title: A feasibility study of photosensor charge signal transmission to preamplifier using long cable for development of hybrid PET-MRI.
abstract: OBJECTIVE
  A new positron emission tomography (PET) detector signal processing method, the charge signal transmission approach, is proposed for the development of a hybrid PET-magnetic resonance imaging (MRI). A number of experiments were performed to demonstrate that the Geiger-mode avalanche photodiode (GAPD) charge output could be transmitted to a preamplifier using a long cable without degrading the PET signal performance.
  
  
  METHODS
  A PET module consisted of LYSO and a GAPD with a 4 x 4 array. The GAPD output was transmitted to the preamplifier through flexible flat cables. The effect of the cable length on the PET performance was examined using seven different lengths ranging from 10 to 300 cm outside and inside the 7 T animal MRI. Four parameters (rise time, fall time, amplitude, and area of the preamplifier output) were measured as a function of the cable length using a 10 GS/s oscilloscope and three parameters (photopeak position, energy resolution, and time resolution) were measured using a 100 MS/s DAQ unit. The effect of the cable length on the MR phantom images was investigated. In addition, the effect of the PET module configuration on its temperature stability was assessed by acquiring the energy and time spectra.
  
  
  RESULTS
  There were no significant changes in the PET module performance as a function of the cable length, both outside and inside MRI. The performance changes in energy information, such as the amplitude, area, photopeak position, and energy resolution, were <3% with cable lengths ranging from 10 to 300 cm and the change in the time resolution was <6%. There were no obvious artifacts or changes in the line profile in the MR phantom images. Moreover, no manifest changes in the photopeak position and coincidence counting rate were observed in the PET modules employing the charge signal transmission approach, whereas considerable degradation of the PET module performance was observed in the voltage signal transmission approach.
  
  
  CONCLUSIONS
  This study demonstrated that it is feasible to design a hybrid PET-MRI using the charge signal transmission approach, which is expected to have more advantages than other approaches.
authors.affiliation: Department of Electronic Engineering, Sogang University, 1 Shinsu-Dong, Mapo-Gu, Seoul 121-742, Republic of Korea.
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kang
authors.forename: Yong
authors.initials: Y
authors.lastname: Choi
authors.forename: Key Jo
authors.initials: KJ
authors.lastname: Hong
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Jung
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: Yoon Suk
authors.initials: YS
authors.lastname: Huh
authors.forename: Hyunkeong
authors.initials: H
authors.lastname: Lim
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Kim
mesh_terms: D000669:Amplifiers, Electronic; D000818:Animals; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014584:User-Computer Interface