1970s medical physics

Radioactivity

In January 1975 Frank T Farmer in his Presidential Address of 1974 (Farmer BJR 1975; 48(565): 1-9) gave an interesting historical review of the physical basis of radiology and demonstrated a diffraction patterns as obtained by Von Laue. Radioactivity has many uses other than the purely medical and in 1978 the Silvanus Thompson memorial Lecture was given by Sir John Hill from the United Kingdom Atomic Energy Authority on the still very topical subject of nuclear power and the environment (Hill BJR 1979; 52(613): 2-13). John Hill made the important point that radiation has always been present in the earth and that levels have been higher in the past than they have been today. His review is worth reading.

In March 1970 Eric Pochin reviewed the development of the quantitative basis for radiation protection (Pochin BJR 1970; 43(507): 155-160). Eric Pochin was Chairman of ICRP from 1962 to 1969. The Silvanus Thompson Memorial Lecture of 1973 was given by FW Spiers from Leeds (Spiers BJR 1974; 47(564): 833-844) and he reviewed the effects of radium and strontium on bone. His comments on the long lasting effects of radium are most salutary.

In March 1970 M Cryer and others (Cryer, Hilditch and Vennart BJR 1970; 43(507): 205-208) reviewed placental localisation. They say “in view of present concern about the possibility of deleterious effects arising in childhood as a result of prenatal radiography, it is prudent to review the possible alternatives to X-ray methods of placental localisation.” They describe and review doses received by placental radiography and radioisotope techniques. They mention other techniques such as ultrasound and thermography. There was concern about possible injurious effects of ultrasound.

Von Laue photograph of sapphire crystal

 Image source: Farmer BJR 1975; 48(565): 1-9

 

The EMI/CT Scanner

The invention of the CT scanner marked the paradigm shift between traditional diagnostic radiology and modern medical imaging.  

The 32nd Annual Congress of the British Institute of Radiology was held on April 20-21 1972 with the opening address by Lord Aberdare from the DHSS describing the increasing amount of money that the government was spending on radiological equipment (BJR 1973; 46(542): 147-148). 

A session on ‘New techniques for diagnostic radiology’ was held and was chaired by George du Boulay. The first paper was by James Ambrose and Godfrey Hounsfield from Atkinson Morley’s Hospital in South London (BJR  1973; 46(542): 148-149). The invention of the CT scanner was the most important event in radiography after the discovery of X-rays.

In the 1960s Godfrey Hounsfield was working at EMI Ltd. in Middlesex. Hounsfield was interested in pattern recognition and at internal structure and considered a closed box with an unknown number of items inside. The box could be looked at from many directions using a γ-ray source and a radiation detector. Hounsfield then looked at practical applications of the technique and approached the Department of Health in London. Hounsfield was introduced to Dr Ewan Lennon a radiological advisor to the Department of Health. Contact was made with three radiologists, Frank Doyle (from the Hammersmith Hospital), James Ambrose and Louis Kreel (from the Royal Free Hospital), and the three radiologists then worked closely with EMI. Frank Doyle supplied bone specimens, James Ambrose supplied brain specimens and Louis Kreel supplied abdominal specimens.  The initial results of specimen radiography were very promising and it was agreed to build a prototype machine to be located at Atkinson Morley's Hospital. James Ambrose developed a close relationship with Godfrey Hounsfield and the prototype scanner was installed in the hospital on the 1st October 1971. The scanning time was four minutes per slice with a slice thickness of a little over one centimetre.  There was no computer attached to machine and the data was taken on magnetic tape to be analysed by EMI.  Ambrose had felt that at least six months of work was needed to build up an appreciation of the normal and abnormal. The first patient was a 41 year old lady with a possible frontal lobe tumour. The data was acquired and the tapes were sent to EMI. The results were returned after two days. The tumour in the frontal lobe was clearly shown and Ambrose said the result caused Hounsfield and himself to jump up and down like football players who had just scored a winning goal. Radiology was changed forever. The first EMI CT scanner is on display in the Science Museum in South Kensington.

