title: Real-time handheld emission spot allocator (rthESA) for simultaneous fusion imaging with ultrasound.
abstract: OBJECTIVE
  First, to report on initial experiences and technical parameters of a newly developed real-time handheld emission spot allocator (rthESA), and second, to report on the simultaneous acquisition of rthESA and US data as rthESA/US fusion images.
  
  
  METHODS
  The rthESA consisted of five semiconductor-detectors arranged in alternate position in two rows. This design allowed the examination of focal activities in the same plane as US. The signals were interpreted by an ad hoc software and the real-time allocation of spot radiation sources within air- and water phantoms was investigated for (99m)Tc, 131I, and 18F. A compact US probe was fixed in plane with the rthESA and connected to a standard US equipment. Experiments with a liver phantom were performed to verify the integration of (99m)Tc-rthESA data and US images.
  
  
  RESULTS
  The allocation proved to be successful for all radionuclides. The system showed a noticeable performance latency, most pronounced for positions far from the detector (1 cm distance: 0.7 ± 0.5 s; 4 cm distance: 6.1 ± 3.2 s). Within the liver phantom, the rthESA enabled the correct allocation of a spot radiation source within a live US image.
  
  
  CONCLUSIONS
  The rthESA allowed an exact localization of spot radiation sources in single plane, with additional consideration of the distance from the detector, leading to real-time allocation and simultaneous overlay with US images. In spite of clear technical limitations in need of further development, this proof-of-concept study shows that this hybrid detector has the potential to provide integrated simultaneous nuclear medicine and US images.
authors: Martin Freesmeyer, M.D., Clinic of Nuclear Medicine, Jena University Hospital, Bachstraße 18, 07743 Jena, Germany, Tel. +49/(0)36 41/93 32 20, Fax +49/(0)36 41/93 32 44, E-mail: martin.freesmeyer@med.uni-jena.de.
authors: M
authors: M
authors: Freesmeyer
authors: T
authors: T
authors: Winkens
authors: C
authors: C
authors: Kühnel
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008904:Miniaturization; D064847:Multimodal Imaging / Q000295:instrumentation*; D010865:Pilot Projects; D011874:Radiometry / Q000295:instrumentation; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000295:instrumentation*; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation*; D014463:Ultrasonography / Q000295:instrumentation*
keywords: US fusion imaging; emission spot allocator; emission spot allocator / US fusion; emission tomography; ultrasound/nuclear medicine