Download REINFORCING THE TREATMENT CHAIN - Scan-O

REINFORCING
THE TREATMENT
CHAIN
REINFORCING
THE TREATMENT
CHAIN
Radiation therapy has evolved considerably during the
past few decades, with the introduction of increasingly
conformal treatment techniques as well as capabilities for on-board volumetric imaging in the treatment
VOLUMETRIC
IMAGING
TREATMENT
PLANNING
rooms. This has enabled a new level of accuracy in
the delivered dose distributions with a corresponding
improvement in clinical outcomes.
Looking at the treatment chain as a whole there is
however still room for improvement. While many links
are now strong, others remain weak. Only when all the
links have been strengthened, the complete chain will
be stronger.
It’s time to continue the work of reinforcing the treatment chain.
Image quality issues
due to respiratory
motion
Information loss in
multimodal imaging
Lack of dynamic
information
SETUP OF
IMOBILIZATION
DEVICES
Placement and
adjustment errors
PATIENT
IDENTIFICATION
PATIENT SETUP
& POSITIONING
Identity mix-ups
Posture errors
TREATMENT
DELIVERY
Undetected
intrafraction motion
Undetected
anatomical
changes
Risk of collision
Insufficient
protection of risk
organs
Couch shift
inaccuracies
Patient health
uncertainty
^
^
^
Works in progress. Not for sale in the US.
OVERVIEW
The Catalyst™ system consists of a next generation optical
surface scanning and re-projection hardware device coupled with a highly optimized application software designed
for work-flow integration.
SETUP AND POSITIONING
OF EQUIPMENT
The Catalyst™ projects the patient
specific setup instructions directly
onto the couch surface. It also confirms the identity, placement, and
configuration of the immobili-zation
Installation requires only one hardware unit in the treatment
room. The unit is mounted to the ceiling at the foot end of
the couch where it has an unobstructed view of the patient
independently of any motion of the gantry or its on-board
imagers. To ensure a flexible installation and virtually eliminate the risk of interference from other equipment, the
scanner unit is connected to the Catalyst™ workstation in
the control area using a fiber optic link.
devices according to the patientspecific setup.
PATIENT IDENTIFICATION
Patient identity is automatically
verified through detection of biometric features. Identity mismatch
is clearly indicated by an alarm.
SETUP AND POSITIONING
Reassuring
Radiation therapy is a complex process, where many pieces of equipment, in many cases from
different vendors, need to work together during the different steps of the treatment chain. The
Catalyst™ provides automatic and independent verification of many critical parameters that were
previously only possible to check manually. The Catalyst™ thus reinforces the treatment chain.
DESIGNED FOR
WORKFLOW
INTEGRATION
BACKGROUND
Radiation therapy has evolved considerably
during the past few decades, with the introduction of increasingly conformal treatment techniques as well as capabilities for on-board volumetric imaging in the treatment rooms. This has
enabled a new level of accuracy in the delivered
dose distributions with a corresponding improvement in clinical outcomes.
Looking at the treatment chain as a whole there is
however still room for improvement. While many
links are now strong, others remain weak. Only
when all the links have been strengthened, the
complete chain will be stronger.
THE TREATMENT CHAIN
Volumetric Imaging
The radiation therapy process begins with volumetric imaging, and everything that follows is based on the accuracy and fidelity of the patient´s
planning CT data-set. While treatment planning
systems are designed to work with conventionally acquired planning CTs, they will never rise
to their full potential in the case of image blurring
due to respiratory motion. The main challenge,
of course, is to be able to precisely delineate the
target structures and risk organs, since this is a
requirement for reaching the goal of maximizing
the target dose while minimizing the side effects
to healthy tissue.
It’s time to continue the work of reinforcing the
treatment chain.
The Catalyst™ works with modern oncology
CTs, providing the required respiratory signal for
OF PATIENTS
Information on posture and positioning errors is continuously projected
directly onto the patient’s skin. The
calculated couch shift can be sent to
a compatible couch control system,
enabling auto-setup.
Intuitive
Requiring minimal user interaction, the Catalyst™ acts
as an always present decision support system where the
required information is projected directly on the couch
or patient. The system’s high performance provides immediate and real-time feedback, which means that the
therapist can keep focusing on ensuring the best possible
patient comfort and treatment outcome.
Connected
The Catalyst™ software is built from the ground up for
a networked environment. Tight integration with other
systems in the clinic ensures a smooth work-flow where
data is transferred automatically via industry standard
or vendor specific interfaces. When the patient is selected in the R&V system, the same patient is automatically
selected in the Catalyst™, and computed shifts can in most cases also be applied automatically. The central patient database ensures that the correct settings are always available
even in cases where the patient needs to be treated in a different room.
