Irradiation Room Research Articles

Overview and current challenges at the Calibration Laboratory of the Paul Scherrer Institute

The Calibration Laboratory of the Paul Scherrer Institute (PSI) is a secondary calibration laboratory accredited by the Swiss Accreditation Service (SAS) in accordance with ISO 17025. It also acts as a verification body authorized by the Swiss Federal Institute of Metrology (METAS). The Laboratory is equipped with X-ray, gamma and neutron irradiation facilities, providing characterized reference radiation fields for gamma 137Cs, 60Co, narrow spectrum X-rays from N-15 to N-300 and neutron radionuclide sources 252Cf, 252Cf (D2O-moderated) and 241Am-Be. The laboratory performs routine calibrations, organizes intercomparison measurements for individual monitoring services in Switzerland, and participates in various research projects, e.g., by performing irradiations in reference fields. For this reason, the proper characterization of reference radiation fields is of utmost importance for ensuring high quality irradiations and calibrations of personal dosemeters and radiation protection instruments. In this contribution, we provide an overview of the irradiation facilities at the Calibration Laboratory at PSI and discuss the challenges of characterizing reference radiation fields. In particular, we will discuss the factors affecting the determination of the distance between the source and irradiated dosemeters and detectors, as well as issues related to 252Cf decay and contribution of 250Cf. We will also demonstrate the use of Monte-Carlo simulations in determining the optimal position of the source and irradiation facility within the irradiation room.

Neutron dose evaluation inside high-energy accelerator irradiation vault using LR-115

Recently, a new radiation therapy using a high-energy accelerator irradiation vault has attracted significant attention. This therapy is very effective in destroying cancer cells because it uses much higher energy than conventional radiation therapy. Nevertheless, it also has disadvantages due to its high energy and dose, resulting in the generation of secondary radiation such as X-rays and neutrons. In particular, neutrons have a higher radiation weighting factor than photons; therefore, they are more harmful to normal tissues. However, the popular neutron dosimeter CR-39 cannot evaluate high-dose neutrons.This paper proposes a novel method for measuring high-dose neutrons generated during cancer treatment. LR-115, which has low detection efficiency but is expected to be useful for evaluating high-dose neutrons, was used to evaluate the effective dose of neutrons in a high-energy accelerator irradiation room. The results were verified using MCNP 6.2, a Monte Carlo-based particle transport code. This study provides the lower limit for evaluating neutron effective dose using LR-115. The experimental results showed that the neutron effective dose increased linearly with beam current. These findings provide basic data for evaluating neutron effective dose for radiation protection.

Design and testing of an irradiation room with low room-scattering for neutron calibration

IntroductionThis laboratory plans to establish neutron reference radiation fields with three neutron sources to calibrate neutron-measuring devices. To perform calibration at multiple dose rates, neutron ambient dose equivalent rate H˙*(10) needs to range 1 μSv/h to 10 mSv/h. The lower limit requires that the maximum available calibration distance should be at least 4.5 m. MethodsTo reduce room-scattered neutrons and extend the available calibration distance, MC simulations were conducted to determine the material and size of the irradiation room. A 3″ Bonner sphere and a LB6411 environmental neutron dosimeter were used to characterize the irradiation room. ResultsA 14.32 × 14.32 × 12.00 m3 irradiation room was built based on simulation results. Floor, roof, and walls are made of 75 cm concrete covered by a coating layer of 2 cm BPE and 3 cm PE. Experimental maximum available calibration distance reaches 4.65 m. The range of H˙*(10) for calibration covers 1 μSv/h to 10 mSv/h. Neutron and photon H˙*(10) outside the room are within 0.19 μSv/h and 0.22 μSv/h, respectively.

