Proton Beam Facility Research Articles

Measurement of neutron spectra for various thicknesses of concrete and steel shielding at 24-GeV/c proton beam facility using Bonner sphere spectrometer

ABSTRACT Neutron energy spectra down to thermal energy were measured using a Bonner sphere spectrometer (BSS) for various thicknesses of concrete and steel shielding at the CERN/CHARM facility, where high-energy neutrons were produced by 24-GeV/c protons incident on a thick copper target. The thicknesses of the concrete and steel shielding blocks ranged from 40 cm to 200 cm and from 20 cm to 80 cm, respectively. The BSS consisted of a spherical 3He proportional counter and five polyethylene moderators with diameters of 7.62 cm, 10.2 cm, 12.7 cm, 17.8 cm, and 24.1 cm, respectively. In addition, polyethylene moderators combined with a lead or copper inner shell were used to increase the sensitivity to high-energy neutrons. The neutron energy spectra were deduced using an unfolding method. The initial guesses were obtained using the PHITS code for each experimental geometry. The response function for the BSS was determined using the MCNP6.2 code with JENDL-4.0/HE. The neutron energy spectra over the entire energy region from 10−4 eV to 10 GeV were successfully obtained for the different shielding conditions. The validity of the response function and the contribution of each moderator are discussed referring to previous studies and tests at the standard neutron fields of AIST.

Simulation of a proton beam facility in the TOPAS MC software package

The aim of this work is to simulate the formation system of therapeutic proton beams at the accelerator of the Institute of Nuclear Research, Russian Academy of Sciences, using the TOPAS MC software package and to calculate, on this basis, the characteristics of irradiation of biological objects. As such characteristics, the dependence of the absorbed dose and linear energy transfer (LET) on the proton range in water and the effective dose of irradiation of HT-29 and HCT-116 cell lines used in real experiments are considered. Also, the uniformity of irradiation with a high dose rate of the studied biological objects was evaluated during the operation of the radiation unit in FLASH-therapy modes. The research is aimed at preparing and conducting radiobiological experiments with proton beams with a record dose rate.

Proton beam therapy for gliomas: a multicenter prospective registry study from all proton beam facilities in Japan

Abstract We reviewed the outcomes of glioma patients enrolled in a prospective observational registry study of proton beam therapy (PBT) in Japan. The inclusion criteria were glioma patients registered in the Electronic Data Capture system, the Proton-net, between May 2016 and July 2019. Data on patient characteristics, treatments, late adverse events, survival status, recurrence and secondary tumors were extracted and statistically analyzed. The primary endpoint was the overall survival (OS) rate, and the secondary endpoints were the progression-free survival (PFS) rate and cumulative local recurrence rate (cLRR). Of the 65 primary brain tumor patients registered, 29 glioma patients from eight of 19 PBT facilities met the inclusion criteria. There were 19 glioblastoma patients, eight of other malignant gliomas, and two of low-grade gliomas. For glioblastomas, with a median follow-up period of 16 months, the median survival time was 21.2 months and the OS at 1, 2, 3 and 4 years were 77.4%, 44.9%, 23.9% and 23.9%, respectively. The median PFS period was 10.1 months, the 1, 2, 3 and 4-year PFS were 32.4%, 19.4%, 9.7% and 9.7%, respectively. The 1, 2, 3 and 4-year cLRR were 56.1%, 68.8%, 78.4 and 78.4%, respectively. Grade 3 brain necrosis was observed in two patients. No secondary tumor was observed. This is the first report on the current status of PBT for gliomas in Japan. For glioblastomas, the outcomes of PBT are estimated to be equivalent to historical data of photon therapy. The results of a prospective comparative evaluation of PBT and photon therapy are awaited.

