PMID- 12007278
OWN - NLM
STAT- MEDLINE
DCOM- 20020701
LR  - 20171101
IS  - 1011-6125 (Print)
IS  - 1011-6125 (Linking)
VI  - 76
IP  - 1
DP  - 2001
TI  - Miniature multileaf collimator as an alternative to traditional circular 
      collimators for stereotactic radiosurgery and stereotactic radiotherapy.
PG  - 47-62
AB  - PURPOSE: To evaluate the miniature multileaf collimator (MMLC) as an alternative 
      to traditional circular collimators for radiosurgery. MATERIALS AND METHODS: 
      'Circular' fields were created with the Radionics MMLC (leaf width 3.53 mm at 
      isocenter). Beam data, including tissue maximum ratios, output factors, penumbrae 
      and isodose distributions of these fields were measured. These were compared to 
      the Radionics circular collimators traditionally used for radiosurgery. The MMLC 
      data were input to the XKnife Treatment Planning System. Treatment plans were 
      completed and evaluated using both the MMLC 'circular' fields and the circular 
      collimators. RESULTS: MMLC fields using 3, 5, 7, 9, 11, and 13 leaves on each 
      side of the Radionics MMLC were created to approximate circular fields. The TMRs 
      are essentially identical to those of comparable-size circular collimators. 
      Measured at isocenter at 5-cm depth for 6 MV, the 80-20% penumbra widths are 
      comparable to circular collimators, but are increased by as much as 1 mm at the 
      leaf intersections (steps) where scalloping occurs. Isodose distributions were 
      matched to those of circular collimators with comparable 50% isodose widths. 
      Treatment plans for the MMLC 'circular' fields with four arcs (totaling 360 
      degrees) are essentially identical to those of comparable circular collimators. 
      Dose-volume histograms revealed clinically insignificant differences between the 
      two in doses to the target, to the volume surrounding the target, and to adjacent 
      critical normal tissues. There is very little discrepancy between the dose 
      distribution calculated with the approximated MMLC fields and with those of 
      simulated arcs with the actual MMLC fields. CONCLUSIONS: With the MMLC simulating 
      circular fields, dose distributions may be obtained which are essentially 
      identical to comparable-size circular collimators. The mechanical accuracy of the 
      MMLC is as good as that of the circular collimators, and the leakage dose is 
      less. The diameter of 'circular' fields is limited by the MMLC leaf width to 1 cm 
      and greater in increments of 7 mm. Attention needs to be paid to mechanical 
      collisions because the MMLC is bulkier than the circular collimators.
CI  - Copyright 2002 S. Karger AG, Basel
FAU - Urie, M M
AU  - Urie MM
AD  - University of Massachusetts Memorial Medical Center, Worcester 01655, USA. 
      m_urie@hotmail.com
FAU - Lo, Y C
AU  - Lo YC
FAU - Litofsky, S
AU  - Litofsky S
FAU - FitzGerald, T J
AU  - FitzGerald TJ
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Switzerland
TA  - Stereotact Funct Neurosurg
JT  - Stereotactic and functional neurosurgery
JID - 8902881
SB  - IM
MH  - Humans
MH  - Radiosurgery/*instrumentation/*methods/statistics & numerical data
MH  - Radiotherapy/instrumentation/methods/statistics & numerical data
EDAT- 2002/05/15 10:00
MHDA- 2002/07/02 10:01
CRDT- 2002/05/15 10:00
PHST- 2002/05/15 10:00 [pubmed]
PHST- 2002/07/02 10:01 [medline]
PHST- 2002/05/15 10:00 [entrez]
AID - 56494 [pii]
AID - 10.1159/000056494 [doi]
PST - ppublish
SO  - Stereotact Funct Neurosurg. 2001;76(1):47-62. doi: 10.1159/000056494.