Experimental determination of the effective point of measurement and the displacement correction factor for cylindrical ionization chambers in a 6 MV photon beam.
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| Title: | Experimental determination of the effective point of measurement and the displacement correction factor for cylindrical ionization chambers in a 6 MV photon beam. |
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| Authors: | Legrand, C.1 c.legrand@dkfz-heidelberg.de, Hartmann, G. H.1, Karger, C. P.1 |
| Source: | Physics in Medicine & Biology. 11/7/2012, Vol. 57 Issue 21, p6869-6880. 12p. |
| Subjects: | Ionization chambers, Photon beams, Gamma rays, Correction factors, Absorption, Particle beams, Ionization (Atomic physics) |
| Abstract: | The displacement effect of cylindrical ionization chambers is taken into account either by an effective point of measurement (EPOM) or, alternatively, by using a displacement correction factor. The dependence of these effects on water was examined as a function of the cavity radius for 60Co gamma radiation in a previous paper. This paper describes results for high-energy photon beams using the same measurement technique. Additionally, the displacement correction factor was directly measured. Absorbed doses measured under reference conditions following the international protocol IAEA TRS-398 and theGerman protocol DIN 6800-2 agreed well between the chambers with different cavity radii within a standard uncertainty of 0.2%. However, there was a constant difference of 0.2% between both protocols. Similar to our observations made in 60Co, absorbed doses measured with the different chambers at depths beyond the maximum showed deviations of up to 0.6% and 0.5% for IAEA TRS-398 and DIN 6800-2, respectively, and deviations of more than 1% were found for both protocols in the build-up and maximum region. We therefore propose modified formulas for the determination of the EPOM and the displacement correction factor. [ABSTRACT FROM AUTHOR] |
| © 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 82832360 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Experimental determination of the effective point of measurement and the displacement correction factor for cylindrical ionization chambers in a 6 MV photon beam. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Legrand%2C+C%2E%22">Legrand, C.</searchLink><relatesTo>1</relatesTo><i> c.legrand@dkfz-heidelberg.de</i><br /><searchLink fieldCode="AR" term="%22Hartmann%2C+G%2E+H%2E%22">Hartmann, G. H.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Karger%2C+C%2E+P%2E%22">Karger, C. P.</searchLink><relatesTo>1</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Physics+in+Medicine+%26+Biology%22">Physics in Medicine & Biology</searchLink>. 11/7/2012, Vol. 57 Issue 21, p6869-6880. 12p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Ionization+chambers%22">Ionization chambers</searchLink><br /><searchLink fieldCode="DE" term="%22Photon+beams%22">Photon beams</searchLink><br /><searchLink fieldCode="DE" term="%22Gamma+rays%22">Gamma rays</searchLink><br /><searchLink fieldCode="DE" term="%22Correction+factors%22">Correction factors</searchLink><br /><searchLink fieldCode="DE" term="%22Absorption%22">Absorption</searchLink><br /><searchLink fieldCode="DE" term="%22Particle+beams%22">Particle beams</searchLink><br /><searchLink fieldCode="DE" term="%22Ionization+%28Atomic+physics%29%22">Ionization (Atomic physics)</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: The displacement effect of cylindrical ionization chambers is taken into account either by an effective point of measurement (EPOM) or, alternatively, by using a displacement correction factor. The dependence of these effects on water was examined as a function of the cavity radius for 60Co gamma radiation in a previous paper. This paper describes results for high-energy photon beams using the same measurement technique. Additionally, the displacement correction factor was directly measured. Absorbed doses measured under reference conditions following the international protocol IAEA TRS-398 and theGerman protocol DIN 6800-2 agreed well between the chambers with different cavity radii within a standard uncertainty of 0.2%. However, there was a constant difference of 0.2% between both protocols. Similar to our observations made in 60Co, absorbed doses measured with the different chambers at depths beyond the maximum showed deviations of up to 0.6% and 0.5% for IAEA TRS-398 and DIN 6800-2, respectively, and deviations of more than 1% were found for both protocols in the build-up and maximum region. We therefore propose modified formulas for the determination of the EPOM and the displacement correction factor. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>© 2025 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1088/0031-9155/57/21/6869 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 12 StartPage: 6869 Subjects: – SubjectFull: Ionization chambers Type: general – SubjectFull: Photon beams Type: general – SubjectFull: Gamma rays Type: general – SubjectFull: Correction factors Type: general – SubjectFull: Absorption Type: general – SubjectFull: Particle beams Type: general – SubjectFull: Ionization (Atomic physics) Type: general Titles: – TitleFull: Experimental determination of the effective point of measurement and the displacement correction factor for cylindrical ionization chambers in a 6 MV photon beam. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Legrand, C. – PersonEntity: Name: NameFull: Hartmann, G. H. – PersonEntity: Name: NameFull: Karger, C. P. IsPartOfRelationships: – BibEntity: Dates: – D: 07 M: 11 Text: 11/7/2012 Type: published Y: 2012 Identifiers: – Type: issn-print Value: 00319155 Numbering: – Type: volume Value: 57 – Type: issue Value: 21 Titles: – TitleFull: Physics in Medicine & Biology Type: main |
| ResultId | 1 |