Simulation of a Proton Beam Facility in the TOPAS MC Software Package

Simulation of a Proton Beam Facility in the TOPAS MC Software Package

New setup for basic radiobiology studies using a 3 MV TandetronTM: Design and developments

The aim of the study was to upgrade the Horia Hulubei National Institute for Physics and Nuclear Engineering existing facility - a 3 MV TandetronTM accelerator - to be used in radiobiology experiments. Irradiations were performed with 1.95 MeV protons (beam with uniform distribution over a 30 mm2). Particle fluence was determined with plastic track detectors and live monitored using Rutherford Backscattering Spectrometry technique. Absolute and relative dose (Advanced Markus ion chamber) and the lateral quality of the irradiation spot (radiochromic film) were measured. The dosimetric measurements were confirmed by Geant4 simulations of the dose averaged Linear Energy Transfer, the Bragg peak profile and the beam lateral energy distribution. A complete setup for exposing in vitro cell cultures to the particle beams was constructed from scratch. Preliminary data of survival rate of V79 fibroblast cells are reported. The obtained results are similarly with data reported using other proton beam facilities.

Development of high voltage-CMOS sensors within the CERN-RD50 collaboration

This paper presents work done by the CERN-RD50 collaboration to develop and study monolithic CMOS sensors for future hadron colliders, especially in terms of radiation tolerance, time resolution and granularity. Currently CERN-RD50 is completing the performance evaluation of RD50-MPW2 and has recently submitted RD50-MPW3, the second and third prototype sensor chips designed by the collaboration. The paper gives an overview of the main design aspects and performance evaluation results of the first two prototype chips RD50-MPW1 and RD50-MPW2, and details the design of the latest prototype RD50-MPW3. RD50-MPW2 is a small prototype with an 8 x 8 matrix of active pixels which implement analogue readout electronics only and solutions for low leakage currents. This prototype has been evaluated in the laboratory and also at proton and ion beam facilities, before and after irradiation with neutrons up to 2⋅1015neq/cm 2. RD50-MPW3 is a more advanced prototype with a matrix of 64 x 64 pixels which integrate both analogue and digital readout electronics inside the sensing diodes. To alleviate routing congestion and minimise crosstalk noise, the pixels are serially configured and organised in a double column scheme. This prototype has optimised peripheral readout electronics for effective chip configuration, based on the I2C protocol, and fast data transmission.

Reduce Patient Treatment wait time in a Proton Beam Facility – A Gatekeeper Approach

Patient wait time can negatively impact treatment quality in a proton therapy center, where multiple treatment rooms share one proton beam. Wait time increases patient discomfort that can lead to patient motion, dissatisfaction, and longer treatment delay. This study was to develop a patient call-back model that reduced patient wait while efficiently utilizing the proton beam. A "Gatekeeper" logic allowing therapists to adjust the time of a patient's call-back to the treatment room was developed. It uses a two-pronged approach to minimize overlap of long treatment and the possibility of excessive wait in the queue to receive the proton beam. The goal was to reduce the maximum wait time to less than eight minutes per field for a four-room facility. The effectiveness of this logic was evaluated through simulation, and five scenarios were compared. Four scenarios implementing various levels of gatekeeper logic were compared with the original scenario without the logic. The best performing model provided a reduction of the maximum field wait by 26% and met the predefined goal. Adjusting call-back extended the treatment day length by an average of 6min and a maximum of 12min in total. The use of this gatekeeper logic significantly reduces patient field wait with minimal impact on treatment day length for a four-room proton facility. A sample interface that adopts this logic for therapists to make informed decision on patient call-back time is demonstrated.

Measurements and Monte Carlo simulations of high-energy neutron streaming through the access maze using activation detectors at 24 GeV/c proton beam facility of CERN/CHARM

ABSTRACT A measurement of high-energy neutron streaming was performed through a maze at the CERN (Conseil Européen pour la Recherche Nucléaire) High-energy AcceleRator Mixed-field (CHARM) facility. The protons of 24 GeV/c were injected onto a 50-cm-thick copper target and the released neutrons were streamed through a maze with several corridor-legs horizontally designed with the shield walls in the facility. Streaming neutrons were measured by using aluminum activation detectors placed at 10 locations in the maze. From the radionuclide production rate in the activation detectors, the attenuation profile along the maze was obtained for the reaction of 27Al(n,α)24Na. Monte Carlo simulations performed with two codes, the Particle and Heavy Ion Transport System (PHITS) and CERN FLUktuierende KAskade (FLUKA), gave good agreements with the measurements within a factor of 1.7 for the production rates ranging over more than 3 orders of magnitude.

