Synchrotrons for hadron therapy: Part I

Abstract

The treatment of cancer with accelerator beams has a long history with linacs, cyclotrons and now synchrotrons being exploited for this purpose. Treatment techniques can be broadly divided into the use of spread-out beams and scanned 'pencil' beams. The Bragg-peak behaviour of hadrons makes them ideal candidates for the latter. The combination of precisely focused 'pencil' beams with controllable penetration (Bragg peak) and high, radio-biological efficiency (light ions) opens the way to treating the more awkward tumours that are radioresistant, complex in shape and lodged against critical organs. To accelerate light ions (probably carbon) with pulse-to-pulse energy variation, a synchrotron is the natural choice. The beam scanning system is controlled via an on-line measurement of the particle flux entering the patient and, for this reason, the beam spill must be extended in time (seconds) by a slow-extraction scheme. The quality of the dose intensity profile ultimately depends on the uniformity of the beam spill. This is the greatest challenge for the synchrotron, since slowextraction schemes are notoriously sensitive. This paper reviews the extraction techniques, describes methods for smoothing the beam spill and outlines the implications for the extraction line and beam delivery system.

Hadron accelerators for radiotherapy

“…The other widespread accelerator technology in use is the synchrotron [46], as typified by the Loma Linda (LLUMC) facility -the first purpose-built hospital-based proton therapy centre -and by the Hitachi PROBEAT 250 MeV synchrotron design installed by both Hitachi and Mitsubishi [64][65][66][67][68][69][70][71][72][73]. In contrast to cyclotrons, synchrotrons accommodate the change in p during acceleration by increasing the vertical guide field B y (t) so that ρ may be kept constant.…”

Beam Delivery Systems for Particle Radiation Therapy: Current Status and Recent Developments

“…Dedicated proton synchrotrons [5,26,27] with a typical diameter of 6-8 m, as well as synchrotrons for carbon ion therapy [27][28][29][30][31][32][33][34][35] with a typical diameter of 25 m, are offered by companies. The latter can also be used to accelerate other ion species, including protons.…”

Rotators for matching non-symmetric ion-therapy beams to rotating gantries

“…A "non-symmetric beam" stands for a beam with different emittance patterns in the two transverse planes. 2 There are several possibilities of matching these nonsymmetric beams to rotating gantries. [3][4][5] In this paper, the emphasis is paid to a technique based on a special matching section called the rotator.…”