PMID- 21784685
OWN - NLM
STAT- MEDLINE
DCOM- 20130111
LR  - 20120618
IS  - 1724-191X (Electronic)
IS  - 1120-1797 (Linking)
VI  - 28
IP  - 3
DP  - 2012 Jul
TI  - QA of dynamic MLC based on EPID portal dosimetry.
PG  - 262-8
LID - 10.1016/j.ejmp.2011.06.046 [doi]
AB  - PURPOSE: Dynamic delivery of intensity modulated beams (dIMRT) requires not only 
      accurate verification of leaf positioning but also a control on the speed of 
      motion. The latter is a parameter that has a major impact on the dose delivered 
      to the patient. Time consumed in quality assurance (QA) procedures is an issue of 
      relevance in any radiotherapy department. Electronic portal imaging dosimetry 
      (EPID) can be very efficient for routine tests. The purpose of this work is to 
      investigate the ability of our EPID for detecting small errors in leaf 
      positioning, and to present our daily QA procedures for dIMRT based on EPID. 
      METHODS AND MATERIALS: A Varian 2100 CD Clinac equipped with an 80 leaf 
      Millennium MLC and with amorphous silicon based EPID (aS500, Varian) is used. The 
      daily QA program consists in performing: Stability check of the EPID signal, 
      Garden fence test, Sweeping slit test, and Leaf speed test. RESULTS AND 
      DISCUSSION: The EPID system exhibits good long term reproducibility. The mean 
      portal dose at the centre of a 10 x 10 cm(2) static field was 1.002 +/- 0.004 
      (range 1.013-0.995) for the period evaluated of 47 weeks. Garden fence test shows 
      that leaf position errors of up to 0.2 mm can be detected. With the Sweeping slit 
      test we are able to detect small deviations on the gap width and errors of 
      individual leaves of 0.5 and 0.2 mm. With the Leaf speed test problems due to 
      motor fatigue or friction between leaves can be detected. CONCLUSIONS: This set 
      of tests takes no longer than 5 min in the linac treatment room. With EPID 
      dosimetry, a consistent daily QA program can be applied, giving complete 
      information about positioning/speed MLC.
CI  - Copyright (c) 2011 Associazione Italiana di Fisica Medica. Published by Elsevier 
      Ltd. All rights reserved.
FAU - Richart, J
AU  - Richart J
AD  - Radiotherapy Department, Hospital Clinica Benidorm, E-03501 Benidorm, Alicante, 
      Spain. joserichart@clinicabenidorm.com
FAU - Pujades, M C
AU  - Pujades MC
FAU - Perez-Calatayud, J
AU  - Perez-Calatayud J
FAU - Granero, D
AU  - Granero D
FAU - Ballester, F
AU  - Ballester F
FAU - Rodriguez, S
AU  - Rodriguez S
FAU - Santos, M
AU  - Santos M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20110723
PL  - Italy
TA  - Phys Med
JT  - Physica medica : PM : an international journal devoted to the applications of 
      physics to medicine and biology : official journal of the Italian Association of 
      Biomedical Physics (AIFB)
JID - 9302888
SB  - IM
MH  - Electrical Equipment and Supplies/*standards
MH  - Quality Control
MH  - Radiometry/*instrumentation/*standards
EDAT- 2011/07/26 06:00
MHDA- 2013/01/12 06:00
CRDT- 2011/07/26 06:00
PHST- 2010/01/18 00:00 [received]
PHST- 2011/06/24 00:00 [revised]
PHST- 2011/06/28 00:00 [accepted]
PHST- 2011/07/26 06:00 [entrez]
PHST- 2011/07/26 06:00 [pubmed]
PHST- 2013/01/12 06:00 [medline]
AID - S1120-1797(11)00091-3 [pii]
AID - 10.1016/j.ejmp.2011.06.046 [doi]
PST - ppublish
SO  - Phys Med. 2012 Jul;28(3):262-8. doi: 10.1016/j.ejmp.2011.06.046. Epub 2011 Jul 
      23.