Possibilities of Proton FLASH Therapy on the Accelerator at the Russian Academy of Sciences’ Institute for Nuclear Research

The proton accelerator at the Russian Academy of Sciences’ Institute for Nuclear Research provides a mode of irradiation of biological samples with a single pulse when the average dose rate coincides with the pulse dose rate and approaches 1 · MGy s−1. The proton beam facility is described, along with the technique of local film dosimetry used for irradiating cell cultures in laboratory plates. The radiation characteristics of each well in the plates are determined, as are the record values of the dose rate for protons.

Search for the K L → π 0 γ decay in the KOTO experiment

We report a preliminary result of a new search for the K L → π 0 γ decay, which is forbidden by the Lorentz invariance and gauge principle. The search was carried out using the data obtained from 2016 to 2018 at the J-PARC proton beam facility using the KOTO detector. The achieved single event sensitivity was (6.9 ± 0.3stat. ± 1.5syst.) × 10−8. No signal candidate was found in the signal region and the upper limit was set to B(K L → π 0 γ) < 1.7 × 10−7 at the 90% con dence level.

Decay pion spectroscopy: A new approach

We propose a new experiment for decay pion spectroscopy of light hypernuclei at electron- and proton-beam facilities, using the recoil distance technique for separation of produced hypernuclei and a magnetic spectrometer for precise measurement of the decay pion momentum. Low-pressure MWPCs are advocated for low-energy recoil detection as they provide position and time information and are highly insensitive to gamma-ray and electron background. The position and timing characteristics of such a recoil detector were studied using ~5 MeV {\alpha}-particles. By using the present proposed approach the rate of the detected hypernuclei can be increased by one-to-two orders of magnitude compared to a recent experiment carried out at the MAMI electron accelerator in Mainz. The possibility of realizing a high luminosity decay pion spectroscopy experiment with proton beams is also discussed.

A Literature Review of Proton Beam Therapy for Prostate Cancer in Japan.

Aim: Patients of proton beam therapy (PBT) for prostate cancer had been continuously growing in number due to its promising characteristics of high dose distribution in the tumor target and a sharp distal fall-off. Considering the large number of proton beam facilities in Japan, the further increase of patients undergoing this treatment is due to the emendations by Japanese National Health Insurance (NHI) and the development of medical equipment and technology, it is necessary to know what kind of research and advancements has been done on proton therapy for prostate cancer in the country. For these reasons, this literature review was conducted. The aim of this review is to identify and discuss research studies of proton beam therapy for prostate cancer in Japan. These include observational, interventional, and secondary data analysis of published articles. Method: A literature review on published works related to proton beam therapy for prostate cancer in Japan was conducted using articles that were gathered in the PubMed database of June 2018. We went through abstracts and manuscripts written in English with the keywords ‘proton beam therapy’, ‘prostate cancer’, and ‘Japan’. Results: A total of 23 articles were included. Fourteen articles were observational studies, most of which focused on the adverse effects of Proton Beam Therapy (PBT). Seven articles were interventional studies related on treatment planning, equipment parts, as well as target positioning. Two were secondary data analysis. The included studies were published in 13 different journals by different institutions using various equipment. Conclusion: Despite the favorable results of proton beam therapy, future research should include more patients and longer follow-up schedules to clarify the definitive role of PBT, yet, up to recent retrospective studies, included in this paper, concluded that PBT can be a suitable treatment option for localized prostate cancer. In addition, interventional studies were conducted by several institutions to further embellish proton therapy.

