Therapy Facility Research Articles

MONTE CARLO N PARTICLE EXTENDED (MCNPX) RADIATION SHIELD MODELLING ON BORON NEUTRON CAPTURE THERAPY FACILITY USING D-D NEUTRON GENERATOR 2.4 MeV

Based Studies were carried out to analyze the internal dose of radiation for workers at Boron Neutron Capture Therapy (BNCT) facility base on Cyclotron 30 MeV with BSA and a room that was actually designed before. This internal dose analyzation included interaction between neutrons and air. The air contained N2 (72%), O2 (20%), Ar (0.93%), CO2, Neon, Kripton, Xenon, Helium and Methane. That internal dose to the worker should be below the dose limit for radiation workers which is an amount of 20 mSv/years. From the particles that are present in the air, only Nitrogen and Argon can change into radioactive element. Nitrogen-14 activated to Carbon-14, Nitrogen-15 activated to Nitrogen-16, and Argon-40 activated to Argon-41. Calculation using tally facility in Monte Carlo N Particle version Extended (MCNPX) program for calculated Neutron flux in the air 3.16x107 Neutron/cm2s. The room design in the cancer facility has a measurement of 200 cm in length, 200 cm in width, and 166.40 cm in height. Neutron flux can be used to calculate the reaction rate which is 80.1x10-2 reaction/cm3s for carbon-14 and 8.75x10-5 reaction/cm3s. The internal dose exposed to the radiation worker is 9.08E-9 µSv.

Influence of fringing field and second-order aberrations on proton therapy gantry beamline

Abstract Huazhong University of Science and Technology has been developing a proton therapy facility based on a superconducting cyclotron. As an important section of the facility, the gantry beamline has been designed using TRANSPORT code with simplified fringing field model and linear transfer matrix. However, realistic magnetic fringing field and second-order terms of particle motion cannot be precisely described in this approach, which may deviate the actual result from the design value and thereby increase uncertainties for radiation therapy during beam delivery. For this consideration, the specific effects of fringing field and second-order aberrations have been investigated using OPERA code and ODE solvers. For the potential problems of the designed gantry beamline, COSY INFINITY code, which can calculate transfer matrix of any order under the realistic fringing field represented by Enge function, was used to optimize the optics of present gantry beamline. The final results suggest the beam analysis and optimization methods mentioned in this paper are effective and valuable for relevant applications.

Effects of 12 Weeks of Tai Chi Intervention in Patients With Chronic Ankle Instability: A Randomized Controlled Trial.

Tai Chi is a physical activity modality which is widely practiced over the world. The effectiveness of Tai Chi on postural control and balance has been described in older population, but until recently there are no studies that include patients with chronic ankle instability. The aim of this study was to evaluate the effectiveness of 12 weeks of Tai Chi intervention on dynamic balance and self-reported instability in patients with chronic ankle instability. A randomized controlled trial was carried out. University physical therapy facility. Fifty-two participants were allocated to an intervention group (n = 26) based on Tai Chi training or a control group (n = 26) who received no intervention. The participants completed 12 weeks of Tai Chi intervention (1h session/2times per week) or no intervention in the control group. Outcome measures included postural control and self-reported instability feeling assessed by the Star Excursion Balance Test and the Cumberland Ankle Instability Tool, respectively. There was observed significant improvement in all Star Excursion Balance Test reach distances (anterior [F = 6.26, P < .01]; posteromedial [F = 9.58, P < .01], and posterolateral [F = 8.42, P < .01]) in the Tai Chi group with no change in the control group (P < .01). The intervention group demonstrated significant improvement on self-reported instability feeling assessed by the Cumberland Ankle Instability Tool questionnaire (F = 21.36, P < .01). The obtained results suggested that 12 weeks of Tai Chi intervention have positive effects on postural control and self-reported instability feeling in patients with chronic ankle instability.

Simulations of the Activation of a Proton Therapy Facility Using a Complete Beamline Model With BDSIM

A detailed model of the IBA Proteus One compact gantry system has been created with BDSIM (Beam Delivery Simulation) that has been validated against experimental data. Results regarding activation studies have been obtained for the first time using seamless simulations of the transport of protons in the beamline and their interactions with the environment. The activation of the concrete shielding of the system is estimated after a period of 20 years of operation. These main results are presented and discussed in detail.

