Impact of Beam Quality Q for 137Cs on NK and ND,W for Different Types of Ionization Chambers

Hassan, G.M.; Rabie, Nader; Shousha, Hany A.; Ezzat, Magdy A.

doi:10.5539/apr.v3n1p115

Cited by 1 publication

(1 citation statement)

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“…At the time of measurement the dose rates measured at P1, P2, and P3 were found to be within 1.5% of the stated look-up table values of 11.235 Gy/min, 3.311 Gy/min, and 2.326 Gy/min, respectively. Since the expected uncertainty of these dose rate measurements is about 1.1% given all the related uncertainties for such a measurement added in quadrature, based on the uncertainty contribution factors from a recent publication summarizing the uncertainty of 137 Cs dosimetry(Hassan et al 2011), the stated look-up table values were used. 137 Cs has a physical half-life of 30.2 years and as such the output is very stable and only needs to be corrected by the time decay factor (annual decay of 2.3%).…”

Section: Methodsmentioning

confidence: 99%

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

Brodin¹,

Chen²,

Yaparpalvi³

et al. 2016

Health Physics

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Shielded 137Cs irradiators are routinely used in pre-clinical radiation research to perform in vitro or in vivo investigations. Without appropriate dosimetry and irradiation protocols in place, there can be large uncertainty in the delivered dose of radiation between irradiated subjects that could lead to inaccurate and possibly misleading results. Here, a dosimetric evaluation of the JL Shepard Mark I-68A 137Cs irradiator and an irradiation technique for whole-body irradiation of small animals that allows one to limit the between subject variation in delivered dose to ±3% are provided. Mathematical simulation techniques and Gafchromic EBT film were used to describe the region within the irradiation cavity with homogeneous dose distribution (100% ±5%), the dosimetric impact of varying source-to-subject distance, and the variation in attenuation thickness due to turntable rotation. Furthermore, an irradiation protocol and dosimetry formalism that allows calculation of irradiation time for whole-body irradiation of small animals is proposed, that is designed to ensure a more consistent dose delivery between irradiated subjects. To compare this protocol with the conventional irradiation protocol suggested by the vendor, high-resolution film dosimetry measurements evaluating the dose difference between irradiation subjects and the dose distribution throughout subjects was performed, using phantoms resembling small animals. Based on these results, there can be considerable variation in the delivered dose of > ±5% using the conventional irradiation protocol for whole-body irradiation doses below 5 Gy. Using the proposed irradiation protocol this variability can be reduced to within ±3% and the dosimetry formalism allows for more accurate calculation of the irradiation time in relation to the intended prescription dose.

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Section: Methodsmentioning

confidence: 99%

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

Brodin¹,

Chen²,

Yaparpalvi³

et al. 2016

Health Physics

View full text Add to dashboard Cite

show abstract

Impact of Beam Quality Q for 137Cs on NK and ND,W for Different Types of Ionization Chambers

Abstract: The calibration of different types of ionization chambers in radiotherapy level is done using different beam qualities i.e. -rays from

Cited by 1 publication

References 3 publications

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

Dosimetry Formalism and Implementation of a Homogenous Irradiation Protocol to Improve the Accuracy of Small Animal Whole-Body Irradiation Using a 137Cs Irradiator

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