Status and Utilization of the Beam Facility at KOMAC

Korea Multi-Purpose Accelerator Complex (KOMAC) has been supporting a user beam service using 20- and 100-MeV proton beam facilities since the second half of 2013, and recently, beam facilities for radioisotope production and a low-flux proton beam have been built. A 100-MeV low-flux proton beam facility was constructed in 2007, which was due to the strong requirements of users in various R&D fields, such as space radiation, medical/biology, and radiation detectors. For the low-flux beam facility, the compact modules for beam flux control were designed, and various beam diagnosis tools were installed in the target room. In the process room, a user-friendly measurement system, consisting of DC power supplies, electrometers, NIM modules, was designed for data processing and acquisition. In addition, the ion beam facilities based on gas and metal ion sources provide an ion implantation service. In particular, beam analysis services, such as PIXE and RBS, have been started using the tandem accelerator. Moreover, analysis equipment for the material, device/electronic, and bio/medical fields was installed at KOMAC for confirming the effects of beam irradiation on various samples. Finally, we aim to provide users with a one-stop service from beam irradiation to measurement at KOMAC.

Research Facility for Radiobiological Studies at the University Proton Therapy Dresden.

In order to take full advantage of proton radiotherapy, the biological effect of protons in normal and tumor tissue should be investigated and understood in detail. The ongoing discussion on variable relative biological effectiveness along the proton depth dose distribution (eg, Paganetti 2015), and also the administration of concomitant treatments, demands dedicated in vitro trials that prepare the translation into the clinics. Therefore, a setup for radiobiological studies and the corresponding dosimetry should be established that enables in vitro experiments at a horizontal proton beam and a clinical 6 MV photon linear accelerator (Linac) as reference. The experimental proton beam at the University Proton Therapy Dresden is characterized by high beam availability and reliability throughout the day in parallel to patient treatment. For cell irradiation, a homogeneous 10 × 10 cm2 proton field with an optional spread-out Bragg-peak can be formed. A water-filled phantom was installed that allows for precise positioning of different sample geometries along the proton path. Depth-dose profiles within the phantom and dose homogeneity over different cell samples were characterized for the proton beam and the photon reference source. A daily quality assurance protocol was implemented that provides absolute dose information required for significant and reproducible in vitro experiments. Cell survival test experiments were performed to demonstrate the feasibility of such experiments. In the experimental room of the University Proton Therapy Dresden, clinically relevant conditions for proton in vitro experiments have been realized. The established cell phantom and dosimetry facilitate irradiation in an aqueous environment and are transferable to other proton, photon and ion beam facilities. Precise positioning and easy exchange of cell samples, monitor unit-based dose delivery, and high beam availability allow for systematic in vitro experiments. The close vicinity to the radiotherapy and radiobiology departments provides access to clinical linacs and the interdisciplinary basis for further translational steps.

Standardisation of the ion beam facility at Chandigarh cyclotron for simultaneous PIXE and PESA analysis

Abstract The proton beam facility at variable energy cyclotron (VEC) Panjab University, Chandigarh, India is being used for Particle Induced X-ray Emission (PIXE) analysis of different environmental, biological and industrial samples. The PIXE method, however, does not provide any information of low Z elements like carbon, nitrogen, oxygen and fluorine. As a result of the increased need for rapid and multi-elemental analysis of biological and environmental samples, the PIXE facility was upgraded and standardized to facilitate simultaneous measurements using PIXE and Proton Elastic Scattering Analysis (PESA). Both PIXE and PESA techniques were calibrated and standardized individually. Finally, the set up was tested by carrying out simultaneous PIXE and PESA measurements using a 2 mm diameter proton beam of 2.7 MeV on few multilayered thin samples. The results obtained show excellent agreement between PIXE and PESA measurements and confirm adequate sensitivity and precision of the experimental set up.

