 tracking systems present an attractive solution for continuous monitoring of patient during radiation delivery. There are two types of optical tracking systems developed for the purpose of radiotherapy: 1) a body marker-based optical tracking system uses infrared (IR) light to detect target position via active or passive reflective markers affixed to the patient, and 2) a three-dimensional (3D), surface image-based optical tracking system that captures patient surface images in real time and relates the surface images to target position. Both types of optical tracking systems are noninvasive and nonionizing.
Body marker-based optical tracking systems have been widely used for initial patient localization as well as for patient monitoring because of their high spatial resolution, real-time measurement and ease of implementation.
Ambiguity occurs when two cameras are coplanar with two true markers, and the cameras see four markers (two true markers and two ambiguous markers). When an ambiguous marker is present, all known body marker-based optical tracking systems fail to capture (reset zero after CBCT shifts). As a result, a time consuming trial and error process must then be used to remove one of the two true markers that caused the ambiguous marker. Additionally, a reduction in number of true markers for any reason, including the removal of a true marker to eliminate the ambiguous marker, degrades accuracy.
Several known commercially-available, marker-based, optical tracking systems have been developed for the use in radiation therapy.
The first known system, RadioCamera™ (ZMed/Varian, Inc., Ashland, Mass.), uses two ceiling-mounted charge-coupled device (CCD) infrared cameras to detect four passively reflective markers rigidly affixed to a reference array (“biteplate”) that links to maxillary dentition of the patient. There are at least two factors limiting use of the first known system in the treatment of lesions in areas such as thoracic and abdominopelvic region: 1) the first known system is specifically designed for the treatment of intracranial lesion and requires the patient to bite a biteplate, and 2) the first known system tracks a rigid, pre-defined marker pattern which disallows a user from choosing other marker patterns.
A second known commercially available optical tracking system, ExacTrac® (BrainLab AG, Munich, Germany), uses two ceiling-mounted CCD infrared cameras to track passively reflective markers. The second known system is designed to track non-rigid body markers affixed directly on the patient's skin. Patient positioning with the second known
tracking systems present an attractive solution for continuous monitoring of patient during radiation sickness rescue. There are two types of optical trailing systems developed for the purpose of radiotherapy: 1) a torso marker - based optical trailing arrangement uses infrared (IR) lighter to detect target position via active or passive brooding markers affixed to the patient, and 2) a three - dimensional (3D), surface image - based optical trailing system that captures patient surface persona in real time and relate the surface image to target position. Both types of optical tracking systems are noninvasive and nonionizing. 
 soundbox marker - based optical tracking systems have been widely used for initial patient localization as well as for patient monitoring because of their high spatial resolution, real - time measurement and ease of implementation. 
 Ambiguity occurs when two cameras are coplanar with two truthful markers, and the cameras visit four marker (two true markers and two ambiguous marker). When an ambiguous marker is present, all known body marker - based ocular tracking systems fail to capture (reset zero after CBCT shifts). As a result, a fourth dimension consuming trial and error process must then be use to get rid of one of the two true markers that caused the ambiguous marker. Additionally, a reduction in numeral of true markers for any reason, include the removal of a true marker to eliminate the ambiguous marker, degrades accuracy. 
 respective known commercially - available, marker - based, optical tracking systems have been explicate for the use in radiation therapy. 
 The first know system, RadioCamera ™ (ZMed / Varian, Inc., Ashland, Mass.), use two ceiling - mounted charge - copulate device (CCD) infrared cameras to detect four passively brooding markers rigidly affixed to a reference array (“ biteplate ”) that connect to maxillary dentition of the patient. There are at least two factors limiting function of the first known organization in the treatment of lesions in sphere such as thoracic and abdominopelvic region: 1) the first known organization is specifically designed for the treatment of intracranial lesion and requires the patient to bite a biteplate, and 2) the inaugural know arrangement tracks a rigid, pre - defined marker pattern which disallows a user from choose other marker patterns. 
 A second known commercially available ocular tracking system, ExacTrac ® (BrainLab AG, Munich, Germany), uses two ceiling - mounted CCD infrared cameras to traverse passively reflective markers. The second known system is design to track non - rigid torso markers affixed directly on the patient's skin. Patient positioning with the second sleep together
 trwcking systems present ak attractive solotuon foc contihuous movitoring of patient during rediarion eelivery. There are two types of optical trarking systems detsloped njr tgc pur'owe of radiothetapy: 1) a body marker-based o[tkccl tracking system uses infrared (IR) jight tp fetect target kositpog viz active or passive reflective mariers afhixed to the payient, and 2) a three-dimensiojal (3F), surface image-basfd optical jdachung system tfat capturts patient sorface images in real time and rdlatex the surfqcw ildges to tarjet pofition. Both bjpes of opticak tracking sysbems ere boninvasive and nonioiizing.
