3. INTRODUCTION
• STEREOTAXY (Greek : orientation in space)
• It is method which defines a point in patient’s body using an external
3D- COORDINATE SYSTEM which is rigidly attached to patient.
• The result is high precise delivery of Radiation due to exactly defined
target volume.
SRS (STEREOTACTIC RADIOSURGERY)
1 SESSION OR FRACTIONS OF 2 TO 5
SESSIONS(FSR)
SRT (STEREOTACTIC RADIOTHERAPY)
6 or more radiation FRACTIONS
4. DIFFERENCE BETWEEN IMRT/3D-CRT AND SBRT
Characteristic 3D/IMRT SBRT
DOSE/FRACTION 1.8-3GY 6-30GY
NO. OF FRACTIONS 10-30 1-5
TARGET DEFINITIONS GTV,CTV,PTV Well defines tumor GTV=CTV
MARGINS centimeter Millimeter
Required high spatial setup and
during treatment accuracy
Moderately confirmed Strictly enforced
Primary imaging modality for
treatment planning
CT CT/MR/PETCT
Respiratory motion
management need
Moderate Highest
5. RADIOSURGERY
Radiosurgery uses precisely
targeted radiation to destroy
lesions anywhere in the body in
1-5 fractions/stages
Alternative to surgery
Benefits
1. No incisions
2. No general
anesthesia
3. Lower risks of
complications
4. Limited
number of
treatment
sessions
Clinical applications
• Intracranial
radiosurgery
• Extracranial
radiosurgery
spine
lung
liver
pancreas
prostate
other
6. 1. Gamma knife
2. Modified LINAC radiosurgery
systems- CYBER KNIFE
3. X- knife
4. Tomotherapy
5. Proton beam systems
SRS CAN BE
DELIVERED WITH
7. HISTORICAL BACKGROUND
• Radiosurgery was coined by neurosurgeon LARS
LEKSHELL in 1951
• Leksell built the first isotope radiation machine in 1968,
the Gamma knife.
• Swedish physicist Larson proposed to use LINAC instead
of Co60 in early 80’s
• CYBER KNIFE WAS INVENTED BY JOHN R ADLER,
NEUROSURGERY PROFESSOR FROM STANFORD
UNIVERSITY IN 1990.
• FIRST TREATMENT CARRIED OUT IN 1994.
PROF. LARS
LEKSHELL
8. CYBER KNIFE
The CyberKnife System is
a radiation therapy device
manufactured by Accuray
Incorporated. The system is
used to deliver radiosurgery for
the treatment of benign
tumors, malignancy tumours
and other medical conditions.
9. INTRODUCTION
• The device combines a compact LINAC mounted on a
robotic manipulator, and an integrated image
guidance system.
• Uses X band (7 to 11.2 GHz) LINAC in the robotic arm–
uses higher frequency of microwaves to reduce weight
of the LINAC.
• The image guidance system acquires stereoscopic kV
images during treatment, tracks tumour motion, and
guide the robotic manipulator to precisely and
accurately align the treatment beam to the moving
tumour.
10. INTRODUCTION
• Pencil beam of radiation for treatment.
• Three radiation beams are delivered and then delivery pauses and a
pair of images are acquired –based on these images ,a corrected
position is transmitted to the robot ,which adapts beam pointing to
compensate for any patient movement.
• The system is SPECIALLY designed for stereotactic radiosurgery (SRS)
and stereotactic body radiation therapy (SBRT).
16. FIXED COLLIMATOR
12 TUNGSTEN CONE
5-60 MM DIAMETER
• TWELVE SECONDARY COLLIMATORS
ADVANTAGES:
1. SHARPER PENUMBRA
2. NO FIELD SIZE UNCERTAINTY
3. USED FOR SMALL TARGETS
4. SPHERICAL TARGETS
17. IRIS - VARIABLE APERTURE
COLLIMATOR
• TWO STACKED BANKS OF 6 TUNGSTEN SEGMENTS
• CREATES A 12 SIDED VARIABLE APERTURE
• MULTIPLE BEAM APERTURES PER ROBOT POSITION
• UTILIZES 12 DIFFERENT APERTURE SIZES IN A SINGLE TREATMENT
PATH.
• REDUCES TREATMENT TIME BY CONSOLIDATING MULTIPLE
COLLIMATORS INTO SINGLE PATH.
• AUTOMATICALLY CHANGES SIZE ACCORDING TO TREATMENT PLAN.
