PMID- 28632501
OWN - NLM
STAT- MEDLINE
DCOM- 20180215
LR  - 20191210
IS  - 1361-6560 (Electronic)
IS  - 0031-9155 (Linking)
VI  - 62
IP  - 16
DP  - 2017 Jul 31
TI  - Evaluation of automatic dose rate control for flat panel imaging using a spatial 
      frequency domain figure of merit.
PG  - 6610-6630
LID - 10.1088/1361-6560/aa7a9d [doi]
AB  - Current automatic dose rate controls (ADRCs) of dynamic x-ray imaging systems 
      adjust their acquisition parameters in response to changes in patient thickness 
      in order to achieve a constant signal level in the image receptor. This work 
      compares a 3 parameter (3P) ADRC control to a more flexible 5-parameter (5P) 
      method to meet this goal. A phantom composed of 15 composite poly(methyl) 
      methacrylate (PMMA)/aluminium (Al) plates was imaged on a Siemens Artis Q dynamic 
      system using standard 3P and 5P ADRC techniques. Phantom thickness covered a 
      water equivalent thickness (WET) range of 2.5 cm to 37.5 cm. Acquisition 
      parameter settings (tube potential, tube current, pulse length, copper filtration 
      and focus size) and phantom entrance air kerma rate (EAKR) were recorded as the 
      thickness changed. Signal difference to noise ratio (SDNR) was measured using a 
      0.3 mm iron insert centred in the PMMA stack, positioned at the system isocentre. 
      SDNR was then multiplied by modulation transfer function (MTF) based correction 
      factors for focal spot penumbral blurring and motion blurring, to give a spatial 
      frequency dependent parameter, SDNR(u). These MTF correction factors were 
      evaluated for an object motion of 25 mm s(-1) and at a spatial frequency of 
      1.4 mm(-1) in the object plane, typical for cardiac imaging. The figure of merit 
      (FOM) was calculated as SDNR(u)(2)/EAKR for the two ADRC regimes. Using 5P versus 
      3P technique showed clear improvements over all thicknesses. Averaged over 
      clinically relevant adult WET values (20 cm-37.5 cm), EAKR was reduced by 13% and 
      27% for fluoroscopy and acquisition modes, respectively, while the SDNR(u) based 
      FOM increased by 16% and 34% for fluoroscopy and acquisition. In conclusion, the 
      generalized FOM, taking into account the influence of focus size and object 
      motion, showed benefit in terms of image quality and patient dose for the 
      5-parameter control over 3-parameter method for the ADRC programming of dynamic 
      x-ray imaging systems.
FAU - Dehairs, M
AU  - Dehairs M
AD  - Medical Imaging Research Centre, Medical Physics and Quality Assessment, 
      Katholieke Universiteit Leuven, 3000 Leuven, Belgium.
FAU - Bosmans, H
AU  - Bosmans H
FAU - Desmet, W
AU  - Desmet W
FAU - Marshall, N W
AU  - Marshall NW
LA  - eng
PT  - Evaluation Study
PT  - Journal Article
DEP - 20170731
PL  - England
TA  - Phys Med Biol
JT  - Physics in medicine and biology
JID - 0401220
RN  - 9011-14-7 (Polymethyl Methacrylate)
SB  - IM
MH  - Air
MH  - Automation
MH  - Fluoroscopy/instrumentation/*methods
MH  - Humans
MH  - Phantoms, Imaging
MH  - Polymethyl Methacrylate
MH  - *Radiation Dosage
MH  - Signal-To-Noise Ratio
EDAT- 2017/06/21 06:00
MHDA- 2018/02/16 06:00
CRDT- 2017/06/21 06:00
PHST- 2017/06/21 06:00 [pubmed]
PHST- 2018/02/16 06:00 [medline]
PHST- 2017/06/21 06:00 [entrez]
AID - 10.1088/1361-6560/aa7a9d [doi]
PST - epublish
SO  - Phys Med Biol. 2017 Jul 31;62(16):6610-6630. doi: 10.1088/1361-6560/aa7a9d.