The document discusses the development of CobraLeaf, a new mechanical multileaf collimator (MLC) addon for cobalt-60 teletherapy machines. It was developed to address the widespread use of cobalt-60 therapy worldwide and lack of MLC availability for these machines, limiting modern treatment techniques. The CobraLeaf MLC uses innovative brass leaf and passive pneumatic drive designs to provide a low-cost yet robust and safe solution. Dosimetric measurements show penumbras of 1.29cm in-plane and 1.25cm cross-plane with low leakage. Key opinion leaders have expressed support for CobraLeaf in improving safety, conformity and enabling 3D techniques for developing nations dependent on cobalt-60 therapy.

1. 25.11.2013
The all new mechanical Add-on MLC for Co-60 teletherapy
Stefan Ueltzhöffer
© 2013 Precisis AG
25.11.2013 1

2. CobraLeaf®
•
Background
•
•
Rationale for CobraLeaf
•
•
Worldwide application Co-60
Specifications
CobraLeaf
•
Development
•
Dosimetry
•
Workflow
•
Safety
•
Advantages
Content
© 2013 Precisis AG
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3. Cobalt worldwide
• 2 types of treatment machines: Cobalt vs. Linac
• Cobalt: Power independent, low maintenance, lower cost
• Linac: High sophisticated electron gun, high cost + maintenance
• > 2.000 Co60 machines worldwide + > 30 new installations per yr
Distribution of RT machines by regions
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4. Cobalt worldwide
Dirac Database of IAEA
http://www-naweb.iaea.org/nahu/dirac/map.asp
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5. Region
Region Number
RT Centers
Clinical Accel.
Co60
TPS
Med. Phys
Caribbean
Subtotal
32
25
22
27
59
Central Africa
Subtotal
7
8
7
10
22
East Africa
Subtotal
8
4
8
9
18
East Asia
Subtotal
1933
1147
592
2105
1472
Eastern Europe and Northern Asia
Subtotal
397
439
464
560
999
Indian Ocean Islands
Subtotal
2
1
3
3
5
Mexico and Central America
Subtotal
107
87
75
106
74
Middle East
Subtotal
187
282
102
215
499
North Africa
Subtotal
69
76
46
81
166
North America
Subtotal
2787
4085
158
326
2085
South Asia
Subtotal
350
204
384
280
225
Southeast Asia
Subtotal
124
149
83
107
215
Southern Africa
Subtotal
41
63
15
43
54
Southern and Western Pacific
Subtotal
66
164
2
119
239
Temperate South America
Subtotal
117
129
53
89
124
Tropical South America
Subtotal
359
405
145
238
402
West Africa
Subtotal
14
10
8
15
28
Western Europe
Subtotal
1035
2532
108
1581
2701
Gesamtergebnis
7635
9810
2275
5914
9387
© 2013 Precisis AG
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6. Rationale
Problem
• No MLC for Cobalt available, despite demand
• Limitations of current techniques, modern techniques (e.g. IMRT) not available
• Linac MLC too expensive (~ 300.000 €)
Solution
• Re- / New development for specific task
• Cobalt only
• Close cooperation with
(Best Theratronics, Ottawa, Canada)
© 2013 Precisis AG
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7. CobraLeaf device
© 2013 Precisis AG
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8. © 2013 Precisis AG
CobraLeaf attached to Cobalt machine
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9. Specifications
MLC:
•
3D conformal
•
Single Focus + Rounded Leaf-Ends
•
Leaf width 10 mm / Field size 20x30 cm2*
Mechanical:
•
Independencies
•
Robustness
•
Inserted in Lower enclosure
•
Combinable with standard wedges
Cobalt:
•
 Co-60: 1.17 MeV und 1.33 MeV
© 2013 Precisis AG
* at 80 cm SAD / Quelle: Wikipedia, Ali et al. 2012 PMB
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10. Specifications
Adapter in lower enclosure
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11. Development
© 2013 Precisis AG
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12. Development
Innovative Leaf and Drive concept
Drive: Passive Pneumatics*
Leaf material: Brass
High power / low maintenance
*patent pending
© 2013 Precisis AG
Low cost

μCuZn39Pb3
HVL
6*HVL
=
=
=
=
8.47 g/cm3
0.4311 cm-1
1.6079 cm
9.65 cm ≙ 1.563 %
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13. Development
Setup Cut
© 2013 Precisis AG
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14. Development
Full view
© 2013 Precisis AG
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15. © 2013 Precisis AG
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16. Details
25.11.2013 16

