Hadron Therapy Centers Research Articles

The clinical roadmap in a dual-beam hadrontherapy centre: tumour-based and patient-tailored selection criteria, management of range uncertainties and oncological patient pathway

PurposeIn the present short report, we encompass the radiobiological and dosimetric advantages of particle beam radiotherapy and we illustrate the oncological pathway for patients eligible for hadrontherapy being used at the National Center for Oncological Hadrontherapy (CNAO).MethodsWith a narrative approach, we examined the clinical and practical aspects of hadrontherapy compared to traditional photon beam radiotherapy. We described the need to select patients considering the intrinsic characteristics both of the tumour and the patient. Moreover, we described the decisional oncological tree and the patient pathway by our facility.ResultsConsidering the dosimetric and radiobiological characteristics of particle beam radiotherapy, the selection of patients can not be done regardless of the intrinsic tumour and patient hallmarks. In particular, the tumour radioresistance, the patient radiosensitivity and the need to avoid post-actinic toxicities in long-term survivors should guide the clinical indication. The finite range of particles should be considered to avoid treatment uncertainties. Multidisciplinary national and international collaboration is crucial to better manage patients to treat with hadrontherapy and to create robust clinical evidence.ConclusionHadrontherapy, with its distinctive physical and biological advantages, heralds a promising era in the field of precision radiotherapy. Patients’ radiosensitivity, tumour radioresistance, and treatment uncertainties should be considered to enhance the efficacy and to ameliorate the selection of patients.

Energy saving magnets for beam lines

Beam lines magnets for high rigidity particles can have a large power dissipation. In presence of a high duty cycle, this translates in a considerable amount of energy waste. The call for sustainability of large research infrastructures, like particle accelerator centers, and the recent increase of the cost of energy, require to take measures to reduce the energy consumption, even at cost of moderate investment. A study program called ESABLIM (Energy SAving Beam LIne Magnets) has been set up at the LASA lab of University and INFN Milano, aimed at revamping existing normal-conducting magnets for beam lines with the target of cutting the peak power by a factor 10 to 20 and reducing the energy consumption by factor 5 or more. The idea is to replace the water cooled coils of iron-dominated magnets with new superconducting coils cooled at 10-20 K by means of a cryocooler, while to reusing the iron yoke pole assembly. We envisage using MgB2 for its moderate cost, however, high temperature superconductors (HTS) will also be considered as conductor. We present the first advanced design for revamping of a large bending dipole in a hadron therapy center, and the conceptual design for magnets in a nuclear physics laboratory and we try to define the domain where this transformation of normal-conducting into super-ferric magnets can be technically and economically advantageous.

Heavy-ions shielding data for hadrontherapy application with Monte Carlo methods.

In hadrontherapy centers, ion beams are accelerated by a cyclotron or synchrotron through electric and magnetic fields and, once the treatment energy is reached, ions interact with the patient. The interaction of the beam with magnets, other elements of particle accelerator or with the patient generates secondary radiation and the calculation for the design of the shielding is required. A first assessment of the shielding, generally made by concrete, can be performed by using Monte Carlo simulations, in which neutron yields and the ambient dose equivalent, H*(10), spatial distribution are obtained. The aim of this work is to evaluate, with a Monte Carlo approach, ambient dose equivalent values at various concrete depths generated by the secondary radiation. Simulations are performed considering helium, lithium, carbon, oxygen and iron primary beams. For existing facilities that already accelerates carbon ion, an equivalent carbon ratio is introduced to estimate the ion currents to get, in a given point, the same ambient dose equivalent as a carbon ion. Numerical results have been obtained simulating an ion beam that impinges on a thick iron or international commission on radiation units and measurements (ICRU) tissue, respectively, representing magnets and patient. The secondary radiation is transported through a large concrete shielding where ambient dose equivalent values are calculated as function of concrete thickness.

