Universität zu Köln

Quast, Ulrich, Kaulich, Theodor W., Alvarez-Romero, Jose T., Tedgren, Asa Carlsson, Enger, Shirin A., Medich, David C., Mourtada, Firas, Perez-Calatayud, Jose ORCID: 0000-0002-1854-5688, Rivard, Mark J. and Abu Zakaria, G. (2016). A brachytherapy photon radiation quality index Q(BT) for probe-type dosimetry. Phys. Medica, 32 (6). S. 741 - 749. OXFORD: ELSEVIER SCI LTD. ISSN 1724-191X

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Abstract

Introduction: In photon brachytherapy (BT), experimental dosimetry is needed to verify treatment plans if planning algorithms neglect varying attenuation, absorption or scattering conditions. The detector's response is energy dependent, including the detector material to water dose ratio and the intrinsic mechanisms. The local mean photon energy E(r) must be known or another equivalent energy quality parameter used. We propose the brachytherapy photon radiation quality index Q(BT) ((E) over bar), to characterize the photon radiation quality in view of measurements of distributions of the absorbed dose to water, D-w, around BT sources. Materials and methods: While the external photon beam radiotherapy (EBRT) radiation quality index Q(EBRT) ((E) over bar) = TPR1020((E) over bar) is not applicable to BT, the authors have applied a novel energy dependent parameter, called brachytherapy photon radiation quality index, defined as Q(BT) ((E) over bar) = D-prim(r = 2 cm; theta(0) = 90 degrees)/D-prim(r(0) = 1 cm; theta(0) = 90 degrees), utilizing precise primary absorbed dose data, D-prim, from source reference databases, without additional MC-calculations. Results and discussion: For BT photon sources used clinically, Q(BT) ((E) over bar) enables to determine the effective mean linear attenuation coefficient (mu) over bar (E) and thus the effective energy of the primary photons E-prim(eff)(r(0), theta(0)) at the TG-43 reference position P-ref (r(0) = 1 cm; theta(0) = 90 degrees) being close to the mean total photon energy (E) over bar (tot)(r(0), theta(0)). If one has calibrated detectors, published (E) over bar (tot)(r) and the BT radiation quality correction factor k(Q, Q0)(BT) ((E) over bar, r, theta) for different BT radiation qualities Q and Q(0), the detector's response can be determined and D-w(r, theta) measured in the vicinity of BT photon sources. Conclusions: This novel brachytherapy photon radiation quality index Q(BT) characterizes sufficiently accurate and precise the primary photon` s penetration probability and scattering potential. (C) 2016 Published by Elsevier Ltd on behalf of Associazione Italiana di Fisica Medica.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Quast, Ulrich UNSPECIFIED UNSPECIFIED UNSPECIFIED Kaulich, Theodor W. UNSPECIFIED UNSPECIFIED UNSPECIFIED Alvarez-Romero, Jose T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Tedgren, Asa Carlsson UNSPECIFIED UNSPECIFIED UNSPECIFIED Enger, Shirin A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Medich, David C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Mourtada, Firas UNSPECIFIED UNSPECIFIED UNSPECIFIED Perez-Calatayud, Jose UNSPECIFIED orcid.org/0000-0002-1854-5688 UNSPECIFIED Rivard, Mark J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Abu Zakaria, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-273703
DOI:	10.1016/j.ejmp.2016.03.008
Journal or Publication Title:	Phys. Medica
Volume:	32
Number:	6
Page Range:	S. 741 - 749
Date:	2016
Publisher:	ELSEVIER SCI LTD
Place of Publication:	OXFORD
ISSN:	1724-191X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ENERGIES RELEVANT; DOSE CALCULATIONS; IR-192; WATER; CALIBRATION Multiple languages Radiology, Nuclear Medicine & Medical Imaging Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27370