Study of scattered radiation for in-air calibration by a multiple-distance method using ionization chambers and an HDR192Ir brachytherapy source

2006 ◽  
Vol 79 (940) ◽  
pp. 347-352 ◽  
Author(s):  
N P Patel ◽  
B Majumdar ◽  
V Vijayan
Keyword(s):  
Scattered Radiation ◽  
Ionization Chambers ◽  
Distance Method ◽  
Brachytherapy Source

scholarly journals Determination of contributions of scatter and distance error to the source strength of 192Ir HDR brachytherapy source

2016 ◽  
Vol 22 (3) ◽  
pp. 55-59
Author(s):  
Shwetha Bondel ◽  
Manickam Ravikumar
Keyword(s):  
High Dose Rate ◽  
High Dose ◽  
Hdr Brachytherapy ◽  
Iterative Technique ◽  
Distance Measurements ◽  
Distance Method ◽  
Distance Error ◽  
Air Kerma ◽  
Air Kerma Rate ◽  
Brachytherapy Source

Abstract High dose rate (HDR) brachytherapy commonly employs a 192Ir encapsulated source to deliver high dose to the malignant tissues. Calibrations of brachytherapy sources are performed by the manufacturer using a well-type chamber or by in-air measurement using a cylindrical ionization chamber. Calibration using the latter involves measurements to be carried out at several distances and room scatter can also be determined. The aim of the present study is to estimate the scatter contribution from the walls, floor and various materials in the room in order to determine the reference air kerma rate of an 192Ir HDR brachytherapy source by in-air measurements and also to evaluate the error in the setup distance between the source centre and chamber centre. Air kerma measurements were performed at multiple distances from 10 cm to 40 cm between the source and chamber. The room scatter correction factor was determined using the iterative technique. The distance error of −0.094 cm and −0.112 cm was observed for chamber with and without buildup cap respectively. The scatter component ranges from 0.3% to 5.4% for the chamber with buildup cap and 0.3% to 4.6% without buildup cap for distances between 10 to 40 cm respectively. Since the average of the results at multiple distances is considered to obtain the actual air kerma rate of the HDR source, the seven distance method and iterative technique are very effective in determining the scatter contribution and the error in the distance measurements.

scholarly journals A PRELIMINARY STUDY OF RADIATION QUALITY CORRECTION FACTOR (KQ) DETERMINATION FOR WELL-TYPE IONIZATION CHAMBER

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Assef Firnando F ◽  
Okky Agassy Firmansyah ◽  
Cahya Wulandari ◽  
R. Pramuji Ramadhani S
Keyword(s):  
Correction Factor ◽  
Ionization Chamber ◽  
Planning System ◽  
Treatment Planning System ◽  
Radiation Quality ◽  
Ionization Chambers ◽  
Air Kerma ◽  
A Value ◽  
Brachytherapy Source

This paper deals with the determination of the radiation quality correction factor (kQ) well-type ionization chamber for the measurement of Co-60 brachytherapy. The measurement of the brachytherapy source has been done in the hospital brachytherapy facilities. The measurement of air Kerma has been done using three different ionization chambers 0.6 cm3, 30 cm3, 80 cm3, which have calibration factor traceability for Co-60 and one well-type ionization chamber which calibrated for Ir-192. The determination of the radiation quality correction factor (kQ) was determined based on the results of the air Kerma ratio between measurements using ionization chambers, which have traceability to Co-60 and Ir-192 sources. The results of the measurement of the reference air Kerma rate (RAKR) obtained from the three chambers were 21.36, 19.87, 19.34 mGy.m2.h-1, while the results of measurements with ionization chambers get a value of 19.01 mGy.m2.h-1. The kQCal results from 0.6 cm3 ionization chamber get a value of 1.07. The kQCal value was compared with the value of Andreas Schuller’s et al. kQreff of 1.05 and get a deviation of 2.2%. Implementation of the booth kQ value on the results of the RAKR from the HDR1000Plus well-type ionization chamber in the measurement of brachytherapy in two different facilities gets maximal deviation 1.7% with dose value from Treatment Planning System (TPS). The deviation was in the acceptable range of ±5%. Based on this, the use of radiation quality correction factor (kQ) value can be implemented as one method if it does not have the traceability factor calibration of the Co-60 brachytherapy source.

National primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2019

2020 ◽  
pp. 8-12
Author(s):  
Alexandr V. Oborin ◽  
Anna Y. Villevalde ◽  
Sergey G. Trofimchuk
Keyword(s):  
Gamma Radiation ◽  
Energy Flux ◽  
Primary Standard ◽  
Average Energy ◽  
Ion Pair ◽  
X Rays ◽  
Exposure Rate ◽  
Ionization Chambers ◽  
Air Kerma ◽  
Air Kerma Rate

The results of development of the national primary standard of air kerma, air kerma rate, exposure, exposure rate and energy flux for X-rays and gamma radiation GET 8-2011 in 2019 are presented according to the recommendations of the ICRU Report No. 90 “Key Data for Ionizing-Radiation Dosimetry: Measurement Standards and Applications”. The following changes are made to the equations for the units determination with the standard: in the field of X-rays, new correction coefficients of the free-air ionization chambers are introduced and the relative standard uncertainty of the average energy to create an ion pair in air is changed; in the field of gamma radiation, the product of the average energy to create an ion pair in air and the electron stopping-power graphite to air ratio for the cavity ionization chambers is changed. More accurate values of the units reproduced by GET 8-2019 are obtained and new metrological characteristics of the standard are stated.

Applying the Method of Lagrange Multipliers to Derive an Estimator for Unsampled Soil Properties

2014 ◽  
Vol 11 (1) ◽  
pp. 15
Author(s):  
Set Foong Ng ◽  
Pei Eng Ch’ng ◽  
Yee Ming Chew ◽  
Kok Shien Ng
Keyword(s):  
Soil Properties ◽  
Lagrange Multipliers ◽  
Unbiased Estimator ◽  
Soil Property ◽  
Minimum Variance ◽  
Distance Method ◽  
True Value ◽  
A Site ◽  
Method Of Lagrange Multipliers ◽  
Inverse Distance

Soil properties are very crucial for civil engineers to differentiate one type of soil from another and to predict its mechanical behavior. However, it is not practical to measure soil properties at all the locations at a site. In this paper, an estimator is derived to estimate the unknown values for soil properties from locations where soil samples were not collected. The estimator is obtained by combining the concept of the ‘Inverse Distance Method’ into the technique of ‘Kriging’. The method of Lagrange Multipliers is applied in this paper. It is shown that the estimator derived in this paper is an unbiased estimator. The partiality of the estimator with respect to the true value is zero. Hence, the estimated value will be equal to the true value of the soil property. It is also shown that the variance between the estimator and the soil property is minimised. Hence, the distribution of this unbiased estimator with minimum variance spreads the least from the true value. With this characteristic of minimum variance unbiased estimator, a high accuracy estimation of soil property could be obtained.

Applying analytical procedures for performance audit of customs authorities

2020 ◽  
Vol 19 (6) ◽  
pp. 1035-1055 ◽  
Author(s):  
S.V. Pankova ◽  
V.V. Popov
Keyword(s):  
Distance Method ◽  
Scientific Methods ◽  
Scientific Hypothesis ◽  
Financial Audit ◽  
Promising Area ◽  
History Of ◽  
Performance Audit ◽  
Analytical Procedures ◽  
And Performance ◽  
Customs Administration

Subject. The article considers the development of a set of methods and indicators of economic analysis, which can be used for performance audit of customs authorities, using the Volga Customs Administration case. Objectives. The aim is to justify the use of analytical procedures to rank the effectiveness of customs payments for the purpose of performance audit of customs authorities. Methods. We employ general scientific methods of research, i.e. dialectical and monographic methods, logical analysis, comparison, as well as the Euclidean distance method. Results. We reviewed works by Russian and foreign scholars on the history of customs audit development and internal financial control of customs authorities, gave scientific credence to attributing the system of customs payment and performance to the indicators of economic activity of customs authorities. Due to the lack of methods for assessing the performance of customs authorities, the use of analytical procedures during the performance audit seems to be a promising area. Conclusions. When verifying the scientific hypothesis put forward in the study, we established that the introduction and development of the ranking system for the performance of customs authorities related to the collection of customs duties can contribute to effective financial audit of customs authorities in general.

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