room shared later by a mobile superficial Philips Grenz Ray machine, replacing an earlier Chaoul machine, and later a GE ST-150 kVp machine was installed.

At Queen Mary Hospital the radium sources were kept in a Chubb Safe in a modified toilet at the end of the corridor where Radiotherapy clinics were held, at the other end of the first floor of the hospital to the Diagnostic X-ray Department and close to the office and laboratory of the Medical Physicists. Radium sources were prepared either in the storage area or close by and sent to the Operating Theatre, after sterilization, on the 6th floor. Some initial treatment using Phosphrus-32 was also undertaken with dose distributions performed using a collimated Geiger counter. At this time solid state equipment was not common such that most of the instrumentation into the early 1960’s were of the thermionic tube kind and thus bulky and heavy.

Medical Physics was not restricted to Radiotherapy at the Queen Mary Hospital but also was involved with Diagnostic X-ray procedures and measurements, at that time restricted to ionization chambers and photographic film. The high humidity made the use of chambers problematic at times and as the self-charging electrostatic Victoreen electrometer was used initially with interchangeable chambers for the calibration of X-ray machines, humidity problems were a common problem. Chambers were also later used with a battery-driven electrometer for the measurement of dose distributions in phantom material. Some decades later although the ionization chamber methods are still sometimes used for radiation dosimetry measurements, but with updated and more reliable instrumentation, solid state and thermo-luminescent dose measuring techniques have taken over much of what was once achieved with ionization chambers.

Around 1960 the Isotope Laboratory at the Queen Mary Hospital was opened in the former “Linen Store Room” adjacent to the Queen Mary Hospital Canteen at ground level outside the main building. A Siemens Rectilinear Scanner using a 1 inch Sodium Iodide crystal was used to scan patients who had been given in-vivo diagnostic amounts of radioactive materials. This machine was later upgraded to a 3 inch crystal with improved performance but was transferred in 1964 to the Queen Elizabeth Hospital. A Philips rectilinear scanner subsequently replaced the Siemens machine at Queen Mary Hospital. Although the Isotope Laboratory was equipped with the latest radiation detection equipment, some home-made electronic instruments were also developed, sparked by the need to detect and measure radioactive fall-out following the detonation of Chinese nuclear bombs in the early 1960’s. The Royal Observatory collected fallout in a number of ways and the fallout on filter papers or solid samples were sent to the Queen Mary Hospital for analysis and measurement. This took place between measuring uptakes and distributions of iodine-131 or other isotopes in patients, and the required in-vitro measurements. HAECo at Kai Tak Airport also sent us rags used in the cleaning of aircraft for monitoring and as some of these were highly active, it was necessary to keep them for a while before incinerating them. The home built single channel scanning gamma spectrometer helped in identifying the nuclear components while the radioactive life-time curves of the rags let us know which was the contributing explosion. A measure of radiation monitoring was also undertaken for radiation workers using film badges but this did not really take off until the transfer of administrative operations to Queen Elizabeth Hospital in 1964.

The Industrial Health Department shortly after my arrival was also very concerned about the public radiation safety in Hong Kong and so we were involved with visiting suspect factories, or samples were brought to Queen Mary Hospital to determine whether or not radioactive materials were being used. Radium paint was a problem for watch and clock factories were subcontracting out the hand-painting of dials with radium activated luminous paint to families in villages, even on Cheung Chau, where children were using tooth picks for the purpose. The safety of the child was a great concern. A Code of Practice for the safe use of radioactive materials and irradiating apparatus was also being drawn up by Dr. Ho, Legal and Industrial Health officials, based at the time on legislation from New Zealand as very few countries had such legislation available. This later became the foundation for the Radiation Ordinance in Hong Kong first promulgated in 1959 with its Regulations being issued in 1965. Plans were also under way for the Radiology and Radiotherapy requirements for the Queen Elizabeth Hospital, the opening of which eventually took place in September 1963, although Radiology and Radiotherapy moved in during early 1964 upon commissioning and calibration of the newly installed equipment. Initially this new radiotherapy equipment consisted of two 6 Mev Linear Accelerators using a new concept with replaceable accelerator tubes but were found to be somewhat unstable. In 1970/71 the two linear accelerators were modified to work more reliably at 4 Mev. They subsequently became reliable workhorses. A Brown Boveri 35 Mev Betatron was also installed around 1964 for high energy electron therapy. There was also a superficial X-ray therapy machine, a mould room, a simulator, and a full range of instrumentation for nuclear medicine although automated brachytherapy equipment was delayed to a later time. It was well set-up and paid for by the Jockey Club of Hong Kong. Full Medical Physics services were also available for both the radiotherapy and diagnostic requirements within what officially became The Royal Hong Kong Jockey Club Institute of Radiology.