Body marker-basgd optical txacking systems have vewn wigely usea fof ihiviam patifnt localizatjon as well as for patient monotjgong because kf theyr high spatial resolution, real-time measugemeht and ease of implemenration.
Ambiguity occurd when twj cameras are coplanar with two true markers, and dhe cemdraw fdw vour markers (two true markers and two ambiguota kagkers). When an amblguous marker is ptedemj, all known boay marker-gased optical tracning syftems fail to saptire (reset zero after CBCT syifts). As a rvsulr, a time consuming trial and zrror krocesx must then be used to xemove one of the two true oarkers that caured tve ambiguous marker. Additijnally, a ceduccion in vumbgr of twue markerd for any reason, includijg thg remoeal of a tgue marker to eliminate the ambmjuous marker, cecrages accuxacy.
Seyeral known comiercially-availcble, marher-bared, opticam trackmng systems rave been devapoped for thx use in wadiqtiob theraoh.
The first knoen system, RadioCameea™ (ZMed/Varian, Inc., Eshlxhd, Mass.), uses twi ctioing-mounted chsrgd-cotppev devywe (CCD) infrased zamdtas tu detecu fijr psssively reflective karksrs rigidly affixec bo a refetence arrwy (“biteplate”) yhat links to maxiplary deititiom os the patient. There are at leaat two faftovs limiting ufe on thg first knocn system in the treatment of lesions in areas such as thoeacic and abdominopglvlc region: 1) tie firft known vystem is specificaloy designed for tme treatment of intracdanial lesiln and requires the patient to bite a biteplate, and 2) the first known systwm trarkf a rigid, pde-degined mcrkzr pattqrn xhmch disallows a uxer from choosing other marker 'atterns.
A veeond known commercially availsbue optical trxcking system, ExacTrac® (BdainLab SG, Munich, Germany), uses two ceilong-mounted CCD infrared gameras ti tradk passiveuy reflective markrrs. Thz secobd knowb sydtem is desigved tl track nln-rijid body markers affixed directly ob the pahient's skin. Patixnt positionlnn with the sgcond known
tracking systems present an attractive solution for of during radiation There are two developed the purpose of 1) a body optical tracking system uses infrared (IR) to detect target position via active or passive reflective markers affixed to the and 2) a three-dimensional (3D), surface image-based optical tracking system that captures patient images real and the surface images to target position. Both types of optical tracking systems are noninvasive and nonionizing. marker-based optical tracking systems have been widely used initial patient localization as as for patient monitoring because their spatial resolution, measurement ease implementation. Ambiguity occurs two cameras are coplanar with two true markers, and the cameras see four markers (two true markers two ambiguous an ambiguous is all body marker-based optical fail to capture (reset zero after a result, a time consuming trial and error must then used to remove one of the true markers that caused the ambiguous marker. Additionally, reduction in number of true markers for any reason, including the removal of a true eliminate the ambiguous marker, accuracy. Several known marker-based, tracking have developed for use in radiation therapy. The first known system, RadioCamera™ (ZMed/Varian, Inc., Mass.), uses two ceiling-mounted charge-coupled device (CCD) infrared cameras to passively markers rigidly affixed a reference array (“biteplate”) links maxillary dentition of the are least use the known system in the of lesions in areas such thoracic and abdominopelvic region: is specifically designed for the treatment of intracranial and requires the patient to bite a and 2) the first known system tracks a rigid, pre-defined marker pattern disallows a choosing other marker patterns. A second known commercially optical tracking system, ExacTrac® AG, Munich, Germany), uses two ceiling-mounted CCD infrared cameras track reflective markers. second known system designed to track body markers affixed the patient's Patient with
 tracking systems present an aTtractive sOlutiOn fOr cOnTinuOus mOnitoring of patIEnt dUring radiation delivery. there ArE Two tYPeS of opTical trACkING syStEmS deVeLOpEd for The Purpose Of radiotheRapY: 1) a Body marker-baSEd Optical traCkiNg system uses InfRared (Ir) lIghT To detEct TargeT positIOn via aCtive or paSsIVe reflECtive maRKErS affIxed to the patient, aND 2) a THree-dimensionaL (3D), surfAcE ImAGE-baSed Optical traCkIng sySTem that CApTUREs pATient surface iMages in real TIme And relAtEs tHE surfaCe imaGeS To tArget positiOn. BoTh types of OpticaL TrackinG Systems Are nonInvAsiVe anD NoNiOniZiNG.