Energy comparison of room temperature and superconducting synchrotrons for hadron therapy

The yearly energy requirements of room temperature (RT) and superconducting (SC) magnet options of a new hadron therapy (HT) facility are compared. Special reference is made to the layouts considered for the proposed SEEIIST facility. Benchmarking with the RT CNAO HT centre in Pavia (Italy) was carried out. The energy comparison is centred on the different synchrotron solutions, assuming the same injector and lines in the designs. The beam current is 20 times higher than in present generation facilities: this allows efficient multi-energy extraction (MEE), which shortens the therapy treatment and is needed especially in the SC option, because of the slow magnet ramping time. Hence, power values of the facility in the traditional mode were converted into MEE ones, for a fair comparison between RT and SC magnets. Cryocoolers (c.c.) and a liquefier are also compared, for synchrotron refrigeration. This study shows that a RT facility in MEE mode requires the least average energy, followed by the SC synchrotron solution with a liquefier, while the most energy intensive solution is the SC one with c.c.

A European Collaboration to Investigate Superconducting Magnets for Next Generation Heavy Ion Therapy

Next generation ion therapy magnets both for gantry and for accelerator (synchrotron) are under investigation in a recently launched European collaboration that, in the frame of the European H2020 HITRI <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">plus</i> and I.FAST programmes, has obtained some funding for work packages on superconducting magnets. Design and technology of superconducting magnets will be developed for ion therapy synchrotron and -especially- gantry, taking as reference beams of 430 MeV/nucleon ions (C-ions) with 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> ions/pulse. The magnets are about 60–90 mm diameter, 4 to 5 T <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">peak</i> field with a field change of about 0.3 T/s and good field quality. The paper will illustrate the organization of the collaboration and the technical program. Various superconductor options (LTS, MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or HTS) and different magnet shapes, like classical CosTheta or innovative Canted CosTheta (CCT), with curved multifunction (dipole and quadrupole), are under evaluation, CCT being the baseline. These studies should provide design inputs for a new superconducting gantry design for existing facilities and, on a longer time scale, for a brand-new hadron therapy centre to be placed in the South East Europe (SEEIIST project).

The Measurement of the Neutron Yield of the 7Li(p,n)7Be Reaction in Lithium Targets

Simple SummaryA compact neutron source has been proposed and created at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. The source comprises an original design tandem accelerator, solid lithium target, and a neutron beam shaping assembly. The neutron source is capable of producing the high neutron flux for boron neutron capture therapy (BNCT). Currently, the BNCT technique has entered into clinical practice in the world: two clinics began treating patients, and four more BNCT clinics are ready to start operating. The neutron source proposed at the Budker Institute served as a prototype for a facility created for a clinic in Xiamen (China). It is planned to equip the National Medical Research Center of Oncology (Moscow, Russia) and National Oncological Hadron Therapy Center (Pavia, Italy) with the same neutron sources. Due to the impending use of an accelerator neutron source for treating patients, the validation of the neutron yield of the 7Li(p,n)7Be reaction in lithium metal targets is required. The theoretical neutron yield has not been evaluated experimentally so far.A compact accelerator-based neutron source has been proposed and created at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. An original design tandem accelerator is used to provide a proton beam. The neutron flux is generated as a result of the 7Li(p,n)7Be threshold reaction using the solid lithium target. A beam shaping assembly is applied to convert this flux into a beam of epithermal neutrons with characteristics suitable for BNCT. The BNCT technique is being tested in in vitro and in vivo studies, and dosimetry methods are being developed. Currently, the BNCT technique has entered into clinical practice in the world: after successful clinical trials, two clinics in Japan began treating patients, and four more BNCT clinics are ready to start operating. The neutron source proposed at the Budker Institute of Nuclear Physics served as a prototype for a facility created for a clinic in Xiamen (China). It is planned to equip the National Medical Research Center of Oncology (Moscow, Russia) and National Oncological Hadron Therapy Center (Pavia, Italy) with the same neutron sources. Due to the impending use of an accelerator neutron source for treating patients, the validation of the neutron yield of the 7Li(p,n)7Be reaction in lithium metal targets is required. The theoretical neutron yield has not been evaluated experimentally so far.