Preliminary study of a new gamma imager for on-line proton range monitoring during proton radiotherapy

We designed and tested new concept imaging devices, based on a thin scintillating crystal, aimed at the online monitoring of the range of protons in tissue during proton radiotherapy. The proposed crystal can guarantee better spatial resolution and lower sensitivity with respect to a thicker one, at the cost of a coarser energy resolution. Two different samples of thin crystals were coupled to a position sensitive photo multiplier tube read out by 64 independent channels electronics. The detector was equipped with a knife-edge Lead collimator that defined a reasonable field of view of about 10 cm in the target. Geant4 Monte Carlo simulations were used to optimize the design of the experimental setup and assess the accuracy of the results. Experimental measurements were carried out at the Skandion Clinic, the recently opened proton beam facility in Uppsala, Sweden. PMMA and water phantoms studies were performed with a first prototype based on a round 6.0 mm thick Cry019 crystal and with a second detector based on a thinner 5 × 5 cm2, 2.0 mm thick LFS crystal. Phantoms were irradiated with mono-energetic proton beams whose energy was in the range between 110 and 160 MeV. According with the simulations and the experimental data, the detector based on LFS crystal seems able to identify the peak of prompt-gamma radiation and its results are in fair agreement with the expected shift of the proton range as a function of energy. The count rate remains one of the most critical limitations of our system, which was able to cope with only about 20% of the clinical dose rate. Nevertheless, we are confident that our study might provide the basis for developing a new full-functional system.

Secondary neutron ambient dose equivalent measurement of the wobbling system of a proton beam radiotherapy facility

PurposeThe purpose of this study was to assess the neutron ambient dose equivalent (H*(10)) per prescribed proton dose (D), H*(10)/D, for a wobbling system of the first proton beam facility in Taiwan and compare the H*(10)/D values with those of other facilities, including two wobbling system, two double scattering system, and one uniform scanning proton facilities. Materials and methodsA wide energy neutron detector, WENDI-II, was used to measure the H*(10) at a distance, d, of 50–225cm between the center of WENDI-II and the isocenter. The effects of proton beam range and SOBP width were assessed for a middle wobbling diameter. Thereafter, the H*(10)/D values were compared with those of the uniform scanning proton beam facility. The H*(10)/D values were measured at a d of 50–225cm by using beam energy of 230 and 150MeV as well as an SOBP width of 6 and 10cm. The H*(10)/D values of the maximum energy and 150MeV of the proton beam facilities were compared. ResultsThe measured H*(10)/D values were a function of a proton beam range for SOBP widths of 5 and 10cm. The H*(10)/D values ranged from 0.2 to 2.3 mSv/Gy at a range of 50–269mm for 5-cm SOBP beams and from 0.2 to 2.9 mSv/Gy for 10-cm SOBP beams. The H*(10)/D values for 230-MeV proton beams increased by 20.4% when the width of SOBP was increased from 6 to 10cm. These values for 230MeV at a d of 50cm were four times those of 150MeV. The H*(10)/D values increased with the beam scanning area. Moreover, the H*(10)/D values of the medium and large wobbling diameters were respectively 2.1 and 3.3 times those of the small wobbling diameter. ConclusionWe assessed the H*(10)/D values of the wobbling system of the first proton beam radiotherapy facility in Taiwan. The H*(10)/D values increased as the wobbling size increased, and these values decreased with increasing distance between the measurement position and isocenter. The H*(10)/D values of the wobbling nozzle proton beam system were higher than those of the uniform scanning system because of the interaction between proton beams and the internal components of the nozzle. The discrepancies in H*(10)/D values between facilities depend on the design of a proton beam line and the operational setup of the irradiated condition. Our experiment can serve as a reference for comparing secondary neutron radiation in wobbling system of the proton beam system.

