Phantom size in brachytherapy source dosimetric studies

被引:126
作者
Pérez-Calatayud, J
Granero, D
Ballester, F
机构
[1] Univ Valencia, Dept Atom Mol & Nucl Phys, CSIC, E-46100 Burjassot, Spain
[2] Univ Valencia, IFIC, CSIC, E-46100 Burjassot, Spain
关键词
D O I
10.1118/1.1759826
中图分类号
R8 [特种医学]; R445 [影像诊断学];
学科分类号
1002 ; 100207 ; 1009 ;
摘要
An important point to consider in a brachytherapy dosimetry study is the phantom size involved in calculations or experimental measurements. As pointed out by Williamson [Med. Phys. 18, 776786 (1991)] this topic has a relevant influence on final dosimetric results. Presently, one-dimensional (1-D) algorithms and newly-developed 3-D correction algorithms are based on physics data that are obtained under full scatter conditions, i.e., assumed infinite phantom size. One can then assume that reference dose distributions in source dosimetry for photon brachytherapy should use an unbounded phantom size rather than phantom-like dimensions. Our aim in this paper is to study the effect of phantom size on brachytherapy for radionuclide Cs-137, Ir-192, I-125 and Pd-103, mainly used for clinical purposes. Using the GEANT4 Monte Carlo code, we can ascertain effects on derived dosimetry parameters and functions to establish a distance dependent difference due to the absence of full scatter conditions. We have found that for Cs-137 and Ir-192, a spherical phantom with a 40 cm radius is the equivalent of an unbounded phantom up to a distance of 20 cm from the source, as this size ensures full scatter conditions at this distance. For I-125 and Pd-103, the required radius for the spherical phantom in order to ensure full scatter conditions at 10 cm from the source is R = 15 cm. A simple expression based on fits of the dose distributions for various phantom sizes has been developed for Cs-137 and Ir-192 in order to compare the dose rate distributions published for different phantom sizes. Using these relations it is possible to obtain radial dose functions for unbounded medium from bounded phantom ones. (C) 2004 American Association Qf Physicists in Medicine.
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页码:2075 / 2081
页数:7
相关论文
共 30 条
[1]  
AGOLTINELLI S, 2003, NUCL INSTRUM METHODS, V506, P250
[2]   An analytical dosimetry model as a step towards accounting for inhomogeneities and bounded geometries in 192Ir brachytherapy treatment planning [J].
Anagnostopoulos, G ;
Baltas, D ;
Karaiskos, P ;
Pantelis, E ;
Papagiannis, P ;
Sakelliou, L .
PHYSICS IN MEDICINE AND BIOLOGY, 2003, 48 (11) :1625-1647
[3]   ACCURATE MONTE-CARLO CALCULATIONS OF THE COMBINED ATTENUATION AND BUILDUP FACTORS, FOR ENERGIES (20-1500 KEV) AND DISTANCES (0-10 CM) RELEVANT IN BRACHYTHERAPY [J].
ANGELOPOULOS, A ;
PERRIS, A ;
SAKELLARIOU, K ;
SAKELLIOU, L ;
SARIGIANNIS, K ;
ZARRIS, G .
PHYSICS IN MEDICINE AND BIOLOGY, 1991, 36 (06) :763-778
[4]   A Monte Carlo investigation of the dosimetric characteristics of the CSM11 137Cs source from CIS [J].
Ballester, F ;
Lluch, JL ;
Limami, Y ;
Serrano, MA ;
Casal, E ;
Pérez-Calatayud, J ;
Lliso, F .
MEDICAL PHYSICS, 2000, 27 (09) :2182-2189
[5]   Monte Carlo calculations of dose rate distributions around the Amersham CDCS-M-type 137Cs source [J].
Casal, E ;
Ballester, F ;
Lluch, JL ;
Pérez-Calatayud, J ;
Lliso, F .
MEDICAL PHYSICS, 2000, 27 (01) :132-140
[6]   SPECIFIC ABSORBED FRACTIONS FOR PHOTON POINT SOURCES WITHIN A SCATTERING MEDIUM [J].
ELLETT, WH .
PHYSICS IN MEDICINE AND BIOLOGY, 1969, 14 (04) :615-&
[7]   MONTE-CARLO CALCULATION OF ENERGY BUILDUP FACTORS IN THE RANGE FROM 15KEV TO 100KEV, WITH SPECIAL REFERENCE TO THE DOSIMETRY OF I125 SEEDS [J].
HERBOLD, G ;
HARTMANN, G ;
TREUER, H ;
LORENZ, WJ .
PHYSICS IN MEDICINE AND BIOLOGY, 1988, 33 (09) :1037-1053
[8]  
*IGWG, 1990, INT BRACH THER PHYS
[9]   Monte Carlo and TLD dosimetry of an 192Ir high dose-rate brachytherapy source [J].
Karaiskos, P ;
Angelopoulos, A ;
Sakelliou, L ;
Sandilos, P ;
Antypas, C ;
Vlachos, L ;
Koutsouveli, E .
MEDICAL PHYSICS, 1998, 25 (10) :1975-1984
[10]  
KARAISKOS P, 2002, MED PHYS, V30, P712