Dependence of overall correction factor of a cylindrical ionization chamber on field size and depth in medium-energy x-ray beams

1996 ◽  
Vol 23 (10) ◽  
pp. 1789-1796 ◽  
Author(s):  
Jan Seuntjens ◽  
Frank Verhaegen
Keyword(s):  
Correction Factor ◽  
Ionization Chamber ◽  
Field Size ◽  
Medium Energy ◽  
X Ray ◽  
Cylindrical Ionization Chamber

Free-air ionization chamber, FAC-IR-300, designed for medium energy X-ray dosimetry

2017 ◽  
Vol 12 (01) ◽  
pp. T01008-T01008 ◽  
Author(s):  
S.M. Mohammadi ◽  
H. Tavakoli-Anbaran ◽  
H.Z. Zeinali
Keyword(s):  
Ionization Chamber ◽  
Medium Energy ◽  
X Ray ◽  
Free Air ◽  
Air Ionization

scholarly journals Comparison of entrance surface air kerma measurement with MTS-N (LiF: Mg, Ti) chips with a kilovoltage X-ray source

2021 ◽  
Vol 22 (1) ◽  
pp. 20-34
Author(s):  
Akintayo Daniel Omojola ◽  
Samuel Olaolu Adeneye ◽  
Michael Onoriode Akpochafor ◽  
Isiaka Olusola Akala ◽  
Azuka Anthonio Agboje
Keyword(s):  
Ionization Chamber ◽  
Radiation Detectors ◽  
Field Size ◽  
Peak Voltage ◽  
X Ray ◽  
Air Kerma ◽  
Image Distance ◽  
The Mean ◽  
Dose Accuracy ◽  
Entrance Surface Air Kerma

Objective: Radiation detectors are key components that ensure the accuracy and performances of dosimetry equipment. The study is aimed to compare the mean entrance surface air kerma (ESAK) between a DCT-10mm ionization chamber (IC) and MTS-N (LiF: Mg, Ti) chips when both detectors are exposed to ≤ 5mGy with a 10 by 10 field size, with an X-ray source and to determine the accuracy of the Thermoluminescent (TL) chips. Also, the dose will be compared to similar studies. Materials and Methods: A functional, Digital Radiography (DR) X-ray System was used. A DCT-10mm ionization chamber (IC) and an XR Multidetector was positioned at a Source to Image Distance (SID) of 100cm on polystyrene, about 20cm thick. An X-ray spectrum generated at a Practical Peak Voltage (PPV) of 60-107kV with Half Value Layer (HVL) of 2.4-4.3mmAl and filtration > 3mmAl was used. The same setup was used for the MTS-N chips. Results: The mean doses for 1-5 mGy with the MTS-N chips were 1.07±0.07, 1.60±0.13, 2.23±0.11, 2.58±0.07 and 3.45±0.10 mGy respectively, with accuracies of 7, 20, 26, 36 and 31%. Dose accuracy at 1and 2mGy was within 25% respectively. Dose accuracies at 3, 4 and 5mGy was within >25%. The correction factor for 1-5mGy was 0.94, 1.25, 1.35, 1.55 and 1.45 respectively. Conclusion: Validation of the MTS-N chips with the reference ionization chamber to this study was within 36%. The Radiation and Nuclear Safety Authority (STUK) recommends that ESAK be within 25% for entrance surface dose. ESAK accuracy mostly increased with dose as observed in this study.

scholarly journals Evaluation of using radiographic films in measurements of penumbra width for radiotherapy applications and stereotactic radiosurgery

2018 ◽  
Vol 14 (1) ◽  
pp. 5204-5212
Author(s):  
Ehab A Hegazy
Keyword(s):  
Stereotactic Radiosurgery ◽  
Ionization Chamber ◽  
Field Size ◽  
Physical Parameters ◽  
Ionization Chambers ◽  
X Ray ◽  
Radiation Fields ◽  
Economic Method ◽  
Width Measurements ◽  
Penumbra Region

The accuracy of treatment field size in is a success key in cancer radiotherapy. As Increase in dose may lead to overdose side effects, and decrease in dose lead to subtherapeutic effect which increased incidence of tumor recurrence or incomplete recovery of patient. Many physical parameters should be measured very accurately in order to predict the dose distribution as physical penumbra of radiation fields. Ionization chamber is considered as slandered tools for measuring penumbra. Mega voltage x-ray energy penumbra is measured using ionization chamber due to its high accuracy in measuring absolute dose. This technique can produce the gold standard for penumbra measurements; however, it is a very time consuming and demanding process. Aim of this work is to evaluate the using radiographic films in penumbra width measurements for radiotherapy applications and stereotactic radiosurgery by comparing results obtained by standard ionization chambers to radiographic films as new tool for penumbral width measurements. Comparison between penumbra region measured by ionization chamber and o-xmat v Kodak radiographic films were carried out under the same physical and dosimeteric conditions. Penumbra width differences were found to be less than 1 mm for 6 mev, 15 mev photon beam and 6 mv, 15 mv electron beam used in radiotherapy. Measured differences were considered very small and has no effect on penumbra width measurements however o-xmat v Kodak films provide fast .easy and economic method for penumbra measurement used in radiotherapy dosimetery. 

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