The British Society of Neuroradiologists met in Glasgow on October 12th 1972 and James Ambrose spoke about the new technique of computerised transverse axial scanning (BJR 1973; 46(545): 401-402).

The December 1973 edition of the BJR contained three papers on the new computerised transverse axial scanning (BJR 1973; 46(552): 1015-1015).The papers appeared as three parts. The first paper was by Godfrey Hounsfield (from the Central Research Laboratories of EMI Limited, Hayes, Middlesex) on “Computerised transverse axial scanning (tomography): Part 1. Description of system” (Hounsfield BJR 1973; 46(552): 1016-1022). Hounsfield described and illustrated the theories behind and applications of the new scanner. In the second paper James Ambrose (from Atkinson Morley’s Hospital, London, SW10) wrote on “Computerised transverse axial scanning (tomography): Part 2. Clinical Application” (Ambrose BJR 1973; 46(552): 1023-1047). In this paper Ambrose described the technique for scanning and illustrated the scans obtained with comparisons to anatomical specimens, angiography and nuclear medicine isotope brain scans. In the third paper BJ Perry and C Bridges (both from St. George’s Hospital in London) wrote on “Computerised transverse axial scanning (tomography): Part 3. Radiation dose considerations” (Perry and Bridges BJR 1973; 46(552): 1048-1051). This was an important topic.

R Paxton and James Ambrose spoke to the British Society of Neuroradiologists in a meeting held at Atkinson Morley’s Hospital (St. George’s Hospital) on the 19th January 1974 about this new technique of EMI scanning and the hospital had now scanned 650 patients (BJR 1974; 47(560): 515-517)  and in September 1974 they published what they called a ‘brief review’ but the paper is actually a long and detailed analysis of their pioneer work (Paxton and Ambrose BJR 1974; 47(561): 530-565). The prototype scanner had by then been installed for two years with the first year being devoted to evaluation; however in the second year the machine was put to full clinical use. In the November of 1974 James Ambrose with Glynn Lloyd (from Moorfields Eye Hospital) and JE Wright described their experience of the CT scanner (The “Emiscan”) in orbital disease (Ambrose, Lloyd and Wright BJR 1974; 47(563): 747-751). The initial CT scanner used an 80x80 matrix for image display however in this paper a 160x160 matrix was used and the detail obtained was dramatically improved.

In 1974 James Ambrose and Godfrey Hounsfield received the Barclay Prize of the British Institute of Radiology and the honorary membership of the Institute in 1980.

In 1977 the neuroradiologist James W D Bull, from the National Hospital in Queen Square, stated that the result of Hounsfield’s discovery had been to transform investigative medicine and that until his discovery X-ray photography had not advanced fundamentally since Röntgen X-rayed his wife’s hand in his laboratory in Würzburg in 1895.

The initial EMI scanner images were obtained as Polaroid photographs. The digital images could be reviewed on the scanner. By December 1974 RA Shields, Ian Isherwood and RB Pullan from Manchester had scanned 1500 patients and were viewing the images on a console independent of the scanner itself (Shields, Isherwood and Pullan BJR 1974; 47(564): 893-895).

Following the success of the head scanner the first body scanner was installed at Northwick Park Hospital under the directorship of Louis Kreel. The results obtained transformed our views of the body and changed forever how medicine was practiced.

In July 1976 AK Ommaya and others including James Ambrose and Godfrey Hounsfield wrote an interesting paper on the estimation of spatial and density resolution in CT scanning (Ommaya, Murray, Ambrose, Richardson & Hounsfield BJR 1976; 49(583): 604-611). They emphasised the value of CT scanning in non-invasive diagnosis and serial evaluation of cerebral disease.

The radiation dose to patients from the CT scanner (EMI brain and body scanners) was investigated by BF Wall from the NRPB and DAC Green from EMI Medical Ltd in March 1979 (Wall, Green and Veerappan BJR 1979; 52(615): 189-196). They concluded that at that time doses were similar to conventional radiography.

