PMID- 22843372
OWN - NLM
STAT- MEDLINE
DCOM- 20130125
LR  - 20220408
IS  - 1349-9157 (Electronic)
IS  - 0449-3060 (Print)
IS  - 0449-3060 (Linking)
VI  - 53
IP  - 5
DP  - 2012 Sep
TI  - Quality assurance of MLC leaf position accuracy and relative dose effect at the 
      MLC abutment region using an electronic portal imaging device.
PG  - 798-806
LID - 10.1093/jrr/rrs038 [doi]
AB  - We investigated an electronic portal image device (EPID)-based method to see 
      whether it provides effective and accurate relative dose measurement at abutment 
      leaves in terms of positional errors of the multi-leaf collimator (MLC) leaf 
      position. A Siemens ONCOR machine was used. For the garden fence test, a 
      rectangular field (0.2 20 cm) was sequentially irradiated 11 times at 2-cm 
      intervals. Deviations from planned leaf positions were calculated. For the nongap 
      test, relative doses at the MLC abutment region were evaluated by sequential 
      irradiation of a rectangular field (2 20 cm) 10 times with a MLC separation of 2 
      cm without a leaf gap. The integral signal in a region of interest was set to 
      position A (between leaves) and B (neighbor of A). A pixel value at position B 
      was used as background and the pixel ratio (A/B 100) was calculated. Both tests 
      were performed at four gantry angles (0, 90, 180 and 270 degrees ) four times over 1 
      month. For the nongap test the difference in pixel ratio between the first and 
      last period was calculated. Regarding results, average deviations from planned 
      positions with the garden fence test were within 0.5 mm at all gantry angles, and 
      at gantry angles of 90 and 270 degrees  tended to decrease gradually over the month. For 
      the nongap test, pixel ratio tended to increase gradually in all leaves, leading 
      to a decrease in relative doses at abutment regions. This phenomenon was affected 
      by both gravity arising from the gantry angle, and the hardware-associated 
      contraction of field size with this type of machine.
FAU - Sumida, Iori
AU  - Sumida I
AD  - Department of Oral and Maxillofacial Radiology, Osaka University Graduate School 
      of Dentistry, 1-8 Yamada-oka, Suita, Osaka, 565-0871 Japan. 
      isumida@dent.osaka-u.ac.jp
FAU - Yamaguchi, Hajime
AU  - Yamaguchi H
FAU - Kizaki, Hisao
AU  - Kizaki H
FAU - Koizumi, Masahiko
AU  - Koizumi M
FAU - Ogata, Toshiyuki
AU  - Ogata T
FAU - Takahashi, Yutaka
AU  - Takahashi Y
FAU - Yoshioka, Yasuo
AU  - Yoshioka Y
LA  - eng
PT  - Journal Article
DEP - 20120710
PL  - England
TA  - J Radiat Res
JT  - Journal of radiation research
JID - 0376611
SB  - IM
MH  - Humans
MH  - Neoplasms/radiotherapy
MH  - Quality Assurance, Health Care/methods
MH  - Radiotherapy Planning, Computer-Assisted/instrumentation/standards/statistics & 
      numerical data
MH  - Radiotherapy, Intensity-Modulated/instrumentation/*standards/statistics & 
      numerical data
PMC - PMC3430416
EDAT- 2012/07/31 06:00
MHDA- 2013/01/26 06:00
PMCR- 2012/07/10
CRDT- 2012/07/31 06:00
PHST- 2012/07/31 06:00 [entrez]
PHST- 2012/07/31 06:00 [pubmed]
PHST- 2013/01/26 06:00 [medline]
PHST- 2012/07/10 00:00 [pmc-release]
AID - rrs038 [pii]
AID - 10.1093/jrr/rrs038 [doi]
PST - ppublish
SO  - J Radiat Res. 2012 Sep;53(5):798-806. doi: 10.1093/jrr/rrs038. Epub 2012 Jul 10.