BDSIM Developments for Hadron Therapy Centre Applications

BDSIM Developments for Hadron Therapy Centre Applications

Beam loss monitoring with unfolding techniques

Since the first particle accelerator’s construction in 1931, an exponential spread of these machines occurred worldwide, in different kinds of applications. Nowadays, these are mainly used for industrial (60%) and medical (35%) purposes and for scientific research (5%). High energy secondary mixed fields produced by the particle beams interaction with matter imply a complex environmental dosimetry and special radiation protection regulations able to guarantee workers and population safety. In the medical field, this aspect is particularly emphasized in hadrontherapy centres, where high energy charged particles such as protons and carbon ions modify environmental doses, with a significant increase in the neutron contribution. This work proposes a technique to identify points of losses of the primary particle beam around an acceleration ring and has been developed within the radiation protection section at the National Centre for Oncological Hadrontherapy situated in Pavia. In the first part, the radiation field produced by protons and carbon ions interactions with structural materials at different energies was investigated. The main instrument of analysis is the Monte Carlo code for particle transport FLUKA, supported by experimental measurements in the treatment room carried out with the rem counter LUPIN, designed for pulsed neutron fields dosimetry. This first step allowed an analysis of both the angular and energetic instrumental response and a comparison of experimental results with simulations. The second part proposes a description of the technique for beam loss positions reconstruction around the acceleration ring at CNAO based on the application of unfolding codes.

Dose intercomparison at Italian hadrontherapy centers

PurposeTo perform the first dosimetric intercomparison for proton beams in Italy using ionization chambers, according to the IAEA TRS-398 code of practice. MethodsMeasurement sites included: National Center for Oncological Hadron Therapy (CNAO, Pavia), Center for Proton Therapy (CTP, Trento) and Center for Hadron Therapy and for advanced Nuclear Applications (CATANA, Catania). For comparison we also included a 6 MV photon beam produced at Istituti Clinici Scientifici Maugeri (ICSM, Pavia). For proton beams, both single pseudo-monoenergetic layers (in order to obtain a planned dose of 2 Gy at the reference depth of 2 cm in a water phantom) and Spread-out Bragg peaks (SOBP) have been delivered. Measurements were performed with a PTW Farmer 30010-1 and a PTW Advanced Markus type 34,045 ionization chamber. ResultsData obtained at CATANA, CNAO and CPT in terms of absorbed dose to water depth show good consistency within the experimental uncertainties, with a weighted mean of 1.99 ± 0.01 Gy and a standard error of 0.003 Gy, with reference to a nominal dose of 2 Gy as designed by the treatment planning system. ConclusionsThe results showed a standard deviation of less than 1% for single layer and SOBP beams, for all chambers and a percent deviation less than 1.5% for single layer measurements. The weighted means of the absorbed doses for clinical proton beams (118.19 MeV and 173.61 MeV) are consistent within less than 1%. These results agree within the 1.5% difference considered acceptable for national dose intercomparison.

Impact of ion source stability for a medical accelerator

MedAustron is a synchrotron-based hadron therapy center located in Lower Austria. Accelerated proton beams with energies of 62–252 MeV/u are used to treat patients since 2016. The carbon ion beam is currently under commissioning and will provide treatment in 2019 with energies of 120–400MeV/u. Two of the four irradiation rooms are used for clinical treatment while the preparation of the Gantry beam line is ongoing. Proton beams of up to 800 MeV will be provided for non-clinical research. The Injector features three identical ECRIS from Pantechnik, two of which are used to generate the proton and the carbon beam respectively. The medical environment of the accelerator puts strict requirements on the ion source long-term stability operation. The extracted beam current from the source allow for maximum current fluctuations on the order of ±2.5% on continuous run. In this work we discuss the impact of the ion source performances on the characteristics and stability of the entire accelerator. Further, we discuss the latest progress on carbon commissioning and the future perspectives with particular emphasis on the source requirements.