Analysis and Design of an Energy Verification System for SC200 Proton Therapy Facility

The purpose of this study is to provide an energy verification method for the nozzle of the SC200 proton therapy facility to ensure safe redundancy of treatment. This paper first introduces the composition of the energy selection system of the SC200 proton therapy facility. Secondly, according to IEC60601 standard, the energy verification requirement that correspond to 1 mm error in water is presented. The allowable difference between the measured magnetic field and the reference are calculated based on the energy verification requirements to select the field resolution of the Hall probe. To ensure accuracy and stability, two Hall probes are mounted on the dipole to monitor the magnetic field strength to verify the proton beam energy in real time. In addition, the test results of the residual field of the dipole show that the probe system meets the accuracy requirements of energy verification. Furthermore, the maximum width of the slit of the energy selection system in accordance with the IEC standard at the corresponding energy is calculated and compared with the actual position of the movable slit to verify the momentum divergence of the proton beam. Finally, we present an energy verification method.

Investigation of multi-intensity compensation for a medical proton therapy facility using the quadrupole scanning method

Abstract In cyclotron-based particle therapy facilities, when degrading from maximum to minimum energy use, strong beam loss on degraders and collimators results in a ratio of current up to 10 3 . Considering patient safety and precision, the beam intensity should vary with energy by a factor of approximately quadrupole scanning and the Monte Carlo method . The main design features of the beamline, detailed optimization process of beam optics, transmission calculation, and intensity compensation have been done successfully. A passive scheme of defocusing high energy beams at specific collimators was adopted as the final solution. In the intensity compensation scheme, the beam optics and transmission were implemented with different strategies depending on the energy range. Studies reported that intensity compensation should be divided into different parts. Regarding low energies, there is only one beam optic design and the field values of all magnets should be scaled with beam rigidity. Moreover, the intensity of the primary beam cannot be increased to compensate for the poor transmission. At high energies, beam losses in the degrader system cause beam intensity variations over two orders of magnitudes. This could be limited by producing intentional losses at selected collimators.

Building of a gene therapy facility: a Singapore experience

Background & Aim In recent years, using gene-modified cell therapy products for treatment of diseases has gained traction. This is largely due to the improved safety profile of the newer generation of viral vectors and several of such therapies have already obtained marketing authorisation. With time, the number of available treatment and demand are likely to increase. As these products can only be produced ex-vivo using patients’ cells, there is a need for a production site within Singapore that can meet both biosafety and good manufacturing practice (GMP) requirements. Methods, Results & Conclusion The Cell Therapy Facility at Health Sciences Authority, Singapore houses two independent clean room facilities. The older of the two was constructed in 2006 and it was used to prepare cell therapy products intended for haematopoietic transplantation and immunotherapy. Operations were relocated to a bigger facility in 2011 to accommodate an increasing demand for such products. This facility had since obtained GMP compliance status from the local regulatory body and JACIE accreditation. With current advances in the gene therapy field, it is timely that the older facility can be put into better use by converting it into a separate Gene Therapy Facility for viral vector related cell manufacturing. However, as compared to building a new facility from scratch, modification of an existing facility comes with a different set of challenges. The design and layout of the Gene therapy Facility has to comply to GMP regulations while navigating the constraints of an existing pre-defined space and retaining most of the original infrastructure such as the air control and mechanical ventilation systems. After much consideration, the space is reconfigured to include one large negative-pressured grade B room for cell processing (bubble air-lock design for bio-containment). Additional adjacent grade B and C rooms are carved out for a two-stage gowning process prior to entry into the processing suite and for a unidirectional personnel flow through a different exit. Numerous pass-through windows are installed for proper movement of cell therapy products, supplies and waste. There is one limitation for this design whereby only a single product can be processed at a time. Handling of multiple products has to be managed with proper process controls such as time segregation, proper decontamination and changeover procedures.

Study of the charge sensing node in the MAPS for therapeutic carbon ion beams

Beam monitoring system in heavy ion therapy facilities ensures the beam energy deposition can accurately cover the dedicated tumour region. For the purpose of building a high-precision beam monitoring system, a Monolithic Active Pixel Sensor (MAPS) is under development. The charge sensing node in the MAPS is formed by an n-well −p− epitaxial layer junction and it collects charge by drift and diffusion. In order to optimize the performance of the charge sensing node, the depletion region, the diode capacitance, the charge collection efficiency and the charge collection time have been studied with TCAD simulations. This paper discusses the simulation results with different bias voltage, node structures and heavy ion hitting locations.

