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Calculation of kQ factors for Farmer-type ionization chambers following the recent recommendations on new key dosimetry data
摘要： Purpose: To calculate by Monte Carlo simulations kQ factors for Farmer-type ionization chambers in megavoltage photon beams using the new key dosimetry data recommended by the International Commission on Radiation Units and Measurements (ICRU) Report 90. Methods: Monte Carlo calculations were performed with the EGSnrc code system using both the ICRU 90 and the ICRU 37 data. Farmer-type ionization chambers with graphite and plastic walls and with graphite wall and a plastic waterproofing sleeve were considered (Nuclear Enterprise NE 2571, IBA FC65-G and FC65-P). kQ factors were calculated for photon beams in the range 6–25 MV using phase-space files as input radiation sources. The photon beam qualities in terms of TPR20,10 and %dd(10)x were established by simulating the depth-dose curves in water. Absorbed doses to the air cavity and to water were calculated using the egs_chamber user code with a target statistical uncertainty below 0.1%. Results: The update of key dosimetry data according to the ICRU report 90 had an impact of ?0.2% in the absorbed dose to water and up to 0.5% in the absorbed dose to the air cavity. Nevertheless, changes partially offset each other when entering in kQ as ratio, and the final impact on the kQ values was below 0.3%. Conclusions: The calculated values of kQ tend to be lower than the current values in the IAEA TRS-398 protocol with differences up to about 0.5%. A slightly better agreement (within 0.3%) is observed with the Monte-Carlo calculated values provided by the addendum to the AAPM’s TG-51 protocol.
关键词： Monte-Carlo calculated kQ,Beam quality correction factor,kQ,Radiotherapy dosimetry,ICRU 90
更新于2025-09-19 17:15:36
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Theoretical Analysis and Determination of the Correction Factor for a Waveguide Microcalorimeter
摘要： This paper proposes a new method for determining the correction factor of a newly developed waveguide primary power measurement system (i.e., microcalorimeter), based on the electromagnetic field theory analysis for waveguide thermal isolation section (TIS) in foil short measurement mode. The new method determines the contribution of the power dissipated within the TIS into the correction factor, in term of the physical dimensions of the TIS. Performance comparison and analysis show that the newly proposed method can significantly reduce the measurement uncertainty when evaluating the correction factor of waveguide microcalorimeters.
关键词： primary standards,microcalorimeter,correction factor,electromagnetic field theory
更新于2025-09-16 10:30:52
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Impact of Nonplanar Panels on Photovoltaic Power Generation in the Case of Vehicles
摘要： We investigate the impact of nonplanar panels on power generation in the case of photovoltaic panels mounted on vehicles. The power generation of nonplanar photovoltaic panels on vehicles is analyzed using the numerical geometric model, comprising the incident angle distribution of irradiation. We calculated power generated by the photovoltaic panels equipped on the roof, side, and tilted surfaces of vehicles, showing that even the panels on the side, which are ?tted vertically to the ground, generate more than a quarter of the total power as that generated by the panel horizontal to the ground. Furthermore, we evaluated the curve correction factor that re?ects the relative power generation of nonplanar panels with respect to the reference ?at panels on vehicles. The geometrical model reproduces a simple relationship between the curve correction factor and effective surface ratio between the nonplanar and reference ?at panels. Our ?ndings indicate that the curve correction factor is useful to estimate power generation for nonplanar photovoltaic devices on vehicles; this provides a guiding principle for designing nonplanar photovoltaic devices for vehicles.
关键词： Curve correction factor,photovoltaic panel,photovoltaic system,vehicles
更新于2025-09-16 10:30:52
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Multiple scattering correction factor estimation for aethalometer aerosol absorption coefficient measurement
摘要： We estimate the multiple scattering correction factor (????????), which is an empirical constant required to correct aerosol absorption coefficient (??????) measurements for the multiple scattering artefacts of aethalometer, using a multiplier derived from a linear regression method ( ???????? ?????? ). Estimated ???????? ?????? values during the Cheju ABC Plume Monsoon EXperiment (CAPMEX) are 3.99 (405 nm), 4.48 (532 nm), and 5.46 (781 nm) using aethalometer and 3-wavelength PhotoAcoustic Soot Spectrometer (PASS-3). The difference between these ???????? ?????? values and those of a previous study ( ???????? ??03 ; Weingartner et al. 2003) are -8.0% (405 nm), 20.1% (532 nm), and 30.2% (781 nm); the larger. ???????? difference is greater at larger wavelengths because the linear regression line intercept is ??03 varies by up to 121% with increasing aerosol absorption coefficient (??????) ?????? determined ?????? varies by only 36.8%. ???????? ??03 and ???????? ??03 ?????? ??03 and ?????? ??03 and ?????? from ?????? ?????? and ?????? ??03 and ?????? ???????? than ?????? agrees better with ?????? ????????. This suggest that square difference of ?????? ???????? are -23.1 and 25.8%; however, those of ?????? ???????? are -9.0 and 17.9%, respectively. LLN and ALT both exhibit a greater Absorption Photometer (CLAP; ?????? ??03 from ?????? ???????? than between ?????? difference between ?????? ?????? can be applied to year-round aethalometer measurements. Furthermore, ?????? ???????? during CAPMEX were applied to year-round aethalometer ?????? measurements (?????? ??????, respectively) at Gosan (GSN), Lulin (LLN), and Alert (ALT) stations. ?????? ?????? were compared to concurrent ?????? measurements from Continuous Light ????????). At GSN, the bias difference and root mean ??03 in all three environments.
关键词： CLAP,multiple scattering correction factor,aerosol absorption coefficient,PASS-3,aethalometer
更新于2025-09-09 09:28:46
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Experimental Measurement and Monte Carlo Simulation the Correction Factor for the Medium-Energy X-ray Free-air Ionization Chamber
摘要： A key comparison has been made between the air-kerma standards of the National Institute of Metrology (NIM), China, and other Asia Pacific Metrology Programme (APMP) members in the medium-energy X-ray. This paper reviews the primary standard Free-air ionization chamber correction factor experimental method and Monte Carlo simulation method in the NIM. The experimental method and the Monte Carlo simulation method are adopted to obtain the correction factor for the medium-energy X-ray primary standard free-air ionization chamber at 100 kV, 135 kV, 180 kV, 250 kV four CCRI reference qualities. The correction factor has already been submitted to the APMP as key comparison data and the results are in good agreement with those obtained in previous studies. This study shows that the experimental method and the EGSnrc simulation method are usually used in the measurement of the correction factor. In particular, the application of the simulation methods is more common.
关键词： Correction factor,Air-kerma,Experimental method,Free-air ionization chamber,Monte Carlo simulation
更新于2025-09-04 15:30:14