Dose Delivery and Image-Based Monitoring Strategies in TERA Linac Complexes for Hadron Therapy

Hadron therapy (HT) uses the physical and biological properties of charged particles to treat solid tumors. This thesis aims to contribute to two main HT research topics: the development of affordable beam accelerators complexes and of detector systems allowing the monitoring and control of the delivered dose. Two new linac accelerators for HT of the TERA Foundation are further studied, consolidating the bridge between the accelerators and medical physics worlds. The study includes the development of a 3D simulation software, FLUKA Monte Carlo-based, capable to track particles through the accelerator lines ending in the patient’s body and fully predict HT beam characteristics. A new monitoring technique, called fast range verification, was developed and experimentally validated with the aim of verifying the Bragg Peak range for hadron treatments. It is based on Positron Emission Tomography and consists in β+ emitters detection from a short and low-dose pre-irradiation of a tumor part

Sparse proportional re-scanning with hadron beams

Spot Scanning is a well-established technique to deliver the dose with hadron therapy systems. For many years re-scanning (called also re-painting) has been used to achieve uniform dose distribution in particular for moving organs, although it leads to an increase of the treatment time. Reducing this time is a major focus of present research. In this paper, after reviewing the current re-scanning techniques, sparse proportional re-scanning is defined and applied to 29 proton patient cases for a total of 54 fields. In this technique, only the highest weighted spot in the whole target is visited a number of times that is equal to the number N of re-scans. The number of visits of the beam spot to all remaining spots is scaled down proportionally to their weight. Sparse proportional re-scanning is advantageous especially in volumetric re-scanning. In order to quantify the potential advantages of this technique in terms of treatment time, a reduction factor of the number of scanned spots has been introduced, evaluated and analysed for 54 proton fields. The conclusion is that the reduction factor is a function of N (having values equal to 2.8 ± 0.3 and 3.6 ± 0.4 for N = 5 and N = 12 respectively) and does not depend either on the shape and volume of the target or on the distance between the scanned layers and the spot grid. The same values are approximately valid also for carbon ion treatments

Coupling of Cyclotrons to Linacs for Medical Applications

Cyclotron and Linac technologies cover the vast majority of accelerator solutions applied to medicine. Cyclotrons with beams of H+/H-around 20 MeV are found for radioisotope production and cyclotrons with beams up to 250 MeV are widely used for protontherapy. Linacs are present in every medium-sized hospital with electron beams up to 20 MeV for radiotherapy and radioimaging. They have also recently become available as commercial products for protontherapy. The coupling of these two strong technologies enables to expand the capabilities of cyclotrons by using linacs as boosters. This opens the way to innovative accelerator systems allowing both radioisotope production and ion beam therapy (cyclinacs), new treatment techniques (high energy protontherapy) and new imaging techniques (proton radiography). This paper provides an overview of the technical challenges linked to coupling cyclotrons to linacs and the various solutions at hand

FLUKA particle therapy tool for Monte Carlo independent calculation of scanned proton and carbon ion beam therapy

While Monte Carlo (MC) codes are considered as the gold standard for dosimetric calculations, the availability of user friendly MC codes suited for particle therapy is limited. Based on the FLUKA MC code and its graphical user interface (GUI) Flair, we developed an easy-to-use tool which enables simple and reliable simulations for particle therapy. In this paper we provide an overview of functionalities of the tool and with the presented clinical, proton and carbon ion therapy examples we demonstrate its reliability and the usability in the clinical environment and show its flexibility for research purposes. The first, easy-to-use FLUKA MC platform for particle therapy with GUI functionalities allows a user with a minimal effort and reduced knowledge about MC details to apply MC at their facility and is expected to enhance the popularity of the MC for both research and clinical quality assurance and commissioning purposes

Few-seconds range verification with short-lived positron emitters in carbon ion therapy

: In-beam PET (Positron Emission Tomography) is one of the most precise techniques for in-vivo range monitoring in hadron therapy. Our objective was to demonstrate the feasibility of a short irradiation run for range verification before a carbon-ion treatment. To do so a PMMA target was irradiated with a 220 MeV/u carbon-ion beam and annihilation coincidences from short-lived positron emitters were acquired after irradiations lasting 0.6 s. The experiments were performed at the synchrotron-based facility CNAO (Italian National Center of Oncological Hadrontherapy) by using the INSIDE in-beam PET detector. The results show that, with 3·107 carbon ions, the reconstructed positron emitting nuclei distribution is in good agreement with the predictions of a detailed FLUKA Monte Carlo study. Moreover, the radio-nuclei production is sufficiently abundant to determine the average ion beam range with a σ of 1 mm with a 6 s measurement of the activity distribution. Since the data were acquired when the beam was off, the proposed rapid calibration method can be applied to hadron beams extracted from accelerators with very different time structures

Beam parameters optimization and characterization for a TUrning LInac for Protontherapy

TULIP (TUrning LInac for Protontherapy) is a novel compact accelerator system for protontherapy mounted on a rotating gantry (Amaldi et al., 2013, 2010, 2009). Its high-energy Linac has the unique property of being able to modulate the beam energy from one pulse to the next, in only a couple of milliseconds. The main purpose of this study is to optimize the properties of the beam exiting the Linac to make them compatible to medical therapy and to characterize their medical physics properties for later implementation in a Treatment Planning System. For this purpose, multi-particle tracking and Monte Carlo (MC) simulations are used to follow the particles through their path up to the treatment isocenter, following the so-called phase-space method. The data compiled includes particle fluences in air and depth-dose curves and provides the basis for a specific model of the TULIP beam

Beam parameters optimization and characterization for a TUrning LInac for Protontherapy

TULIP (TUrning LInac for Protontherapy) is a novel compact accelerator system for protontherapy mounted on a rotating gantry (Amaldi et al., 2013, 2010, 2009). Its high-energy Linac has the unique property of being able to modulate the beam energy from one pulse to the next, in only a couple of milliseconds. The main purpose of this study is to optimize the properties of the beam exiting the Linac to make them compatible to medical therapy and to characterize their medical physics properties for later implementation in a Treatment Planning System. For this purpose, multi-particle tracking and Monte Carlo (MC) simulations are used to follow the particles through their path up to the treatment isocenter, following the so-called phase-space method. The data compiled includes particle fluences in air and depth-dose curves and provides the basis for a specific model of the TULIP beam