Prevalence of Methicillin-Resistant Staphylococcus sp. (MRS) in Different Companion Animals and Determination of Risk Factors for Colonization with MRS.

The aim of this study was to detect the prevalence of methicillin-resistant Staphylococcus sp. (MRS) in populations of companion animals that either have previously been exposed or have not been exposed to antibiotic therapy or veterinary facilities, and if owners’ healthcare profession had an influence on colonization with MRS. In addition, the antimicrobial resistance pheno- and genotype were investigated and risks for colonization with MRS were assessed. During this study, 347 nasal swabs (dogs n = 152; cats n = 107; rabbits n = 88) were investigated for the presence of methicillin-resistant Staphylococcus aureus (MRSA). In addition, 131 nasal swabs (dogs n = 79; cats n = 47; rabbits = 3; guinea pigs = 2) were examined for the presence of MRSA but also other MRS. In total, 23 MRS isolates belonged to nine staphylococcal species: Staphylococcus epidermidis (n = 11), Staphylococcus warneri (n = 3), Staphylococcus hominis (n = 2), Staphylococcus pseudintermedius (n = 2), and singletons Staphylococcus cohnii, Staphylococcus sciuri, Staphylococcus fleurettii, Staphylococcus lentus, and Staphylococcus haemolyticus. Twenty isolates displayed a multidrug-resistant phenotype. Various resistance and biocide resistance genes were detected among the examined staphylococci. Risk assessment for MRS colonization was conducted using a number of factors, including animal species, breed, age, gender, recent veterinary health care hospitalization, and antibiotic prescription, resulting in recent veterinary health care hospitalization being a significant risk factor. The detection of multidrug-resistant MRS in healthy animals is of importance due to their zoonotic potential.

BIOLOGICAL DOSE UNIFORMITY IN SPREAD-OUT BRAGG PEAK OF PROTON SCANNING BEAM THERAPEUTIC FACILITY

Introduction. Biological dose uniformity in SOBP of the modem proton therapy facilities is an important issue. The results of a number of studies reveal an increased biological efficiency at the distal area of SOBP. The aim of the study was to verify this effect for Prometeus facility, which provides proton therapy with a scanning pencil beam. Material and methods. The study was conducted at A. Tsyb MRRC. Melanoma B16F10 cells were used for the experiments. The biological efficacy of protons was evaluated by clonogenic assay (cell survival) and comet assay (DNA damage). Proton dose range within the experiments was 4-8 Gy. Cells were irradiated both in monolayer and suspension conditions. Proton biological efficacy along SOBP was evaluated in the proximal, middle and distal positions. All irradiations were carried out with one field. Results of in vitro experiments indicate that Prometeus facility treatment planning system in case of single-field irradiation provides the uniformity of the biological dose in SOBP. According to cell survival, there is a tendency for a slightly greater efficiency of protons in the proximal part of SOBP. Data on DNA damage confirm this conclusion. Conclusion. Therefore, unlike a number of modern installations for proton therapy in the case of the facility used in the study, there is no increase of biological dose in the distal area of SOBP.

