CONFIDENTIAL MATERIAL - 1 - Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September,...
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Transcript of CONFIDENTIAL MATERIAL - 1 - Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September,...
CONFIDENTIAL MATERIAL - 1 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Ionization Chamber Array for External Beam Radiotherapy
Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
CONFIDENTIAL MATERIAL - 2 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Project goal
oAbsolute dose measurement
oMachine quality assurance
oPatient quality assurance
MV X-Rays ~100÷230MeV protons
A short summary
CONFIDENTIAL MATERIAL - 3 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Outline
o Experimental Activity• Characterization at IBA DosLab• Characterization at Klinikum rechts der Isar & University
of California (San Francisco)-Radiation Oncology dep.• Characterization at Proton Therapy Center Czech s.r.o.
o ARDENT project: trainings, conferences, secondments
o Ongoing activities and future work
CONFIDENTIAL MATERIAL - 4 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Experimental Activity
Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
CONFIDENTIAL MATERIAL - 5 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Detector evolution
First Prototype
Second Prototype
Measurement setup
o 80 ionization chambers, 3.5mm pitch
CONFIDENTIAL MATERIAL - 6 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Example: two 60Co irradiations (detector biased at 100V).
Current ~ 10pA
Characterization at IBA DosLabPrototype optimization
Main debug issue: time stability of the chamber current.
0 -20 40 60
Sig
nal
(no
rmal
ized
)
Time (s)
0 20 40 60 80 90 100 120 -0.2
0
0
.2
0.4
0
.6
0.8
1
1
.2 Sig
nal
(no
rmal
ized
)
Time (s)
0 50 100 150 200 250 300
0
.92
0.
96
1.0
0
1.0
4
Optimization of signal routing led to a better time stability of the sensor:
o Pretty good stability in time of the signal
o Prompt rise and fall time
Signal about 8pA (@2.2Gy/min)
Sensitivity 200pC/Gy
Fluctuation 0.3% (st.dev.)
60Co, 150V bias, Tint=0.8s
CONFIDENTIAL MATERIAL - 7 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Charge collection efficiency
Characterization at IBA DosLabo Charge collection efficiency higher than 99% already at 150V (99.5% ± 0.3% at 250V)
0 50 100 150 200 250 300 350 400 4500.86
0.88
0.9
0.92
0.94
0.96
0.98
1
Bias voltage (V)
Effi
cien
cy
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1630
640
650
660
670
680
690
700
710
720
730
1/Bias (V-1)
Sig
nal (
pC)
Ion-chamber array data
Linear fit
Theoretical (Boag, 1950)
Measured, ion-chamber array
Elekta Agility linac10MVFFF beam quality2.67mGy/pulse220MU/min
CONFIDENTIAL MATERIAL - 8 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at IBA DosLabSensitivity dependence on dose per pulse
0 0.5 1 1.5 2 2.5 30.985
0.99
0.995
1
1.005
Dose per pulse (mGy)
Sen
sitiv
ity (
norm
aliz
ed)
10MV FFF beam quality6MV beam quality
Elekta Agility linac
SDD 77cm
SDD 59cm
SDD 150cm
SDD 100cm
o ± 0.8% sensitivity change on dose per pulse in the range 0.09÷2.67mGy/pulse
CONFIDENTIAL MATERIAL - 9 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at IBA DosLabTissue to phantom ratio measurement
0 50 100 150 200 250 300
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
depth (mm)
TP
R (
norm
aliz
ed to
max
imum
)
ion-chamber arrayIBA PPC05
10 20 30 400.95
0.96
0.97
0.98
0.99
1
1.01
Elekta Agility linac6MV beam quality430 MU/minSDD 100cm10x10cm2 field
o Very good agreement with PPC05 (better than 0.5%) at every depth of measurement
CONFIDENTIAL MATERIAL - 10 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at IBA DosLabElekta Agility Output Factors
a:Si flat panel, a prototype optimized for dosimetry
-2.4% -3.7%
o Good agreement with reference for small fields, reduced sensitivity with large fields
CONFIDENTIAL MATERIAL - 11 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at IBA DosLabBeam profiles (photons)
-100 -80 -60 -40 -20 0 20 40 60 80 1000
0.2
0.4
0.6
0.8
1
1.2
Distance from central axis (mm)
Dos
e (n
orm
aliz
ed)
a:Si flat panelIon-chamber arrayMatriXX Evolution
1x1cm2
10x10cm2
Elekta Agility linac6MV beam qualitySDD 100cm@11cm depth
CONFIDENTIAL MATERIAL - 12 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at MRIMachine QA: virtual wedges, MLC QA, dose in depth (see pics)
-200 -150 -100 -50 0 50 100 150 2000
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
position (mm)
pro
file
no
rm
MapCheck21D IC Prototype II
o Secondment, 22nd April - 3rd May, Klinikum rechts der Isar (Munich)
Varian Clinac DHX
MapCheck2 (SunNuclear) diode array
CONFIDENTIAL MATERIAL - 13 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at MRI
-100 -50 0 50 100-0.2
0
0.2
0.4
0.6
0.8
1
1.2
position (mm)
dose
pro
file
norm
aliz
ed to
max
imum
MapCheck2EBT31D IC array
Example of patient QA
Varian Trilogy, Millennium MLC,VMAT delivery technique
50 100 150 200 250 300 350 400 450 500 550
50
100
150
200
250
300
350
400
EBT3
CONFIDENTIAL MATERIAL - 14 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at UCSFClinical tests & clinical training
o Secondment, 28th July - 8th August, UCSF department of Radiation Oncology;o Detector characterization through clinical test;o Clinical training:
• Machine QA;• Introductory training to Pinnacle TPS;• Use of gafchromic films;• Joined the daily activity of medical physicists.
