PMID- 11213924
OWN - NLM
STAT- MEDLINE
DCOM- 20010419
LR  - 20170214
IS  - 0094-2405 (Print)
IS  - 0094-2405 (Linking)
VI  - 28
IP  - 1
DP  - 2001 Jan
TI  - Leaf position error during conformal dynamic arc and intensity modulated arc 
      treatments.
PG  - 67-72
AB  - Conformal dynamic arc (CD-ARC) and intensity modulated arc treatments (IMAT) are 
      both treatment modalities where the multileaf collimator (MLC) can change leaf 
      position dynamically during gantry rotation. These treatment techniques can be 
      used to generate complex isodose distributions, similar to those used in 
      fix-gantry intensity modulation. However, a beam-hold delay cannot be used during 
      CD-ARC or IMAT treatments to reduce spatial error. Consequently, a certain amount 
      of leaf position error will have to be accepted in order to make the treatment 
      deliverable. Measurements of leaf position accuracy were taken with leaf 
      velocities ranging from 0.3 to 3.0 cm/s. The average and maximum leaf position 
      errors were measured, and a least-squares linear regression analysis was 
      performed on the measured data to determine the MLC velocity error coefficient. 
      The average position errors range from 0.03 to 0.21 cm, with the largest 
      deviations occurring at the maximum achievable leaf velocity (3.0 cm/s). The 
      measured MLC velocity error coefficient was 0.0674 s for a collimator rotation of 
      0 degrees and 0.0681 s for a collimator rotation of 90 degrees. The distribution 
      in leaf position error between the 0 degrees and 90 degrees collimator rotations 
      was within statistical uncertainty. A simple formula was developed based on these 
      results for estimating the velocity-dependent dosimetric error. Using this 
      technique, a dosimetric error index for plan evaluation can be calculated from 
      the treatment time and the dynamic MLC leaf controller file.
FAU - Ramsey, C R
AU  - Ramsey CR
AD  - Department of Radiation Oncology, Thompson Cancer Survival Center, Knoxville, 
      Tennessee 37921, USA. cramsey@utk.edu
FAU - Spencer, K M
AU  - Spencer KM
FAU - Alhakeem, R
AU  - Alhakeem R
FAU - Oliver, A L
AU  - Oliver AL
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  - Biophysical Phenomena
MH  - Biophysics
MH  - Humans
MH  - Male
MH  - Prostatic Neoplasms/radiotherapy
MH  - Radiotherapy Dosage
MH  - Radiotherapy, Conformal/instrumentation/*methods/statistics & numerical data
EDAT- 2001/02/24 12:00
MHDA- 2001/04/21 10:01
CRDT- 2001/02/24 12:00
PHST- 2001/02/24 12:00 [pubmed]
PHST- 2001/04/21 10:01 [medline]
PHST- 2001/02/24 12:00 [entrez]
AID - 10.1118/1.1333410 [doi]
PST - ppublish
SO  - Med Phys. 2001 Jan;28(1):67-72. doi: 10.1118/1.1333410.