Radiation protection aspects in the design of a Boron Neutron Capture Therapy irradiation room

Boron Neutron Capture Therapy (BNCT) is a radiotherapy whose effect is due to the combination of low-energy neutron irradiation prior chemical targeting of tumour tissues with boron-10. The context of this work is the design of a clinical BNCT facility based on a Radio-Frequency Quadrupole proton accelerator, manufactured by the Italian National Institute of Nuclear Physics (INFN). Such a machine can provide a neutron beam suitable for the treatment of deep-seated tumours when coupled to a beryllium target and a Beam Shaping Assembly whose main constituent is densified lithiated aluminium fluoride. This paper refines the design of the facility, already addressed in preliminary studies, from the point of view of dosimetric quantities in the room and in the patient. The presented calculations have been performed with different Monte Carlo codes, and assess the time evolution of the dose due to the neutron activation of the irradiated materials. A comprehensive evaluation of the dose absorbed in the healthy organs of the patient is provided, with focus on the residual radioactivity of the patient urine, for three different treatment positions. Borated concrete is confirmed to be the best material for constructing the walls of the treatment room. A lead shielding at the beam-port is proposed to reduce the gamma dose at the irradiation position due to the activation of the Beam Shaping Assembly.

Activation level of the concrete building and pressure vessel in JAEA-Tokai tandem accelerator

ABSTRACT The activation level of the JAEA-Tokai tandem accelerator facility was investigated experimentally in advance of the future decommissioning. JAEA-Tokai tandem accelerator facility has a higher terminal voltage of 18 MV and a larger total floor area, Compared to other electrostatic accelerators with terminal voltage of 1 MV to 6 MV. Therefore, determination for ‘where,’ ‘what,’ and ‘how many’ nuclides are produced in the facility is crucial. Thermal neutrons generated by beam losses associated with accelerator operations contribute significantly to the activation of equipment and facilities. The accumulated activities of60Co and152Eu; the most considerable radionuclides at the decommissioning, can be deduced by the thermal neutron fluence rate during the accelerator operation. In this study, thermal neutron fluence measurement on the surface of the pressure vessel and concrete building was conducted with conventional methods using dosimeters and metal foil detectors as well as a new method using a portable γ-ray detector. The thermal neutron fluence in the facility during the accelerator operation ranges from 101 to 104 n/cm2/s. The sum of deduced activities of60Co and152Eu in 50 years is much lower than the clearance level of 0.1 Bq/g in all areas except in the irradiation room.

The contribution of the air and room scattered neutrons in the PTB calibration facility

Neutron detectors and dosimeters used for radiation protection purposes are commonly calibrated with radioisotope-based neutron sources in dedicated calibration facilities. Due to interactions of the neutrons emitted by the sources with components of the calibration room, the neutron fluence at the measuring point is a sum of several components. As the results of calibration procedures should ideally be independent of the environment in which the measurements are performed, the effects caused by neutrons which are not directly reaching the device under test need to be considered, i.e. the influence of scattered neutrons needs to be determined and corrections have to be made. The contribution of the neutrons scattered from the air and the room to the fluence and dose must be taken into consideration, especially in the case of small and medium sized calibration rooms. The scattered neutron component can be evaluated numerically provided a detailed model of the calibration facility is available. In this work, a realistic MCNP6 model of the calibration room at the Physikalisch-Technische Bundesanstalt (PTB) has been developed in order to evaluate carefully the contribution of scattered neutrons from the air, wall, and equipment in the irradiation room for 252Cf, 241Am–Be and D2O moderated 252Cf (with and without Cd-shielding) neutron sources at different reference points and with and without shadow objects. The calculation also considers new fission spectral data for the neutron reference field and recent cross section data libraries. The results show that the contribution of air out-scattered neutrons depends on the detector position and on the neutron source spectrum. This effect is particularly significant for the moderated 252Cf source. More than a third of the total scored neutrons come from the walls and ceiling and the total contributions of the scattered neutrons to the total fluence at the reference position 170 cm away from the source are 50.6 %, 46.6 %, 55.0 % and 52.5 % for 252Cf, 241Am–Be, D2O-252Cf–Cd and D2O-252Cf sources respectively.

