Speaker
Nigel Allinson
(U)
Description
Proton therapy as an alternative to conventional radiotherapy is rapidly gaining momentum. Forty-eight treatment centres are in operation worldwide, with a further 38 planned or under construction. The first large-scale hospital-based facility opened in 1990. Some 100,000 patients have been treated using protons – a small fraction of the total numbers who have received radiotherapy as part of their curative treatment; but the prospects for much increased use of proton therapy for childhood cancers, tumours near critical organs and potentially the effective treatment of lung cancer.
Advantage of proton, and other charged hadron therapies, is the ability to deliver very high doses into small volumes, possibly deep inside a patient, with much reduced damage to surrounding healthy tissue. This is because protons produce more ionisation (and therefore cause more cellular damage) at one particular depth that is strongly dependant on the energy of the proton – the Bragg Peak. This prime advantage is also the major challenge.
PRaVDA is a consortium of six universities, four NHS Trusts, and the South African National Research Foundation (iThemba Laboratory for Accelerator-Based Sciences) that is developing a unique instrument for the real-time monitoring of proton dose and distribution as well as the creation of Proton CT imagery.
The instrument employs 12 custom strip detectors to track the individual protons entering and, under the imaging conditions, exiting the patient. The residual energy of the egressing protons is recorded using a range telescope consisting of 24 layers of wafer-scale radiation-hardened CMOS imagers operating at over 1,000 fps.
This presentation will discuss the design philosophy of the instrument, selected findings from extensive simulations and initial experiments on proton beams up to 200 MeV; as well as the theory and practice underlying the fully analytic reconstruction of Proton CT images.
PRaVDA is supported by a Translational Grant awarded by the Wellcome Trust.
Author
Nigel Allinson
(U)