История и перспективы протонной лучевой терапии

Purpose: Presentation of the history, status and prospects for the development of proton therapy. Material and methods: The history of proton therapy (PT) is divided into two periods. The first one – the experimental period lasted since 1954 to 1990, when proton therapy was carried out at the ten facilities in physical institutes. The research accelerators and the horizontal proton beams with a fixed direction are used. The second period is from 1990, when the first clinical proton center was commissioned in a multi-field hospital in the city of Loma Linda, USA. In the first period, the necessary technical tools were developed and the advantages of using accelerated protons in remote radiation therapy formulated by R. Wilson in 1946 were confirmed on a limited (about 9,000) patient population: halving the radiation load on the healthy tissues surrounding the tumor and on the organism as a whole compared to γ- and electron irradiation and high dose gradients at the borders of the dose distributions and the tumors. This allows to increase the dose in the tumor (target), increase the probability of the tumor resorption and at last to irradiate tumors, including small sizes, located near critical organs and structures. By 1990, in three experimental centers in Russia (JINR, ITEP, PNPI) accumulated about 30 % of world clinical experience. Today, more than 70 multi-cabin and several single-cabin clinical based proton therapy centers operate in the world. Almost all centers are equipped with gantry installations for PT for 95 % of patients. Today proton therapy is indicated and is used for the treatment of 10–15 % of all malignancies of cancer incidence structure. Results: Healthcare in Russia needs 10–15 multi-cabin proton (and ion) centers. Currently, there are one experimental PT center in the JINR, where up to 100 patients are exposed pea year. The modern proton center was commissioned at the Medical Institute Sergei Berezin in St. Petersburg with two gantry of company Varian. The IBA proton center in Dimitrovgrad is expected. The single-cabin proton complex of domestic production has been operating in Obninsk since 2017. 20th-century technologies and the horizontal beam (without the possibility of its rotation) are used in this complex for treatment of patients with small head and neck tumors. Conclusion: Equipping the Russian health care facilities with proton therapy facilities is inevitable. Russia will buy them worldwide for decades, like almost all types of high-tech medical equipment, are bought today, or can produce them locally. All the prerequisites needed for production (rich physical – technical experience, scientific and industrial potential) are available.

An Interactive Virtual Reality Tour for Adolescents Receiving Proton Radiation Therapy: Proof-of-Concept Study.

BackgroundChild life therapists provide patient education for children undergoing radiation therapy to assist in coping with and understanding their treatment.ObjectiveThis proof-of-concept study aimed to determine the feasibility of incorporating a 360-degree video tour via a virtual reality system for children scheduled to receive radiation therapy. The secondary objective was to qualitatively describe each subject’s virtual reality experience.MethodsChildren aged ≥13 years scheduled to receive proton radiation therapy were included in the study. Subjects watched the 360-degree video of the radiation therapy facility in an immersive virtual reality environment with a child life therapist experienced in coaching children receiving radiation therapy and completed a survey after the tour.ResultsEight subjects consented to participate in the study, and six subjects completed the 360-degree video tour and survey. All the enrolled patients completed the tour successfully. Two subjects did not complete the survey. Two subjects requested to pause the tour to ask questions about the facility. Five subjects said the tour was helpful preparation before undergoing proton radiation therapy. Subjects stated that the tour was helpful because “it showed [them] what’s to come” and was helpful to see “what it’s like to lay in the machine.” One subject said, “it made me feel less nervous.” Six subjects stated that they would like to see this type of tour available for other areas of the hospital, such as diagnostic imaging rooms. None of the subjects experienced nausea or vomiting.ConclusionsThe 360-degree video tour allowed patients to explore the treatment facility in a comfortable environment. Participants felt that the tour was beneficial and would appreciate seeing other parts of the hospital in this manner.

Study on Magnets for Beam Transport System of SC200 Superconducting Proton Therapy Facility

The SC200 proton therapy facility is consisting of a superconducting cyclotron, a gantry treatment room and a fixed beam room. The proton beams are transported mainly with beam transport devices, such as dipole magnets, quadrupole magnets, and corrector magnets which lie on the beam transport line layout of which is based on the beam optics design. A series of dipole, quadrupole, and corrector magnets ultimately make high-quality transmission of proton beams possible. Dipole magnets are mainly for beams deflection, quadrupole magnets are for beam focusing, and corrector magnets for orbit correction of beams. This paper shows the design of such magnets for the beam transport line. Besides, main parameters of magnets are presented and magnetic analysis work is also illustrated in this paper. The magnetic fields of dipole and quadrupole magnets are measured by hall mapping system and rotary coil measuring system. The results show that the measuring results are a little worse than the simulation results. However, both methods can meet the design requirement and the basic trend is similar to each other.

Design of the Fast Scanning Magnets for SC200 Proton Therapy Facility

At the Institute of Plasma Physics of the Chinese Academy of Sciences, a design of the pencil beam scanning nozzle is being planned. The main goal of the design is to meet the requirements of the radiation field and the scanning speed of the superconducting accelerators SC200 and to achieve a compact structure. Scanning magnets are one of the core components in the pencil beam scanning system and used to control the trajectory of the proton beam to form a radiation field to be tumor shape. This paper mainly discusses the physical considerations and requirements of the scanning system and scanning electromagnetic design. The tapered air gap of scanning magnet Y was used to accommodate the deflection envelope of the scanning magnet X. Since the two scanning magnets are excited by alternating currents and the maximum repetition frequency are up to 50 Hz and 12.5 Hz, respectively, eddy currents and losses are expected to be significant. To study the eddy current effect, the eddy current and steady-state thermal simulation of the magnet end plate were carried out, and the results of the simulation were discussed.