Hadron Therapy in Iran: Patient Indication Estimation and Challenges Ahead

Introduction: Radiotherapy with heavy charged particles such as protons and carbon ions (hadron therapy) has been recognized as an advanced technique for the treatment of various cancers. For some indications such as pediatric and radio-resistant tumors, it is considered the preferred method. However, despite its remarkable benefits, development of hadron therapy centers in the world has always been subject to major constraints due to a number of reasons including the high costs of constructing and maintaining the centers, the need for strong infrastructures, and the lack of adequate research on the estimation of the number of patients eligible for utilizing this technique. Therefore, this study aimed to investigate the initial estimation of the number of patients eligible for hadron therapy in the Fars Province and Iran as a whole. Materials and Methods: In the absence of comprehensive national cancer registry data, the information for the initial estimation of the number of patients residing in the province were collected from the medical records of the patients who were treated at the Radiotherapy Department of Shiraz Namazi Hospital in 2014. First, the patients’ demographic data (place of residence, age, and sex) as well as the type of cancer were extracted according to the patients’ pathology reports. Only the patients residing in Fars were selected. Then, all of the resulting indications were classified based on the methodology proposed in previous studies, and by applying separate coefficients on each, all the indications suitable for the hadron therapy in Fars were determined. Subsequently, by applying a coefficient of 16.4 (the ratio of the total population of the country to that of the Fars Province in 2014), the number of the patients eligible for hadron therapy in the whole country was calculated. Results: Of the total 2,932 cases studied, 1536 patients were residing in Fars, 22.9% of whom were eligible for hadron therapy. Accordingly, the total number of patients in the country was estimated to be 5765 cases/year. Considering similar studies from other countries with such clinics, at least two hadron therapy centers are needed for treating the eligible estimated population. Conclusion: The analysis performed in this study (solely considering patient numbers and treatment indications) suggests that at least two geographically-spread hadron therapy centers are indicated (covering two northern and southern regions of similar populations). The limitations in having access to accurate patient data and the insufficiencies in the national cancer registry system hinders accurate estimations, which potentially lead to underestimation of patient numbers. Also, other economic factors, experience of other countries and expert advice should be considered. The need for extensive cost-benefit studies versus lower-cost radiotherapy equipment before investment is emphasized.

41. Dose intercomparison at European hadrotherapy centers

Purpose To perform the first intercomparison study on nominal doses delivered by the Treatment Planning System in various European hadrontherapy centers, using an ionization chamber for reference dosimetry in water, according to IAEA TRS398 code of practice. Methods Measurement sites include the following clinical therapy centers: CNAO (Pavia) and HIT (Heidelberg) for protons and carbon ions; TPC - (Trento) and CATANA (Catania) for protons; Fondazione Maugeri (Pavia) for 6 MV photons. For ion beams, both single monoenergetic layer and SOBP, have been delivered to obtain a nominal dose of 2 Gy at the reference depth zref = 2 cm in a water phantom. The energies used were: in CNAO for protons (118.19 MeV, 173.61 MeV) and for carbon ions (208.58 MeV/u, 332.15 MeV/u), in Fondazione Maugeri 6 MV and in TPC - for protons (118 MeV, 173 MeV) [1] . Measurements were made with a PTW Farmer 30010-1 ionization chamber. Results CNAO, Fondazione Maugeri and TPS data show consistency within the experimental uncertainties, with a maximum relative deviation of 2.8%. The full set of measurements is planned to be completed in 2018. Conclusions Absorbed dose for clinical proton beams (118.19 MeV and 173.61 MeV) is consistent within less than 3% between CNAO and TPS, as well as for 6 MV photons. This work was performed within INFN projects RDH and MC-INFN.

