DIGITAL SEARCH ADVERTISING – THE ROLE OF POST-CLICK FACTORS IN GENERATING PURCHASE CONVERSIONS

A lot of research is available on the effectiveness of search as an advertising channel. Most of these studies tend to treat a click on a search ad as a binary event. All of them study the events leading to the click. This paper goes beyond this to study the post click actions taken by a user subsequent to clicking on a search ad, and refers to those actions as depth of interaction, and testing the variables that have an effect on the nal outcome. We use a prescriptive research design employing binary logistic regression analysis. Results indicate that the duration of time spent, device used, and recency of visit have a very high positive effect on the nal outcome.

High-energy photon depth of interaction calculation based on light-sharing-window method / 医疗卫生装备

Objective To propose a method for high-energy photon 3D decoding of PET detector to decode reactive crystal position and calculate γ ray depth in the scintillating crystal. Methods Light transmitting windows were set between the crystal arrays, visible photon groups were guided to distribute in the photoelectric sensor array during a single event, and sensor signal intensity was regulated to realize position and depth decoding of the high-energy photon.Monte Carlo method was used to compare the designs of different light transmitting windows to determine the effects of the crystal surface treatment mode on the results. Experiments were executed for further verification. Results The experimental results had consistency with simulation ones;the signal received through the reaction crystal was always stronger than that through the adjacent, which could decode the reaction crystals; the relations between the depth of interaction (DOI) and energy differences of the photo sensors were monotonic with the changes of DOI,and thus could be used to calculate the DOI;when using single window,the DOI vs.Diff.Energy curves had two segments which were not desired for DOI measurement;crystals with rough surfaces were more desired since the qualities of their DOI vs.Diff.Energy curves were better;the dual window method had the best DOI vs.Diff.Energy curves in term of linearity.Conclusion The method can realize 3D decoding of the discrete crystal array,which improves the energy resolution of the PET system. [Chinese Medical Equipment Journal, 2018,39(5):22-28,63]

Development of a Small Animal Positron Emission Tomography Using Dual-Layer Phoswich Detector and Position Sensitive Photomultiplier Tube: Preliminary Results / 대한핵의학회잡지

PURPOSE: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). MATERIALS AND METHODS: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite (LuYAP) was used to construct dual layer phoswitch crystal. 8 X 8 arrays of LSO and LuYAP pixels, 2 mm X 2 mm X 8 mm in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. RESULTS: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 cps/micro Ci at the center of FOV. CONCLUSION: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

Development of PET scanner for small animals / 医疗卫生装备

In comparison with the clinical PET scanner,PET scanner for small animals puts forward a higher demand in spacial resolution and sensitivity. This article describes the development of the PET scanner for small animals and compares the characteristics of several kinds of contemporary typical PET scanners for small animals in different aspects based on the development of detectors. Meanwhile,it also introduces the development of the detectors designed for measuring depth of interaction (DTC) to reduce parallax error.