With the advent of the Queen Elizabeth Hospital, the massive upgrading of the Queen Mary Hospital and the opening of the Prince of Wales, Tuen Mun, Nethersole Pamela Youde and upgraded Princess Margaret Hospitals initially run by the Hong Kong Government and now under the Hospital Authority, new radiotherapy and diagnostic services and equipment were installed at each Centre. Medical Physics Divisions under the leadership of a Senior Medical Physicist were included within those hospitals with Radiotherapy and Oncology Departments, or handling open and sealed radioactive materials. X-ray Workshops were also added to these departments as a first line repair and back-up service, as well as for the development and construction of special appliances used in both the various diagnostic and therapeutic procedures. Physicists and X-ray Workshop staff in the different hospitals knew each other and were in communication as needed.

Modern Radiotherapy and Radiology Departments now use complex equipment both in the diagnosis of disease and in the treatment of patients. These include a variety of Linear Accelerators, Orthovoltage and superficial therapy X-ray machines, Brachytherapy equipment, CT Scanners, MRI machines, Gamma Cameras of various types, including PET Scanners, various conventional and Digital X-ray systems, Ultrasound diagnostic imaging equipment, a variety of in-vitro radio-isotope analysis and handling instruments, Radiotherapy Planning Computers with associated Planning Simulators or CT Scanners, and other related computer systems. There are frequently necessary interactive connections between some of the above facilities. Medical Physicists are required to understand the operation and function of these facilities, be able to use a number of them, regularly ensure quality control and reliability assurance, and be involved with the maintenance of such equipment in the service of the patients. The Medical Physicists are also involved with the Clinical aspects of radiotherapy and usually with the aid of specialized computers, provide detailed radiation dose distribution information to enable the medical profession to deliver the required treatment dose while sparing as much as possible damage to healthy body tissues. Such procedures may at times require radiation measurements to be made on patients during treatment. Medical Physicists also need to be constantly alert to ensure the radiation safety for staff and the public within the hospital environment. The development of new radiation facilities also involves Medical Physicists who must determine the appropriate shielding and protective arrangements in association with the planning architects. A Senior Medical Physicist is usually involved with the formulation of the detailed specifications and contractual requirements for the purchase of new specialized equipment and in its preparation for presentation to the purchasing authority.

