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

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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