PMID- 19994507
OWN - NLM
STAT- MEDLINE
DCOM- 20100112
LR  - 20191210
IS  - 0094-2405 (Print)
IS  - 0094-2405 (Linking)
VI  - 36
IP  - 11
DP  - 2009 Nov
TI  - Liquid crystal display response time estimation for medical applications.
PG  - 4984-90
AB  - PURPOSE: Accurate characterization of diagnosis instruments is crucial in medical 
      applications such as radiology and clinical neurosciences. While classical CRT 
      medical displays have been replaced almost exclusively with liquid crystal 
      devices (LCDs), the assessment of their temporal properties (response times) is 
      still largely based on heuristic methods, which have not been evaluated 
      thoroughly yet. The authors introduce a novel approach and show that it improves 
      the accuracy and reliability compared to the common heuristic recommended by ISO 
      9241-305 substantially for a wide range of settings. METHODS: The approach is 
      based on disentangling the signal from the modulatory backlight through division 
      (division approach). They evaluated this method in two different ways: First, 
      they applied both methods to luminance transition measurements of different LCD 
      monitors. Second, they simulated LCD luminance transitions by modeling the LCD 
      optical responses according to a physical liquid crystal director orientation 
      model. The simulated data were generated for four different response times, each 
      with four different backlight modulation frequencies. Both the novel and the ISO 
      convolution method were applied to the data. RESULTS: Application of the methods 
      to the simulated data shows a bias of up to 46% for the ISO approach, while the 
      novel division approach is biased at most 2%. In accordance with the simulations, 
      estimates for real measurements show differences in the two approaches of more 
      than 200% for some LCD panels. CONCLUSION: The division approach is robust 
      against periodic backlight fluctuations and can reliably estimate even very short 
      response times or small transitions. Unlike the established method, it meets the 
      accuracy requirements of medical applications. In contrast, the popular 
      convolution approach for estimating response times is prone to misestimations of 
      time by several orders of magnitude and tend to further worsen as advances in LCD 
      technology lead to shorter response times.
FAU - Elze, Tobias
AU  - Elze T
AD  - Max-Planck Institute for Mathematics in the Sciences, Research Group Complex 
      Structures in Biology and Cognition, Leipzig 04103, Germany. 
      tobias-elze@tobias-elze.de
FAU - Tanner, Thomas G
AU  - Tanner TG
LA  - eng
PT  - Evaluation Study
PT  - Journal Article
PL  - United States
TA  - Med Phys
JT  - Medical physics
JID - 0425746
SB  - IM
MH  - Computer Simulation
MH  - Electronics, Medical/*instrumentation
MH  - Light
MH  - *Liquid Crystals
MH  - Models, Theoretical
MH  - Optics and Photonics/instrumentation
MH  - Time Factors
EDAT- 2009/12/10 06:00
MHDA- 2010/01/13 06:00
CRDT- 2009/12/10 06:00
PHST- 2009/12/10 06:00 [entrez]
PHST- 2009/12/10 06:00 [pubmed]
PHST- 2010/01/13 06:00 [medline]
AID - 10.1118/1.3238154 [doi]
PST - ppublish
SO  - Med Phys. 2009 Nov;36(11):4984-90. doi: 10.1118/1.3238154.