One very important aspect of the work of Medical Physicists is in the field of radiation health. Initially the Medical Physicists in the hospitals would be required, often in company with Industrial Health Officers, to visit hospitals, clinics, factories and facilities using or storing irradiating apparatus or radioactive materials to check on their safe usage. A film badge radiation monitoring service was set up at the Queen Elizabeth Hospital and made available to the public in Hong Kong. Initially the coverage was small but grew quickly and as monitoring film was adversely affected by Hong Kong’s high humidity when used outside an air-conditioned environment, monitoring was on a frequent fortnightly basis. The demand led eventually to the creation in 1982 of the Radiation Health Unit (RHU) which was staffed by Medical Physicists in the field of Radiation Health and Safety, with a Senior Medical Physicist in charge. The Medical Physicists later became Health Physicists as the two fields diverged with the creation of the Hospital Authority and the Department of Health. The Radiation Health Unit keeps record of radiation levels of those making use of the service and warns the individual if internationally accepted levels are being exceeded. It also undertakes regular visits to clinics, factories and locations where ionizing radiations are in use, as well as investigates the illegal use of radioactive materials and irradiating apparatus. The RHU also issues licenses to those companies, hospitals, clinics and operations where such equipment or radioactive materials are in use or in store, while ensuring that the protection requirements are suited to the situation. In more recent years the film badge has been replaced by the more stable and sensitive thermo-luminescent dosimeters (TLD). The RHU is also responsible for the safe storage or disposal in Hong Kong of radioactive waste or residues and used or broken X-ray tubes. It also produces information available to the public concerning ionizing radiations and health.

One field of activity not mentioned is that of teaching. The Medical Physicists are required to give lectures to aspiring doctors seeking higher degrees, memberships or Fellowships of Academic Colleges overseas, as well as to Radiographers and other staff members as deemed necessary. On occasions a physicist may be asked to give a lecture or series of lectures on specific topics to specialized groups such as X-ray Workshop staff or from other departments. Such lectures are vital for the overall development of hospital facilities and the development of the Medical or Health Physicists themselves. On occasions a Medical or Health Physicist may have opportunity to go overseas to attend a course, or a conference.

The work of Medical Physicists continues. Whereas in the earlier years the Medical Physicists tended to be “Jacks of all trades” and would meet various difficult situations at they arose, there was a goodly measure of individual expertise among the early team. Mr. Lam was clinically most capable as was Mr. Lo while Mr. Woo had a real talent with electronics and engineering which was invaluable. Mr. Shen, Mr. Kwei and Mr. Abesser were talented in the fields of radiation safety, and nuclear medicine, which included the use of unsealed and sealed radioactive sources such as radium needles and tubes, checking their physical integrity against bending or breakage and radium or radon gas leakage, and Radiographers’ preparation of sources for clinical use. As the Medical Physicist Divisions grew and matured, the levels of expertise also increased such that today there is a wealth of experience and ability in the various specialty fields of Medical, and Health Physics. Several private hospitals in Hong Kong have also employed Medical Physicists to provide improved and more accurate radiotherapy and other treatment procedures to patients, and also develop improved diagnostic capability. These developments can only be to the benefit of Hong Kong’s medical and health expertise and thus of benefit to the whole community of Hong Kong.

In final comment I wish to record that Medical Physics in Hong Kong has been, and still is a great and wonderful adventure and I am grateful to all my colleague friends, young and old, for making it so. It is a joy to see the profession so full of life and it is indeed in very good hands, which speaks well for its future service to the people of Hong Kong. The quality of those in service aided by equipment beyond imagination in those “early days”, well before digital computers had ever been conceived, will ensure the continuing highest quality of service, innovation and expansion of Medical Physics in the years to come.

An unofficial note.

An early unofficial activity at the Queen Mary Hospital was the result of the Diagnostic and Therapy centres, including Dr. Ho’s Office, being at one end of the first floor while the clinics and radtiotherapy doctors rooms and Medical Physics were at the other end, quite a walk between the two. Although telephone connection was available, the manually operated exchange was slow and at times frustratingly so. It was felt that an intercom system of some kind would be helpful and so such a system was designed by the medical physicists, using thermionic tubes as solid state was at that time relatively difficult to acquire. The Hospital Secretary knew of our intention of putting up “illegal” wires but turned a “blind eye” to it with the result that a home-made but useful intercom system was introduced. This extended not only between the various rooms at each end of the first floor but between to two sections, and was extended to include the Pharmacist, the new Isotope Laboratory and the Operating Theatre on the 6th floor. Since that time intercom systems have been incorporated in all the more recently built hospitals with radiotherapy facilities.