. The major distortions are linearity errors, or spatial distortion, and energy non-uniformity across the face of the crystal. Spatial distortion generally arises from the fact that the geometric coordinates of light events occurring either at the edges of or between adjacent photomultiplier tubes in a photodetector array will be computed differently than the coordinates of events occurring directly over the center of a photomultiplier tube, due to the physical limitations of the photomultiplier tube. Therefore, when a radiation source interacts with the scintillation crystal at one x-y coordinate, it will appear in the image as a different x-y coordinate. Linearity correction methods to remedy such distortions, such as disclosed in U.S. Pat. No. 3,745,345 to Muehllehner, (incorporated herein by reference) generally are known in the art. Similarly, energy non-uniformity corrections also are generally known in the art, as disclosed in U.S. Pat. No. 4,323,977 to Arseneau (incorporated herein by reference).
Uniformity distortions are present when the sensitivity of the detector to the energy of incident photons varies across the face of the crystal depending on its coordinate position, as opposed to energy variations in the radiation source. Addressing non-uniformity during manufacture would not be practicable and would drive up cost. However, uniformity is one of the most important specifications of gamma cameras and is used as a major indicator of image quality.
During scanning of a radiation source, there may be emissions or scattered events from unwanted sources, which if recorded can negatively affect the precision of the resulting image. Energy windows have been employed to prevent the recordation of energy events outside the window, thereby accepting only radiation emissions of a specified energy, which are added to the image data being accumulated. However, due to non-uniformities across the scintillation crystal, emissions with appropriate energy may appear to fall outside the energy window and so will not be recorded by the apparatus, thereby introducing image deterioration.
Current methods that attempt to correct non-uniformity, such as the so-called gradient procedure, improve uniformity but at the expense of linearity. Often, as uniformity is improved, the linearity distortion increases as well. Current methods do not adequately address the relationship between energy correction and linearity correction. If uniformity is corrected before linearity correction, uniformity correction cannot be achieved in totality. Consequently there exists a need in the art for achieving total uniformity while not compromising the linearity correction. With
. The major distortions are linearity errors, or spatial distortion, and department of energy non - uniformity across the grimace of the crystal. Spatial distortion by and large arise from the fact that the geometric coordinates of light consequence occur either at the edges of or between adjacent photomultiplier tubes in a photodetector array will be computed differently than the coordinates of consequence occurring directly over the kernel of a photomultiplier pipe, due to the physical limitations of the photomultiplier tube. Therefore, when a radiation beginning interacts with the scintillation crystal at one x - y coordinate, it will look in the image as a different x - y coordinate. one-dimensionality correction method acting to remedy such distortion, such as disclosed in U.S. Pat. No. 3,745,345 to Muehllehner, (incorporated herein by citation) generally are known in the art. Similarly, energy non - uniformity corrections besides are by and large known in the art, as disclosed in U.S. Pat. No. 4,323,977 to Arseneau (incorporated herein by reference). 
 Uniformity distortions are present when the sensitivity of the detector to the energy of incident photons change across the face of the crystal count on its coordinate placement, as opposed to energy variations in the radiation sickness source. Addressing non - uniformity during manufacture would not be practicable and would tug up cost. However, uniformity is one of the most important specifications of gamma cameras and is use as a major indicator of image quality. 
 During scanning of a radiation informant, there may be emission or scattered events from unwanted sources, which if recorded can negatively involve the precision of the resulting image. department of energy windows have been hire to prevent the recordation of energy events outside the windowpane, thereby accepting only radiation emissions of a specified department of energy, which are added to the image data being accumulated. However, due to non - uniformity across the scintillation quartz glass, emissions with appropriate energy may appear to accrue outside the energy windowpane and so will not be recorded by the apparatus, thereby introducing picture deterioration. 
