A team of experts at the Peter MacCallum Cancer Centre has used complex mathematical modelling to predict the radiation dosage delivered using a powerful new technique that will enable some patients to safely receive their radiation therapy treatment in a single, ten-minute session.
Dr Shankar Siva, Radiation Oncologist in Peter Mac’s Stereotactic Ablative Body Radiation Therapy (SABR) Clinic says, until now, Peter Mac’s specialised TrueBeam stereotactic linear accelerator was fixed to its default ‘flattening filter’ setting, which limited the strength of the radiation beam.
‘Our medical physicists have now introduced an innovative method to predict the radiation dosage when this filter is removed, enabling us to accurately control the peak power of the stereotactic beam to deliver to a tumour a “knock-out punch” of up to 28 Gray of radiation in a single session over only a handful of minutes.
‘This shift is particularly important for our older patients who cannot lie still for prolonged periods and for others who are in discomfort due to their disease,’ he says.
One such patient, 80-year-old Harold Sciberras, will today become the first patient in Victoria to undergo the new flattening filter-free SABR treatment with a small primary lung cancer in his right lung irradiated at Peter Mac’s main site in East Melbourne.
‘The location of the tumour makes it very difficult to operate or target with conventional radiation without affecting my healthy lung tissue, so this new technique has certainly come at the right time for me, and many others in my situation.
‘The best news is I will be back at home in Diggers Rest tonight, and I will only need to return to Peter Mac for follow-up appointments.’
SABR treatment, first introduced to Australia at Peter Mac in 2010, sees patients held still by a vacuum-like plastic wrap while a 4D CT scanner tracks the tumour’s position as it moves when the patient breathes, enabling treatment to be delivered with greater accuracy and, therefore, fewer side-effects. SABR is used to treat small secondary tumours that have spread short distances from the primary tumour, or inoperable primary cancers in highly sensitive locations such as the lung, and is typically delivered over three to five treatment sessions of 40–60 minutes each. In comparison, conventional radiation therapy is delivered daily over a six to eight week period.
Dr Siva says it is a combination of the complex modelling calculations and carefully considered preparation of each case that will enable the SABR team to deliver higher dosages, and reduce treatment time even further.
‘SABR has been a game changer for people with difficult to treat tumours; the sharp delineation of the stereotactic beam greatly reduces damage to healthy tissue and allows for a higher dose through faster, more targeted delivery of radiation therapy and now, thanks to the work of our team, we can deliver this in one controlled blow for some of our patients.’
Source: Peter Mac