ADVANTAGES:
EFFICIENT DELIVERY
SHORTER TREATMENT TIMES
USED FOR SPATIALLY COMPLEX TARGETS
18. INCISE MLC COLLIMATOR
• SYSTEM CAPABLE OF TREATING LARGE COMPLEX
TARGET SHAPES.
• FAST TREATMENT TIMES
• MAXIMUM CLINICAL FIELD SIZE APPROXIMATELY
115 MM X 100 MM AT 80CM SAD
• DISTAL PLANE OF LEAVES TO LINAC SOURCE
DISTANCE: 40CM
• 2 BANKS OF 26 LEAVES
• 3.85 MM THICKNESS
19. INCISE MLC COLLIMATOR
• FULL INTER-DIGITATION
• SECONDARY FEEDBACK SYSTEM GEOMETRY
• STEP AND SHOOT MODE
ADVANTAGES:
• EFFICIENT DELIVERY
• TREATMENT OF LARGE TARGETS
20. XCHANGE ROBOTIC
COLLIMATOR CHANGER
IT ALLOWS THE SYSTEM TO AUTOMATICALLY
CHANGE BETWEEN THE IRIS AND FIXED
COLLIMATOR HOUSING.
A SECONDARY COLLIMATOR HOUSING
ALLOWS AUTOMATIC CHANGE BETWEEN
FIXED COLLIMATOR.
21.
22. CEILING MOUNTED X-RAY
SOURCED
• 2 X-RAY SOURCE -KV ENERGY
• ON CEILING PERPENDICULAR TO
TREATMENT COUCH.
• GENERATES ORTHOGONAL IMAGES
• DETERMINE THE LOCATION OF BONY
STRUCTURES, FIDUCIALS OR SOFT TISSUES
TARGETS THROUGHOUT THE TREATMENT
• IMAGING INTERVAL CAN BE SET FROM 5 TO
150 SECONDS
23. FLOOR MOUNTED SILICON
DETECTORS
• TWO FLOOR MOUNTED CAMERAS.
• AMORPHOUS SILICON DETECTORS.
• BOTH PLACED AT 45 DEGREE
• ANGULATED - CAPTURES IMAGES FROM
OPPOSITE X-RAY SOURCE
25. DELIVERY OF BEAMS
• NODES ARE THE POINTS IN SPACE AROUND THE
TREATMENT CENTER WHERE THE ROBOT STOPS AND
DELIVER RADIATION.
• THERE ARE 130 NODES IN HEAD PATH AND 117 NODES
IN BODY PATH.
• AT EACH NODES 12 DIFFERENT NON ISOCENTRIC BEAM
DIRECTIONS ARE POSSIBLE
• PATHS ARE THE PREDEFINED SETS OF NODES THROUGH
WHICH ROBOT TRAVELS DURING TREATMENT.
26. TREATMENT MANIPULATOR
• MANUALLY POSITION THE TREATMENT
MANIPULATOR
• MOVE THE TREATMENT MANIPULATOR TO
PERCH POSITION
• POSITION THE TREATMENT
27. TRACKING SYSTEMS
1. 6D SKULL TRACKING SYSTEM
2. FIDUCIALS TRACKING SYSTEMS
3. SYNCHRONY TRACKING
SYSTEM
4. X_sight SPINE TRACKING
SYSTEM
5. X_sight LUNG TRACKING
SYSTEM
28. 1. 6D SKULL TRACKING
SYSTEM
• USED FOR INTRACRANIAL
LESION UPTO C2
VERTEBRAE
• BONY ANATOMY OF SKULL
IS USED AS REFERENCE
FOR TRACKING
29. 2. FEDUCIAL TRACKING
• Used for soft tissue tumors
• Gold fiducial can be
implanted
• Minimum of 3 nos. of
fiducial are to be implanted
• Allows translational and
rotational tracking
32. 5. SYNCHRONY CAMERA
ARRAY
• MOUNTED TO THE CEILING NEAR THE FOOT OF THE
TREATMENT COUCH.
• INCLUDES 3 LED DETECTORS THAT DETECT MOTION OF
THE TRACKING MARKER LEDS ON THE SYNCHRONY
TRACKING VEST.
• AS THE TRACKING MARKER LEDS MOVE WITH PATIENT
BREATHING, SIGNALS FROM THE SYNCHRONY CAMERA
ARRAY ARE USED TO DETERMINE BREATHING WAVEFORMS.
• THE BREATHING WAVEFORMS ARE DISPLAYED ON THE
TREATMENT DELIVERY COMPUTER.