An Assessment of the Secondary Neutron Dose in the Passive Scattering Proton Beam Facility of the National Cancer Center

Abstract The purpose of this study is to assess the additional neutron effective dose during passive scattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation was conducted based on a precise modeling of the National Cancer Center's proton therapy facility. A three-dimensional neutron effective dose profile of the interior of the treatment room was acquired via a computer simulation of the 217.8-MeV proton beam. Measurements were taken with a 3 He neutron detector to support the simulation results, which were lower than the simulation results by 16% on average. The secondary photon dose was about 0.8% of the neutron dose. The dominant neutron source was deduced based on flux calculation. The secondary neutron effective dose per proton absorbed dose ranged from 4.942 ± 0.031 mSv/Gy at the end of the field to 0.324 ± 0.006 mSv/Gy at 150 cm in axial distance.

The actual Interest in Radiotherapy for the Utilization of Proton Beam, Highlighting Physics Basis, Technology and Common Clinical Indications

Managing expensive technology is a debated issue in modern radiation oncology. Proton beam therapy (PBT) represents, considering its cost and its foreseen benefits, a typical case of discussion waiting for more robust results demonstrating the presumable clinical gains against the available radiation therapy (XRT) treatment alternatives based on the use of photons. The treatment with particles utilizes many different beams (neutrons, protons, pions, or helium, neon, argon, and carbon ions) that represent a distinct entity respect conventional XRT which uses photons. PBT is the most common form of heavy-particle radiation therapy used so far; it is not a new invention, being its clinical use proposed in a seminal article by R. Wilson in 1946[1] and the first patients treated in 1954 at the Lawrence Berkeley National Laboratory in California[2]. Since cyclotron or synchrotron, used to accelerate protons to therapeutic energies, were used primarily for research in particle or nuclear physics, the initial clinical activity in proton therapy was carried out in research facilities and the use of protons in clinical practice has grown slowly for several years in non-clinical setting. More than fifty years later, after a long period of seminal work in a limited number of Institutions, PBT has gained public attention in recent years because of the rapidly increasing number of centers around the world, regardless of their high cost. Hospital-based proton beam facilities have been in operation since 1990 after the opening of the first dedicated clinical center at Loma Linda Medical University Center in California - US. Since that years, commercial entities began to build cyclotrons and synchrotrons for clinical purposes. Over the last 10 years, PBT has gathered more interest in the scientific community and more media and patient attention and is now flourishing in the US and abroad. As of December, 2015, 57 proton therapy centers are in operation worldwide, others are under construction and many more in a planning phase[3]. Most patients who have been treated with heavy-particle therapy were treated with protons: PTCOG (Particle Therapy Co-Operative Group) reports that between 1954 and 2014, 137 000 patients globally received part or all of their radiation therapy with particles, and in particular 86% of them with protons[4]. The generation of these particles and the building of dedicated centers, however, requires large investments and operational costs and big infrastructure. Only relatively few studies have demonstrated the effectiveness of proton therapy and the effects are surrounded with uncertainty[5] being the cost-effectiveness still the core of the controversy around the use of PBT.

With Gaze Tracking Toward Noninvasive Eye Cancer Treatment.

We present a new gaze tracking-based navigation scheme for proton beam radiation of intraocular tumors and we show the technical integration into the treatment facility. Currently, to treat a patient with such a tumor, a medical physicist positions the patient and the affected eye ball such that the radiation beam targets the tumor. This iterative eye positioning mechanism requires multiple X-rays, and radio-opaque clips previously sutured on the target eyeball. We investigate a possibility to replace this procedure with a noninvasive approach using a 3-D model-based gaze tracker. Previous work does not cover a comparably extensive integration of a gaze tracking device into a state-of-the-art proton beam facility without using additional hardware, such as a stereo optical tracking system. The integration is difficult because of limited available physical space, but only this enables to quantify the overall accuracy. We built a compact gaze tracker and integrated it into the proton beam radiation facility of the Paul Scherrer Institute in Villigen, Switzerland. Our results show that we can accurately estimate a healthy volunteer's point of gaze, which is the basis for the determination of the desired initial eye position. The proposed method is the first crucial step in order to make the proton therapy of the eye completely noninvasive.