IntactProstateContouringGuide
eContourTeam
Youwanttocontour:IntactProstateWhatnow?
• Findyourreferences– RTOGnormalmalepelviscontouringatlas
• h@ps://www.rtog.org/CoreLab/ContouringAtlases/MaleRTOGNormalPelvisAtlas.aspx
– RTOGtrialswithcontouringdescripIonsforIMRTdescribedintheprotocol
• RTOG0815• RTOG0126
– LinktoUCSDvideoofhowtocontourintactprostateslice-by-slice(websiteloginisfree)
*eContour.orgaimstobeyourone-stopshopforcontouringguidelines,withhyperlinkstoabovehigh-yieldreferences!
LeteContour.orghelpyou!
1. SelectCASES
2. Fromdropdowncaselist:GUàProstateàintact(notpost-prostatectomy)
3. Reviewanatomy
4. DrawOARs(rectumandpenilebulb)
5. DrawtheGTVandCTV
6. Addmargin/expansiontocreatefinalPTVfortreatmentplanning.
Quickreviewofbasicanatomyofprostate/pelvis
Penilebulb
Prostate
Bladder
Rectum
SeminalVesicle(SV)
Sacrum
ThefirststepincontouringaccuratelyistounderstandtheperInentanatomy.Onthissagi@alimage,theprostateisborderedbythebladdersuperiorly,thepubicsymphysisanteriorly,andtherectumposteriorly.
Pubicsymphysis
Coronal Axial
Baseofprostate
Apexofprostate
Oncoronalslice,thebladderissuperiortotheprostate.
Onanaxialslice,theprostateisborderedbythebladderandpubicsymphysisanteriorly,therectumposteriorly,andlevatorani/obturatorinternusmuscleslaterally.
Penilebulb
ProstateBladder
RectumObturator Internus
Levator Ani
Notallcasesofintactprostatecancerarecreatedequal!
GUàProstateàintact(notpost-prostatectomy)
– NOTICEtheSTAGE/RISKSCORE!Thisisanintermediateriskcaseinwhichprostateandproximalseminalvesicle(SV)onlyaretreated.
– PaIentswithlow-riskprostatecancerareoaenputonacAvesurveillance.However,iftreaIng,considerprostateonly(noSV).
– PaIentswithhighriskprostatecancerraisemorecontouringquesIons…
• Treatpelvicnodes?Dataiscontroversial.RTOG0924isongoing.• Howmuchseminalvesicle(SV)totreat?Alsocontroversial.
DISCLAIMER:EachcaseisuniqueandrequiresdecisionmakingbasedonclinicaljudgmentofthetreaAngphysician.
Therearenoconsensusguidelines…butthereareseveralprotocolsdefiningtargetvolumesandPTVeContourusesthemostrecenttrials:RTOG0126andRTOG0815
StartwithOARs:Rectum
Levatorani
WearescrollingsuperiorlythroughtheCTslices
• Contouringrectumcanhelpdefinetheposteriorborderoftheprostate.(SagiMalonnextslide)
• Thelevatoraniisathinbroadmusclethatispartofthepelvicfloorwhichsurroundstheanalcanal(atthislevel).Theanalcanalisoaenincludedintherectalcontour.
• Thelevatoranialsosupportstheprostate.
StartwithOARs:Rectum• UsetheSAGITTALviewtomakesureyouarefollowingthecontouroftherectum!
Penilebulb
Prostate
Bladder
Rectum
SeminalVesicle(SV)
NextOAR:PenileBulbTheSAGITTALviewcanalsohelpidenIfythepenilebulb,asitisusuallyatthelevelofthebaseofthepenis.(Axialonnextslide)
Penilebulb
Prostate
Bladder
Rectum
SeminalVesicle(SV)
GUdiaphragm
Baseofpenis
NextOAR:Penilebulb
Penilebulb Baseofpenis
Thepenilebulbisoaenteardrop-shaped,locatedposteriortothebaseofthepenis.
Prostate
Rectum
Pubicsymphysis
ObturatorInternus
Now….contourtheGTV:Prostate
Thesearebloodvessels!Becarefulnottoincludetheseinyourprostatecontour.MRImakesthemeasiertosee.
TIP:ConsiderstarIngyourcontouratthemiddleoftheprostate(wherethebordersarewelldefined).
Levatorani
NOTE:Callingtheprostatea“GTV”isabitofamisnomer…theenAreprostateisnotgrosstumor.Butwewillgowithitpertheprotocols.
