GATE (Geant4 Application for Emission Tomography) is a Monte Carlo simulation platform developed by the OpenGATE collaboration since 2001 and first publicly released in 2004. Dedicated to the modelling of planar scintigraphy, single photon emission computed tomography (SPECT) and positron emission tomography (PET) acquisitions, this platform is widely used to assist PET and SPECT research. A recent extension of this platform, released by the OpenGATE collaboration as GATE V6, now also enables modelling of x-ray computed tomography and radiation therapy experiments. This paper presents an overview of the main additions and improvements implemented in GATE since the publication of the initial GATE paper (Jan et al 2004 Phys. Med. Biol. 49 4543–61). This includes new models available in GATE to simulate optical and hadronic processes, novelties in modelling tracer, organ or detector motion, new options for speeding up GATE simulations, examples illustrating the use of GATE V6 in radiotherapy applications and 0031-9155/11/040881+21$33.00 © 2011 Institute of Physics and Engineering in Medicine Printed in the UK 881

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GATE V6: a major enhancement of the GATE simulation platform enabling modelling of CT and radiotherapy

High-energy beams of charged nuclear particles (protons and heavier ions) offer significant advantages for the treatment of deep-seated local tumors in comparison to conventional megavolt photon therapy. Their physical depth-dose distribution in tissue is characterized by a small entrance dose and a distinct maximum (Bragg peak) near the end of range with a sharp fall-off at the distal edge. Taking full advantage of the well-defined range and the small lateral beam spread, modern scanning beam systems allow delivery of the dose with millimeter precision. In addition, projectiles heavier than protons such as carbon ions exhibit an enhanced biological effectiveness in the Bragg peak region caused by the dense ionization of individual particle tracks resulting in reduced cellular repair. This makes them particularly attractive for the treatment of radio-resistant tumors localized near organs at risk. While tumor therapy with protons is a well-established treatment modality with more than 60 000 patients treated worldwide, the application of heavy ions is so far restricted to a few facilities only. Nevertheless, results of clinical phase I-II trials provide evidence that carbon-ion radiotherapy might be beneficial in several tumor entities. This article reviews the progress in heavy-ion therapy, including physical and technical developments, radiobiological studiesmore » and models, as well as radiooncological studies. As a result of the promising clinical results obtained with carbon-ion beams in the past ten years at the Heavy Ion Medical Accelerator facility (Japan) and in a pilot project at GSI Darmstadt (Germany), the plans for new clinical centers for heavy-ion or combined proton and heavy-ion therapy have recently received a substantial boost.« less

Heavy-ion tumor therapy: Physical and radiobiological benefits

We describe a novel approach to treatment planning for heavy-ion radiotherapy based on the local effect model (LEM) which allows us to calculate the biologically effective dose not only for the target region but also for the entire irradiation volume. LEM is ideally suited for use as an integral part of treatment planning code systems for active dose shaping devices like the GSI raster scan system. Thus it has been incorporated into our standard treatment planning system for ion therapy (TRiP). Single intensity modulated fields can be optimized with respect to a homogeneous biologically effective dose. The relative biological effectiveness (RBE) is calculated separately for each voxel of the patient CT. Our radiobiologically oriented code system has been used since 1995 for the planning of irradiation experiments with cell cultures and animals such as rats and minipigs. It has been in regular and successful use for patient treatment planning since 1997.

https://iopscience.iop.org/article/10.1088/0031-9155/45/11/314/pdf

Treatment planning for heavy-ion radiotherapy: calculation and optimization of biologically effective dose.

Positron emission tomography (PET) imaging of radioactivity distributions induced by therapeutic irradiation is at present the only feasible method for an in situ and non-invasive monitoring of radiooncology treatments with ion beams Therefore, at the experimental carbon ion therapy facility at the Gesellschaft fur Schwerionenforschung Darmstadt, Germany (GSI) a PET scanner has been integrated into the treatment site for quality assurance monitoring simultaneously to the therapeutic irradiation Although the device has been assembled from components of positron emission tomographs developed for nuclear medicine applications, substantial modifications had to be made for meeting the requirements of ion therapy monitoring These changes regard the geometrical detector configuration as well as the data acquisition and processing Since 1997 this technique has been applied to monitor the fractionated irradiation of more than 180 patients predominantly suffering from tumours in the head and neck region It could be demonstrated that this new PET technique is capable of assessing parameters being relevant for quality assurance of carbon ion therapy, ie the particle range in tissue, the position of the irradiated volume with respect to anatomical landmarks and local deviations between the planned and the applied dose distributions

http://mi.sibet.cas.cn/kfjl/xshy/201310/W020131024553489293939.pdf

Charged hadron tumour therapy monitoring by means of PET

Radiotherapy is currently used in around 50% of cancer treatments and relies on the deposition of energy directly into tumour tissue. Although it is generally effective, some of the deposited energy can adversely affect healthy tissue outside the tumour volume, especially in the case of photon radiation (gamma and X-rays). Improved radiotherapy outcomes can be achieved by employing ion beams due to the characteristic energy deposition curve which culminates in a localised, high radiation dose (in form of a Bragg peak). In addition to ion radiotherapy, novel sensitisers, such as nanoparticles, have shown to locally increase the damaging effect of both photon and ion radiation, when both are applied to the tumour area. Amongst the available nanoparticle systems, gold nanoparticles have become particularly popular due to several advantages: biocompatibility, well-established methods for synthesis in a wide range of sizes, and the possibility of coating of their surface with a large number of different molecules to provide partial control of, for example, surface charge or interaction with serum proteins. This gives a full range of options for design parameter combinations, in which the optimal choice is not always clear, partially due to a lack of understanding of many processes that take place upon irradiation of such complicated systems. In this review, we summarise the mechanisms of action of radiation therapy with photons and ions in the presence and absence of nanoparticles, as well as the influence of some of the core and coating design parameters of nanoparticles on their radiosensitisation capabilities.