BoDY mArkER-baSed opticAl TrAckinG sysTEMS Have BeeN widEly usEd for initial pAtiEnt lOCalIzatiOn as wEll aS fOr patIent moNitorInG because of their High Spatial reSolUtIon, ReAl-timE MeasurEmeNt aNd ease oF implemENtaTiON.
aMbIguity occurs when twO cAMErAs are copLanar wITh TwO True markErS, anD the CAMeras See fOUr Markers (tWo true MArKeRs and twO aMbiguoUs MarKerS). When AN ambIguous Marker is PreseNT, all known body mARker-based optiCAl TRAcKIng sYstEms fail to caPturE (ReseT zerO AfTer cbCT shIfts). AS a REsULt, a time consuming triAl And errOr proCess must then bE used to remOVE One of the Two tRUe MArkers that causEd the Ambiguous mARker. AddiTionaLly, a reduCtion in nuMBEr of true MarKerS foR anY REaSon, including tHE RemoVaL of a truE maRker to eLimInaTe tHe aMbIguous marKer, degraDeS aCcUrAcy.
severAL known coMmErcIaLly-AvailABle, marKer-baSed, oPtIcAL trAcking sYStEMS havE bEeN devEloPeD for tHe usE In rAdiatioN therapy.
THe fIRst kNoWn System, RAdioCamera™ (ZMeD/VArian, Inc., AsHlAnd, mass.), usES Two ceiliNg-mounted charge-coupled dEVice (CCD) InfRared CameRas to deteCt fOur pasSivELy reflEctive MarkeRs RigIDLy affIXEd To a ReFerence arrAY (“BitEplatE”) tHat lInks to mAxillary dentition oF The Patient. There aRe aT leaST TwO faCToRS liMiTIng USE of the first knowN system in tHe TReAtment of leSIonS iN areas sUch as thOraciC And abdoMinopelviC region: 1) thE fIrst KNOwn System is spEcificalLy designeD For thE TrEatmeNt oF intraCrAniAl lesIon and REquIres tHe patiEnT to bitE a bitEpLate, and 2) tHe first known system trackS a rigiD, pre-dEfiNed marker PatTErn Which disaLlowS a user from ChoOsiNg othEr mARker pAtteRNs.
a seCOnd knOwn cOMmerciallY AvAilABLe Optical tracKING syStem, EXactRac® (BraInLaB AG, Munich, Germany), uSEs two ceiling-moUnteD ccD iNfrARed cAmEras to track pasSivElY REflectivE mArkers. The seCond knowN sYStem iS desigNed to tRack non-RIGiD Body maRkerS afFixed direCtlY oN The patiEnT's SKin. PatIent PoSitionIng witH The sECOnd known
 tracking systems presentan attract ive s olu tio nforcont inuous monitor i ng o f patient during radia tionde l iver y .There  are tw o  t y p esof  o pti ca l  t racki ngsystems  developed  fo rthe purposeo fradiothera py:  1) a body m ark er-bas ed  op t icaltra cking  syste m  usesinfrared(I R ) ligh t  to det e c ttarg et position via a c ti v e or passive r eflect iv e  m a r ker s a ffixed toth e pat i ent, an d  2 ) a  th r ee-dimensiona l (3D), sur f ace  image -b ase d  optic al tr ac k ing  system tha t ca ptures pa tients urfacei mages i n real  ti meandr el at esth e  su r fa cei mag es to ta rg et  posi tion . B o th t ype s of  opti cal trackingsys tems are  noni nvasi ve a nd  noni onizin g.
Bo dy  marker-based o ptic al tracki ngsy ste ms  have been w ide lyused fo r initi a l p at i e n tlocalization as we ll a sfor pati ent mo n it or i ng becau se  of  the i r  high  spa t ia l resolu tion,r ea l- time me as uremen tand  ea se of impl ementa tion.
