Florea Scarlat
National Institute for Laser, Plasma and Radiation Physics, Romania
Title: Basic principles in conventional and laser driven therapy accelerators
Biography
Biography: Florea Scarlat
Abstract
Radiation beams used in therapy for a malignant tumor treatment located in a patient's body, should meet two conditions: 1. to have sufficient energy to penetrate to the depth of the tumor; and 2. the radiation intensity after equalization on the radiation field at the entrance to the tumor to provide the energy absorbed per unit mass of 2 Gy per session. The paper presents the principles of electromagnetic acceleration of leptons and hadrons used in radiotherapy. Particle beams are provided by conventional accelerators based on the principle of electromagnetic acceleration in the field of radiofrequency, non-resonant (betatron and betatron linear), resonant with cavities (microtron, isochronous cyclotron, synchro-cyclotron and synchrotron) and resonant with waveguides (linac). Conventional accelerators based on radiofrequency technology have the deficiency of a relatively low acceleration gradient which leads to a small ratio between the length of the acceleration space and the length of the trajectory traveled by the beam. In order to increase this ratio and to reduce the weight of the accelerator, the superconducting magnets technology was used. Acceleration principles for new models of accelerators are presented: fixed field alternating gradient accelerator (FFAG) - a combination of cyclotron and synchrotron, dielectric wall accelerator (DWA), which is the type of conventional induction accelerator and dielectric laser accelerator (DLA) - which instead of radiofrequency waves it uses a laser beam to generate electric fields for accelerating in the dielectric structure. The disadvantage of RF waves about acceleration gradient is removed by using the relativistic mode when laser provide a peak amplitude of the transverse electric field of a linear polarized laser pulse greater with about four orders of magnitude. The principles of laser acceleration of electrons, gases and plasmas and the principles of acceleration TNSA and RPA for hadrons are presented.