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Gold nanoparticles for cancer radiotherapy: a review

We describe a novel code system, TRiP, dedicated to the planning of radiotherapy with energetic ions, in particular 12C. The software is designed to cooperate with three-dimensional active dose shaping devices like the GSI raster scan system. This unique beam delivery system allows us to select any combination from a list of 253 individual beam energies, 7 different beam spot sizes and 15 intensity levels. The software includes a beam model adapted to and verified for carbon ions. Inverse planning techniques are implemented in order to obtain a uniform target dose distribution from clinical input data, i.e. CT images and patient contours. This implies the automatic generation of intensity modulated fields of heavy ions with as many as 40 000 raster points, where each point corresponds to a specific beam position, energy and particle fluence. This set of data is directly passed to the beam delivery and control system. The treatment planning code has been in clinical use since the start of the GSI pilot project in December 1997. Forty-eight patients have been successfully planned and treated.

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Treatment planning for heavy-ion radiotherapy: physical beam model and dose optimization.

The invention relates to a device and a method for controlling a raster scanner used in ion-beam therapy. Such a device for controlling a raster scanner comprises power supply units for supplying a magnetic current to ion-beam scanner magnets which deflect horizontally and vertically in relation to the ion-beam centre. The power supply units are controlled by control and read-out modules for the scanner magnets. The device further comprises a position-sensitive detector for position measurements, which is controlled via a control and read-out module. A sequence-control device controls the control and read-out process of the different apparatus of the device. A circuit in the sequence-control device comprises a feedback loop between the control and read-out modules for the control magnets and the control and read-out module of the position-sensitive detector. In addition, the control and read-out modules for the scanner magnets and the control and read-out module of the position-sensitive detector are arranged in the sequence-control device in such a way, as regards circuit connections and sequence control, that the control and read-out modules for the scanner magnets are series-connected downstream of the control and read-out module of the position-sensitive detector.

Device and method for controlling a raster scanner in ion-beam therapy

Target motion is one of the major limitations of each high precision radiation therapy. Using advanced active beam delivery techniques, such as the magnetic raster scanning system for particle irradiation, the interplay between time-dependent beam and target position heavily distorts the applied dose distribution. This paper presents a simulation environment in which the time-dependent effect of target motion on heavy-ion irradiation can be calculated with dynamically scanned ion beams. In an extension of the existing treatment planning software for ion irradiation of static targets (TRiP) at GSI, the expected dose distribution is calculated as the sum of several sub-distributions for single target motion states. To investigate active compensation for target motion by adapting the position of the therapeutic beam during irradiation, the planned beam positions can be altered during the calculation. Applying realistic parameters to the planned motion-compensation methods at GSI, the effect of target motion on the expected dose uniformity can be simulated for different target configurations and motion conditions. For the dynamic dose calculation, experimentally measured profiles of the beam extraction in time were used. Initial simulations show the feasibility and consistency of an active motion compensation with the magnetic scanning system and reveal some strategies to improve the dose homogeneity inside the moving target. The simulation environment presented here provides an effective means for evaluating the dose distribution for a moving target volume with and without motion compensation. It contributes a substantial basis for the experimental research on the irradiation of moving target volumes with scanned ion beams at GSI which will be presented in upcoming papers.

https://iopscience.iop.org/article/10.1088/0031-9155/49/14/001/pdf

Online compensation for target motion with scanned particle beams: simulation environment.

An arrangement and a method for controlling a radiation device, in particular for heavy ion therapy, are described. The arrangement comprises a chain of circuit modules (11-17), each circuit module (11-17) having a separate communication connection to a preceding circuit module and a separate communication connection to a following circuit module. In the method for controlling the radiation device by means of control modules (11-17) arranged in a chain, each control module (11-17) communicates separately with a preceding control module and separately with a following control module.

Apparatus and method for controlling a radiation device

PROBLEM TO BE SOLVED: To provide a device and method for controlling a radiation irradiator, especially, in a heavy-ion therapy. SOLUTION: This device is provided with a series of circuit modules (11-17), each circuit module (11-17) has a connection for communication to a preceding circuit module independently, and has a connection for communication to a subsequent circuit module independently. In the method for controlling a radiation irradiator by control modules (11-17) arranged in one chain, each control module (11-17) communicates with a preceding control module independently, and communicates with a subsequent control module independently.

Thomas Haberer

Papers

Treatment planning for heavy-ion radiotherapy: physical beam model and dose optimization.

Device and method for controlling a raster scanner in ion-beam therapy

Online compensation for target motion with scanned particle beams: simulation environment.

Apparatus and method for controlling a radiation device

Device and method for controlling radiation irradiator