Download Proton SRT

Delivery Systems II – Dedicated LINACS,
Protons & Specialized Systems
Proton SRT
Indra J. Das, PhD, FAAPM, FACR, FASTRO
Department of Radiation Oncology
Indiana University School of Medicine
Indianapolis, IN
IJDas [1]
Outline of Presentation
 Proton Beam
o Production
o Characteristics
 Clinical applications
o Depth dose
o Dose distribution
o Applicability
 Treatment
o True TGRT
o Role of SRT

Ocular melanoma
o Pretreatment imaging
o Post treatment imaging
 Imaging devices
o DIPS: Digital image processing system
o CT-on rail
o CBCT
 Summary
IJDas [2]
What is a proton ?
Discovery of Nucleus by Alpha Particle Scattering
Nobel prize winner 1908 in Chemistry
1911- Atomic theory
1913 –Atomic Model
by Niles Bohr & Rutherford
1919-1920 Rutherford concluded that
nucleus of H is positively charged integer.
He probably called it Proton after
following reaction
IJDas [3]
Ernest Rutherford
N14 + a  O17 + H+
IUCF/IU Health Proton Therapy Center Cyclotron
IJDas [4]
Modern
Cyclotron
IJDas [5]
Synchrotron for ion beam (H+, He2+, C6+, O8+), Heidelberg, Germany (120 m)
IJDas [6]
IU Health Proton Therapy Gantry
IJDas [7]
100
200 MeV Proton
P(66)/Be Neutron
Spread out
proton beam
80
8 MV Photon
Dose (%)
60
Co-60
40
20
20 MeV Electron Watch for tail in
electron and
proton
0
0
IJDas [8]
5
10
15
Depth in Water (cm)
20
25
30
55
Proton Range in Water
50
y = 0.0005x2 + 0.033x
R² = 0.9993
45
40
Range (cm)
35
30
25
20
15
10
5
0
0
IJDas [9]
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Proton Energy (MeV)
3.0
Spread-out Bragg Peak (SOBP)
2.5
Bragg Peak
Relative Dose
2.0
1.5
1.0
0.5
0.0
0
IJDas [10]
5
10
15
Depth (cm)
20
25
30
Dose (%)
SOBP Redistribution
Depth (cm)
IJDas [11]
Frontal & Distal Dose
SOBP
Unwanted dose
IJDas [12]
Jäkel et al, Med Phys 35 ,3653, 2008
1.40
1.30
1.20
1.10
1.00
0.90
0.80
0.70
0.60
050
0.40
0.30
0.20
0.10
0.00
IJDas [13]
Why SRS/SRT?
 High dose per fraction, 1-5 fractions
 Critical structures nearby (H&N), Spine etc
 High degree of accuracy
o SRS- mm
o SRT <5 mm
 Fixation devices
o Invasive
o Non-invasive
 IGRT
o Fiducial markers
o External markers
IJDas [14]
Proton SRS Mechanism
MGH, Boston
IJDas [15]
MGH, Boston
IJDas [16]
Proton Beam