Out-of-field dosimetry using a validated PHITS model and computational phantom in clinical BNCT.

The out-of-field radiation dose for boron neutron capture therapy (BNCT), which results from both neutrons and γ-rays, has not been extensively evaluated. To safely perform BNCT, the neutron and γ-ray distributions inside the treatment room and the whole-body dose should be evaluated during commissioning. Although, certain previous studies have evaluated the whole-body dose in the clinical research phase, no institution providing BNCT covered by health insurance has yet validated the neutron distribution inside the room and the whole-body dose. To validate the Monte Carlo model of the BNCT irradiation room extended for the whole-body region and evaluate organ-at-risk (OAR) doses using the validated model with a human-body phantom. First, thermal neutron distribution inside the entire treatment room was measured by placing Au samples on the walls of the treatment room. Second, neutron and gamma-ray dose-rate distributions inside a human-body water phantom were measured. Both lying and sitting positions were considered. Bare Au, Au covered by Cd (Au+Cd), In, Al, and thermoluminescent dosimeters were arranged at 11 points corresponding to locations of the OARs inside the phantom. After the irradiation, γ-ray peaks emitted from the samples were measured by a high-purity germanium detector. The measured counts were converted to the reaction rate per unit charge of the sample. These measurements were compared with results of simulations performed with the Particle and Heavy Ion Transport code System (PHITS). A male adult mesh-type reference computational phantom was used to evaluate OAR doses in the whole-body region. The relative biological effectiveness (RBE)-weighted doses and dose-volume histograms (DVHs) for each OAR were evaluated. The median dose (D50% ) and near-maximum dose (D2% ) were evaluated for 14 OARs in a 1-h-irradiation process. The evaluated RBE-weighted doses were converted to equivalent doses in 2Gy fractions. Experimental results within 60cm from the irradiation center agreed with simulation results within the error bars except at±20, 30cm, and those over 70cm corresponded within one digit. The experimental results of reaction rates or γ-ray dose rate for lying and sitting positions agreed well with the simulation results within the error bars at 8, 4, 11, 7 and 7, 4, 7, 6, 5, 6 out of 11 points, respectively, for Au, Au+Cd, In, Al, and TLD. Among the detectors, the discrepancies in reaction rates between experiment and simulation were most common for Au+Cd, but were observed randomly for measurement points (brain, lung, etc.). The experimental results of γ-ray dose rates were systematically lower than simulation results at abdomen and waist regions for both positions. Extending the PHITS model to the whole-body region resulted in higher doses for all OARs, especially 0.13Gy-eq increase for D50% of the left salivary gland. The PHITS model for clinical BNCT for the whole-body region was validated, and the OAR doses were then evaluated. Clinicians and medical physicists should know that the out-of-field radiation increases the OAR dose in the whole-body region.

Investigation the Performance Accuracy of Contoured Dual Ring Double Scatterer System for Flat Beam Generation at Proton Therapy

At proton radiotherapy, the extracted beam from accelerator is not initially suitable for tumor treatment and a modification is needed for beam shape and energy due to tumor dimension and site. One clinical strategy is the use of double scattering systems known as passive dose delivery technique to generate proper flattening, transversely. This work aims to design and simulate a new version of double scattering system and compare its performance with another available scatterer system, quantitatively. In this analytical study, Monte Carlo FLUKA code is utilized to simulate the performance of proposed system in generating lateral flat beam. The simulation process is very close to real experimental condition, performed at proton beam irradiation room at Tohoku University in Japan. Moreover, the presence of secondary neutrons, produced due to protons collision with proposed scattering system, is considered as main issue. Final results represent that the proposed scattering system is robust to generate 40 mm flat region with an acceptable uniformity degree. Energy loss caused by current dual scatterer is more than simple ring technique, while the secondary neutrons produced by proposed system are larger than other system. This study simulates the performance of a new dual ring double scattering system. Final results show that there is a close correlation between proposed system and current scattering system. The only concern is about the presence of secondary neutrons mainly at high energy proton particles.

