1400 imrt impact of icru-83
TRANSCRIPT
Thailand/Indra/2011
IMRT: Impact of ICRU-83
Indra J. Das, PhD, FACRDepartment of Radiation Oncology
Indiana University School of MedicineIndianapolis, USA Thailand/Indra/2011
ICRU:International Commission on Radiation Units and Measurements
1978, ICRU-29; Dose specification for reporting external beam therapy with photon and electron beams.
1993, ICRU-50; Prescribing, recording and reporting photon beam therapy.
1999, ICRU-62; Prescribing, recording and reporting photon beam therapy (Supplement to ICRU 50).
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Nomenclature
GTV Gross Tumor Volume
CTV Clinical Target Volume
IM Internal Margin
ITV Internal Target Volume
SM Set Up Margin
PTV Planning Target Volume
OR Organ at Risk
PRV Planning organ at Risk Volume
TV Treated Volume
IR Irradiated volume
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Tu
mor
Cel
l D
ensi
ty
Distance
Tumor
Vessel
Lymph node
GTV
CTV I CTV II
high
Low?, Zero?
? ?
?
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GTV
CTV
ITV
PTV
Irradiated Volume
(IV)
Treated Volume
(TV)
IR=TV + penumbra
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SM = Setup margin is uncertainties in patients
positioning, and alignment during treatment.
It is physical parameter associated with
geometry and technical factors.
SM is easy to control by immobilization devices
and maintenance of accuracy and stability of
machine.
PTV = ITV + SM
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GTV
Subclinical disease
CTV
IM
ITV= CTV+IM
SM
PTV= CTV+SM
OR
Set up margin
Internal margin
PRV, Planning organ
at Risk Volume
PTV & PRV
Schema
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Radical vs Palliation
ICRU defines that if adequate dose
cannot be delivered to the GTV, the
whole aim of therapy should be
termed as palliative.
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Conformity Index; ICRU-50
CIiso=TV covered by % Isodose
Planning Target Volume
CI = > optimized closed to 1.0
Conformity index (CI) =TV/PTV
TV= treated volume is the tissue volume that
receives at least the dose selected and specified
by radiation oncologist.
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Dose Reporting
Dose must be reported to the ICRU reference point
ICRU Reference point is usually isocenter
It could be a point in the center of the PTV
Maximum and minimum Dose must be reported in PTV
Whenever possible Dose should be reported to PRV
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Digital Dose Era
IMRT is a digital dose
distribution
3D is an analogue dose
distribution
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Traditional Treatment
3D-CRT Treatment
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IMRT Plan
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IMRT Plan of head and neck nodes
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Difference between 3DCRT and IMRT
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Paradigm Shift
In 3D conformal therapy, ICRU-50 recommended Uniform dose to PTV (-5% to +7%)
Report dose @ isocenter
IMRT represents ≈40% of the radiation treatment with a paradigm shift Non uniform dose (dose painting)
Large dosimetric variations
Isocenter dose is meaningless
Radiobiological consequence of large heterogeneous dose is uncertain (ie 180cGy/day versus 250cGy/day)
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3D-CRT vs IMRT
Simple
No need of volume and OAR
Forward calculation
Give what you wish to target volume
Uniform fluence
Exact solution
Uniform dose
Low MU
Analogue dose
Dose defined to volume but specified at isocenter
Complex
Target and OAR must be present
Inverse calculation
Requires dose-volume constraints and cost function
Non-uniform
Approximate solution
High gradient dose
High MU
Digital dose
Isocenter dose undefined and meaningless
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Software
Inverse planning
(simulated
annealing)
Optimization
Gradient search
Global minimum
Cost functions
Hardware
Mimic (binary
MLC by NOMOS)
MLC
Tomotherapy
Compensator
Based
IMRT APPROACHES
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IMRT Terminology Number of Fields
Non opposing, odd/even numbers
Coplanar/noncoplanar
Beam divided into:
Beamlet (5, 10, 15, 30 etc)
Segments (no longer rectangular field)
Beamlet =segments
Bixels (resolution of the MLC)
Level (dose painting in a Bixel)
Intensity level
Integer number (5, 7, 10, 15, 20 etc)
