Accelerator science in medical physics

Peach, Ken; Wilson, Puthenparampil; Jones, Bleddyn

doi:10.1259/bjr/16022594

Cited by 19 publications

(15 citation statements)

References 8 publications

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“…The former, due to their fast cycling and larger beam current characteristics, provide higher dose rates than the latter. More advanced accelerator designs, such as the non-scaling fixed-field alternating gradient (NS-FFAG) and dielectric wall accelerators [14][15][16], could, in principle, deliver much higher dose rates, with the potential advantage of shorter patient treatment times and some degree of improved throughput, even though set-up time is usually longer than treatment time. Personal observations of synchrotron treatments in Japan can take over 2 h to deliver a single radical fraction, although at least half of the time is taken up by positioning of patients and verification of each of four different treatment fields.…”

mentioning

confidence: 99%

Revisiting the ultra-high dose rate effect: implications for charged particle radiotherapy using protons and light ions

Wilson

Jones²,

Yokoi³

et al. 2012

BJR

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Objective: To reinvestigate ultra-high dose rate radiation (UHDRR) radiobiology and consider potential implications for hadrontherapy. Methods: A literature search of cellular UHDRR exposures was performed. Standard oxygen diffusion equations were used to estimate the time taken to replace UHDRRrelated oxygen depletion. Dose rates from conventional and novel methods of hadrontherapy accelerators were considered, including spot scanning beam delivery, which intensifies dose rate. Results: The literature findings were that, for X-ray and electron dose rates of around 10 9 Gy s -1 , 5-10 Gy depletes cellular oxygen, significantly changing the radiosensitivity of cells already in low oxygen tension (around 3 mmHg or 0.4 kPa). The time taken to reverse the oxygen depletion of such cells is estimated to be over 20-30 s at distances of over 100 mm from a tumour blood vessel. In this time window, tumours have a higher hypoxic fraction (capable of reducing tumour control), so the next application of radiation within the same fraction should be at a time that exceeds these estimates in the case of scanned beams or with ultra-fast laser-generated particles. Conclusion: This study has potential implications for particle therapy, including lasergenerated particles, where dose rate is greatly increased. Conventional accelerators probably do not achieve the critical UHDRR conditions. However, specific UHDRR oxygen depletion experiments using proton and ion beams are indicated.

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mentioning

confidence: 99%

Revisiting the ultra-high dose rate effect: implications for charged particle radiotherapy using protons and light ions

Wilson

Jones²,

Yokoi³

et al. 2012

BJR

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“…In contrast to x-ray therapy, radiotherapy with charged hadronic species such as protons feature a depth-dose curve that concentrates the dose around the Bragg peak, a characteristic of the Bethe-Bloch energy loss for these particles. 24,25,26,27,28 The depth at which the peak occurs increases with particle energy; for incident protons above 70 MeV an approximate rule of thumb is that protons lose around 1 MeV per millimetre of water traversed, although this reduces with increasing incident energy. The range of a 230 MeV proton is roughly 33 cm in water, so that this energy is sufficient to be used for tumour treatment in a typical adult patient.…”

Section: Particle Therapymentioning

confidence: 99%

Technologies for delivery of proton and ion beams for radiotherapy

Owen

Holder

Alonso

et al. 2014

Int. J. Mod. Phys. A

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Recent developments for the delivery of proton and ion beam therapy have been significant, and a number of technological solutions now exist for the creation and utilisation of these particles for the treatment of cancer. In this paper we review the historical development of particle accelerators used for external beam radiotherapy and discuss the more recent progress towards more capable and cost-effective sources of particles.

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“…Protons are not absorbed; they deposit their kinetic energy gradually and at a rate inversely proportional to that energy (that is, inversely proportional to the velocity squared for nonrelativistic particles), so that most of the energy is deposited near to the end of the proton's range in a target; this highdose end is the Bragg peak. The Bethe-Bloch equation that describes this varies slightly according to which corrections are used [29][30][31], but a common formula (from the Particle Data Group [32]) is…”

Section: Hadron Therapymentioning

confidence: 99%

“…As its inventor Ernest Lawrence realisedand for which he was awarded a Nobel Prize -as low energy protons are accelerated their speed increases with their kinetic energy such that their revolution frequency remains constant [31,[47][48][49].An alternating voltage applied with constant frequency to the gap between the dees enables the protons to be accelerated when crossing the gap in either direction, the applied frequency f a being either the same as the revolution frequency f r or some harmonic of it h = f r / f a ; h is termed the harmonic number. Lawrence's key insight was the observation that the bend radius ρ in a given field strength B is proportional to the proton momentum p such that…”

Section: Cyclotronsmentioning

confidence: 99%

Hadron accelerators for radiotherapy

Owen

Mackay

Peach

et al. 2014

Contemporary Physics

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Over the last twenty years the treatment of cancer with protons and light nuclei such as carbon ions has moved from being the preserve of research laboratories into widespread clinical use. A number of choices now exist for the creation and delivery of these particles, key amongst these being the adoption of pencil beam scanning using a rotating gantry; attention is now being given to what technologies will enable cheaper and more effective treatment in the future. In this article the physics and engineering used in these hadron therapy facilities is presented, and the research areas likely to lead to substantive improvements. The wider use of superconducting magnets is an emerging trend, whilst further ahead novel high-gradient acceleration techniques may enable much smaller treatment systems. Imaging techniques to improve the accuracy of treatment plans must also be developed hand-in-hand with future sources of particles, a notable example of which is proton computed tomography.

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Accelerator science in medical physics

Cited by 19 publications

References 8 publications

Revisiting the ultra-high dose rate effect: implications for charged particle radiotherapy using protons and light ions

Revisiting the ultra-high dose rate effect: implications for charged particle radiotherapy using protons and light ions

Technologies for delivery of proton and ion beams for radiotherapy

Hadron accelerators for radiotherapy

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