4. Evolution of Technology
1970’s: Cobalt-60, treatment guided by
surgical anatomy and plain radiographs. Doses
calculated from depth-dose charts.
1980’s: Cross-sectional imaging (CT)
available to guide treatment delivery.
1990-1995: “Home-grown” 3D conformal
radiotherapy planning systems appearing
allowing Beam’s Eye View
5.
6. Evolution of Technology
1995-2000: Commercial 3D CRT planning
systems available with routine adoption by
most centers.
1998: Sibley acquires 3D planning system.
1999-2003: Patients routinely planned and
treated with 3D CRT and 3D dose calculation.
2002: Sibley Cancer Center opens 11/02 with
state-of-the-art digitally controlled linear
accelerators.
7.
8. External-Beam Radiotherapy
Photon energy 6-23 MV
Fields collimated by
internal jaws
Fields shaped by internal
leaves (MLC’s)
Digital information transfer
9. Evolution of Technology
2003: 5/03 first patient treated with Intensity-
Modulated Radiotherapy (IMRT)
2004: CT scanner/simulator installed in Cancer
Center
2006: Gold fiducial markers implanted
routinely for prostate cancer for Image-Guided
Radiotherapy (IGRT)
2008: Tomotherapy with Stereotactic
Radiotherapy capability (SRT)
11. Intensity-Modulated RT
(IMRT)
Requires exacting definition of target
structures and use of definitions: GTV, CTV,
PTV
GTV: Gross tumor volume
CTV: Clinical target volume = region at risk for
subclinical spread
PTV: Planning target volume = margin added for
setup uncertainty
12. IMRT: Intensity-Modulated RT
Treatment typically delivered through five or seven
beams with multiple segments treated to various
intensities (i.e. intensity modulated)
End result is a dose distribution that closely matches
request
Requires expert physicians, expert physicists,
expensive technology and significant amounts of time
22. IGRT: Image-Guided RT
Daily targeting of internal structures instead of
skin marks or bony landmarks.
Performed since 2006 by us for all prostate
cancers by using gold “fiducial” seeds.
Trilogy and Tomotherapy are technologies that
provide daily “CT-like images” that are matched
to planning CT images for positioning.
New standard for state-of-the-art radiotherapy
25. Stereotactic Radiotherapy (SRT)
Initially used only for cancers and disorders in
the brain.
Stereotactic Body Radiotherapy (SBRT) uses
similar concepts to treat cancers outside of the
brain.
SRT is not radiotherapy. One to five very large
doses are used to “kill” everything within the
defined target, i.e. radiosurgery.
26. SRT Machines
Trilogy is a modified linac that delivers SRT through
setup and monitoring with a kV imager.
CyberKnife is a dedicated SRT machine that is not
designed to provide radiotherapy capability. Small,
precise beams and long treatment delivery times.
Tomotherapy is a linac that images and delivers
treatment through a rotational gantry (like CT).
Provides image guidance with every treatment and
can simultaneously treat multiple targets quickly.
31. HI-ART Tomotherapy Unit
Gun Board Linac
Control
Computer
Circulator
Magnetron
Pulse Forming
Network and
Modulator
Data Acquisition System
High Voltage
Power Supply Beam Stop Detector
32. TomoTherapy Advantages
•No Gantry-Patient Collision
•No Wedges
•No Gantry Angles
•No Collimator Angles
•No Table Angles
•No Hand Pendants
•No MLC Shapes or Coordinates
•No MLC Motors
•No Field/Jaw size
•No Field Light
•No Electrons
•No Electron Cones
33. Image-guided Therapy: Principles
Image guidance ensures that relative
positions of isocenter and target are the
same during treatment and in treatment
plan
This potentially allows:
Reduced treatment margins
Increased dose
Reduced complications
Avoid misses
34. CT VRCT 2cGy
Image 1
CT and VRCT
Image sets Image 2
using same
window and
level
adjustments Image 3
Image 4
Courtesy of University of Wisconsin
35. Esophagus IGRT
After 2400cGy (12 Fx)
Original Planning CT CT of the day (TomoImage)
Courtesy: Dr. Dan Petereit M.D., Rapid City Regional Hospital
T-MKT-AP0068
37. SBRT for Stage I Lung
Institution # Patients Local Control
Yamanishi, Japan 257 86%* (92%)
Japan 131 96%
Aarhus (Denmark) 89 89%
Wash U 70 83%
Indiana U (protocol) 70 88%
Cleveland Clinic 94 97%
Amsterdam 206 97%
39. SRT- The Simulation
4D-CT simulation is performed (3D plus
motion). 36 multislice CT synchronized with
chest tension belt provides images at each
phase of respiration.
Abdominal pressure plate added (when
needed) to limit respiratory motion
Gating utilized (when needed) for excessive
motion
50. SRT- The Treatment
Many fractionation schedules have been used,
but the “winning” regimens…
20 Gy x 3 = 60 Gy
12 Gy x 4 = 48 Gy (near sensitive structures)
51. SRT- Complications
Emerging treatment with paucity of long-term
data, but…
Peripheral lesions: develop rib fractures in
13/31, 9/42, 3/131, 9/86
Apical lesions: (37/273 pts at IU, 89% LC) 7/37
developed gr 2-4 brachial plexopathy (1 hand
paralysis)
Misc: bronchovascular fistula, pneumonitis
Multi-inst study: 11/70 Gr 3-5 toxicity
52. Patients courtesy
of University of
Alabama
Potential
New Clinical
Opportunities:
Re-treatment for patients
not eligible
for radiation therapy
before TomoTherapy due to
cord tolerance
53. SRS-Applications
Highly effective and time efficient
Most common sites: brain, spine, lung, liver
Useful for recurrent tumors in previously
irradiated fields
Tumor control is seen in 80-90% of metastases
treated, but survival is not impacted
Curative for Stage I lung cancers…new
standard of care for medically inoperable
patients
54. Summary
Image-Guided Radiotherapy is new gold
standard for radiotherapy
Tomotherapy is elegant solution for IGRT and
works well “out of the box”
Stereotactic Radiosurgery is effective and time
efficient method of palliation
TomoTherapy delivers SRS as well, without
need for fiducial markers