Beamlet, single level
1
2 3
4
7
5
Multi level, beamlet
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IMRT Segments
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IMRT Field
Subfields (beamlets)
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0 1 1 1 0
0 1 1 1 0
0 0 1 1 0
0 1 1 1 0
0 1 0 1 0
0 1 1 1 0
0 1 1 1 0
0 0 1 1 0
0 1 1 1 0
0 1 0 1 0
0 1 1 1 0
0 1 1 1 0
0 0 1 1 0
0 1 1 1 0
0 1 0 1 0
0 1 1 1 0
0 1 1 1 0
0 0 1 1 0
0 1 1 1 0
0 1 0 1 0
0 4 4 4 0
0 4 4 4 0
0 0 4 4 0
0 4 4 4 0
0 4 0 4 0
Digital Dose Matrix
& Understanding
Intensity Level=
Layer of dose level
Level 1
Level 4
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Segmentation
Beam’s Eye View , BEV
Selection of grid size (mm)
Split fields in small building
block, beamlets, bixels
Segment = Collection of
beamlets with same
intensity level
PTV
Map (Fluence) =
Collection of segments
with different intensity
level
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Calculation of beamlet/ segmentation
Rx with 5 fields of 10x10 cm2 and 5 levels
10x10 mm =>100x5 = 500
5x5 mm =>20x20x5 = 2000
4x4 mm =>25x25x5 = 3125
3x3 mm =>33x33x5 = 5445
2x2 mm =>50x50x5 = 12500
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S S S wijk(Dopt-Dcal)2 = minimum
i,j,k
wijk= weight for constraint of an organ
Optimization & Cost Function
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Imaging
Target volume
DVHConstraints Inverse
planning
Transfer& sequencing
Beamletsequencing
Phantom Plan
Dose MeasurementsFilm dosimetry
Treatment
Record &Verification
PortalImaging
IMRT
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Inverse Planning Systems Corvous; NOMOS Corp, Pennsylvania, USA
Pinnacle, ADAC, Philips, California, USA
Eclipse/Helios, Varian, California, USA
Conrad, DKFZ, Germany
Helax, TMS, Upsala, Sweden
Oncentra (TPP+Helax), Nucletron Corp, Canada
Plato, Nucletron, Netherlands
Xio, CMS, St Loius, MO, USA
Xplan, Radionics, Boston, USA
Brainlab, California, USA
PLUNC, Chapel Hill, NC
Prowess, CA
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Three Selected Clinical Cases
Lung
Head and Neck
5 Fields
7 Fields
9 Fields
1
2
34
5
1
2
3
4
5
6
7
8
9
1
2
3
45
6
7
Prostate
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PTV - Prostate
0
10
20
30
40
50
60
70
80
90
100
60 65 70 75 80 85 90 95 100 105 110 115 120
% Dose
% V
olu
me
Brainlab
CMS-XiO
Corvus
Eclipse
Helax
Konrad
Oncentra
Pinnacle
Plato
Prowess
Radionics
Constraints
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0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 800
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80
Brainlab
CMS-XiO
Corvus
Eclipse
Helax
Konrad
Oncentra
Pinnacle
Plato
Prow ess
Radionics
Constraints
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 1200
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
BladderRectum
Rt Femoral Head
Dose (%)
Vo
lum
e (%
)
Lt Femoral Head
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PTV- Lung
0
10
20
30
40
50
60
70
80
90
100
70 75 80 85 90 95 100 105 110 115 120
% Dose
% V
olu
me
BrainlabCMS-XiOCorvusEclipseHelaxKonradOncentraPinnaclePlatoProwessRadionicsConstraints
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0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80
Brainlab
CMS-XiO
Corvus
Eclipse
Helax
Konrad
Oncentra
Pinnacle
Plato
Prowess
Radionics
Constraints
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
HeartLt Lung
Cord
% Dose
% V
olu
me
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PTV - Head and Neck
0
10
20
30
40
50
60
70
80
90
100
60 65 70 75 80 85 90 95 100 105 110 115 120 125 130
% Dose
% V
olu
me
Brainlab
CMS-XiO
Corvus
Eclipse
Helax
Konrad
Oncentra
Pinnacle
Plato
Prowess
Radionics
Constraints
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0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110
Brainlab
CMS-XiO
Corvus
Eclipse
Helax
Konrad
Oncentra
Pinnacle
Plato
Prowess
Radionics
Constraints
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
Lt Parotid
Rt Optic NerveOptic Chiasm
Brainstem% V
olu
me
% Dose Thailand/Indra/2011
Inter- and intra-planner variation
One TPS system (Eclipse/Helios)
Identical Machine (6 MV, Varian)
Five institutions
Sewel, NJ
Orlando, Florida
Buffalo, NY
Worcester, Massachusetts
Waterbury, CT
Identical constraints
Independent planning of each site 3 times
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Inter-Planner Variation, Prostate
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
Dose (%)
Volu
me
(%)
PTV