Policies for reirradiation of recurrent high-grade gliomas: a survey among Italian radiation oncologists.

To assess the contribution of Italian radiation oncologists in the current management of recurrent high-grade gliomas (HGG), focusing on a reirradiation (reRT) approach. In 2015, the Reirradiation and the Central Nervous System Study Groups on behalf of the Italian Association of Radiation Oncology (AIRO) proposed a survey. All Italian radiation oncologists were individually invited to complete an online questionnaire regarding their clinical management of recurrent HGG, focusing on a reRT approach. A total of 37 of 210 questionnaires were returned (18% of all centers): 16 (43%) from nonacademic hospitals, 14 (38%) from academic hospitals, 5 (13%) from private institutions, and 2 (6%) from hadron therapy centers. The majority of responding centers (59%) treated ≤5 cases per year. Performance status at the time of recurrence, along with a target diameter <5 cm and an interval from primary radiation ≥6 months, were the prevalent predictive factors considered for reRT. Sixty percent of reirradiated patients had already received a salvage therapy, either chemotherapy (40%) or reoperation (20%). The most common approach for reRT was fractionated stereotactic radiotherapy to a mean (photon) dose of 41.6 Gy. Although there were wide variations in the clinical practice of reRT across the 37 centers, the core activities were reasonably consistent. These findings provide a basis for encouraging a national collaborative study to develop, implement, and monitor the use of reRT in this challenging clinical setting.

A Preliminary Study on the Estimation of the Number of Cancer Patients Eligible for Hadron Therapy in Iran and Fars Province.

Hadron therapy (HT) with protons and carbon ions is an advanced radiotherapy technique. As the first report addressing this topic, the present study aimed to estimate the number of patients eligible for HT in Fars province and the whole of Iran. The data were collected through direct inspection of medical records of the patients treated at the Radiotherapy Department, Namazi Hospital, Shiraz, Iran in 2014. The patients who were treated with external-beam radiotherapy and declared to be a resident of Fars province were extracted from the medical records. After classification based on appropriate indications and factors, the number of eligible patients in Iran was calculated by scaling (Iran: Fars population). Of the 2,932 medical records, 1,943 patients were treated with external-beam radiotherapy, among which 1,536 were from Fars. The total number of patients eligible for HT in Fars was >351 cases/year (22.9% of the treated patients). The cancer site distribution of the eligible Fars residents was central nervous system primary tumors (n=31), brain metastases (n=64), eye (n=7), head and neck (n=28); thyroid (n=4), lung (n=17), breast (n=56), esophagus (n=5); pancreas (n=5), gastric (n=32), liver and bile duct (n=0), rectum and anus (n=26); prostate (n=27), bladder (n=8), cervix (n=6), soft tissue (n=17); kidney (n=1), Hodgkin lymphoma (n=9), non-Hodgkin lymphoma (n=4), and bone metastases (n=4). A total number of 5,756 cases/year was estimated for the entire country. Considering the experiences of other countries, these results suggest that establishing at least two HT centers (covering the northern and southern parts of Iran) is justified based on the total number of patients. Further accurate estimations and cost evaluations are recommended.

