PMID- 28409334
OWN - NLM
STAT- MEDLINE
DCOM- 20180326
LR  - 20180326
IS  - 1879-5447 (Electronic)
IS  - 0158-9938 (Linking)
VI  - 40
IP  - 2
DP  - 2017 Jun
TI  - Investigation of X-ray focal spot alignment using a jig of novel design.
PG  - 455-461
LID - 10.1007/s13246-017-0549-z [doi]
AB  - The X-ray focal spot and the centre of the flattening filter should be placed as 
      close as possible to the central axis (CAX) on a linear accelerator (linac) to 
      produce a radially symmetric beam. The aim of this study is to devise a method to 
      easily optimise the focal spot position of Varian linac photon beams generated 
      with a flattening filter. A simple and robust jig was designed and built to be 
      inserted into the largest electron applicator. Accessory and jaw position 
      interlocks were overridden to enable photon beam operation. The jig was made from 
      aluminium and consists of a plate permanently fixed inside a low melting point 
      alloy (LMPA) insert frame and a block machined to suspend an ion chamber below 
      the plate, such that the axis of the chamber is at the linac isocentre. The jig 
      was used to optimise the position of the X-ray beam focal spot with respect to 
      the device central axis (CAX). This was achieved by minimising the percentage 
      change in ionisation chamber signal between collimator rotations from 90 degrees  to 270 degrees  
      as position steering was changed. As part of the investigation, in-plane (radial) 
      and cross-plane (transverse) profiles obtained from water phantom scans were used 
      to quantify how large the percentage ionisation change can be before profiles are 
      distorted in the region of the CAX.
FAU - Yuen, Lockie
AU  - Yuen L
AD  - W.P. Holman Clinic, Launceston General Hospital, Launceston, TAS, Australia. 
      lockie.yuen@ths.tas.gov.au.
FAU - McLucas, Cameron
AU  - McLucas C
AD  - W.P. Holman Clinic, Launceston General Hospital, Launceston, TAS, Australia.
LA  - eng
PT  - Journal Article
DEP - 20170413
PL  - Netherlands
TA  - Australas Phys Eng Sci Med
JT  - Australasian physical & engineering sciences in medicine
JID - 8208130
RN  - 059QF0KO0R (Water)
SB  - IM
MH  - Equipment Design
MH  - Phantoms, Imaging
MH  - Radiometry/*instrumentation
MH  - Water
MH  - X-Rays
OTO - NOTNLM
OT  - Alignment
OT  - Commissioning
OT  - Focal spot
OT  - Quality assurance
EDAT- 2017/04/15 06:00
MHDA- 2018/03/27 06:00
CRDT- 2017/04/15 06:00
PHST- 2016/06/14 00:00 [received]
PHST- 2017/04/03 00:00 [accepted]
PHST- 2017/04/15 06:00 [pubmed]
PHST- 2018/03/27 06:00 [medline]
PHST- 2017/04/15 06:00 [entrez]
AID - 10.1007/s13246-017-0549-z [pii]
AID - 10.1007/s13246-017-0549-z [doi]
PST - ppublish
SO  - Australas Phys Eng Sci Med. 2017 Jun;40(2):455-461. doi: 
      10.1007/s13246-017-0549-z. Epub 2017 Apr 13.