Rectum
Rt Fem Head
Das I. J, Cashon K.W., Chopra K.L., Khadivi K.O., Malhotra, H.K.,
Mayo, C.S.. Med. Phys., 32(6), 2147, 2005 Thailand/Indra/2011
Inter-Planner Variation, Prostate
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
Dose (%)
Vo
lum
e (%
)
PTV
Rectum
Rt Fem Head
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Inter-Planner Variation, Lung
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
Dose (%)
Vo
lum
e (%
)
PTV
Heart
Lt LungCord
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Inter-Planner Variation, H&N
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100 110 120
Dose (%)
Vo
lum
e (%
)
PTV
Optic NerveOptic Chiasm
Lt Eye
Parotid
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Intra-planner variation, Prostate
0
5
10
15
20
25
30
1 2 3 4 5 6 7
Beam Number
% V
aria
tion
in
MU
Planner #1
Planner #2
Planner #3
Planner #4
Planner #5
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0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800
Patient Number
Pre
scri
pti
on D
evia
tion:
(Pla
nned
/Pre
scri
bed
Dose
)
MinimumMaximumMedianIsocenter
Institution 1 Institution 2 Institution 3 Institution 4 Institution 5
Variations in doses in 803 patients among institutions
63%
46%
Das et al. J Natl Cancer Inst 100 (5), 300-3007, 2008Thailand/Indra/2011
Irrelevent Dose Recording @ Isocenter
Isocenter
position
in low
dose
region
near or in
OAR
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ICRU-83 views
Maximum dose is defined as D2%
Median dose, D50% is closed to prescription dose
and very close to reference dose
Median and mean dose are very close
D98%, considered minimum in PTV
Use of PET imaging should be explored for
CTV & PTV definition along with CT and MRI
Definition of sub volume with overlaps
Thailand/Indra/2011 Thailand/Indra/2011
Waiting Time with Physicians
0
10
20
30
40
50
60
70
80
Bra
inL
ab
Co
rvo
us
Ecl
ipse
On
cen
tra
Pin
nac
le
Pla
to
Plu
nc
Rad
ion
ics
XiO
To
tal
tim
e/p
atie
nt
(hr)
Prostate
Head & Neck
Lung
Das et al, JACR, 6, 514-517, 2009
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Contouring & Processing Time
0
4
8
12
16
20
24
28
32
36
40
Bra
inL
ab
Co
rvo
us
Ecl
ipse
On
cen
tra
Pin
nac
le
Pla
to
Plu
nc
Rad
ion
ics
XiO
To
tal
tim
e/p
atie
nt
(hr)
Prostate
Head & Neck
Lung
Das et al, JACR, 6, 514-517, 2009Thailand/Indra/2011
Dose Calculation Time
0
1
2
3
4
5
6
7
8
9
10
Bra
inL
ab
Co
rvo
us
Ecl
ipse
On
cen
tra
Pin
nac
le
Pla
to
Plu
nc
Rad
ion
ics
XiO
To
tal
tim
e/p
atie
nt
(hr)
Prostate
Head & Neck
Lung
Das et al, JACR, 6, 514-517, 2009
Thailand/Indra/2011
Time for all operations excluding physician waiting time
0
5
10
15
20
25
30
35
40
45
50
Bra
inL
ab
Co
rvo
us
Ecl
ipse
On
cen
tra
Pin
nac
le
Pla
to
Plu
nc
Rad
ion
ics
XiO
To
tal
tim
e/p
atie
nt
(hr)
Prostate
Head & Neck
Lung
Das et al, JACR, 6, 514-517, 2009
Thailand/Indra/2011
Treatment Sites
8
7
6
5
4
3
2
1
0
-1
-2
-3
-4
Mea
sure
men
t D
iffe
rence
(%
)
CNS GIGU GYN H&N HEM PED
SAR
THOR
Dong et al, IJROBP, 56, 867-877, 2003
Acceptable accuracy ±5% and 3 mm
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ICRU-83 Reporting
Dose homogeneity
HI = [D2-D98%]/D50%
Dose Confomality as ICRU-50
Clinical & Biological Evaluation
TCP: Tumor control probability
NTCP: Normal tissue complication probability
EUD: Equivalent uniform dose
Uncertainty & confidence interval
Dose reporting of OAR and PRVThailand/Indra/2011
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Verification & Evaluation
Thailand/Indra/2011Sanchez-Doblado et al, IJROBP, 68,301-310, 2007
Monte Carlo simulation Clinical condition
Verification & Evaluation
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Summary ICRU-83 Recommendation
Use of PET imaging should be explored for
CTV & PTV definition along with CT and MRI
Definition of sub volume with overlaps
Optimazation should be fully explored
Maximum dose is defined as D2%
Median dose, D50% is closed to prescription dose
and very close to reference dose
D98%, considered minimum in PTV
Thailand/Indra/2011
-Summary ICRU-83 Recommendation
DVH is a measure of delivered dose, and be used in clinical practices
Quality assurance for IMRT optimization and uniqueness of the IMRT solution should be thoroughly investigated
Commissioning of accelerator should include thorough investigation of MLC leaf, gap and transmission
Treatment planning system should incorporate advance algorithm for inhomogeneity correction & MUST be used for dose calculation
Thailand/Indra/2011
Thanks