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Lineal accelerator

Hisashi Nakano, Daisuke Kawahara, Kaoru Ono, Yukio Akagi, Yutaka Hirokawa
The effect of dose-delivery time with flattening filter (FF) and flattening filter-free (FFF) photon beams based on microdosimetric kinetic model (MKM) was investigated in this study. Monte Carlo simulation with the particle and heavy ion transport code system (PHITS) was performed to calculate the dose-mean lineal energy yD (keV/μm) of FF and FFF 6 MV photon beams using the IAEA phase-space files of Varian TrueBeam linear accelerator. Human non-small cell lung cancer NCI-H460 cells were used to determine the MKM parameters under the condition that dose-delivery times with continuous irradiation were 1, 5, 10, 30, and 60 min, and the adsorbed dose was 2, 4, and 8 Gy in this study...
2018: PloS One
Linh T Tran, David Bolst, Susanna Guatelli, Alex Pogossov, Marco Petasecca, Michael L F Lerch, Lachlan Chartier, Dale A Prokopovich, Mark I Reinhard, Marco Povoli, Angela Kok, Vladimir L Perevertaylo, Naruhiro Matsufuji, Tatsuaki Kanai, Michael Jackson, Anatoly B Rosenfeld
BACKGROUND: The aim of this study was to measure the microdosimetric distributions of a carbon pencil beam scanning (PBS) and passive scattering system as well as to evaluate the relative biological effectiveness (RBE) of different ions, namely 12 C, 14 N, and 16 O, using a silicon-on-insulator (SOI) microdosimeter with well-defined 3D-sensitive volumes (SV). Geant4 simulations were performed with the same experimental setup and results were compared to the experimental results for benchmarking...
May 2018: Medical Physics
Cristina Roldan-Jimenez, Antonio Cuesta-Vargas, Paul Bennett
BACKGROUND: In recent years, there has been a great interest in analyzing upper-limb kinematics. Inertial measurement with mobile phones is a convenient and portable analysis method for studying humerus kinematics in terms of angular mobility and linear acceleration. OBJECTIVE: The aim of this analysis was to study upper-limb kinematics via mobile phones through six physical properties that correspond to angular mobility and acceleration in the three axes of space...
May 20, 2015: JMIR Rehabilitation and Assistive Technologies
Lennart Lindborg, Martha Hultqvist, Å Carlsson Tedgren, Hooshang Nikjoo
In a recent paper, the authors reported that the dose mean lineal energy, [Formula: see text] in a volume of about 10-15 nm is approximately proportional to the α-parameter in the linear-quadratic relation used in fractionated radiotherapy in both low- and high-LET beams. This was concluded after analyses of reported radiation weighting factors, WisoE (clinical RBE values), and [Formula: see text] values in a large range of volumes. Usually, microdosimetry measurements in the nanometer range are difficult; therefore, model calculations become necessary...
September 2015: Radiation Protection Dosimetry
Aslam, W Matysiak, J Atanackovic, A J Waker
This study investigates the response of a REM-500 to assess neutron quality factor and dose equivalent in low energy neutron fields, which are commonly encountered in the workplace environment of nuclear power stations. The McMaster University 3 MV Van de Graaff accelerator facility was used to measure the response of the instrument in monoenergetic neutron fields in the energy range 51 to 727 keV by bombarding a thin LiF target with 1.93-2.50 MeV protons. The energy distribution of the neutron fields produced in the facility was measured by a (3)He filled gas ionization chamber...
June 2012: Health Physics
Hiroyuki Okamoto, Toshiyuki Kohno, Tatsuaki Kanai, Yuki Kase, Yoshitaka Matsumoto, Yoshiya Furusawa, Yukio Fujita, Hidetoshi Saitoh, Jun Itami
PURPOSE: Microdosimetry has been developed for the evaluation of radiation quality, and single-event dose-mean lineal energy y(D) is well-used to represent the radiation quality. In this study, the changes of the relative biological effectiveness (RBE) values under the therapeutic conditions using a 6 MV linac were investigated with a microdosimetric method. METHODS: The y(D) values under the various irradiation conditions for x-rays from a 6 MV linac were measured with a tissue-equivalent proportional counter (TEPC) at an extremely low dose rate of a few tens of microGy/min by decreasing the gun grid voltage of the linac...
August 2011: Medical Physics
F Spurný, K Pachnerová Brabcová, O Ploc, I Ambrožová, Z Mrázová
Active mobile dosimetry unit (Liulin), passive plastic nuclear track detectors (PNTD) and thermoluminescent detectors (TLD) were exposed in a C290 MeV/n beam at HIMAC-BIO (NIRS, Japan). Two different types of beam configuration were used--monoenergetic beam (MONO) and spread-out Bragg peak (SOBP); the detectors were placed at several depths from the entrance up to the depths behind the Bragg peak. Relative response of TLDs in beams has been studied as a function of the depth, and it was re-proved that it can depend on the linear energy transfer (LET)...
