What we do
The majority of radiotherapy treatments involve the use of x-rays or electrons (small charged particles). Sophisticated equipment is used to produce beams of radiation made of these particles, at NNUH we have a range of treatment units including several high and low energy linear accelerators. Each treatment unit is designed to include complex control mechanisms to assure the user of the quality and quantity of radiation delivered to the patient. All radiotherapy equipment is maintained by qualified electronic and mechanical engineers and routinely tested by Clinical Scientists who keep detailed records of machine performance. Maintaining equipment of such complexity is a multi-disciplinary task and requires active input from all staff who operate the equipment to ensure any issues are resolved as soon as they are identified, ensuring the quality of the service we provide.
Each patient receiving radiotherapy treatments is given independent consideration by a Radiation Oncologist and a radiation treatment strategy is determined that will maximise the radiation dose to the target volume and minimise any damage to surrounding body tissues. Advanced computer programmes are used to predict the radiation dose distributions from the various treatment options, from which the optimal plan is chosen. Dosimetrists are therapy radiographers who have received extensive, specialist training in the use of such software. Consideration of patient comfort such as the practicality of set-up and treatment time is also given high importance when creating each patient’s treatment plan.
Treatment planning is a multi-disciplinary task, Dosimetrists work with Clinical Oncologists to meet specific goals for each patient and are supported by Clinical Scientists who can assist with complex plans and to implement new protocols. Mould Room staff also work in conjunction with Dosimetrists to ensure the setup and immobilisation of patients is achievable, comfortable and reproducible.
The majority of radiotherapy treatments require high doses of ionising radiation to be administered to the patient. With such high doses, the margin between a successful clinical outcome and tissue damage can be small. It is therefore essential that when a radiation dose is prescribed by a Radiation Oncologist, the exact required dose is delivered to the patient.
One of the key roles of the Clinical Scientists working in Radiotherapy Physics is to accurately calibrate the radiotherapy treatment machines, so that we can be certain of the quantity of radiation delivered by the treatment machine. To ensure consistency, our calibrations can be traced back to the National Physics Laboratory and we routinely participate in national audits of our service.
Radiation dosimetry is a complex field requiring an in-depth knowledge of ionising radiation and its properties. Many factors affect the dose output of our treatment machines which must be calculated to a high degree of accuracy in order for them to be calibrated. All of our linear accelerators are calibrated such that they are identical, allowing us to treat the same patient on any machine.
We are currently using transit dosimetry which uses the on-board imager to measure dose from treatment beam after it has travelled through the patient, which allows us to confirm the correct delivery of the treatment.
Brachytherapy uses sources of radiation which are placed directly into or close to a tumour, permanently or temporarily, resulting in a localised delivered dose and minimal damage to healthy tissues.
At the NNUH, we perform HDR (high dose rate) brachytherapy, whereby applicators are inserted into the patient, and connected to the treatment machine which controls the positioning of the source. The source is then temporarily transported into the patient and the radiation dose is delivered in a number of seconds. Our radiotherapy service was the first globally to install the Bravos afterloader, and have since worked with the manufacturer to develop treatments for prostate and gynaecological cancers.
Clinical Scientists are responsible for the quality assurance of the machine. As well as creating the treatment plan to ensure the dose is delivered in the desired area.
Despite their therapeutic value, the potential hazards of dealing with ionizing radiations should never be underestimated. A key role of the Radiotherapy Physics Department is to provide advice about the risks and safe use of ionizing radiations and ensure the safety of all those within or nearby the department. Instructions and procedures are written to be fully compliant with national and international guidelines. New radiation areas within the hospital, such as treatment rooms and radionuclide storage facilities are carefully planned to minimise radiation exposure and regularly monitored.
All Radiotherapy Physics staff are trained in radiation protection and Clinical Scientists hold a post-graduate degree in Radiation Physics.
Geometric accuracy is paramount in radiotherapy to ensure we are treating the intended volume. We use a variety of immobilisation techniques to confirm the patient is in the correct location and position each time that they are treated. Examples of these methods are; immobilisation shells, vacbags and body boards, all of which are customised for each patient. In addition, Radiation Oncologists may require certain body tissues to be individually shielded. The manufacture of these immobilization and shielding devices is the responsibility of the Radiotherapy Physics Mould Room Technicians.
Mechanical Electronic Engineering
The Radiotherapy department contains a large amount of highly complex equipment which require constant monitoring and regular preventative maintenance. Our Electronic Engineers are highly trained in keeping equipment peak of performance and operating safely and efficiently. Should a piece of equipment fail, it is crucial that it is working again as soon as possible to minimise delays in treatment for our patients. Our Engineers work closely with Clinical Scientists as well as the manufacturers of our equipment.
Radiotherapy Physics Projects
Radiotherapy is a rapidly developing field, and a key role of all Radiotherapy Physics staff is to continue to update their knowledge of recent any changes in technology or clinical practice. We aim to implement relevant advances to ensure Radiotherapy service we provide is modern and consistent with other centres.
Recently completed development projects include:
- Treating spine SABR patients
- Implementing SunCHECK, an independent quality assurance program
- Commissioning the Acuros dose calculation algorithm
- Using Pro-Know to compare our plans to national standards
- Treating breast cancer using IMRT
Current development projects include:
- Commissioning a new CT scanner
- Commissioning a new linear accelerator
- SGRT (surface guided radiotherapy) – to improve accuracy of patient set-up matching and treatment when using breath hold techniques
- Introduction of RapidPlan – plans generated by a machine learning model to improve consistency and dose distribution.
- AI contouring – the use of AI to outline structures onto a CT scan.