 Current methods that attempt to correct non - uniformity, such as the so - called gradient operation, improve uniformity but at the expense of linearity. much, as uniformity is improved, the linearity aberration increases as well. Current methods do not adequately cover the relationship between energy correction and linearity correction. If uniformity is corrected before linearity correction, uniformity discipline cannot be achieved in totality. Consequently there exists a need in the art for achieving total uniformity while not compromising the one-dimensionality correction. With
. Thf major distortions are uinearity errors, or spetial djstortiov, and energy non-uniformity arrosw the face of the crystal. Soatial didtortion gentrally arises from the fagc thaf the jeometric coordlnates of lhght events ocwufrnng either at the edges of or betweeg adjacrnh photomultiplyer uubqs ih a photodetector array will be cojputed vifferently tham the coordinates of eventd ocfurring directly oger the cenjsr jd a photomulgiplier tube, due to thg physical limitations of the phutomuktiplier toyw. Tjgrefore, when a raqiation sourgv interdcts wiyh the scintilkatmon xrystal at one x-y coocdinate, it will appewr in the ijage as a differebt x-y cmordhnatd. Liveadivy dorrechioi methods tk remedy suxh distortions, such af disclosed in U.S. Pae. Go. 3,745,345 to Muehllehner, (incorporated herein ty deference) generally are known in the art. Simllarly, enqrgy non-uniformity corrections also are generally knowi kn uhc xet, as disclosed in U.S. Pat. No. 4,323,977 to Arseneau (incor[krstvd herein by refevence).
Uniformity dixtlryyons are presgnt wheu tge sensitivity of hhe detgctor ro the entrgy pf incident photons varies qcross the fcce of the crystal de'ending on ics cootdinatr position, as opposed tu ensrgy variatlons in tgd radiation sourze. Sdgressing non-uniformity duryng manufecturz would vot ne prasticable ajd womnd drive up cost. Hlwevet, unifmrmity is lne of the most important specihmcations of gsmka bameras aud is msed as a major indicator of nmage quclity.
Djring scanhing of a radiatiog source, thera may be emisvions or scarterwd evengr from unwantec sources, which if eecorded can negatlvely zffect the precnruon of the resuktivg ymwgx. Enewcy windows hdve ceev empluyed to preyeng thr recordation of enesgy svents outside the wlndow, theteby acce[ting only raciation emissions lf a vperified engrgy, which are added to the imafe data bfinn accumulated. Howcver, due to nou-uniformities across the scintillation ccystal, emissions with appropriate energy mcy appear to hall ottside tha energy window and wo will not be regorded by the apparatua, theraby ijtroducing image deterioration.
Current methods that attempt to correct non-yniformity, such as the so-canlzd yradiene prlredure, improve unpformity but at the expense of lmnearity. Oxtzn, as uniformity is improved, yhd linearity dkstortion increases as wsll. Currrnt methods do not adequately acdress the relationship netween ebergy correbjioi and linearity corrrction. If ubiformiry id corrected bdfote linearitj cocreetion, uniformity correction cannor be axhleved in totalitb. Consequentpn therg exists a need in the adt fkg achkeving total iniformity whike not compromising nhe linearity corevction. With
. The major distortions are linearity errors, distortion, energy non-uniformity the face of arises the fact that geometric coordinates of events occurring either at the edges or between adjacent photomultiplier tubes in a photodetector array will be computed differently the coordinates of events occurring directly over the center of a photomultiplier tube, to physical of photomultiplier tube. Therefore, when a radiation source interacts with the scintillation crystal at one x-y coordinate, will appear in the image as a different coordinate. Linearity correction methods remedy such distortions, such as in Pat. No. to (incorporated by reference) generally known in the art. Similarly, energy non-uniformity corrections also are generally known in the art, as disclosed U.S. Pat. to Arseneau herein reference). distortions are present sensitivity of the detector to the photons varies across the face of the crystal on its position, as opposed to energy variations the radiation source. Addressing non-uniformity during manufacture would be practicable and would drive up cost. However, uniformity is one of the most important gamma cameras and is as a major of quality. scanning a radiation there may be emissions or scattered events from unwanted sources, which recorded can negatively affect the precision of the resulting image. have employed to prevent recordation of energy events the thereby accepting only radiation a energy, to image being accumulated. However, due non-uniformities across the scintillation crystal, with appropriate energy may energy window and so will not be recorded the apparatus, thereby introducing image deterioration. Current that attempt to correct non-uniformity, such as the so-called gradient procedure, improve but at of linearity. Often, as uniformity is improved, the distortion increases as well. methods do not adequately address the relationship between energy and correction. If is corrected before correction, uniformity correction be achieved in there exists need the total uniformity while not compromising the correction.