ContourtheGTV:Prostate
ProstateLevatorani Avoidincluding
levatoraniinyourprostatecontour.
Prostate
Rectum
Obturatorinternus
Levatorani
ContourtheGTV:Prostate
Levatoranicanhelpvisualizeapexofprostate,butavoidincludingitinyourprostatecontour.
ContourtheGTV:Prostate
ThemostinferiorprostatecontourshouldbeonesliceabovetheGUdiaphragm.
GenitourinaryDiaphragm(GUD)asalandmark?
Levatorani
Genitourinarydiaphragm=hourglassshape,locatedatconvergenceoflevatorani
Aka“urogenitaldiaphragm”outsideradonc
TheprostatesitsjustabovetheGUdiaphragmwhichsitsjustabovethepenilebulb.Problemis…theGUDishardtoseeonCT!AnMRIobtainedpriortotreatmentcanbefusedtothesimCTandaidcontourdelineaIon.MRIenhancessubtledifferencesbetweenthesesoaIssues.
ContourtheGTV:ProstateAlternaAveinferiorborder…Ifyoucan’tfindtheGUdiaphragm,justendyourprostate/GTVatleast0.7cmabovepenilebulb(ensuresPTVdoesnotoverlappenilebulb).
Penilebulb
Prostate
Bladder
Rectum
SeminalVesicle(SV)
Genitourinarydiaphragm
Prostatebase
SeminalVesicles
NowcontourtheSeminalVesicles
Theinferiorseminalvesicles(SVs)areinthesameaxialplanasthebaseoftheprostate–includeinCTV!
SuperiorborderofSV
Contourthetheproximal1cmoftheSV(proximalmeaningclosestoPROSTATE)…howdoIknow1cm?Nextslide…
WhentotreatSV?Thisisoaenbasedonclinicaljudgment(likelihoodofinvolvementbasedonextentofdisease,relaIverisk/benefitsincetreaIngSVincreasesdosetorectum).IntheRTOG0126,theproximal1cmisincludedinallpaIents.
MeasureSV(OpIon1)
Lookinlowerleaofyourscreenforthe“Z”coordinate.Scrollupordownoneslice,andthedifferenceistheCTslicethickness.ThenesImatenumberofslicestocontourby1cm/slicethickness.
MeasureSV(OpIon2)
Wewanttoincludeonlytheproximal1cm(meaningproximalorclosesttoprostate)ofSV.TIP:IntheSAGITTALview,usethemeasuringtooltochecktheverIcalextentofyourcontour.
GTV(prostate)+SV=CTV
Usethebooleantooltocombineprostate/GTVandSeminalVesicle(SV)intoasingleCTV.
TIP:ContouringprostateandSVseparatelyaffordsflexibilityincreaAngyourCTV(iecandecreasedosetoSVandboostprostateonlyifrectaldoseistoohigh).
AddamarginforPTV
RTOG0126andRTOG0815specify5-10mmformarginfromCTVtoPTV.ThisisoaeninsItuIonal,anddependsonimmobilizaIonanddailyimaging(forexample,kvX-rayswouldrequireabiggermarginthanCBCT).
Oaentheposteriormarginontherectumislesstoreduceriskoftoxicity,soweused7mmexcept5mmposteriorly.HowdoIaddanasymmetricmargin?(Seenextpage!)
AddamarginforPTV
“Marginforstructure”
NOTE:posteriormarginisless
Sagi@al Coronal
Alwayscheckyourfinalvolumesinsagi@alandcoronalviewstomakesureyouhavecontouredavolumethatmakessensein3dimensions!
FORFUN:OverlayRTDoseineContour
CTV
PTV
D95%
95%ofprescripIondose(79.2Gy)=75GyThisallowsustolookatthe95%isodoselinetoassesscoverageandconformality.
Oncethecontoursarecreated,aradiaIonplaniscreatedbytheDosimetrists.ThisstepisthenusuallythefirststepofradiaIonplanreview!
References
• RTOGnormalmalepelviscontouringatlas– h@ps://www.rtog.org/CoreLab/ContouringAtlases/MaleRTOGNormalPelvisAtlas.aspx
• RTOGtrialswithcontouringprotocols• RTOG0815• RTOG0126
• LinktoUCSDvideoofhowtocontourintactprostateslice-by-slice(websiteloginisfree)
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