February 2011: Radiation Protection Dosimetry
S Torra, L Ilzarbe, J R Malagelada, M Negre, A Mestre-Fusco, S Aguadé-Bruix, E Florensa, P Suñé, B Gras, J J Hernandez, R Casamitjana, M Andreu Garcia, F Bory Ros, S Delgado-Aros
BACKGROUND: Entry of nutrients into the small intestine activates neuro-hormonal signals that regulate food intake through induction of satiation. OBJECTIVE: To evaluate whether caloric intake can be decreased by pharmacologically accelerating gastric emptying (GE) of nutrients into the small intestine. METHODS: Subjects were tested in 2 days, at baseline (day1) and after randomly receiving, in a double-blind manner, a 1 h infusion of erythromycin (3 mg Kg(-1), to accelerate GE) or placebo (day 2)...
June 2011: International Journal of Obesity: Journal of the International Association for the Study of Obesity
Shunsuke Yonai, Yuki Kase, Naruhiro Matsufuji, Tatsuaki Kanai, Teiji Nishio, Masao Namba, Wataru Yamashita
PURPOSE: Successful results in carbon-ion and proton radiotherapies can extend patients' lives and thus present a treatment option for younger patients; however, the undesired exposure to normal tissues outside the treatment volume is a concern. Organ-specific information on the absorbed dose and the biological effectiveness in the patient is essential for assessing the risk, but experimental dose assessment has seldom been done. In this study, absorbed doses, quality factors, and dose equivalents in water phantom outside of the irradiation field were determined based on lineal energy distributions measured with a commercial tissue equivalent proportional counter (TEPC) at passive carbon-ion and proton radiotherapy facilities...
August 2010: Medical Physics
J J Aristu, R Ciérvide, J Guridi, M Moreno, L Arbea, J D Azcona, L I Ramos, J L Zubieta
Stereotactic radiotherapy is a form of external radiotherapy that employs a system of three dimensional coordinates independent of the patient for the precise localisation of the lesion. It also has the characteristic that the radiation beams are conformed and precise, and converge on the lesion, making it possible to administer very high doses of radiotherapy without increasing the radiation to healthy adjacent organs or structures. When the procedure is carried out in one treatment session it is termed radiosurgery, and when administered over several sessions it is termed stereotactic radiotherapy...
2009: Anales del Sistema Sanitario de Navarra
S Pellejero, S Lozares, F Mañeru
Both the planning systems and the form of administering radiotherapy have changed radically since the introduction of 3D planning. At present treatment planning based on computerised axial tomography (CAT) images is standard practice in radiotherapy services. In recent years lineal accelerators for medical use have incorporated technology capable of administering intensity modulated radiation beams (IMRT). With this mode distributions of conformed doses are generated that adjust to the three dimensional form of the white volume, providing appropriate coverage and a lower dose to nearby risk organs...
2009: Anales del Sistema Sanitario de Navarra
Tatsuhiko Sato, Akira Endo, Maria Zankl, Nina Petoussi-Henss, Koji Niita
The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation and tissue weighting factors, w(R) and w(T), respectively, as revised in ICRP Publication 103 were employed. The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of the absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS...
April 7, 2009: Physics in Medicine and Biology
Phillip J Taddei, Thomas B Borak, Stephen B Guetersloh, Brad B Gersey, Cary Zeitlin, Lawrence Heilbronn, Jack Miller, Takeshi Murakami, Yoshiyuki Iwata
A tissue-equivalent proportional counter (TEPC) has been used as a dosimeter in mixed radiation fields. Since it does not measure LET directly, the response function must be characterized in order to estimate quality factor and thus equivalent dose for the incident radiation. The objectives of this study were to measure the response of a spherical TEPC for different high-energy heavy ions (HZE) having similar velocity and to determine how quality factors can be determined. Data were obtained at the HIMAC heavy ion accelerator for (4)He and (12)C at 220 +/- 5 MeV/nucleon (beta = 0...
October 2006: Radiation Measurements
Satoru Endo, Masashi Takada, Yoshihiko Onizuka, Kenichi Tanaka, Naoko Maeda, Masayori Ishikawa, Nobuyuki Miyahara, Naofumi Hayabuchi, Kiyoshi Shizuma, Masaharu Hoshi
Microdosimetric single event spectra as a function of depth in a phantom for the 290 MeV/nucleon therapeutic carbon beam at HIMAC were measured by using a tissue equivalent proportional counter (TEPC). Two types of geometries were used: one is a fragment particle identification measurement (PID-mode) with time of flight (TOF) method without a backward phantom, and the other is an in-phantom measurement (IPM-mode) with a backward phantom. On the PID-mode geometry, fragments produced by carbon beam in a phantom are identified by the DeltaE-TOF distribution between two scintillation counters positioned up- and down-stream relative to the tissue equivalent proportional counter (TEPC)...