Photon dose rate distribution inside and outside a brachytherapy room.

In a brachytherapy room irradiated with an Iridium-192 (192Ir) source, the spatial distributions of photon dose rates were measured and calculated for the dose distribution both inside and outside the room. The spatial distributions were measured using a thermoluminescent dosimeter (LiF-100) on the surfaces of the concrete walls and barriers of the irradiation room. The calculations were performed using the particle and heavy ion transport code system (PHITS) by considering the detailed model of the brachytherapy room and the radiation source used in the measurements. The measured and calculated doses exhibited a similar distribution pattern within and outside the brachytherapy room. To reduce the edge effect at the entrance door, the addition of a 3-mm thick lead layer on the surface of the concrete wall on the left doorstop is recommended. For the 60Co source, with the existing walls and lead door thickness, the dose at the control console and in front of the entrance maze increased by a factor of approximately 60.

Construction of a System That Links Treatment RIS Terminals and Smartphones to Facilitate Radiation Therapy Operations

Confirmation of patient information is required to ensure the safety of radiation therapy. The purpose of this study was to construct a system that facilitates radiation therapy operations by linking a radiation therapy information system to a smartphone. By linking a smartphone to a radiation therapy operation support system, without using a PC terminal, we were able to input information about the patient's position and fixation into images taken with a smartphone. In addition, patient information could be directly linked into the radiation therapy information system. In addition, patient information could be verified in the irradiation room by synchronizing the smartphone with the radiation therapy support system. The questionnaire was highly evaluated in terms of radio reception, usability, visibility and barcode reading. In this study, by linking a smartphone to a radiotherapy information system, it was possible to construct a system that facilitates radiotherapy operations by checking and registering patient information at hand.

Filtration effectiveness of N95 medical mask exposed to repeated ultraviolet germicidal irradiation room

ABSTRACTBackground: The global Coronavirus disease (COVID-19) pandemic has created shortages of personal protective equipment (PPE) including N95 respirator medical masks. Ultraviolet Germicidal Irradiation (UVGI) is an effective way for disinfection of N95 masks before reuse. The UVGI chamber is an effective method of disinfection against SARS-CoV-2, however its effect on the N95 medical masks filtration ability is still uncertain. Purpose: To evaluate filtration effectiveness of N95 mask after repeated UV-C irradiation in the UVGI chamber. Method: This was a parallel two-group experimental study to see the effect of repeated UVGI exposure on the filtration of 2 types of N95 medical masks (type 8210 and 1860), with 25 pieces each group, using an aerosol particle counter, after 10 cycles of repeated UVGI exposure in the UVGI chamber of the ORL-HNS Department Dr. Cipto Mangunkusumo Hospital. Result: There were no significant differences in the filtration effectiveness of N95 medical masks after repeated UVGI exposure up to 10 cycles for 2 types of N95 masks and there was no significant change in the filtration ability of the N95 medical masks after repeated UVGI exposure. Conclusion: The filtration of N95 medical masks type 8210 and 1860 filtration were maintained >95% after repeated UVGI exposure with cumulative dose of 10,126-16.200 mJ/cm2 in UVGI chamber of ORL-HNS Department, Dr. Cipto Mangunkusumo Hospital. ABSTRAKLatar belakang: Pandemi Coronavirus disease 2019 (COVID-19) menyebabkan keterbatasan tersedianya alat pelindung diri (APD) termasuk masker respirator N95. Ultraviolet Germicidal Irradiation (UVGI) merupakan salah satu cara desinfeksi yang menjanjikan dan efektif, sehingga masker N95 dapat digunakan kembali. Bilik UVGI merupakan metode yang efektif dalam disinfeksi terhadap SARS-CoV-2, namun efek paparan UVGI terhadap kemampuan filtrasi masker N95 belum diketahui. Tujuan: Untuk mengevaluasi efektivitas filtrasi masker N95 setelah paparan UV-C berulang di Bilik UVGI. Metode: Penelitian ini adalah studi ekperimental dua kelompok paralel untuk melihat efek paparan UVGI berulang terhadap filtrasi 2 tipe masker N95 (tipe 8210 dan 1860) sebanyak 25 masker di setiap grup, menggunakan aerosol particle counter setelah paparan UVGI berulang sebanyak 10 siklus di Bilik UVGI Departemen THT-KL RSCM. Hasil: Tidak didapatkan perbedaan bermakna pada masker N95 pasca-paparan UVGI berulang sebanyak 10 siklus dengan rerata filtrasi pada 2 tipe masker, serta tidak terdapat perubahan signifikan kemampuan filtrasi masker N95 pasca-paparan UVGI berulang. Kesimpulan: Filtrasi masker N95 pada penelitian ini dapat dipertahankan 95% pasca-paparan UVGI berulang hingga dosis kumulatif 10.126˗16.200 mJ/cm2 di bilik UVGI Departemen THT-KL RSCM.

