Characteristics of the photon radiation field of flat sources in tissue-equivalent plates

1989 ◽  
Vol 67 (5) ◽  
pp. 829-836
Author(s):  
V. Yu. Golikov ◽  
A. N. Barkovskii ◽  
I. A. Likhtarev
Keyword(s):  
Radiation Field ◽  
Photon Radiation ◽  
Tissue Equivalent

Measurement System Design of Micro-Dose Experimental Spectrum

2020 ◽  
Vol 34 (12) ◽  
pp. 2054031
Author(s):  
Min Zhu ◽  
Ming Guo ◽  
Hao Hong ◽  
Sheng’ao Wang ◽  
Biao Li
Keyword(s):  
Energy Transfer ◽  
Ionizing Radiation ◽  
Radiation Field ◽  
Proportional Counter ◽  
Linear Energy Transfer ◽  
Photon Radiation ◽  
Radiation Quality ◽  
Detector Signal ◽  
Tissue Equivalent ◽  
Tissue Equivalent Proportional Counter

Tissue equivalent proportional counter (TEPC) is used to measure the micro-dose spectrum of ionizing radiation. Through changing tissue-equivalent gas pressure, TEPC can simulate the case of radiation energy deposition in different sizes of human cells. Various dosimetric quantities can be obtained such as absorbed dose, radiation quality factor and micro-dose equivalent. Because TEPC simulated cell size is less than the range of ionizing radiation particles, TEPC can be used as linear energy transfer spectroscopy, which can identify different linear energy transfer particles in a mixed radiation field and play an important role in mixed neutron–photon radiation field monitoring and protection. A tissue equivalent proportional counter is designed and manufactured in this paper. Through the built of micro-dose detector signal testing platform, and the realization of measurement of micro-dose detector signal debugging and important parameters (stability, energy resolution, etc.) by [Formula: see text] source method, micro-dose energy spectrum analysis and experimental measurements of Cf-252 source were ultimately achieved. Results show that the detector has good sealing performance and stability, with 12 h stability better than 2.7%. Based on all the above spectra, micro-dosing spectrum of Cf-252 source was experimentally obtained.

On Some Methodological Issues of Studying Cytogenetic Effects in Cancer Patients Treated with Neutron Therapy Using U-120 Cyclotron

2018 ◽  
Vol 63 (2) ◽  
pp. 47-54
Author(s):  
В. Лисин ◽  
V. Lisin
Keyword(s):  
Radiation Field ◽  
Chromosome Aberrations ◽  
Absorbed Dose ◽  
Neutron Radiation ◽  
The Body ◽  
Beam Intensity ◽  
Whole Body ◽  
Γ Radiation ◽  
Cytogenetic Effect ◽  
Tissue Equivalent

Purpose: To study dosimetric characteristics of neutron radiation field, to determine their role in the formation of the total cytogenetic effect in the patient’s body and to assess the cytogenetic dosimetry capabilities in improving the quality of NT. Material and methods: A therapeutic beam with the average neutron energy of ~6.3 MeV was obtained from the V-120 cyclotron. The radiation field of the beam was investigated with the help of two ionization chambers with different sensitivity to neutrons. Chamber with high and low sensitivities were made of polyethylene and graphite, respectively. To exclude the uncertainty associated with the change in beam intensity in time, a dosimeter monitor operating in the integral mode was used. Results: The dependence of the monitor factor on the irradiated area was measured. The distributions of the absorbed dose of neutrons and γ-radiation over the depth of the tissue-equivalent medium were found. The contribution of γ-radiation to the neutron dose was increased from ~10 % at the entry to the medium to ~30 % at a depth of 16 cm. Dose distributions of scattered neutron and γ-radiation in the plane of the end face of the forming device were obtained. The contribution of these radiations to the dose received by the patient’s body was estimated. This contribution was shown to be comparable with that from the therapeutic beam. The analysis of the influence of NT on the estimation of the frequency of chromosome aberrations in the blood of patients was carried out. Conclusion: The frequency of chromosome aberrations in the blood of patients was determined by the whole-body dose, including dose due to scattered radiation. When using equal focal doses, the cytogenetic effect was found to be dependent on the area of the irradiated field and the depth of the tumor in the patient’s body. The differences in the RBE of neutrons and γ-radiation as well as the instability of the therapeutic neutron beam intensity create uncertainties that do not allow for the necessary control over the doses using the cytogenetic dosimetry. Therefore, cytogenetic dosimetry should be combined with an effective instrument dosimetry method. The use of biodosimetry based on the assessment of the frequency of chromosome aberrations is promising for controlling the average whole-body dose, on which the overall radiation response of the body depends.

scholarly journals Effective doses for external exposure from the photon radiation field of soil contamination

2019 ◽  
Vol 2 (1) ◽  
pp. 84-90
Author(s):  
Tran Van Hung
Keyword(s):  
Soil Contamination ◽  
Effective Dose ◽  
Radiation Field ◽  
Photon Radiation ◽  
External Exposure ◽  
Mcnp Code ◽  
Photon Sources ◽  
Effective Doses ◽  
Dose Coefficients

Organ and effective doses of adult for external exposure to photons uniformly distributed in soil were calculated using a MIRD-5 type phantom and MCNP code. The calculations were performed for mono-energic photon sources with source energies from 0.01 MeV to 5 MeV. The effective dose coefficients in this calculation using MCNP code were compared to the calculated results in report of Keith F. Eckerman và Jeffrey C. Ryman.

scholarly journals Medical Applications of the GEMPix

2021 ◽  
Vol 11 (1) ◽  
pp. 440
Author(s):  
Johannes Leidner ◽  
Fabrizio Murtas ◽  
Marco Silari
Keyword(s):  
Radiation Therapy ◽  
Field Size ◽  
Photon Radiation ◽  
Medical Applications ◽  
Drift Region ◽  
Particle Track ◽  
Track Reconstruction ◽  
Tissue Equivalent ◽  
Gafchromic Films ◽  
Time Projection

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow of a gas mixture such as Ar:CO2:CF4, Ar:CO2 or propane-based tissue equivalent gas is supplied externally at a rate of 5 L/h. This article reviews the medical applications of the GEMPix. These include relative dose measurements in conventional photon radiation therapy and in carbon ion beams, by which on-line 2D dose images provided a similar or better performance compared to gafchromic films. Depth scans in a water phantom with 12C ions allowed measuring the 3D energy deposition and reconstructing the Bragg curve of a pencil beam. Microdosimetric measurements performed in neutron and photon fields allowed comparing dose spectra with those from Tissue Equivalent Proportional Counters and, additionally, to obtain particle track images. Some preliminary measurements performed to check the capabilities as the detector in proton tomography are also illustrated. The most important on-going developments are: (1) a new, larger area readout to cover the typical maximum field size in radiation therapy of 20 × 20 cm2; (2) a sealed and low-pressure version to facilitate measurements and to increase the equivalent spatial resolution for microdosimetry; (3) 3D particle track reconstruction when operating the GEMPix as a Time Projection Chamber.

Characterization of the AURORA FXR Photon Radiation Field for SREMP Studies

1977 ◽  
Vol 24 (6) ◽  
pp. 2476-2483 ◽  
Author(s):  
W. L. Chadsey ◽  
H. Bloomberg ◽  
R. Ford ◽  
V. Pine ◽  
D. Strickland
Keyword(s):  
Radiation Field ◽  
Photon Radiation
Sign in / Sign up

Export Citation Format

Share Document