17. Workflow
© 2013 Precisis AG
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18. Planning
© 2013 Precisis AG
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19. Field preparation
• Import of DICOM or
any field outline file
• Fully automated
processing
• Adaptation if required
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20. Milling
© 2013 Precisis AG
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21. Template
Individual shape
Reusable base
© 2013 Precisis AG
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22. Motion Drive
Leaves
Pneumatics
Field Template

23. Tools for faster process – opening / closing

24. Tools for faster process - Pumping

25. Template insertion - > Leaf adjustment
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26. © 2013 Precisis AG
Device attached to Cobalt machine
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27. Irradiation
© 2013 Precisis AG
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28. Dosimetry
Penumbra
In plane: 1.29 cm
Cross plane: 1.25 cm
Field 10 x 10 cm
Depth 10 cm,
SAD 80 cm
© 2013 Precisis AG
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29. Dosimetry
Leakage
Leakage 1,92%
Interleaf: < 2,4%
Gap: 6%
1.2
Relative leakage normalized to average
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
© 2013 Precisis AG
0
50
100
150
Position (pixel values)
200
250
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30. Safety
Concept
Implementation of various measures to
prevent errors and damages
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31. Safety
No setup errors possible
Planning PC
CNC Milling
Drill (Home position)
Template blank & milled shape
CNC Index pin
Corner bars
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32. Templates
Defined holes
Indexing pins
Prevents rotation or off-centre
© 2013 Precisis AG
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33. Interlock
Base coding (###)
Connector in
CobraLeaf
Prevents wrong fields
© 2013 Precisis AG
Tray + Wedge No. (###)
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34. Advantages
Treatment
• Increased safety
• Better conformity
• Combinable with wedges
• Modern 3D techniques
Usability
• Power independent
• Instant installation
Maintenance
• Mechanical parts, no wearing
• Long intervals
Investment
• Quick return
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35. Opinions
Testimonials of Key opinion leaders, Radiotherapy
Prof. Dr. Wolfgang Schlegel, DKFZ, Germany
“So far, such radiation collimators were available only for linear accelerators,
with CobraLeaf, the shape of the leaves is adjusted manually. But this is a
great advancement over previously used rectangular radiation beams.”
Prof. Dr. Lokesh Viswanath M.D, Kidwai Memorial Institute of
Oncology in Bangalore (KMIO), India
“There is a real and urgent need to demonstrate to the world, that a costeffective 3D CRT, which is the basic minimum standard of care in Radiation
Therapy can be given on a Telecobalt Machine with a MLC. A simple low cost
accessory like this will benefit many patients throughout the world, especially
in many developing nations. Hence, we deeply appreciate the effort by
Precisis AG and DKFZ to bring this to the market.”
© 2013 Precisis AG
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36. Thank you for the attention
© 2013 Precisis AG
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37. © 2013 Precisis AG
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38. Backup
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39. © 2013 Precisis AG
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40. Dosimetry
Material & Methods
Material

PTW IC

Theratron Elite80 (Ø1.5cm) &
Theratronics Equinox (Ø2.0cm)

GafChromic EBT Film

PTW Phantom/Virtual Water
Methods

80cm/85cm/100cm SSD

pdd & skin dose

Interleaf & End2End Leakage

Penumbra: 80% / 20%
© 2013 Precisis AG
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41. read more…
© 2013 Precisis AG
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42. Entwicklungspartner
Background & Partners
• Small (10 empl.) medical device developer / manufacturer
• Specialized in precision techniques in Neurosurgery + Radiotherapy
• Cooperation partner of DKFZ
• State funded, world renown Cancer Research institution
• 2500+ employees, 1000+ scientists
• Long history in MLC development (formerly with Siemens)
• 2011: Joint idea of using Know-how in MLC technology to develop new device
for large need in developing / emerging countries
(300+ employees), CA based market leader for Cobalt machines
supports (technical + marketing) as add-on to their machines
© 2013 Precisis AG
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43. Kontakt
Precisis
Stefan Ueltzhöffer
Head of Innovation Management
Project Manager CobraLeaf
Precisis AG · Hauptstr. 73 · 69117 Heidelberg
Tel: +49 6221 6559300 / mobile: +49 177 7523924
E-Mail: s.ueltzhoeffer@precisis.de · www.cobraleaf.com · www.precisis.de
Resources
• IAEA, 2011: Inequity in Cancer Care: A Global Perspective
• IAEA, 2008: Setting up a radiotherapy progamme
• AMPICON, 2012: Baumann et al.: A manual Multileaf Collimator for use in Cobalt-60 Teletherapy.
Proceedings of 33rd Annual Conference of the Association of Medical Physicists of India, 2012 (O-02 12070902)
• Web: Cobraleaf / DKFZ / Best Theratronics / PR09/12 / Embassy Info / PR12/12
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