Proton beam therapy is an advanced form of external radiotherapy that uses high-energy proton beams instead of photon x-ray beams or electrons. Carefully measured doses of protons are delivered to the precise area needing treatment, using the latest IBA ProteusONE technology. This ensures that the delivery of proton beam therapy is highly accurate and prevents the risk of radiation reaching surrounding healthy tissue.
Radiotherapy is used to kill and destroy cancer cells. It utilises radiation in the form of high-energy x-rays, known as photons, to kill and damage the cancerous cells and prevent their growth and reproduction. It can be used as a non-surgical option to treat cancer, and it can also be used to shrink a tumour or in combination with other treatments.
The Rutherford Cancer Centres and Elekta are bringing the next generation of personalised adaptive radiotherapy technology to oncology centres across the UK, with the new MR-linac Elekta Unity now available at the Rutherford Cancer Centre North West in Liverpool.
The knowledge of proton depth-dose curves, or "Bragg curves," is a fundamental prerequisite for dose calculations in radiotherapy planning, among other applications. In various cases it is desirable to have an analytical representation of the Bragg curve, rather than using measured or numerically calculated data. This work provides an analytical approximation of the Bragg curve in closed form.
The underlying model is valid for proton energies between about 10 and 200 MeV. Its main four constituents are: (i) a power-law relationship describing the range-energy dependency; (ii) a linear model for the fluence reduction due to nonelastic nuclear interactions, assuming local deposition of a fraction of the released energy; (iii) a Gaussian approximation of the range straggling distribution; and (iv) a representation of the energy spectrum of poly-energetic beams by a Gaussian with a linear "tail."
Based on these assumptions the Bragg curve can be described in closed form using a simple combination of Gaussians and parabolic cylinder functions. The resulting expression can be fitted to measurements within the measurement error. Very good agreement is also found with numerically calculated Bragg curves.
Bortfeld T. An analytical approximation of the Bragg curve for therapeutic proton beams. Med Phys. 1997 Dec;24(12):2024-33. doi: 10.1118/1.598116. PMID: 9434986.
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