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Title: An Approximate Method for Linear Signal Decomposition in Gamma-ray Tracking Detectors

Abstract

An approximate method for signal decomposition in gamma-ray tracking detectors is presented, based on Singular Value Decomposition (SVD). With this algorithm, the CPU time scales linearly with the number of possible interaction sites for any number of interactions per gamma ray. The method is also robust to uncertainty in the signal start time, and is applicable to any gamma-ray detectors with highly segmented crystals, as well as any inverse problem that can be reduced to a search among a countable set of precalculated forward solutions.

Authors:
 [1];  [2];  [2];  [1];  [2]
  1. ORNL
  2. Tech-X Corporation
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holifield Radioactive Ion Beam Facility
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
932046
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment; Journal Volume: 580; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; SIGNAL CONDITIONING; RADIATION DETECTORS; GAMMA DETECTION; ALGORITHMS

Citation Formats

Radford, David C, Doxas, I., Nieter, C., Lagergren, Karin B, and Cary, John R. An Approximate Method for Linear Signal Decomposition in Gamma-ray Tracking Detectors. United States: N. p., 2007. Web.
Radford, David C, Doxas, I., Nieter, C., Lagergren, Karin B, & Cary, John R. An Approximate Method for Linear Signal Decomposition in Gamma-ray Tracking Detectors. United States.
Radford, David C, Doxas, I., Nieter, C., Lagergren, Karin B, and Cary, John R. Mon . "An Approximate Method for Linear Signal Decomposition in Gamma-ray Tracking Detectors". United States. doi:.
@article{osti_932046,
title = {An Approximate Method for Linear Signal Decomposition in Gamma-ray Tracking Detectors},
author = {Radford, David C and Doxas, I. and Nieter, C. and Lagergren, Karin B and Cary, John R.},
abstractNote = {An approximate method for signal decomposition in gamma-ray tracking detectors is presented, based on Singular Value Decomposition (SVD). With this algorithm, the CPU time scales linearly with the number of possible interaction sites for any number of interactions per gamma ray. The method is also robust to uncertainty in the signal start time, and is applicable to any gamma-ray detectors with highly segmented crystals, as well as any inverse problem that can be reduced to a search among a countable set of precalculated forward solutions.},
doi = {},
journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment},
number = 3,
volume = 580,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • No abstract prepared.
  • Gamma-ray tracking detectors using highly segmented germanium detectors will give higher efficiency, better peak-to-total ratio and much higher position resolution than current generation of detectors. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to fully exploit the physics opportunities provided by the next generation radioactive beam facilities. This paper presents the basic concepts of tracking, examples of physics opportunities, and the status of the project GRETA/GRETINA.
  • Signal variance in gamma ray detector materials is reviewed with an emphasis on intrinsic variance. Phenomenological models of electron cascades are examined and the Fano factor (F) is discussed in detail. In semiconductors F is much smaller than unity and charge carrier production is nearly proportional to energy. Based on a fit to a number of semiconductors and insulators, a new relationship between the average energy for electron-hole pair production and band-gap energy is proposed. In scintillators, the resolution is governed mainly by photoelectron statistics and proportionality of light yield with respect to energy.
  • Purpose: The objective of this work is to characterize and quantify the impact of respiratory-induced prostate motion. Methods and Materials: Real-time intrafraction motion is observed with the Calypso 4-dimensional nonradioactive electromagnetic tracking system (Calypso Medical Technologies, Inc. Seattle, Washington). We report the results from a total of 1024 fractions from 31 prostate cancer patients. Wavelet transform was used to decompose the signal to extract and isolate the respiratory-induced prostate motion from the total prostate displacement. Results: Our results show that the average respiratory motion larger than 0.5 mm can be observed in 68% of the fractions. Fewer than 1% ofmore » the patients showed average respiratory motion of less than 0.2 mm, whereas 99% of the patients showed average respiratory-induced motion ranging between 0.2 and 2 mm. The maximum respiratory range of motion of 3 mm or greater was seen in only 25% of the fractions. In addition, about 2% patients showed anxiety, indicated by a breathing frequency above 24 times per minute. Conclusions: Prostate motion is influenced by respiration in most fractions. Real-time intrafraction data are sensitive enough to measure the impact of respiration by use of wavelet decomposition methods. Although the average respiratory amplitude observed in this study is small, this technique provides a tool that can be useful if one moves to smaller treatment margins (≤5 mm). This also opens ups the possibility of being able to develop patient specific margins, knowing that prostate motion is not unpredictable.« less