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Crister Ceberg

Avdelningschef

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A new method for quantification of image distortion due to pile-up in scintillation cameras

Författare

  • Crister Ceberg
  • Ingemar Larsson
  • Sven-Erik Strand

Summary, in English

Characterization of the count-rate performance of scintillation cameras should include not only the specification of count losses. At high count rates, there is also an image distortion due to the mispositioning of pile-up events. In this paper a simple and clinically relevant procedure to quantify this distortion is presented. The images of a square uniform technetium-99m phantom at high and low count rates are used. The fraction of the total counts being correctly positioned is determined as the peripheral count density divided by the total average count density. This ratio, corrected for the camera non-uniformity at low count rates, is called the 'positioning ability'. According to the National Electrical Manufacturers' Association (NEMA), the 'system count rate performance with scatter' should be reported as the measured count rate giving 20% count losses. In this paper it is suggested that this measure be complemented by a measure of the fraction correct positioned events at this count rate. This fraction, the 'high count rate positioning ability', can be easily and accurately measured using our method. The method has been tested on two different scintillation cameras. For one of them the high count rate positioning ability was determined as 91% at a measured count rate of 30,000 s-1 with 20% count losses. For the other camera, the corresponding figures were 88% at 59,000 s-1 and close to 100% at 38,000 s-1, before and after the installation of a new pile-up rejection circuit, respectively.

Avdelning/ar

  • Medicinsk strålningsfysik, Lund

Publiceringsår

1991

Språk

Engelska

Sidor

959-963

Publikation/Tidskrift/Serie

European Journal Of Nuclear Medicine

Volym

18

Avvikelse

12

Dokumenttyp

Artikel i tidskrift

Förlag

Springer

Ämne

  • Radiology and Medical Imaging

Nyckelord

  • Scintillation camera
  • Pile-up
  • Image distortion
  • Quantification

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 1432-105X