Determining the incident electron fluence for Monte Carlo-based photon treatment planning using a standard measured data set

被引:94
作者
Keall, PJ [1 ]
Siebers, JV [1 ]
Libby, B [1 ]
Mohan, R [1 ]
机构
[1] Virginia Commonwealth Univ, Dept Radiat Oncol, Richmond, VA 23298 USA
关键词
Monte Carlo; initial electron fluence; beam modeling;
D O I
10.1118/1.1561623
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 accurate dose calculation in phantom and patient geometries requires an accurate description of the radiation source. Errors in the radiation source description are propagated through the dose calculation. With the emergence of linear accelerators whose dosimetric characteristics are similar to within measurement uncertainty, the same radiation source description can be used as the input to dose calculation for treatment planning at many institutions with the same linear accelerator model. Our goal in the current research was to determine the initial electron fluence above the linear accelerator target for such an accelerator to allow a dose calculation in water to within, 1% or 1 mm of the measured data supplied by the manufacturer. The method used for both the radiation source description and the patient transport was Monte Carlo. The linac geometry was input into the Monte Carlo code using the accelerator's manufacturer's specifications. Assumptions about the initial electron source above the target were made based on previous studies. The free parameters derived for the calculations were the mean energy and radial Gaussian width of the initial electron fluence and the target density. A combination of the free parameters yielded an initial electron fluence that, when transported through the linear accelerator and into the phantom, allowed a dose-calculation agreement to the experimental ion chamber data to within the specified criteria at both 6 and 18 MV nominal beam energies, except near the surface, particularly for the 18 MV beam. To save time during Monte Carlo treatment planning, the initial electron fluence was transported through part of the treatment head to a plane between the monitor chambers and the jaws and saved as phase-space files. These files are used for clinical Monte Carlo-based treatment planning and are freely available from the authors. (C) 2003 American Association of Physicists in Medicine.
引用
收藏
页码:574 / 582
页数:9
相关论文
共 47 条
[1]   UNCERTAINTIES IN DOSIMETRIC DATA AND BEAM CALIBRATION [J].
ANDREO, P .
INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS, 1990, 19 (05) :1233-1247
[2]  
Briesmeister JF, 1997, LA13181 LOS AL NAT L
[3]   MONTE-CARLO STUDY OF ACCELERATOR HEAD SCATTER [J].
CHANEY, EL ;
CULLIP, TJ ;
GABRIEL, TA .
MEDICAL PHYSICS, 1994, 21 (09) :1383-1390
[4]   Dose discrepancies between Monte Carlo calculations and measurements in the buildup region for a high-energy photon beam [J].
Ding, GX .
MEDICAL PHYSICS, 2002, 29 (11) :2459-2463
[5]   Energy spectra, angular spread, fluence profiles and dose distributions of 6 and 18 MV photon beams: results of Monte Carlo simulations for a Varian 2100EX accelerator [J].
Ding, GX .
PHYSICS IN MEDICINE AND BIOLOGY, 2002, 47 (07) :1025-1046
[6]   The flatness of Siemens linear accelerator x-ray fields [J].
Faddegon, BA ;
O'Brien, P ;
Mason, DLD .
MEDICAL PHYSICS, 1999, 26 (02) :220-228
[7]   A multiple source model for 6 MV photon beam dose calculations using Monte Carlo [J].
Fix, MK ;
Stampanoni, M ;
Manser, P ;
Born, EJ ;
Mini, R ;
Rüegsegger, P .
PHYSICS IN MEDICINE AND BIOLOGY, 2001, 46 (05) :1407-1427
[8]   American Association of Physicists in Medicine radiation therapy committee task group 53: Quality assurance for clinical radiotherapy treatment planning [J].
Fraass, B ;
Doppke, K ;
Hunt, M ;
Kutcher, G ;
Starkschall, G ;
Stern, R ;
Van Dyke, J .
MEDICAL PHYSICS, 1998, 25 (10) :1773-1829
[9]   Photon dose calculation of a three-dimensional treatment planning system compared to the Monte Carlo code BEAM [J].
Francescon, P ;
Cavedon, C ;
Reccanello, S ;
Cora, S .
MEDICAL PHYSICS, 2000, 27 (07) :1579-1587
[10]   Reference dosimetry in clinical high-energy electron beams: Comparison of the AAPM TG-51 and AAPM TG-21 dosimetry protocols [J].
Huq, MS ;
Song, HJ ;
Andreo, P ;
Houser, CJ .
MEDICAL PHYSICS, 2001, 28 (10) :2077-2087