PMID- 9650171
OWN - NLM
STAT- MEDLINE
DCOM- 19980918
LR  - 20170214
IS  - 0094-2405 (Print)
IS  - 0094-2405 (Linking)
VI  - 25
IP  - 6
DP  - 1998 Jun
TI  - A pencil-beam photon dose algorithm for stereotactic radiosurgery using a 
      miniature multileaf collimator.
PG  - 841-50
AB  - A computer-controlled miniature multileaf collimator (MMLC) with 4 mm leaf width 
      and a maximum field size of 6 cm X 6 cm has been designed as a tertiary 
      beam-shaping device for linac-based stereotactic radiosurgery. The purpose of 
      this study is to develop an accurate and efficient dose calculation model for use 
      with the MMLC. A pencil-beam based algorithm using a sum of three Gaussian 
      kernels was developed to model the off-axis ratio of MMLC fields. Because the 
      kernel integration over a rectangular field can be solved in closed form, dose to 
      any point from an arbitrary MMLC field can be calculated efficiently by summing 
      dose contribution from a set of rectangular apertures and transmission blocks 
      that model individual leaf openings or leaf transmissions. The model uses an 
      effective rectangular field and equivalent square method for determination of 
      depth dose and dose output. Results showed that the calculated percentage depth 
      dose was within 1% and output factor was within 1.5% of measured data. The 
      parameters of the pencil beam kernels were extracted by fitting measured off-axis 
      profiles for a few field sizes at a few depths. The accuracy of the calculated 
      off-axis ratio was tested by comparison with measured data for a number of MMLC 
      fields. The algorithm was shown to be accurate to within 1.5% or 1 mm for 
      off-axis ratios. The algorithm computes at a speed of 34,600 data points per 
      second on a DEC Alpha server model 2000/433 (Digital Equipment Corp., Maynard, 
      MA), which is about 15 times faster than a Clarkson-type summation method.
FAU - Dong, L
AU  - Dong L
AD  - Department of Radiation Physics, University of Texas M. D. Anderson Cancer 
      Center, Houston 77030, USA. dong@bethe.mdacc.tmc.edu
FAU - Shiu, A
AU  - Shiu A
FAU - Tung, S
AU  - Tung S
FAU - Hogstrom, K
AU  - Hogstrom K
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Med Phys
JT  - Medical physics
JID - 0425746
SB  - IM
MH  - *Algorithms
MH  - Biophysical Phenomena
MH  - Biophysics
MH  - Evaluation Studies as Topic
MH  - Humans
MH  - Models, Theoretical
MH  - Particle Accelerators
MH  - Photons
MH  - Radiometry
MH  - Radiosurgery/*instrumentation/*statistics & numerical data
MH  - Radiotherapy Planning, Computer-Assisted/*statistics & numerical data
MH  - Technology, Radiologic
EDAT- 1998/07/03 00:00
MHDA- 1998/07/03 00:01
CRDT- 1998/07/03 00:00
PHST- 1998/07/03 00:00 [pubmed]
PHST- 1998/07/03 00:01 [medline]
PHST- 1998/07/03 00:00 [entrez]
AID - 10.1118/1.598294 [doi]
PST - ppublish
SO  - Med Phys. 1998 Jun;25(6):841-50. doi: 10.1118/1.598294.