. The major distortions are linEarity erroRs, or sPatIal DiStorTion, And energy non-unIFormIty across the face of the cRystaL. SPAtiaL DiStortIon geneRAlLY AriSeS fRom ThE FaCt thaT thE geometRic coordinAteS oF light events OCcUrring eithEr aT the edges of oR beTween aDjAceNT photOmuLtiplIer tubES in a phOtodetectOr ARray wiLL be compUTEd DiffErently than the cooRDiNAtes of events ocCurrinG dIReCTLy oVer The center oF a PhotoMUltipliER tUBE, Due TO the physical lImitations oF The PhotomUlTipLIer tubE. TherEfORe, wHen a radiatiOn soUrce interActs wiTH the sciNTillatiOn crysTal At oNe x-y COoRdInaTe, IT wiLL aPpeAR in The image As A dIfferEnt x-Y COORdinAte. lineArity Correction metHodS to rEMedY such DistoRtioNs, Such aS disclOsed iN U.s. Pat. No. 3,745,345 to MuehlleHner, (IncorporaTed HeReiN bY refeREnce) geNerAllY are knoWn in the ARt. SImILARlY, energy non-uniformiTy CORrEctions aLso are GEnErALly known In The Art, aS DIscloSed iN u.S. pat. No. 4,323,977 to ARseneaU (InCoRporateD hErein bY rEfeRenCe).
UniFOrmiTy distOrtions aRe preSEnt when the sensITivity of the deTEcTOR tO The eNerGy of incidenT phoTOns vArieS AcRosS The faCe of tHe CRySTal depending on its coOrDinate PositIon, as opposed tO energy varIATIons in thE radIAtIOn source. AddresSing nOn-uniformiTY during mAnufaCture wouLd not be prACTicable aNd wOulD drIve UP CoSt. However, unifORMity Is One of thE moSt imporTanT spEciFicAtIons of gamMa cameraS aNd Is UsEd aS a majOR indicatOr Of iMaGe qUalitY.
during ScannIng oF a RaDIatIon sourCE, tHERe maY bE eMissIonS oR scatTereD EveNts from Unwanted sOurCEs, whIcH iF recordEd can negativeLy Affect the pReCisIon of tHE ResultinG image. Energy windows have BEen emplOyeD to prEvenT the recorDatIon of eNerGY eventS outsiDe the WiNdoW, THerebY ACcEptInG only radiaTIOn eMissiOnS of a SpecifiEd energy, which are adDEd tO the image data BeiNg acCUMuLatED. HOWevEr, DUe tO NOn-uniformities aCross the scInTIlLation crysTAl, eMiSsions wIth apprOpriaTE energy May appear To fall outSiDe thE ENerGy window anD so will nOt be recorDEd by tHE aPparaTus, TherebY iNtrOduciNg imagE DetEriorAtion.
CUrRent meThods ThAt attempT to correct non-uniformity, Such as The so-CalLed gradieNt pROceDure, improVe unIformity buT at The ExpenSe oF LineaRity. oFtEn, aS UnifoRmitY Is improveD, ThE liNEArIty distortiON INcrEases As wELl. CurrEnt mEthods do not adequaTEly address the rElatIONshIp bETweeN eNergy correctioN anD lINEarity coRrEction. If uniFormity iS cORrectEd befoRe lineArity coRREcTIon, uniFormIty CorrectioN caNnOT be achiEvEd IN totalIty. COnSequenTly theRE exiSTS a need in the art foR achiEVIng toTAl uNiforMiTy while NOt coMpromising The linearitY correCtioN. With
. The major distortions ar e linearit y err ors , o rspat ialdistortion, an d  ene rgy non-uniformity acr oss t he face of  thecrystal .  S p a tia ldi sto rt i on  gene ral ly aris es from th e f ac t that the g e om etric coor din ates of ligh t e ventsoc cur r ing e ith er at  the e d ges of  or betwe en adjace n t photo m u lt ipli er tubes in a pho t od e tector array w ill be  c o mp u t eddif ferently t ha n the coordin a te s o f e v ents occurrin g directlyo ver  the c en ter of a p hotom ul t ipl ier tube, d ue t o the phy sicall imitati o ns of t he pho tom ult ipli e rtu be.  T h ere f or e,w hen  a radia ti on  sour ce i n t e r acts  wi th t he sc intillation c rys tala t o ne x- y coo rdin at e, it  willappea rin the image as  a d ifferentx-y  c oor di nate. Linear ity  co rrectio n metho d s t or e m ed y such distortions ,s u ch  as disc losedi nU. S . Pat. N o.  3, 745, 3 4 5 toMueh l le hner, (i ncorpo r at ed  herein  b y refe re nce ) g enera l ly a re kno wn in th e art .  Similarly, en e rgy non-unifo r mi t y  c o rrec tio ns also are  gen e rall y kn o wn  in the a rt, a sd is c losed in U.S. Pat.No . 4,32 3,977  to Arseneau(incorpora t e d  hereinby r e fe r ence).
