Radiotherapy: 40 years from tracing paper to tomotherapy

NHS

Physicist Andy Moloney and Clinical Oncologist David Morgan reflect on how radiotherapy developed since their early careers

 

We first met in the autumn of 1981, when the NHS was, at 33 years from its inception, but a youngster. Andy had recently joined the Radiotherapy Physics staff at Nottingham General Hospital after graduating in Physics from the University of Nottingham, and David was returning to the clinical Department of Radiotherapy and Oncology after a year’s Fellowship at the Institut Gustave-Roussy in France. A firm friendship rapidly developed, one that continues to this day.

On reflection, joining the radiotherapy fraternity at that time was a leap of faith. The perceived wisdom amongst many of our scientific and clinical colleagues at the time was that this treatment technique was outdated and overshadowed by radical surgical procedures, new chemotherapy agents and biological modifiers poised to reduce radiotherapy to the history books.

picture 063This was a time when, in this Cinderella of specialties, physics planning was achieved by the superposition of two dimensional radiation plots (isodoses) ,using tracing paper and pencils, to produce summated maps of the distribution. The crude patient outlines were derived from laborious isocentric distance measurements augmented by the essential “flexicurve”. The whole planning process was slow and labour intensive fraught with errors and ridiculed by colleagues in the perceived prestigious scientific and clinical disciplines. The principal platform for external beam radiotherapy delivery, the Linear Accelerator (LinAc), had also reached something of a plateau of development, albeit with improved reliability, but few fundamental changes. Caesium tubes were transported from the “radium safe”, locked in an underground vault, to the operating theatre in a lead-lined trolley, where they were only loaded into “central tubes” and “ovoids” after the examination under anaesthetic (which was performed with the patient in the knee-chest position); they were then manually placed into the patient, who went to be nursed on an open ward, albeit behind strategically placed lead barriers.

For no sites outside the cranium was Computer Tomography (CT) scanning available. Magnetic Resonance Imaging (MRI) was still a vision seen only by a small number of enthusiasts.

All these limitations were met by a developing team of scientific and clinical enthusiasts believing in the future of radiotherapy if only technology could deliver solutions to address an improving understanding of the differing cancers and their radiobiology.

picture 066In the latter half of the eighties these solutions began to crystallise. Computers were being introduced across the NHS and their impact was not lost in radiotherapy. Pads of tracing paper were replaced with the first generation of planning computers. The simple “Bentley-Milan” algorithms could account for patient outlines accurately and speedily and optimising different beam configurations became practical. Consideration of Organs at Risk, as defined by the various International Commission on Radiation Units (ICRU) publications, became increasingly relevant. Recognition of the importance of delineating the target volumes and protecting normal tissue required improved imaging and this was provided by the new generation of CT scanners. In the nineties these were shared facilities with diagnostic radiology departments. However, the improvements provided by this imaging, enabling accurate 3-dimensional mapping of the disease with adjacent normal tissues and organs at risk, dictated their inclusion into every radiotherapy department soon after the millennium. The added bonus of using the grey scale pixel information, or Hounsfield numbers, to calculate accurate radiation transport distributions soon followed when the mathematical and computer technology caught up with the task. The value of MR and Positron Emission Tomography (PET) imaging was also recognised in the diagnosis, staging and planning of radiotherapy and the new century saw all of these new technologies embedded within the department.

Mould room technology was also improving with “instant” thermoplastic immobilisation shells replacing the uncomfortable plaster and vacuum forming methods. Custom shielding with low melting high density alloys was becoming routine and it was not long before these techniques were married with the emerging CT planning to provide “conformal” treatments.

picture 067LinAc technology also received added impetus. Computers were firstly coupled as a front end to conventional LinAcs as a safety interface to reduce the potential for “pilot error”. Their values were soon recognised by the manufacturers and were increasingly integrated into the machine, monitoring performance digitally and driving the new developments of Multi Leaf Collimators (MLC) and On Board Imaging (OBI).

The dominos for the radiotherapy renaissance were stacked up, but it needed the radiographers, clinicians and scientists to decide on the direction of travel. Computer power coupled with advanced electro-mechanical design had transformed MLC efficiency and resolution. Conventional conformal planning was now progressively superseded by sophisticated planning algorithms using merged CT and MR images. Intensity Modulated RadioTherapy (IMRT) had arrived in its evolving guises of multiple fixed field, dynamic arc therapy (RapidArc) or Tomotherapy. Whichever technique, they all offered the radiotherapy “Holy Grail” of providing three dimensional homogeneous dose distributions conformed to the Planning Target Volume (PTV) whilst achieving the required dose constraints for organs at risk and normal tissue preservation.

The tools had arrived, but an infrastructure to introduce these “toys” safely into a complex clinical background had also developed alongside. Quality standards (ISO9000), Clinical Trials, Multi Disciplinary Teams and Peer Review were governance mandates for all oncology departments and radiotherapy was leading the way. In forty years, radiotherapy had lost the “Cinderella” image and had been invited back to the clinical ball. Noticeably, breast and prostate adenocarcinoma constituted half of the radical workload.

The question remains of how and why did this transformation occur? Obviously the developing computer power and technology were the pre-requisites for many of the developments, but a key catalyst was the foresight of all of the radiotherapy family from which enduring friendships have been forged. The working lives of the clinicians and physicists involved in radiotherapy planning have probably changed more dramatically than those of any other medical and paramedical groups over the last 35 years.

We may have retired, but we still cogitate about the future direction and science behind this developing and essential cancer treatment and look forward to our younger colleagues enjoying their careers as much as we enjoyed ours.

 


About David Morgan

david morganDr David A L Morgan began training in Radiotherapy & Oncology as a Registrar in 1977, and in 1982 was appointed a Consultant in the specialty in Nottingham, continuing to work there until his retirement in 2011. He joined the BIR in 1980 and at times served as Chair of its Oncology Committee and a Member of Council. He was elected Fellow of the BIR in 2007. He is author or co-author of over 100 peer-reviewed papers on various aspects of Oncology and Radiobiology.

 

About Andrew Moloney

andy moloneyAndy Moloney completed his degree in Physics at Nottingham University in 1980 before joining the Medical Physics department at the Queens Medical Centre in the same city. After one year’s basic training in evoked potentials and nuclear medicine, he moved to the General Hospital in Nottingham to pursue a career in Radiotherapy Physics and achieved qualification in 1985. Subsequently, Andy moved to the new radiotherapy department at the City Hospital, Nottingham, where he progressed up the career ladder until his promotion as the new head of Radiotherapy Physics at the North Staffordshire Royal Infirmary in Stoke-on-Trent. Over the next twenty years Andy has acted as Clinical Director for the oncology department and served on the Radiation Physics and Oncology Committees at the BIR and was appointed a Fellow in 2007. He has been the author and co-author of multiple peer reviewed articles over the years prior to his retirement in 2017.

 

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