Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms

URI http://www.lib.tokushima-u.ac.jp/repository/metadata/110812
Title
Practical method for determination of air kerma by use of an ionization chamber toward construction of a secondary X-ray field to be used in clinical examination rooms
Authors
Maehata, Itsumi
Hayashi, Hiroaki
Kimoto, Natsumi
Takegami, Kazuki
Okino, Hiroki
Kanazawa, Yuki
Tominaga, Masahide
Authors_Transcription
マエハタ, イツミ
ハヤシ, ヒロアキ
キモト, ナツミ
タケガミ, カズキ
オキノ, ヒロキ
カナザワ, ユウキ
トミナガ, マサヒデ
Authors_Alternative
林, 裕晃
金澤, 裕樹
富永, 正英
Authors_Affiliation
School of Health Sciences, Tokushima University
Institute of Biomedical Sciences, Tokushima University Graduate School
Graduate School of Health Sciences, Tokushima University
Keywords
Ionization chamber
Air kerma
Contamination rate
Scattered X-rays
Diagnostic X-ray equipment
Secondary X-ray field
Description

We propose a new practical method for the construction of an accurate secondary X-ray field using medical diagnostic X-ray equipment. For accurate measurement of the air kerma of an X-ray field, it is important to reduce and evaluate the contamination rate of scattered X-rays. To determine the rate quantitatively, we performed the following studies. First, we developed a shield box in which an ionization chamber could be set at an inner of the box to prevent detection of the X-rays scattered from the air. In addition, we made collimator plates which were placed near the X-ray source for estimation of the contamination rate by scattered X-rays from the movable diaphragm which is a component of the X-ray equipment. Then, we measured the exposure dose while changing the collimator plates, which had diameters of 25–90 mmϕ. The ideal value of the exposure dose was derived mathematically by extrapolation to 0 mmϕ. Tube voltages ranged from 40 to 130 kV. Under these irradiation conditions, we analyzed the contamination rate by the scattered X-rays. We found that the contamination rates were less than 1.7 and 2.3 %, caused by air and the movable diaphragm, respectively. The extrapolated value of the exposure dose has been determined to have an uncertainty of 0.7 %. The ionization chamber used in this study was calibrated with an accuracy of 5 %. Using this kind of ionization chamber, we can construct a secondary X-ray field with an uncertainty of 5 %.

Publisher
Springer Japan
Content Type
学術雑誌論文
ISSN・ISBN
18650333
18650341
NCID
AA12236881
Journal Title
Radiological Physics and Technology
Volume
9
ISSUE
2
SPage
193
EPage
201
Published Date
2016-03-18
remark

Copyright © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2016
The final publication is available at Springer via http://dx.doi.org/10.1007/s12194-016-0352-7.

edb id
306432
URL ( Publisher's Version )
set
徳島大学
FullText URL
Language
eng
TextVersion
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