Target delineation in Pelvic malignancies在盆腔恶性肿瘤靶区精选文档.ppt

ICRU definitions,Gross Tumor Volume:GTVClinical Target Volume:CTVInternal Target Volume:ITVPlanning Target Volume:PTVOrgan at Risk:OARPlanning Organ at Risk Volume:PRV,ICRU 50&62,GTV,Demonstrable macroscopic tumour(CT scan,MRI,PET-CT,other).Does not apply to postoperative RT.Does not apply in situations where the tumour is not easy to see:prostate and rectum cancer.Long learning curve,need for training or“retraining”in modern imaging,Lymphatic CTVin the pelvis,Lengel&Scalliet.R&O 2008 EPUB,Common pathways for the pelvic wall and pelvic organs.Minor lymphatics are seldom invaded if major lymphatics are free,Lymphatic CTVin the pelvis,Lengel&Scalliet.R&O 2008 EPUB,Proposal for a common classification in 7 levels,by similarity with H&N or thoracic classification.,Cervix cancer imaging with MRI(GTV),Ptter R et al.R&O 2006,78:67,Initial MRI;FIGO stage IIB;Invasion of right parametria,disparition of cervix rim,fluid collection in cervix canal.Drawing of clinical staging under anesthesia,Cervix cancer imaging with MRI(GTV),Ptter R et al.R&O 2006,78:67,MRI after 50 gy RT-CT,before brachytherapy.Partial restoration of cervix rim.Regression of parametrial invasion.Drawing of clinical staging under anesthesia,Cervix cancer imaging with MRI(GTV),Ptter R et al.R&O 2006,78:67,3D imaging ofbrachytherapy,Ptter R et al.R&O 2006,78:67,Total dose calculated as the sum of the extrenal radiotherapy dose and the brachytherapy dose,with a biological correction for the variation in dose rate and dose per fraction.,Inter-observer variation in delineation for cervix cancer,Dimopoulos J et al.R&O 2008 EPUB,Poor organ definition with CT,Organ definition sometimes difficult with CT due to lack of contrast.MRI offers much better contrast for soft tissue.Combination of CT with MRI offers a good solution for anatomy definition.,CTV for cervix cancer,Small W et al.IJROBP 2008,71:428,Volumes in rectum cancer,Characterisation of rectal cancer:standard is MRI,T2 image through mesorectum demonstrating a large T3 tumour with extramural extension(black arrow).The CRM is 4 mm.,T2 image through mesorectum demonstrating a bulky polypoid rectal tumour extending outside mesorectum(black arrow)and lymph node.,Characterisation of rectal cancer:standard is MRI,Rectum cancer:before and after chemoradiation,Good response,Rectum cancer:before and after chemoradiation,Fatty signal after radiochemo-therapy(T2),Good response,Rectum cancer:before and after chemoradiation,Apparently,the tumour regression is minor,but the signal has changed(T2).At surgery,only mucinous deposits remained.,Prostate cancer,GTV invisibleCTV=prostate,Poor contrast definition on CT.MRI offers better contrast for CTV delineation,Prostate cancer CTV,PTV?,Systematic deviationsRandom deviations,Kupelian P et al.IJROBP 2007,67:1088,Continuous,real time monitoring of the prostate gland position during fractionated radiotherapy,PTV?,Various prostate drift patterns during a single fraction(measured by stereoscopic X-rays with Cyberknife),Yaoqin Shie et al.IJROBP 2008,72:236,Calculating the PTV,Scatter plot of the systematic setup displacement along the 3 directions(AP,CC and lateral),for the head,neck and shoulders,Calculating the PTV,Distribution of the random displacement salong the 3 directions(AP,CC and lateral),for the head,neck and shoulders,Repeated(3/w)portal imaging in 30 patients treated for various tumors,scatter plotreporting thediscrepancies inthe beamaxis ofportal images relative tosimulation films inCentre A andCentre B,(R&0 29:230,1993),ITV?Respiratory movements,Different treatment-planning concepts:conventional free breathing,internal target volume(ITV),gating(at exhale)and mid-position.,Wolthaus JWH et al.IJROBP 2008,70:1229,ITV?,Respiratory movements(16/min)Cardiac beats(80/min)Random movements(bowel,bladder,etc),“Slow”CT acquisition leads to organ deformation,ITV?,A spherical image is distorded in various shapes,depending at what time of the respiratory cycle the image is acquired,ITV?,Question without answer,Towards multidimensional conformal radiotherapy?,Physicalconformality,Physical+biologicalconformality,