CONFIDENTIAL MATERIAL - 15 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at UCSFExample of small field dosimetry and linac commissioning
-25 -20 -15 -10 -5 0 5 10 15 20 25
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
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0.9
1
distance from central axis (mm)
pro
file
(n
orm
aliz
ed
)
Varian TrueBeam facility - UCSFTrueBeam,6MV, 1cmx1cm, SDD=110cm, depth of measurement=10cm
1D IC arrayEBT2a:Si flat panel
-100 -80 -60 -40 -20 0 20 40 60 80 100
0.2
0.4
0.6
0.8
1
1.2
distance from central axis (mm)
pro
file
(n
orm
aliz
ed
)
Varian TrueBeam facility - UCSFTrueBeam,6MV, 10cmx10cm, 45°vw, SDD=110cm, depth of measurement=10cm
1D IC arraya:Si flat panelWP
1x1cm2
Virtual wedge 45°
Varian TrueBeam
CONFIDENTIAL MATERIAL - 16 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Example of linac commissioning measurement
Characterization at UCSF
-100 -80 -60 -40 -20 0 20 40 60 80 1000
0.2
0.4
0.6
0.8
1
1.2
distance from central axis (mm)
pro
file
(n
orm
aliz
ed
)
Varian TrueBeam facility - UCSFTrueBeam,6MV, 10cmx10cm, SDD=110cm, depth of measurement=10cm
-100 -80 -60 -40 -20 0 20 40 60 80 100-5
0
5
10
distance from central axis (mm)
diff
ere
nce
(%
)
1D IC arraya:Si flat panelWater phantom
a:Si - WP1D IC array - WP
Water phantom as reference
CONFIDENTIAL MATERIAL - 17 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Characterization at PTC czech s.r.o.
PBS mode only
1ms pulse duration,
10ms pulse period,
3.5mm spot at 226MeV
10-1
100
101
101
102
103
PPC05 charge (nC)
IC a
rra
y si
gn
al (
pC
)
Linear fitIC array
0.02-2MU/spot33x17 spot mapOutput norm. to 1MU/spot
-0.04%
1.7%
-0.9% 0.8%
-0.1%
-0.05%
0.01%
PPC05 signal (nC)
IC a
rra
y si
gnal
(pC
)Ref detector: PPC05
Dose linearity
CONFIDENTIAL MATERIAL - 18 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Beam profiles (protons)
-80 -60 -40 -20 0 20 40 60 80
0
0.2
0.4
0.6
0.8
1
Distance from central axis (mm)
Dos
e (n
orm
aliz
ed)
Ion-chamber arrayMatriXX PTLynx
PBS mode, 226MeV, 5nA beam current@11mm depth
Characterization at PTC czech s.r.o.
Lynx: a scintillator based detector for PBS mode machine QA
CONFIDENTIAL MATERIAL - 19 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Ongoing activities/Future work
o Long term stability measurements with 60Co
o Further test with PBS proton beams;
o Paper about the characterization of the 1D IC array prototype;
o Extend the technology to a 2D detector - components drawing already started, first prototype assembling foreseen for the end of the year.
CONFIDENTIAL MATERIAL - 20 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Trainings, conferences, secondments…
Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
CONFIDENTIAL MATERIAL - 21 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Secondments
Klinikum rechts der Isar, Munich (22.04 - 03.05.2014)
UCSF RadOnc dep., S.Francisco (28.07 - 08.09.2014)
o Upcoming:
• B&A secondment at STMicroelectronics (Catania, July 2015 tentative)
• UCSF (early 2015 tentative)
CONFIDENTIAL MATERIAL - 22 -Michele Togno - III ARDENT Annual Meeting, Schwarzenbruck - September, 30th 2014
Conferences, trainings…
o AAPM, Austin (TX), 20.07 - 25.07.2014
Poster presentation: “An Ionization Chamber Array with High Spatial Resolution for External Beam Radiotherapy”, M.Togno, D.Menichelli, J.J.Wilkens.
Upcoming: AAPM 2015, …
o Trainings:• Clinical trainings at MRI & UCSF (already mentioned);• Radiation protection training (IBA Dosimetry);• Training on SBRT radiotherapy technique (Klinikum rechts der Isar);
• ARDENT B&A training (CERN): Technology Transfer, Management, Entrepreneurship.
o PhD activities: already spent more than 2 weeks at the University to teach students at physics labs.