Efficacy of peritoneal dialysis in neonates presenting with hyperammonaemia due to urea cycle defects and organic acidaemia.

Newborns with inborn errors of metabolism can present with hyperammonaemic coma. In this study, we evaluated the effect of peritoneal dialysis on plasma ammonium levels and on the short-term outcome in neonatal patients with urea cycle defects and organic acidaemia. Data from infants with hyperammonaemia due to urea cycle defects or organic acidaemia treated with dialysis were collected and retrospectively analyzed. The results of patient groups (group I, survived; and group II, died) were compared. Fourteen neonates were enrolled in this study. In group I, plasma ammonium levels before dialysis were median (IQR) 1652 μg/dL (1165-2098 μg/dL); in group II, they were 1289 μg/dL (1070-5550 μg/dL). There was no statistically significant difference. Urea cycle defects were diagnosed in eight, and organic acidaemia in six patients. The duration of a blood ammonia level >200 μg/dL was longer in group II (P = 0.04). A <60.8% decline in the ammonia level from the beginning of dialysis to the 12th hour of dialysis carried a 3.33-fold higher risk of mortality, when compared with a greater decline. Five patients with urea cycle defects, and one with organic acidaemia, died. The mortality risk was 8.33-fold (95% CI = 0.63-90.86) higher for patients with urea cycle defects than for those with organic acidaemia. In patients with hyperammonaemia treated with peritoneal dialysis, the rate of ammonia removal and the underlying aetiology appear to be important prognostic factors. Neonates with organic acidaemia who are admitted to centres without continuous renal replacement therapy facilities can be effectively treated with peritoneal dialysis.

Radiation therapy treatment facility and overall survival in the adjuvant setting for locally advanced head and neck squamous cell carcinoma.

Treatment at high-volume surgical facilities (HVSFs) provides a survival benefit for patients with head and neck squamous cell carcinomas (HNSCCs); however, it is unknown what role postoperative radiation therapy (PORT) plays in achieving the improved outcomes. From the National Cancer Database, 6844 patients with locally advanced invasive HNSCCs of the oral cavity, oropharynx, larynx, and hypopharynx who underwent definitive surgery with PORT between 2004 and 2013 were identified. HVSFs were those in the top percentile for annual case volume during this period. The median follow-up was 54months. Compared with a lower volume surgical facility (LVSF), an HVSF improved 5-year overall survival (OS; 57.7% at HVSFs vs 52.5% at LVSFs; P=.0003). Overall, 31.6% of the patients changed their radiation therapy (RT) facility after surgery, with this being more common at HVSFs (39.1% vs 28.9% at LVSFs; P<.001). Among those patients undergoing surgery at an HVSF, remaining at the same facility for RT improved 5-year OS (63.1% vs 49.3% with a facility change; P<.0001). A propensity score-matched cohort of patients treated at HVSFs confirmed the improved 5-year OS when patients remained at the treating HVSF for RT (59.2% vs 50.7% with a facility change; P=.005). In a multivariate analysis, treatment at an HVSF and remaining there for RT resulted in a reduced hazard of death (hazard ratio, 0.81; 95% confidence interval, 0.69-0.94; P=.006). The survival benefit associated with HVSFs persists only when patients remain at the facility for RT, and this suggests that facility specialization and/or high-volume PORT may assist in driving the OS improvement.

Energy loss of degrader in SC200 proton therapy facility

The proton beam energy determines the range of particles and thus where the dose is deposited. According to the depth of tumors, an energy degrader is needed to modulate the proton beam energy in proton therapy facilities based on cyclotrons, because the energy of beam extracted from the cyclotron is fixed. The energy loss was simulated for the graphite degrader used in the beamline at the superconducting cyclotron of 200 MeV in Hefei (SC200). After adjusting the mean excitation energy of the graphite used in the degrader to 76 eV, we observed an accurate match between the simulations and measurements. We also simulated the energy spread of the degraded beam and the transmission of the degrader using theoretical formulae. The results agree well with the Monte Carlo simulation.