Abstract ID: 54 The application of the FLUKA Monte Carlo code in medical physics

Monte Carlo codes are increasingly spreading in medical physics community due to their capability of performing a detailed description of radiation transport and interaction with matter. This contribution will address the recent developments of the FLUKA code and its practical application in medical physics. FLUKA is being used in radiation therapy and nuclear medicine. At present, it is of particular interest in the context of particle therapy, thanks to the development of accurate and reliable physical models capable of handling all components of the expected radiation field. At the same time, the code can be interfaced to different radiobiological models. These features become extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. At the same time, in order to support the application of FLUKA in hospital-based environments, the FLUKA graphical interface has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. Therefore, the FLUKA code not only is a reliable instrument for the simulation of therapeutic beams, but it is also used in some of the leading European hadron therapy centers as an accurate tool for Treatment Planning verification and correction. In addition, it allows an accurate prediction of emerging secondary radiation and this is of the utmost importance in innovative areas of research aiming at in vivo treatment verification. Here we shall review the features of the FLUKA code, pointing out the recent refinements of the nuclear models, relevant for the therapeutic energy interval, which lead to an improved description of the mixed radiation field. Benchmarks against experimental data with both proton and ion beams will be shown. Examples of clinical application will be presented, together with a review of some results in medical physics research.

Abstract ID: 37 The BIANCA biophysical model/MC code: calculations of radiation-induced cell damage in view of hadrontherapy treatments

A biophysical model and Monte Carlo code simulating cell death and chromosome damage by different ionizing radiations, including those used in hadrontherapy, will be presented. The model, called BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations [1] , [2] ), assumes that DNA “Cluster Lesions” (CLs) can produce chromosome aberrations (i.e., distance-dependent incorrect rearrangements of chromosome fragments), some of which can lead to cell death. The mean number of CLs per Gy and per cell is the first adjustable parameter; the second parameter is either the probability that a chromosome fragment remains unrejoined, or the characteristic distance governing chromosome-fragment rejoining, depending on which model version is used. Comparisons with experimental dose-response curves for cell survival and/or chromosome aberrations allowed tuning the model parameters for a radioresistant cell line (representative of tumour cell response) and a normal one (representative of the response of healthy tissues), thus producing a database of CL yields for different particle types and LET values. Since the CL yield for a given particle type showed a linear-quadratic increase with LET, a fit of such database allows performing full predictions of cell death and chromosome aberrations in principle for any LET value within the range covered by the experiments. Recently, the model was applied to calculate the dependence of cell death and chromosome damage on depth in tissue for SOBP profiles used in different centres, including the CATANA facility for eye melanoma treatment at INFN-LNS and the CNAO hadrontherapy centre in Pavia. In particular for protons, the biological effectiveness was found to increase in the distal region, and significant levels of damage beyond the distal dose fall-off were observed. In line with other studies, these results suggest that assuming a constant biological effectiveness along a proton SOBP may be sub-optimal.

Physicists' views on hadrontherapy: a survey of members of the Italian Association of Medical Physics (AIFM).

This study was based on a survey to investigate perceptions of hadrontherapy of the members of the Italian Association of Medical Physics (AIFM). The survey was digitally submitted to the 991 members between the end of January and the beginning of April 2016. A 19-item questionnaire was designed focusing on advantages and disadvantages of hadrontherapy, current status and possible future improvements, and need and opportunities for future investments in Italy and abroad. Information about professional qualifications, main fields of clinical involvement and specific competencies of the respondents was also collected. The survey was completed by 121 AIFM members (response rate 12.2%). In the answers collected, it was shown that medical physicists expressed interest in hadrontherapy mainly for reasons of personal interest rather than for professional needs (90% ± 2.5% vs. 52% ± 4.3% of the respondents, respectively), with a good knowledge of the related basic aspects as well as of the pros and cons of its application. However, poor knowledge of the current status of hadrontherapy was observed among the medical physicists not directly involved at a professional level, who were less than 3% of the physicists working in radiotherapy. In light of these results, the implementation of new training and education initiatives should be devised to promote a deeper and global knowledge of hadrontherapy-related issues, not only from a theoretical point of view but also in practical terms. Moreover, a close collaboration between highly specialized medical physicists employed in hadrontherapy centers and others in oncology hospitals should be -encouraged.

