CASCADED MODEL ANALYSIS OF PIXELATED SCINTILLATOR IMAGING DETECTORS

Transcription

1 Biomeicl echtronics Lb SCIN 7 CSCE OEL NLYSIS OF PIXELE SCINILLOR IGING EECORS Ho Kyung Kim, Seung n Yun n Chng Hwy Lim June, 7, 7 School of echnicl Engineering Pusn Ntionl University Republic of Kore

2 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Conventionl R etectors irect-etection scheme High-resolution imging cpbility high F But, noise-lising ue to the high F Lower X-ry sensitivity with the conventionl photoconuctor mterils, e.g., -Se Inirect-etection scheme Higher X-ry sensitivity e.g., CsI:l Reltively poorer F Best wy: use of scintilltor with bn-limite F property intining higher X-ry sensitivity of scintilltor voiing noise-lising ue to the bn-limite F Pixelte scintilltor? Biomeicl echtronics Lb

3 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 How we cn relize elte scintilltor esign? Growing onto el-ptterne substrtes therml evportion Filling scintilltion mterils into el-structure mol Pixelize CsI onto ptterne substrtes Pixelize mol mnufcture by ES process Imge Courtesy: Cho et l., KIS Imge Courtesy: Ko et l., PNU Biomeicl echtronics Lb 3

4 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Objective Investigting fesibility of the elte scintilltor, theoreticlly Using the csce liner-systems trnsfer theory Preicting etective untum efficiency E, which is n essentil metric representing n imge ulity of n imging system Fluence System Gin F E u, v NPS u, v sys u, v G sys u, v NPS u, v sys u, v NNPS u, v eveloping E formlism of the elte scintilltor etector Numericl simultion with respect to vrious esign prmeters ; el pitch, fill fctor, itive noise Compring with the conventionl scintilltor-bse etectors with vrious F properties Biomeicl echtronics Lb

5 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Csce moel of the conventionl scintilltor imger g g 3 g 5 III signl σ Stge escription Symbol Process Incient X-ry Uniform istribution 3 5 untum Binomil g etection = selection untum Binomil g mplifiction = selection untum Stochstic scttering 3 blurring untum conversion g = Binomil selection perture eterministic integrtion 5 blurring 6 Smpling III eterministic process 7 itive noise s eterministic process Biomeicl echtronics Lb 5

6 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Biomeicl echtronics Lb 6 Fluence System gin Noise power spectrum itive electronic noise System F E of the conventionl scintilltor imger σ E k k k I

7 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Csce moeling of the elte scintilltor imger III g 3 g 5 g 6 6 III signl σ stge escription symbol process Incient X-ry uniform istribution Biomeicl echtronics Lb 7 perture eterministic integrtion blurring Smpling III eterministic process untum binomil g etection 3 = selection untum binomil g mplifiction = selection rnom sttisticl reistribution 5 reloction untum binomil g conversion 6 = selection perture eterministic integrtion 7 blurring 8 Smpling III eterministic process 9 itive noise s eterministic process

8 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Stge : Incient X-ry Signl NPS Stge : Screen perture integrtion Signl NPS sinc sinc Stge : X-ry Smpling Signl NPS sinc k k Biomeicl echtronics Lb 8

9 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Biomeicl echtronics Lb 9 Stge 3: untum etection Signl NPS Stge : untum mplifiction Signl NPS Stge 5: Rnom reistribution Signl NPS I I 3 3 s 5 sinc sinc 5 I

10 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Biomeicl echtronics Lb Stge 6: untum conversion Signl NPS Stge 7: perture integrtion Signl NPS 5 6 s sinc I 6 7 sinc sinc 7 I

11 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Biomeicl echtronics Lb Stge 8: Smpling Signl NPS Stge 9: itive noise Signl NPS s sinc sinc k k k I

12 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Biomeicl echtronics Lb E of the elte scintilltor imger Fluence System gin Noise power spectrum itive electronic noise System F σ sinc sinc E k k k I

13 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 oel vlition Experimentl conition 6 kvp, 7 mr icrofocus X-ry source COS photoioe rry Scintilltor L8-, Hmmtsu ungsten noe mm beryllium winow mml -filtrtion C793, Hmmtsu x rry formt 5 mm el pitch 79% fill fctor Columnr structure CsI:I mm thickness ~8% pcking ensity egre E t lower freuencies: ue to the elte esign X-ry unt smpling Improve E t higher freuencies Biomeicl echtronics Lb 3

14 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Numericl simultion efult prmeters Proviing n iel performnce of n imger Incience of X-ry = 6 untum bsorption efficiency of scintilltor = verge conversion efficiency of scintilltor = untum efficiency of photoioe = itive electronic noise s = 3 Scintilltor n el pitch Scintilltor n el Fill fctor Scintilltor n el perture =5mm =8% Biomeicl echtronics Lb

15 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Effect of el pitch ue to X-ry smpling Biomeicl echtronics Lb 5

16 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Effect of el fill fctor E t the lower freuency is grully further ecrese s the fill fctor ecreses ue to the reltively enhnce itive noise term Biomeicl echtronics Lb 6

17 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Comprison with the vrious conventionl imgers F k k = the experimentl fitting prmeter =.6 Lnex Fine =.3 Lnex Regulr =.69 CsI 55mm =.5 Lnex Fst Biomeicl echtronics Lb 7

18 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Effect of the itive noise 8% fill fctor, 5 mm pitch,.3 Lnex Regulr, Pixelte esign is reltively immune to the itionl electronic noise Biomeicl echtronics Lb 8

19 Csce oel nlysis of Pixelte Scintilltor Imging etectors, SCIN 7 Conclusion Pixelte scintilltor imgers egrtion of E t lower sptil freuencies ue to the X-ry unt smpling process However, mintining E properties even in the higher freuency bn ue to the bn-limite F properties Reltively strong to the itive electronic noise pproprite to the high-sensitivity n -resolution imging systems, n imgers with smll el pitch e.g., mmogrphy, Intr-orl imging etc. Bse on this stuy, we propose better esign of the scintilltor-bse imger: Prtilly elte scintilltor Biomeicl echtronics Lb 9