thastro08 igrt1
Post on 26-May-2015
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IMAGE - GUIDED RADIATION THERAPYIMAGE - GUIDED RADIATION THERAPY( IGRT )( IGRT )
Asst.Prof. Surat VINIJSORNAsst.Prof. Surat VINIJSORNDiv. Of Radiation OncologyDiv. Of Radiation OncologyFaculty of Medicine Siriraj HospitalFaculty of Medicine Siriraj HospitalMahidol UniversityMahidol University
Local control
Identification of the target Delivery of radiation
Excellent dose distribution Precision targeting
?
Rationale for IGRTRationale for IGRT
IGRT is a component of the radiation therapy process IGRT is a component of the radiation therapy process that incorporate that incorporate imaging coordinatesimaging coordinates from the from the treatment plan to be delivered in order to ensure the treatment plan to be delivered in order to ensure the patient is properly alignedpatient is properly aligned in the treatment room. in the treatment room.
Goal and Clinical benefitGoal and Clinical benefit
To improve the accuracy of the radiation To improve the accuracy of the radiation field placementfield placement
To reduce the exposure of healthy tissue To reduce the exposure of healthy tissue during radiation treatmentduring radiation treatment
History of “guidance”for treatmentHistory of “guidance”for treatment
Surface and skin marksSurface and skin marks Portal imaging ( PORT FILM )Portal imaging ( PORT FILM ) Electronic portal imaging ( EPID )Electronic portal imaging ( EPID )
Imaging for treatment verificationImaging for treatment verification
Port filmPort film
Emergence of MV portal imagersEmergence of MV portal imagers In-room ultrasound localizationIn-room ultrasound localization Marker-based localizationMarker-based localization Fluoroscopic trackingFluoroscopic tracking
Flat panel imaging (EPID)Flat panel imaging (EPID) KV digital imagingKV digital imaging CT – on railCT – on rail KV-CBCTKV-CBCT MV-CBCTMV-CBCT
1980’s
1990’s
2000’s
IGRTIGRT
Allows us to correct for :
• Set up errors• Inter-fraction organ motion : Inaccurate set up because of organ changes in each fraction• Intra-fraction motion : Organ motion during treatment
IGRTIGRT
Moving targetMoving target PositioningPositioning Tumor shrinkage or expansionTumor shrinkage or expansion Changes in shape of the tumor and Changes in shape of the tumor and
surrounding anatomysurrounding anatomy
Jaffray et al.1999
Indication
IGRTIGRT
Set up errors Inter-fraction organ
motion
Intra-fraction motion
Adaptive Gating
IGRTIGRT
matching planar kilovoltage (kV) radiographs matching planar kilovoltage (kV) radiographs fluoroscopyfluoroscopy
CBCT with two orthogonal imagesCBCT with two orthogonal images megavoltage (MV) images with digital reconstrucmegavoltage (MV) images with digital reconstruc
ted radiographs (DRRs) from the planning CT. ted radiographs (DRRs) from the planning CT.
Two-dimensional (2D) IGRT(2D) IGRT would include would include ::
IGRTIGRT
localization of a localization of a conecone--beambeam computedcomputed tomographytomography (CBCT) (CBCT)
data set with the planningdata set with the planning computedcomputed tomographytomography (CT) data set from (CT) data set from
planningplanning
Three-dimensional (3D) IGRT (3D) IGRT would include would include ::
Adaptive radiotherapyAdaptive radiotherapy
A full implementation of image guided will lead to A full implementation of image guided will lead to the concept of adaptive radiotherapy ( ART )the concept of adaptive radiotherapy ( ART )
In ART the dose delivery for subsequent treatment In ART the dose delivery for subsequent treatment fraction of the course of radiotherapy can be fraction of the course of radiotherapy can be modified to compensate for inaccuracies dose modified to compensate for inaccuracies dose delivery that can not be corrected simply by delivery that can not be corrected simply by adjusting the patient positioning like in the IGRTadjusting the patient positioning like in the IGRT
Adaptive radiotherapyAdaptive radiotherapy ( cont.)( cont.)
Tumor shrinkage during the course of Tumor shrinkage during the course of treatmenttreatment
Patient loss weight during the course of Patient loss weight during the course of treatmenttreatment
Increase hypoxiaIncrease hypoxia during the course of during the course of treatmenttreatment
The courses of inaccuracies may include :
Dynamic Adaptive RT (DART)
Most exciting use of IGRT is the ability to adapt
treatment to changes in the patient and/or tumor patient
Although many tumors shrink over the course of
treatment, it is common to largely ignore these changes
and use a single treatment plan
At best, patients are re-planned once midway through
treatment if large changes occur
The clinical benefit for the patient is The clinical benefit for the patient is the ability to monitor and adapt to the ability to monitor and adapt to changes that may occur during the changes that may occur during the course of radiation treatmentcourse of radiation treatment
Adaptive Radiotherapy
Respiratory GatingRespiratory Gating
Respiratory GatingRespiratory Gating
4D-CT ( Planning CT )4D-CT ( Planning CT ) Virtual Simulation SoftwareVirtual Simulation Software Motion tracking deviceMotion tracking device TPSTPS Linac + Gating optionLinac + Gating option
NEEDS :
IGRT TEAMIGRT TEAM ::
Oncologist : review image fusionOncologist : review image fusion Physicist : performs CT & analysisPhysicist : performs CT & analysis RTT : handle patient careRTT : handle patient care
IGRTIGRT
the process of frequent two and three-dimensiothe process of frequent two and three-dimensional imaging, during a course of radiation treatmnal imaging, during a course of radiation treatment, used to direct radiation therapy ent, used to direct radiation therapy utilizing the utilizing the imaging coordinatesimaging coordinates of the actual radiation trea of the actual radiation treatment plantment plan
The patient is localized in the treatment room in The patient is localized in the treatment room in the same position as planned from the referencthe same position as planned from the reference imaging dataset.e imaging dataset.
Summary :
The verify of image :The verify of image :
4D-CT ( planning CT )4D-CT ( planning CT ) PET-CTPET-CT SPECSPEC ULTRASOUNDULTRASOUND MRIMRI CBCTCBCT
Summary
CBCTCBCT
Support :Support : Patient set upPatient set up Disease targetingDisease targeting Adaptive treatment planningAdaptive treatment planning
Summary
Image matchingImage matching
Planning CT.: bony matchPlanning CT.: bony match CBCT : bony and CBCT : bony and soft tissue matchsoft tissue match
( 2D and 3D match )( 2D and 3D match )
Summary
Imaging for treatment guidance :Imaging for treatment guidance :
FluoroscopyFluoroscopy Computed tomography conventionalComputed tomography conventional Cone beam CT ( KV,MV )Cone beam CT ( KV,MV ) Optical trackingOptical tracking
Summary
IGRT ProcessIGRT Process
Dicom data from the CT reports voxel in the Dicom data from the CT reports voxel in the patient coordinate systempatient coordinate system
Normalize for patient orientation to achieve “CT Normalize for patient orientation to achieve “CT coordinate system”coordinate system”
Affine transformation matrix can then convert to Affine transformation matrix can then convert to room coordinate systemroom coordinate system
Finally, knowledge of the linac isocenter Finally, knowledge of the linac isocenter coordinate and table axis of rotation allows coordinate and table axis of rotation allows shift vector and rotation table calculatedshift vector and rotation table calculated
Move the treatment couch by press one buttonMove the treatment couch by press one button TreatmentTreatment
Correction strategies for patient Correction strategies for patient positioning during IGRTpositioning during IGRT
On-lineOn-line Off-lineOff-line
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