September 2007: Journal of Radiation Research
Satoru Endo, Kenichi Tanaka, Masayori Ishikawa, Masaharu Hoshi, Yoshihiko Onizuka, Masashi Takada, Hiroshi Yamaguchi, Naofumi Hayabuchi, Naoko Maeda, Kiyoshi Shizuma
Microdosimetric single event spectra were determined as a function of depth in an acrylic phantom for the carbon beam at HIMAC using a tissue equivalent proportional counter (TEPC) coupled to a scintillation counter system. The fragments produced by the carbon beam were identified by the deltaE-time of flight distribution obtained from two scintillation counters which were positioned at the up- and down-stream of the TEPC. Lineal energy distribution for the carbon beam and its five fragments, namely, proton, helium, lithium, beryllium, and boron ions, were measured in the lineal-energy range of 5-1000 keV/microm at five phantom depths between 0 and 230 mm...
December 2005: Medical Physics
H M Garnica-Garza
The photoneutron contamination arising from a high-energy medical lineal accelerator is calculated using Monte Carlo simulation, as a function of the radiation field size. The information is used to model the neutron propagation in a radiotherapy treatment room and the transmission across concrete mazes. The Monte Carlo code MCNP4C is used to model the main components of a medical lineal accelerator. Simulations were performed to calculate the photoneutron yields and spectra as a function of the radiation field size...
February 7, 2005: Physics in Medicine and Biology
Cesáreo B Costero-Barrios, Cuauhtémoc Oros-Ovalle
The twenty-fourth case of primary renal angiosarcoma is described, according to the available international literature, this present in a 71-year-old male, a mechanic by trade, without carcinogenic antecedents. Hematuria, pain in flank, and left-side tumoral mass of approximately 20 cm in diameter located in kidney by computerized axial tomography (CT) constituted manifestations. A left nefrectomy was performed. No metastasis was found. The tumor replaced 4/5 of the organ and weighed 1145 g. It showed angiomatous structure with atypical proliferation of endothelial cells in a sinusoldal trauma and anastomosatic vascular channels that invaded neighboring parenchymal and capsule...
July 2004: Gaceta Médica de México
B Reniers, S Vynckier, F Verhaegen
In this work we have compared 125I or 103Pd from a microdosimetric point of view. The photon spectra at different positions around the seeds have first been calculated using EGSnrc Monte Carlo (MC) code. These photon spectra are used as input for the event-by-event MC code TRION to calculate the microdosimetric lineal energy (y) distribution for each isotope. The microdosimetric dose average lineal energy, yD, calculated in a sphere of 1 microm is 3.5 keV microm(-1) for 125I and 4.0 keV microm(-1) for 103Pd, agreeing well with values reported in the literature...
August 21, 2004: Physics in Medicine and Biology
T Nunomiya, S Yonai, M Takada, A Fukumura, T Nakamura
A shielding experiment was performed at the HIMAC (Heavy Ion Medical Accelerator in Chiba), of National Institute of Radiological Sciences (NIRS), to measure neutron dose using a spherical TEPC (tissue-equivalent proportional counter) of 12.55 cm inner diameter. Neutrons are produced from a 5 cm thick stopping length Cu target bombarded by 400 MeV/nucleon C6+ ions and penetrate concrete or iron shields of various thicknesses at 0 degree to the beam direction. From this shielding experiment. y-distribution, mean lineal energy, absorbed dose, dose equivalent and mean-quality factor were obtained behind the shield as a function of shield thickness...
2003: Radiation Protection Dosimetry
Stephen B Guetersloh, Thomas B Borak, Phillip J Taddei, Cary Zeitlin, Lawrence Heilbronn, Jack Miller, Takeshi Murakami, Yoshiyuki Iwata
The response of a tissue-equivalent proportional counter (TEPC) to different ions having a similar linear energy transfer (LET) has been studied. Three ions, 14N, 20Ne and 28Si, were investigated using the HIMAC accelerator at the National Institute of Radiological Sciences at Chiba, Japan. The calculated linear energy transfer (LET( infinity )) of all ions was 44 +/- 2 keV/microm at the sensitive volume of the TEPC. A particle spectrometer was used to record the charge and position of each incident beam particle...
January 2004: Radiation Research
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