Persistent radicals in irradiated imidazolium ionic liquids probed by EPR spectroscopy

Long-lived radicals were observed in irradiated room temperature ionic liquids (RTILs) composed of the bis(trifluoromethylsulfonyl)imide anion (Tf2N−) with 1-hexyl-3-methylimidazolium (hmim+) and1-butyl-3-methylimidazolium (bmim+) cations. The EPR signal intensity increases within hours and the spectral pattern changes during the time after irradiation. The kinetics data obtained indicate the existence of at least two distinct radical cations that have different formation and decay rates. We demonstrate that oxygen does not react rapidly with the radical species formed. The bmim + Tf2N− was selectively deuterated at various positions which allowed us to suggest possible structures of the stable radicals formed. The first structure is a radical cation containing 2 nitrogens and 6 protons all with ca. 8.2 Gauss hyperfine splittings, and 2 protons with 2.8 Gauss splitting. The structure of the second radical cation is similar, but characterized by an odd number of hydrogens with ca. 8.2 Gauss splitting. Extensive quantum chemistry calculations were performed to attempt to identify the structure of these persistent radicals. The most likely candidates are imidazole radical cations having methyl groups at the nitrogen atoms and substituents in the second position of the imidazole ring.

Technical Design Report for a Carbon-11 Treatment Facility.

Particle therapy relies on the advantageous dose deposition which permits to highly conform the dose to the target and better spare the surrounding healthy tissues and organs at risk with respect to conventional radiotherapy. In the case of treatments with heavier ions (like carbon ions already clinically used), another advantage is the enhanced radiobiological effectiveness due to high linear energy transfer radiation. These particle therapy advantages are unfortunately not thoroughly exploited due to particle range uncertainties. The possibility to monitor the compliance between the ongoing and prescribed dose distribution is a crucial step toward new optimizations in treatment planning and adaptive therapy. The Positron Emission Tomography (PET) is an established quantitative 3D imaging technique for particle treatment verification and, among the isotopes used for PET imaging, the 11C has gained more attention from the scientific and clinical communities for its application as new radioactive projectile for particle therapy. This is an interesting option clinically because of an enhanced imaging potential, without dosimetry drawbacks; technically, because the stable isotope 12C is successfully already in use in clinics. The MEDICIS-Promed network led an initiative to study the possible technical solutions for the implementation of 11C radioisotopes in an accelerator-based particle therapy center. We present here the result of this study, consisting in a Technical Design Report for a 11C Treatment Facility. The clinical usefulness is reviewed based on existing experimental data, complemented by Monte Carlo simulations using the FLUKA code. The technical analysis starts from reviewing the layout and results of the facilities which produced 11C beams in the past, for testing purposes. It then focuses on the elaboration of the feasible upgrades of an existing 12C particle therapy center, to accommodate the production of 11C beams for therapy. The analysis covers the options to produce the 11C atoms in sufficient amounts (as required for therapy), to ionize them as required by the existing accelerator layouts, to accelerate and transport them to the irradiation rooms. The results of the analysis and the identified challenges define the possible implementation scenario and timeline.