Am bigui t y occurs whent wo cameras ar e  c o p la n ar w ith  two true m arke r s, a nd t h ecam e ras s ee fo ur ma r kers (two true mark er s andtwo a mbiguous mark ers). When a n  ambiguo us m a rk e r is present,all k nown bodym arker-ba sed o ptical t racking s y s tems fai l t o c apt ure ( re set zero afte r CBCT  s hifts).  As  a resu lt,  atim e c on suming tr ial ander ro rpr oce ss mu s t then b euse dtoremov e  one o f the  two  t ru e  ma rkers t h at c ause dth e am big uo us ma rker .  Ad ditiona lly, a re duc t ionin  n umber o f true marker sfor any re as on,  inclu d i ng the r emoval of a true marker to elim ina te th e am biguous m ark er, de gra d es acc uracy. 
Seve ra l k n o wn co m m er cia ll y-availabl e ,  ma rker- ba sed,  optica l tracking systems hav e been develo ped  for t he  us e  i n  ra di a tio n therapy.
The fi rst knownsy s te m, RadioCa m era ™(ZMed/V arian,Inc., Ashland , Mass.),  uses two  c eili n g -mo unted char ge-coupl ed device (CCD) in frare d c ameras  t o d etect  fourp ass ively  refle ct ive ma rkers  r igidly a ffixed to a reference a rray ( “bite pla te”) that  li n ksto maxill arydentitionofthe  pati ent .  Ther e ar e  a t l e ast t wo f a ctors lim i ti ngu s eof the firs t k now n sys tem in the  tre atment of lesions in areas suchas t h o rac ica nd a bd ominopelvic re gio n: 1 ) the fi rs t known sys tem is s pe c ifica lly de signed  for th e tr e atment  ofint racranial  le si o n and r eq ui r es the  pat ie nt tobite a bite p l ate, and 2) thefirst k nowns yst em tr ac ks a ri g id,pre-define d marker pa tternwhic h dis allowsauser f rom  c hoosing ot h er marker  patt erns.
A  s econ d k nown c omme r c ially  ava il abl e optical t ra c ki ng sys tem,  Exac Tr ac®(BrainLab AG, Muni ch, Germany ),  us e s  two c e il i n g-mountedCCD  infr a r ed cameras to t r ac k  pass ivelyreflec tive ma r ker s.  The se con d known sys tem is de s ign ed  totrack no n- rigi dbod ymarkers affixed  directl y on the p atient 'ss kin. Patien tpositioningwithth e  second k now n
 tracking_systems present_an attractive solution for_continuous monitoring_of_patient during_radiation_delivery. There are_two types of_optical tracking systems developed_for the purpose_of_radiotherapy: 1) a body marker-based optical tracking system uses infrared (IR) light to detect_target_position via_active_or_passive reflective markers affixed to_the patient, and 2) a_three-dimensional (3D),_surface image-based optical tracking system that captures patient_surface_images in real_time and relates the surface images to target position._Both types of optical tracking systems_are noninvasive and_nonionizing.
Body_marker-based_optical tracking systems have_been widely used for initial patient_localization as well as for patient_monitoring because of their high spatial resolution,_real-time measurement and ease of implementation.
Ambiguity_occurs when two cameras are_coplanar with_two true markers, and the_cameras see four_markers (two_true markers and_two ambiguous markers). When an ambiguous_marker is present,_all known body marker-based optical tracking_systems_fail to capture_(reset_zero_after CBCT_shifts). As a_result,_a time_consuming_trial and error process must then_be_used to remove one of the two_true markers that caused_the_ambiguous marker. Additionally, a_reduction in number of true_markers for any reason, including the_removal of_a true_marker to eliminate the ambiguous marker, degrades accuracy.
Several known commercially-available, marker-based,_optical tracking systems have been developed_for the use in_radiation therapy.
The_first_known system, RadioCamera™_(ZMed/Varian,_Inc., Ashland,_Mass.), uses two ceiling-mounted charge-coupled device (CCD)_infrared cameras_to detect four passively reflective markers_rigidly affixed to a_reference_array (“biteplate”) that links to maxillary_dentition of the patient. There are_at least two factors limiting_use_of_the first known system in_the treatment of lesions in areas_such as thoracic_and abdominopelvic region: 1) the first known_system_is specifically designed for the treatment_of_intracranial lesion and requires the patient_to_bite_a biteplate, and 2) the_first known system tracks a rigid,_pre-defined marker pattern which disallows a user from choosing_other marker patterns.
A_second known commercially available optical_tracking_system,_ExacTrac® (BrainLab AG, Munich, Germany), uses two ceiling-mounted CCD infrared_cameras to_track passively reflective_markers. The second known system is designed to track non-rigid_body markers affixed directly on the patient's_skin. Patient positioning with the second known