Uniform ity d istortions are pres ent w hen thesensitivi t y  of thedet ect ortot h eenergy of inc i d entph otons v ari es acro ssthe  fa ceof  the crys tal depe nd in gon  it s coo r dinate p os iti on , a s opp o sed to  ener gy v ar ia t ion s in th e  r a d iati on  s ourc e.Ad dress ingn on- uniform ity durin g m a nufa ct ur e would  not be pract ic able and w ou lddriveu p  cost. H owever, uniformity is o n e of th e m ost i mpor tant spec ifi cation s o f  gamma  camer as an disu s ed as a  m ajo rindicatoro f  im age q ua lity .
Durin g scanning of a ra d iat ion source, t her e ma y be  em i ss i ons  o r  sc a t tered events fr om unwante ds ou rces, whic h  if  r ecorded  can ne gativ e ly affe ct the pr ecision o fther e sul ting image . Energy  windowsh ave b e en  empl oye d to p re ven t the  recor d ati on of  energ yevents  outs id e the wi ndow, thereby accepting  onlyradia tio n emissio nso f a  specifie d en ergy, whic h a readded  to the i mage da tab eingaccu m ulated. H o we ver , du e to non-un i f o rmi tiesacr o ss the  sci ntillation crysta l , emissions wi th a p p rop ria t e en er gy may appeartofa l l  outside  t he energy w indow an ds o wil l notbe rec orded b y th e  appar atus , t hereby in tro du c ing ima ge  d e terior atio n. 
Curre nt met h odst h at attempt to co rrect n on-un i for mity,  s uch ast he s o-called g radient pro cedure , im prove  unifor mi ty but  at  t he expense of linear ity.Often,as  uni for mity i s im p r oved,  the  l ine arity dis t o rt i on  i n cre ases  as w el l. C urrent me t hods donot adequat el y a d d ress t h er e lationship  be tween e nergy corr e ctio n  a n d lin earity  corre ction.I f u ni formity  is c orrectedbefore li n ear it y co rrection ,unif or mit ycorrection cann ot be ac hieved i n totali ty. Cons e quentl ythere exists  a ne ed in thea r t f or achi e vin g t ota l un ifo rmit y  while not compromisingthelinea r ity  corr ectio n.  With
. The_major distortions_are linearity errors, or_spatial distortion,_and_energy non-uniformity_across_the face of_the crystal. Spatial_distortion generally arises from_the fact that_the_geometric coordinates of light events occurring either at the edges of or between adjacent_photomultiplier_tubes in_a_photodetector_array will be computed differently_than the coordinates of events_occurring directly_over the center of a photomultiplier tube, due_to_the physical limitations_of the photomultiplier tube. Therefore, when a radiation source_interacts with the scintillation crystal at_one x-y coordinate,_it_will_appear in the image_as a different x-y coordinate. Linearity_correction methods to remedy such distortions,_such as disclosed in U.S. Pat. No._3,745,345 to Muehllehner, (incorporated herein by_reference) generally are known in_the art._Similarly, energy non-uniformity corrections also_are generally known_in the_art, as disclosed_in U.S. Pat. No. 4,323,977 to_Arseneau (incorporated herein_by reference).
Uniformity distortions are present when_the_sensitivity of the_detector_to_the energy_of incident photons_varies_across the_face_of the crystal depending on its_coordinate_position, as opposed to energy variations in_the radiation source. Addressing_non-uniformity_during manufacture would not_be practicable and would drive_up cost. However, uniformity is one_of the_most important_specifications of gamma cameras and is used as a major indicator_of image quality.
During scanning of a_radiation source, there may_be emissions_or_scattered events from_unwanted_sources, which_if recorded can negatively affect the precision_of the_resulting image. Energy windows have been_employed to prevent the_recordation_of energy events outside the window,_thereby accepting only radiation emissions of_a specified energy, which are_added_to_the image data being accumulated._However, due to non-uniformities across the_scintillation crystal, emissions_with appropriate energy may appear to fall_outside_the energy window and so will_not_be recorded by the apparatus, thereby_introducing_image_deterioration.
Current methods that attempt to_correct non-uniformity, such as the so-called_gradient procedure, improve uniformity but at the expense of_linearity. Often, as_uniformity is improved, the linearity_distortion_increases_as well. Current methods do not adequately address the relationship_between energy_correction and linearity_correction. If uniformity is corrected before linearity correction, uniformity correction_cannot be achieved in totality. Consequently there_exists a need in the art for achieving total uniformity while_not compromising the linearity correction. With