Development of an Ultraviolet-C Irradiation Room in a Public Portuguese Hospital for Safe Re-Utilization of Personal Protective Respirators.

Almost two years have passed since COVID-19 was officially declared a pandemic by the World Health Organization. However, it still holds a tight grasp on the entire human population. Several variants of concern, one after another, have spread throughout the world. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron variant may become the fastest spreading virus in history. Therefore, it is more than evident that the use of personal protective equipment (PPE) will continue to play a pivotal role during the current pandemic. This work depicts an integrative approach attesting to the effectiveness of ultra-violet-C (UV-C) energy density for the sterilization of personal protective equipment, in particular FFP2 respirators used by the health care staff in intensive care units. It is increasingly clear that this approach should not be limited to health care units. Due to the record-breaking spreading rates of SARS-CoV-2, it is apparent that the use of PPE, in particular masks and respirators, will remain a critical tool to mitigate future pandemics. Therefore, similar UV-C disinfecting rooms should be considered for use within institutions and companies and even incorporated within household devices to avoid PPE shortages and, most importantly, to reduce environmental burdens.

Results of the EURADOS international comparison exercise on neutron spectra unfolding in Bonner spheres spectrometry

This paper summarizes the results obtained from an international comparison exercise on neutron spectra unfolding in Bonner spheres spectrometry, organized within the activities of EURADOS working group 6: computational dosimetry. Four realistic situations were considered: a medical accelerator, a workplace field, an irradiation room and a skyshine scenario. The reference solutions are presented, given in terms of idealized fluence-energy distributions and dose rates, along with details of their derivation using verified Monte Carlo codes. The wide variety of unfolded results that were submitted by the participants are then provided, with some shown to agree well with the reference solutions but others showing significant energy-dependent discrepancies. Finally, explanations for some of these discrepancies are proposed, along with suggested methods for how they might be improved.

Total Ionizing Dose Effects on Solar-Blind Ultraviolet Focal Plane Arrays

The study of the effect of γ-rays on the characteristic parameters of the AlGaN ultraviolet focal plane arrays (UVFPA) was carried out to address the problem of degradation of the characteristic parameters of the solar-blind UVFPA after irradiated by energetic particles in the space environment. The AlGaN UVFPA was irradiated with 60Co γ-rays and annealed at room temperature after irradiation. The dark current, noise voltage, responsivity, detectivity, and other characteristics of the UVFPA were compared before and after irradiation and annealing to summarize the changes of the UVFPA characteristics and to analyze the radiation effect mechanism of AlGaN UVFPA. The experimental results show that as irradiation dose increases, the dark current increases, and the responsivity decreases. After annealing of irradiated sample at room temperature, the degradation of the characteristic parameters caused by irradiation is restored. We believe that the effect of ionizing radiation leads to the increase of leakage current in MOS transistor and threshold voltage drift, resulting in the change of the UVFPA operating point and degradation of the characteristic parameters.

Combining CNN and Q-learning for increasing the accuracy of lost gamma source finding

The increasing use of nuclear technology in various fields makes it necessary to provide the required safety to work with this industry. Gamma source is one of the most widely used sources in industry and medicine. Finding a lost gamma source in a gamma irradiation room without human presence is challenging due to the particular arrangements and barriers in the room for radiation shielding and requires an efficient and robust method. In this paper, locating and routing the lost gamma source in the gamma irradiation room containing radiation blocking barriers are done simultaneously by using two methods, convolutional neural network (CNN) and Q-learning, which are powerful algorithms for deep learning and machine learning. Environment simulation with gamma source was performed using Geant4 simulation. The results show that by combining these two methods in geometries with radiation blocking barriers, in addition to locating with 90% accuracy, routing can also be performed. Although the presence of thick barriers in the room reduces the accuracy, increases the time required to finding the lost gamma source or the inefficiency of other methods, nevertheless, the results show that combination of CNN and Q-learning reduces the time and greatly increases the accuracy.