33. RESPIRATORY TRACKING DEVICES
TWO FEATURES TO FORM THE BASIS FOR ACCCURACY
FEDUCIALS ARE IMPLATED
BEFORE TREATMENT
OPTICAL MARKERS ON SPECIAL
PATIENT’S VEST
34. IMAGING SYSTEMS TAKES
POSITIONS OF FEDUCIALS AT
DISCRETE POINT OF TIMES
MARKERS ARE MONITORED
IN REAL TIME BY A CAMERA
SYSTEMS
PRIOR TO TREATMENT START : CREATION OF
DYNAMIC MODEL
37. FIXED SAFETY ZONE
• THE PORTION OF SAFETY ZONE THAT IS STATIC AND FIXED
RELATIVE TO IMAGING CENTER
• USED TO ENSURE THAT THE MANIPULATOR DOES NOT
COLLIDE WITH THE COUCH OR PATIENT.
• DEFINE A VOLUME OF SPACE FROM WHICH THE MANIPULATOR
IS EXCLUDED.
• DIMENSIONS DEPEND ON ANATOMY CHOSEN DURING
TREATMENT
• HEAD
• BODY
38. DYNAMIC SAFETY ZONE
• THE PORTION OF THE PATIENT SAFETY ZONE THAT
DYNAMICALLY TRAVELS WITH THE COUCH AS IT MOVES
• ENTIRE DYNAMIC SAFETY ZONE SHOULD RESIDE WITHIN THE
FIXED SAFETY ZONE DURING TREATMENT.
• SIZE OF THE DYNAMIC SAFETY ZONE IS SELECTED BY THE USER
BASED ON INDIVIDUAL PATIENT SIZE.
39. TREATMENT PLANNING
• Planning is performed using Accuray
Precision® software
• Aims to determine the optimum
geometric arrangement of treatment
beams.
• Uses narrow beams from multiple
noncoplanar directions to cover the
target.
• Because the beams do not cross in a
single point, the dose does not
become heterogenous.
41. INTRODUCTION
• SHORTER NUMBER OF TREATMENT FRACTIONS
• LESIONS THAT ARE ADJACENT TO CRITICAL ORGANS CAN BE EASILY TREATED
• DOES NOT REQUIRES INVASIVE HEAD OR BODY FRAMES TO STABILIZE PATIENT
MOVEMENTS.
• NO NEED OF ANESTHESIA
• VERY LESS RADIATION INDUCED REACTIONS.
• VERY MINIMAL RECOVERY TIME
• DESIGNED TO TREAT TUMOR ANYWHERE IN THE BODY.
• UTILIZES IMAGE GUIDANCE TECHNOLOGY AND COMPUTER ROBOTICS.
• DELIVERS HIGH DOSE OF RADIATION WITH SUB MILLIMETERS OF ACCURACY.
CLINICAL BENEFITS
42. CHARACTERISTICS GAMMA
KNIFE(GK)
CYBER KNIFE
(CB)
comments
IMMOBILIZATION
DEVICES
RIGID FRAME ORIFIT CK has favourable orifit
RT SOURCES Co60 6 MV LA GK need to be replace sources every 5/6
years
PLANNING No complex
planning
Inverse planning Favourable dosimetry in CK
PLANNING METHOD simple complex Mark Complexicity in cyber knife
planning
FRACTIONATIONS Single fraction
mostly
May treat in multiple
fractions
Radiobiology favours CK
TUMOR SIZES mostly smaller
lesions
Larger lesions also can be
treated in fractionated
schedule
Increase indications with CK
ENERGY SOURCES radiation electricity GK can work with less electricity
VERIFICATIONS Not possible possible Even intra fraction movement can be
corrected
INDICATIONS Mainly brain
tumors
Extra and intra cranial
lesions
CK is more economical
43. SUMMARY
• CYBERKNIFE IS A HIGH PRECISION EQUIPMENT WITH ITS OWN
ADVANTAGES OF BEING A NON-INVASIVE PROCEDURE.
• APROPIATE PATIENT SELECTION IS MOST IMPORTANT FACTOR
• ROBOTIC RADIOSURGERY SYSTEMS ARE COMPLEX AND
REQUIRES CAREFUL AND THOROUGH PLANNING.
• CYBER KNIFE IS SAFE AND PATIENT FRIENDLY RADIOTHERAPY
DELIVERY SYSTEM.
• SHORT COURSE ,PRECISE AND HIGH DOSE RT IS BENEFICAL
AND A PROMISING FUTURE ASPECT IN RADIOTHERAPY
DELIVERY.