A method for the dynamic range extension of a pixelated Silicon detector beam profilometer based on the incomplete reset mechanism

The SUCIMA collaboration, within a project supported by the European Commission in the Fifth Framework Program, developed a sensor for non-disruptive real-time beam profilometry for hadron therapy centres. The sensor, named MIMOTERA, has been used at different European facilities, imaging beams by direct impact on the sensor and by the detection of secondary electrons emitted by thin targets. In 2015, the detector has been thinned to 50 μm, integrated in a high vacuum and cryogenic temperature compliant assembly and successfully commissioned as antiproton beam monitor for the AEḡIS experiment at CERN. The detector contributed to the optimisation of the experiment functionality providing the shape and position of the beam on a spill-by-spill basis. However, it failed in measuring the fluctuations of the beam intensity because the deposited energy exceeded the full well capacity and saturated the output signal. In order to recover this information, a method was developed based on the persistence of the signal in a series of frames that follows the one corresponding to the beam impact, due to the incomplete sensor reset. A laboratory test that makes use of a laser with tuneable intensity was designed and the method was qualified. This paper reports the description of the procedure and the main outcomes.

Dose–response of EBT3 radiochromic films to proton and carbon ion clinical beams

We investigated the dose–response of the external beam therapy 3 (EBT3) films for proton and carbon ion clinical beams, in comparison with conventional radiotherapy beams; we also measured the film response along the energy deposition-curve in water. We performed measurements at three hadrontherapy centres by delivering monoenergetic pencil beams (protons: 63–230 MeV; carbon ions: 115–400 MeV/u), at 0.4–20 Gy dose to water, in the plateau of the depth-dose curve. We also irradiated the films to clinical MV-photon and electron beams. We placed the EBT3 films in water along the whole depth-dose curve for 148.8 MeV protons and 398.9 MeV/u carbon ions, in comparison with measurements provided by a plane-parallel ionization chamber. For protons, the response of EBT3 in the plateau of the depth-dose curve is not different from that of photons, within experimental uncertainties. For carbon ions, we observed an energy dependent under-response of EBT3 film, from 16% to 29% with respect to photon beams. Moreover, we observed an under-response in the Bragg peak region of about 10% for 148.8 MeV protons and of about 42% for 398.9 MeV/u carbon ions. For proton and carbon ion clinical beams, an under-response occurs at the Bragg peak. For carbon ions, we also observed an under-response of the EBT3 in the plateau of the depth-dose curve. This effect is the highest at the lowest initial energy of the clinical beams, a phenomenon related to the corresponding higher LET in the film sensitive layer. This behavior should be properly modeled when using EBT3 films for accurate 3D dosimetry.

The FLUKA Code: An Accurate Simulation Tool for Particle Therapy.

Monte Carlo (MC) codes are increasingly spreading in the hadrontherapy community due to their detailed description of radiation transport and interaction with matter. The suitability of a MC code for application to hadrontherapy demands accurate and reliable physical models capable of handling all components of the expected radiation field. This becomes extremely important for correctly performing not only physical but also biologically based dose calculations, especially in cases where ions heavier than protons are involved. In addition, accurate prediction of emerging secondary radiation is of utmost importance in innovative areas of research aiming at in vivo treatment verification. This contribution will address the recent developments of the FLUKA MC code and its practical applications in this field. Refinements of the FLUKA nuclear models in the therapeutic energy interval lead to an improved description of the mixed radiation field as shown in the presented benchmarks against experimental data with both 4He and 12C ion beams. Accurate description of ionization energy losses and of particle scattering and interactions lead to the excellent agreement of calculated depth–dose profiles with those measured at leading European hadron therapy centers, both with proton and ion beams. In order to support the application of FLUKA in hospital-based environments, Flair, the FLUKA graphical interface, has been enhanced with the capability of translating CT DICOM images into voxel-based computational phantoms in a fast and well-structured way. The interface is capable of importing also radiotherapy treatment data described in DICOM RT standard. In addition, the interface is equipped with an intuitive PET scanner geometry generator and automatic recording of coincidence events. Clinically, similar cases will be presented both in terms of absorbed dose and biological dose calculations describing the various available features.