cyber knife introduction

CyberKnife: Radiosurgery system

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Radiosurgery: IndicationsRadiosurgery: Indications

Intra-cranial: Intra-cranial: 1.1.Brain metsBrain mets2.2.MeningiomaMeningioma3.3.Acaustic schwannomaAcaustic schwannoma4.4.AVMsAVMs5.5.TNTN

Extra-cranial: Extra-cranial: 1.1.Lung: Primary & metsLung: Primary & mets2.2.Liver: HCC & metsLiver: HCC & mets3.3.Inoperable pancreasInoperable pancreas4.4.ProstateProstate5.5.Bone metastasisBone metastasis


Robotic RadiosurgeryHighly precise RT delivery system - Respiratory tracking - Fiducial based tracking system - Intra-fraction motion correction - Uncomparable dose distribution - X-ray based image verificationHypofractionated RT - High dose short course RT - Higher BED delivered to target

Ideal for moving targets

- Radiation source is mounted on a precisely controlled industrial robot.

- Image guidance system(continuous tracking system)

- Eliminates the need of gating techniques and restrictive head frames


GTV= Gross tumour volumeCTV= Clinical target volume

IM= Internal marginSM= Setup margin

PTV= Planning target volume

PTV= IM+SM

ICRU 62

CyberKnife in liver tumour: NO IM & SM<1 mm

In Liver, PTV = GTV/ CTV+ 0-1 mm marginIn Liver, PTV = GTV/ CTV+ 0-1 mm margin Copyright @ www.radiosurgery-india.com

Robotic Radiosurgery


5

1

2

3

465


PitchRollYaw


Robot is capable of delivering

radiation from different

100 nodes, with each node is

capable of giving a max 12

different beams.

Usage of these nodes depends

on the treatment room constraints


Table consists of 12 fixed cones and housings of ‘Fixed’ and ‘Iris’ Collimator

Collimator sizes(mm): 5, 7.5, 10, 12.5, 15, 20, 25, 30, 35, 40, 50, 60

Laser Sensor


Cyberknife treatment delivery is based on the following

tracking systems 6D_ Skull tracking system Fiducials tracking system Synchrony tracking system X_sight Spine tracking system X_sight Lung tracking system


6D_ Skull tracking system:used for intra-cranial lesions up to C2Bony anatomy of the skull is used as

reference for tracking


• Fiducial tracking system: used for soft tissues, where gold fiducials can be implanted. Minimum of 3 nos. to be implanted


Day 1 Day 5

Fiducial ‘migration’


Respiratory-induced motion of tumors causes significant targeting uncertainty

Lung, liver, pancreas, Prostate, kidney

Traditional radiation therapy margins are not optimized for high-dose radiosurgery

Two features to form the basis for accuracy

Fiducials, implanted prior to treatment

Optical markers on a special patient vest


Prior to treatment start: creation of dynamic correlation model

Markers are monitored in real time by a camera system

Imaging system takes positions of fiducials at discrete points of time

Prior to treatment start: creation of dynamic correlation model

Markers are monitored in real time by a camera system

Imaging system takes positions of fiducials at discrete points of time

time

disp

lace

men

t

disp

lace

men

t

time

This process repeats throughout the treatment, updating and correcting beam delivery based upon the patient’s current breathing pattern


Immobilization device


Positioning

Tracking device


Tracking & treatment delivery


The mechanical accuracy of the system is 0.12 mm , according to Accuray

The system maintains sub-millimeter tracking accuracy, if the patient positions are within the following limitsLeft / Right (Lat) 10 mmAnt/ Post (Ver) 10 mmSup/ Inf ( Long) 10 mmRoll (Left / Right) 10

Pitch (Head Up / Down) 10

Yaw ( C.W / C.C.W) 30


CK planning

‘‘CyberKnife is an extension of Gamma-KnifeCyberKnife is an extension of Gamma-Knife’’

- Principles of ‘field arrangement’

- Dose distribution pattern

- Multiple isocentre

-Treatment principles

- Treatment delivery accuracy similar

- Delivered dose in single fractions

- Intra-cranial indications

CK & GK: SimilarityCK & GK: Similarity

‘CyberKnife treatment is as good as Gamma-Knife’ Dr Bernadt Wowra Copyright @ www.radiosurgery-india.com

Cyberknife Vs Gamma-Knife: Cyberknife Vs Gamma-Knife: DissimilarityDissimilarityGK CK Comments

Immobilization device

Rigid frame Orfit CK has favorable orfit

RT source Co60 6MV LA GK need to replace sources every 5/6 yrs

Planning No complex planning

Inverse planning Favorable dosimetry in CK

Planning method

Simple Complex Even neurosurgeons can plan in GK

Isodose pres Usually 50% Usually 80-95% GK: more dose heterogeniety

Fractions Single May treat multiple fraction

Radiobiology favorable in CK

Tumour size Only smaller lesions can be treated

Larger lesions also can be treated in fractionated schedule

Increased indications with CK

Energy source Radiation Electricity GK can work with less electricity

Verification Not possible Possible Even Intra-fraction movement can be corrected

Indications Only brain lesions Extra & intra cranial

CK more economical

SummarySummary

CyberKnife Radiosurgery is an ideal machine for both cranial & extracranial radiosurgery

Appropriate patient selection is the most important factor

CyberKnife is safe and patient friendly radiotherapy delivery system

Short course, precise, high dose RT may be beneficial in few indications However, the indications are limited and long-term data of most of the extra-cranial indication is still to be available

With more clinical data, indications are expanding


cyber knife introduction

Healthcare

radiosurgery system

indications intracranial

clinical target volume

im sm icru

tntn extracranial

planning target volume

internal margin sm

liver tumour