Author: Falbo, L.
Paper Title Page
MOPML021 Shorter Treatment Time by Intensity Modulation with a Betatron Core Extraction 439
 
  • M. G. Pullia, E. Bressi, G.M.A. Calvi, M. Donetti, L. Falbo, S. Foglio, V. Lante, A. Parravicini, C. Priano, E. Rojatti, S. Savazzi, C. Viviani
    CNAO Foundation, Milan, Italy
 
  The CNAO (National Center for Oncological Hadrontherapy) main accelerator is a synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Three treatment rooms are available and are equipped with horizontal beam lines; one of the treatment rooms also features a vertical treatment line to allow additional treatment ports. All of the beamlines are equipped with an active beam scanning system for dose delivery. With such a dose distribution technique, particles are sent to different depths by changing the energy from the synchrotron and are moved transversally by means of two scanning magnets. The number of particles to be deposited in each position varies strongly within the same iso-energetic layer. Part of the dose needed in a given position is in fact delivered by particles directed to deeper layers. In order to maintain the required precision on the number of particles delivered to each spot, the intensity is reduced when spots that require low number of particles are present in a layer. A method to shorten the irradiation time based on variable intensity within the same layer is presented that works also with a betatron based extraction scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML021  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPAF010 Empty Sweeping Bucket for Slow Extraction 676
 
  • L. Falbo, E. Bressi, C. Priano
    CNAO Foundation, Pavia, Italy
 
  The extraction process from a synchrotron is one of the most important aspects of an accelerator devoted to clinical purposes, like the hadrontherapy in which hadron beams are used to treat tumors. Indeed the quality of the dose delivered to the patient, in terms of dose uniformity and precision in the beam characteristics, is defined by the way in which the beam is extracted. The quality of the extracted beam (the so called spill) is strongly affected by the stability of the power supplies of the synchrotron magnets whose field stability creates a ripple in the intensity of the extracted beam itself. When it is not possible to improve the power supply stability, it is needed to apply some additional techniques in order to cure the spill ripple. At CNAO, the italian hadrontherapy facility, it has been thought to improve the Empty Bucket Channelling technique by using an energy-moving bucket instead of a stationary bucket. The paper shows the implementation, the advantages and the efficacy of this RF gymnastic, named 'Empty Sweeping Bucket'.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF010  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPAF011 Btrain Calibration with RF-Master Method 679
 
  • L. Falbo, E. Bressi, M. Pezzetta, C. Priano
    CNAO Foundation, Pavia, Italy
 
  CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. It is based on a synchrotron with a 77 m ring equipped with 16 normal conducting dipoles characterized by a long delay in the field stabilization. B-Train system is a fundamental device of the whole machine; it is used in feedback to the dipole power supply in order to regulate the magnetic field reducing the natural stabilization times that would cause long treatments. B-Train system allows to obtain the magnetic field starting from measurements of magnetic field changes: it works as an integrator and then it needs a system to reset the counts compensating the electronic and numerical drift of the system itself. An innovative method has been implemented at CNAO to reset Btrain counts exploiting beam measurements after the RF cavity trapping. This procedure has the advantage to avoid external and additional element like NMR probes. The paper shows the use of B-train system at CNAO and its calibration with this method, called "RF-master method".  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF011  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUZGBF3 Betatron Core Slow Extraction at CNAO 1237
 
  • L. Falbo, E. Bressi, S. Foglio, C. Priano
    CNAO Foundation, Pavia, Italy
 
  CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.  
slides icon Slides TUZGBF3 [2.151 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF3  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)