Advanced Electron Beam (EB) Wastewater Treatment System with Low Background X-ray Intensity Generation

Electron beam wastewater treatment is a very effective method for the destruction of organic and microbiological pollutants. The technology was implemented for municipal and textile industry wastewater treatment. Availability of electron accelerators characterized with different operation parameters make the technology applicable for different end-users and also for installation in confined spaces. In such a case, the design of wastewater irradiation room has to take into account the limited space available for shielding construction, which must restrict X-ray emission. Considering construction of an irradiation room for water treatment facility, it is important to focus not only on a stream formation for irradiation to achieve the desired electron penetration, but also on the reduction in x-ray generation. In the presented work, the X-ray field was tested, using modelling and experimental methods. The final results gave an advanced solution, which can be used in the installation of wastewater treatment, ballast and other types of origin, providing low cost shield and good radiation protection measures.

Intercomparison of Gamma Cell 220 Irradiator Facilities and Dr. Mirzan T Razzak Gamma Irradiators Using Harwell Dosimeters

The gamma irradiator is a multi-purpose facility that possibly used to preserve food, sterilize medical equipment, and conduct genetic engineering and polymerization processes, during which the absorbed dose of the product is critical. The standardization of product quality assurance was regulated by the IAEA Technical Document Number 409 considering Dosimetry for Food Irradiation and ISO 14470 and 11137-3 on Food Irradiation, as well as the Guidance on Dosimetric Aspects of Development, Validation, and Routine Control, respectively. The absorbed dose was influenced by the movement of the product to the source, its position, the amount of radioactive activity in the facility, and the dose rate in the irradiation room. The dosimeter performance test and quality assurance of the system were conducted using the Facility Intercomparison Technique which tested the dosimeter (measuring instrument) at 2 different facilities to determine the performance of the measuring instrument.. In this study, 2 irradiation facilities were tested using a Harwell routine dosimeter in the dose range of 1 kGy to 30 kGy and 20 dose points. The results showed that the highest deviation reached 19% and 21% at the Gamma Cell 220 and the Dr. Mirzan T Razzak Gamma irradiator facilities. This elevated the performance of the dosimeters to determine the precision accuracy of the dose-measuring instrument.

Commissioning of low particle flux for proton beams at MedAustron

MedAustron is a synchrotron-based particle therapy centre located in Wiener Neustadt, Austria. It features three irradiation rooms for particle therapy, where proton beams with energies up to 252.7MeV and carbon ions of up to 402.8MeV/u are available for cancer treatment. In addition to the treatment rooms, MedAustron features a unique beamline exclusively for non-clinical research (NCR). This research beamline is also commissioned for proton energies up to 800MeV, while available carbon ion energies correspond to the ones available in the clinical treatment rooms.Based on the requirements for particle therapy, all irradiation rooms offer particle rates of up to 109particles/s for protons and 107particles/s for carbon ions. However, for research purposes, lower particle fluxes are required and were therefore commissioned for the NCR beamline. Three particle flux settings with particle rates ranging from ≈ 2.4 × 103particles/s to ≈ 5.2 × 106particles/s were established for seven proton energies below 252.7MeV. In addition to the particle rate, the spot sizes and beam energies were measured for these settings. Furthermore, three low flux settings for 800MeV protons with particle rates ranging from ≈ 2 × 103particles/s to ≈ 1.3 × 106particles/s were commissioned. Since the commissioned low flux settings are in a regime well below the limits of the available standard beam diagnostics, setting up the beam under these new operational conditions entirely relied on the use of external detectors. Furthermore, a beam position measurement based alignment without using the standard beam profile monitors was performed for 800MeV protons.