Radiation dosage from CT scan of head

Image source: Wall, Green and Veerappan BJR 1979; 52(615): 189-196

 

Magnetic resonance imaging (MRI)

Some of the earliest articles on magnetic resonance imaging were to appear in the British Journal of Radiology. In 1946 Felix Bloch in Stamford and Edward Purcell built on the work of Rabi in Columbia and performed the first nuclear magnetic resonance experiments. In 1973 Mansfield and Grannell in Nottingham described NMR diffraction in solids and Lauterbur in New York used the shift in resonant frequency to spatially localise the magnetic resonance signal.

In March 1977 P Mansfield and AA Maudsley from Nottingham University described the application of the new magnetic resonance (NMR) method for fast scan proton imaging (Mansfield and Maudsley BJR 1977; 50(591): 188-194).  There is promise of much to come. There are illustrations of a finger in colour with anatomical detail visible and the imaging of tumour tissue was discussed. In November 1978 the Nottingham group of P Mansfield, IL Pykett, G Morris and RE Coupland published a further paper in the BJR (Mansfield, Pykett, Morris and Coupland BJR 1978; 51(611): 921-922) showing a human whole body line-scan image obtained with NMR. Again the images are very primitive and again there was a promise of much in the future.

WS Hinshaw, ER Andrew, PA Bottomly, GN Holland, WS Moore and Brian Worthington from Nottingham produced high-definition cross-sectional images of a rabbit using NMR in April 1978 (Hinshaw, Andrew, Bottomley, Holland, Moore and Worthington BJR 1978; 51(604): 273-280). The paper emphasised that NMR would be able to provide functional information of diagnostic value as well as anatomical information. By January 1979 they were able to demonstrate anatomical detail in the living human fore-arm (Hinshaw, Andrew, Bottomley, Holland, Moore and Worthington BJR 1979; 52(613): 36-43) and anatomical detail was quite recognisable. They saw MRI as more than an alternative to CT scanning since it would become possible to achieve tissue discrimination and characterisation through the analysis of the complex NMR signal. How right they proved to be in this prediction.

Fore-arm and hand NMR imaging 

Image source: Hinshaw, Andrew, Bottomley, Holland, Moore and Worthington BJR 1979; 52(613): 36-43

 

Ultrasound

John Mallard from Aberdeen made many contributions to the development of radiology. In January 1974 in a paper by David Watmough and David Crippin (Watmough, Crippin and Mallard BJR 1974; 47(553): 24-33) he critically assessed the current state of fetal head measurement using ultrasound. The measurement of the fetal head was not easy with the early apparatus as DJ Watmough and D Haddad showed (Whatmough, Crippin and Haddad BJR 1974; 47(558): 352-355).

CR Hill and DA Carpenter gave an interesting account of ultrasound imaging in March 1976 (Hill and Carpenter BJR 1976: 49(579): 238-243). They were interested in the analysis of tissue structure and described recent advances.

By 1979 CR Bow and others from Edinburgh were demonstrating a hand held real-time scanner for abdominal and cardiac scanning (Bow, McDicken, Anderson et al BJR 1097; 52(613): 27-33). This mechanical sector scanner was a real advance on previous ultrasound machines.  The scanner had a rotating transducer as the head. There was an interesting review of recent advances in ultrasound.

Rotating transducer and scan of heart

Image source: Bow, McDicken, Anderson et al BJR 1097; 52(613): 27-33

 

Nuclear medicine

John Mallard from Aberdeen made many contributions to the development of radiology. 
In April 1973 in a paper by AR Bowley and others (Bowley, Taylor, Causer, Barber, Keyes, Undrill, Corefield and Mallard BJR 1973: 46(544): 262-271) he described a new radioisotope scanner that that was capable of rectilinear, arc and longitudinal and transverse sector scanning – the Aberdeen Sector Scanner. Standard scanning techniques were often not enough and isotope tomography was an important development. In May 1973 with WI Keyes we see Mallard showing elegant colour images from a rectilinear scanner that were  ratemeter controlled (Keyes and Mallard BJR 1973; 46(545): 369-374).

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