Dose/fraction, same as photon beam
Rarely hypo fractionation
Critical structures nearby (H&N), Spine etc
High degree of accuracy
o Isocenter –mm
o Penumbra very small (2-5 mm) at shallow depth
 Fixation devices
o Disease specific
 IGRT
o Fiducial markers
o External markers
o Image every fraction every field
IJDas [17]
Penumbra 20%-80% (mm)
Penumbra in Proton Beam
Proton
8 mm
Photon
2-3 mm
IJDas [18]
12 cm
Depth (cm)
Photon
Electron
3D
IMRT
Proton
Proton
IJDas [19]
St. Clair et al, IJROBP, 58, 727–734, 2004
Photon
Proton
IJDas [20]
SBRT, Lung
Photon
Proton
IJDas [21]
Photon Plan; Sarcoma
Proton Plan
IJDas [22]
Photon
Proton
IJDas [23]
Proton: Selective Sparing, Post Fossae Tumor
IJDas [24]
Adenoid Cystic Carcinoma with Proton Beam
IJDas [25]
Imaging
 Pre Treatment
o DIPS (Digital Image Positioning System)
o CT-On Rail
o CBCT
o Proton Radiography/Tomography
 Post Treatment
o Activation
o Prompt gamma
o Compton Camera
 Motion managements
o Broader margin
o Gating
IJDas [26]
 On-off
 Synch
o Time needed
o More research needed
Treatment Table & Robotic systems
 Isocentricity
 Degree of freedom:
(x, y, z), Pitch, roll, Yaw
 Motion accuracy
 Ease for throughput
 Reproducibility
 Adoptability for
devices
 Compatibility
 Safety
IJDas [27]
3
2
1
IJDas [28]
Imaging Panels; DIPS
Need For Repeat Image
DRR from TPS
First Image
Final Image
First Image Shift
AP
Final Image Shift
Lat
IJDas [29]
Impact of daily imaging
IJDas [30]
Impact of daily imaging
Zhao et al, Int J Radia Oncol Biol Phys, 75, S703, 2009
IJDas [31]
Siemens
Primatom
CT on rail
IJDas [32]
Cone Beam CT (CBCT)
IJDas [33]
Jaffray et al, IJROBP, 45, 773-789, 1999
C-arm Based Prototype CBCT in Proton Gantry
IJDas [34]
Courtesy Procure
CBCT, Heidelberg, Germany
IJDas [35]
Post treatment 3-D Treatment
verification (in vivo)
Treatment plan
IJDas [36]
CT-PET fusion image
IJDas [37]
Proton induced PET imaging
C-11
O-15
IJDas [38]
Parodi et al, IJROBP, 68, 920–934, 2007
SRS, Eye Line: MGH, Boston
IJDas [39]
IJDas [40]
SRS, AVM with Proton
17 Gy(RBE) in 1 fraction to a 1-cc treatment volume
IJDas [41]
Hattangadi-Gluth et al, IJROBP, 338-346, 2014
Respiratory Gating: Japanese Method
LED
CCD camera
CT
MRI
Ion Beam RT
IJDas [42]
synchronized with
patient’s expiratory
phase
External marker
Summary
Proton beam provides suitable beam
characteristics for patient treatment
Distal fall off is rapid with no dose outside
Penumbra is relatively small thus tight
margin can be achieved
Proton beam is a true image based
treatment (IGRT) thus there is no need for
SRS for most treatments
IJDas [43]
Proton SRS for majority of the site (except eye) is not
advocated due to
20%
20%
20%
20%
20%
1. Cost factor and work load
2. No suitable SRS devices for proton beam
3. Proton beam is image guided with
precision of 2-3 mm
4. Robotic treatment in proton beam
provides same accuracy as that of SRS
5. SRS may interfere with proton beam
10
IJDas [44]
Range of 230 MeV proton beam used for prostate
treatment?
20%
20%
20%
20%
1.
2.
3.
4.
5.
Falls off exponentially
E/2 and hence 11.5 cm
Proportional to E, so, 23 cm
32 cm
Depend on the type of machine
20%
10
IJDas [45]
Range of 230 MeV proton beam used for
prostate treatment?
4%
12%
38%
45%
1%
IJDas [46]
1.
2.
3.
4.
5.
Falls off exponentially
E/2 and hence 11.5 cm
Proportional to E, so, 23 cm
32 cm
Depend on the type of machine
Answer:
4 – 32 cm
Ref: “Proton therapy Physics, Paganetti, CRC press, 2012 Page 109
IJDas [47]
Proton SRS for majority of the site (except eye) is
not advocated due to
61% 1.
Cost factor and work load
10% 2.
No suitable SRS devices for proton beam
17%
8%
3%
IJDas [48]
3. Proton beam is image guided with precision of
2-3 mm
4. Robotic treatment in proton beam provides
same accuracy as that of SRS
5. SRS may interfere with proton beam
Answer:
achieved
3 – 2-3 mm precision is easily
Ref: “Proton and Charged Particle Radiotherapy, DeLaney & Kooy,
Lippincott Williams & Wilkins 2008, Chapter 7
IJDas [49]
Thanks
IJDas [50]
Delivery Systems II – Dedicated LINACS,
Protons & Specialized Systems
Proton SRT
Indra J. Das, PhD, FAAPM, FACR, FASTRO
Department of Radiation Oncology
Indiana University School of Medicine
Indianapolis, IN
IJDas [51]