Scanned Proton Beam Performance and Calibration of the Shanghai Advanced Proton Therapy Facility

The Shanghai Advanced Proton Therapy facility (SAPT) is a hospital-based facility that began construction in December of 2014 with commissioning of the first scanned proton beam line starting in October of 2017. Proton beams are extracted from a synchrotron accelerator with energies between 70 and 235 MeV. Beam delivery uses the modulated scanning and energy stacking techniques to produce a maximal scanning area of 40 × 30 cm2 at the iso-center. Prior to clinical use, the beam delivery system was characterized and calibrated following the guidelines of the IEC 62667 medical electronic equipment standard including the spot size in air, spot position, depth dose distributions, and lateral dose profiles, as well as the beam monitor calibrations following the IAEA TRS-398 recommendations with small differences.•The measured dosimetric results showed that the full width at half maximum (FWHM) for the beam spot size in air varied approximately from 6 mm to 13 mm. The dose fall-off (DDF) derived from the measured depth dose in water varied from 4.7 mm at 235 MeV to 0.7 mm at 70 MeV. The homogeneity of the scanned field was better than 2% for various energies as expected.•Furthermore, the beam reproducibility and proportionality delivery accuracy was also stable with the results better than 0.1% and 1% respectively. Finally, the dose monitor calibration factor, its reproducibility and stability were tested. Reproducibility tests exhibited a standard deviation (SD) result of less than 1% during the test period.•All the measured dosimetric parameters showed that the design specifications were well achieved and the results are suitable for being used as a part of the clinical commissioning and quality assurance program for treating patients.

Beam Shaping Assembly Optimization for Boron Neutron Capture Therapy Facility Based on Cyclotron 30 MeV as Neutron Source

A design of beam shaping assembly (BSA) installed on cyclotron 30 MeV model neutron source for boron neutron capture therapy (BNCT) has been optimized using simulator software of Monte Carlo N-Particle Extended (MCNPX). The Beryllium target with thickness of 0.55 cm is simulated to be bombarded with 30 MeV of proton beam. In this design, the parameter regarding beam characteristics for BNCT treatment has been improved, which is ratio of fast neutron dose and epithermal neutron flux. TiF3 is replaced to 30 cm of 27Al as moderator, and 1.5 cm of 32S is combined with 28 cm of 60Ni as neutron filter. Eventually, this design produces epithermal neutron flux of 2.33 × 109, ratio between fast neutron dose and epithermal neutron flux of 2.12 × 10-13,ratio between gamma dose and epithermal neutron flux of 1.00 × 10-13, ratio between thermal neutron flux and epithermal neutron flux is 0.047, and ration between particle current and total neutron flux is 0.56.

Microdosimetric specific energy probability distribution in nanometric targets and its correlation with the efficiency of thermoluminescent detectors exposed to charged particles

Due to their common use for dose measurements in space and hadron therapy facilities, it is of fundamental importance to know the efficiency of luminescent detectors for measuring a wide range of particles and energies. However, due to experimental limitations it is often not possible to irradiate the detectors with very high energies, less common isotopes or exotic particles. Furthermore, the efficiency determination at low energies is biased with associated large uncertainties in range, linear energy transfer and dose. This paper presents the recently developed Microdosimetric d(z) Model able to assess the relative efficiency of thermoluminescent detectors for measuring different radiation qualities by relating the simulated dose probability distribution of the specific energy in nanometric targets with an experimentally determined response function. The model was tested in case of LiF:Mg, Ti (MTS) and LiF:Mg,Cu,P (MCP) thermoluminescent detectors exposed to charged particles from 1H to 132Xe in the energy range 3–1000 MeV/u. A comparison with experimentally determined efficiency results showed a very good agreement in case of calculations performed in a simulated target size of 40 nm. This validated model can be used to assess detector efficiency to exotic particles, unavailable radiation qualities and energies at ground level accelerators or complex mixed fields. The assumptions behind the model, its methodology and results are discussed in detail. Furthermore, a systematic investigation on the effect of simulation parameters on the calculated efficiency values is included in the manuscript.