4DCT reconstruction as well as prospectively
gated imaging. The patient´s respiratory characteristics are also recorded, which makes it
possible to verify that the same breathing pattern is reproduced in the treatment room.
In cases where multi-modality imaging is employed to obtain a more complete picture, having
a Catalyst™ in each room provides a common
reference frame for performing image fusion
using the captured data sets.
Treatment Planning
Even with today’s advanced treatment techniques, treatment planning is still typically done
only once, before the first treatment fraction.
Anatomical changes and other dynamic information cannot therefore be taken into account,
which limits the accuracy of treatment delivery.
By incorporating information on the actual patient movement during the fractions already
delivered, the treatment plan for the remaining
fractions can be adapted to compensate for
any deviations, such as patient relaxation after
initial positioning. Stochastic deviations can be
analyzed for determining whether the patient is
properly immobilized and whether the set PTV
margin is appropriate.
Setup of Immobilization Devices
Immobilization devices play an important role
in achieving a reproducible patient setup. It is
therefore very important that the correct devi-
ces be placed at the correct index positions on
the couch, and that any adjustments be done
properly for each patient. This critical information on the exact placement and configuration
of devices is however often documented only as
textual setup instructions in the patient journal,
with no independent means of verification.
With the Catalyst™, the patient specific setup is
recorded once at the first treatment fraction or
even at the time of the planning CT. In the treatment room, the setup instructions are projected
directly onto the treatment couch. Placement of
each immobilization device is verified as are any
adjustments required.
Patient Identification
With the steadily increasing demands on time
efficiency in combination with more flexible treatment scheduling options, making sure that
each patient receives treatment according to
the correct prescription is more challenging
than ever. The obvious solution is to introduce
safety procedures where the patient identity is
checked manually by the therapy staff at each
treatment fraction.
With a Catalyst™, patient identity is instead verified as an integral part of the setup procedure,
ensuring patient safety with minimal overhead.
Any identity mismatch will be clearly indicated
by an alarm.
INTRA-FRACTION
MOTION DETECTION
The patient is continuously monitored
during the entire fraction. Any deviations outside the set tolerances will
be signaled by an audible and visual
alarm, or alternatively a beam hold
signal can be triggered.
CONTINOUS RECORDING OF
PATIENT POSITION AND POSTURE
In adaptive therapy, a CBCT system is
typically used to capture anatomical
changes at each treatment fraction.
Here, the Catalyst™ will record
patient motion during the actual treatment delivery to complete the picture.
RESPIRATORY GATING
The Catalyst™ enables 4DCT or
gated imaging during planning CT
acquisition. In the treatment room,
the patient’s respiratory motion is
monitored to ensure the same breathing pattern as the one recorded
in the CT is present. Finally, gated
treatments are supported where the
actual beam delivery is constrained
to a specific respiratory phase or
breath-hold state.
^
^
^
Works in progress. Not for sale in the US.
HEALTH MONITORING
In cases where a patient’s health
needs to be monitored during
diagnostic imaging or treatment
delivery, the Catalyst™ will provide
a continuous indication of the
detected vital signs.
COLLISION AVOIDANCE
Through continuous monitoring of
the couch, gantry, and patient, the
Catalyst™ detects when there is a
risk of collision and will then issue
an audible alarm.
IMAGE FUSION
In order to get the most information
from diagnostic imaging, there
is sometimes a need to combine
the acquired images from multiple
modalities. The Catalyst™ can, by
recording the patient’s position at
each imaging session, provide a common coordinate system to which the
data sets can be co-registered.
Patient setup and positioning.
While IGRT systems are often used for final
positioning, body tattoos and room lasers are
typically still used for initial setup, meaning that
only three points on the skin surface are used as
the basis for setting up the whole patient. Correcting a setup error means that the patient position must be shifted manually, and then both
sides of the patient checked again for laser/tattoo alignment. Also, it is typically not possible to
detect posture errors or misalignment of patient
extremities with a classic ”3 point set up”.
With the Catalyst™, a complete body surface
is captured continuously and compared to the
previously recorded reference setup image
in real time. Any deviations in posture are immediately indicated by a projection directly
onto the patient’s skin, ensuring a fully interactive work flow. The required couch shift is also
shown, providing instructions for moving the
patient to the treatment position, even if setup
is done at a lower couch height.
Treatment Delivery
During treatment delivery, it is important to continuously monitor the patient to make sure that
no clinically significant movements occur. This is
traditionally done using in-room video cameras
connected to TV monitors in the control area.
While large patient movements can thereby often be detected, this requires the full attention
of the therapists.
The Catalyst™ continuously monitors the patient during the entire fraction. Any movements
outside of clinician set tolerances will trigger an
alarm and optionally pause the beam until the
patient is again within tolerance.
Gantry, couch, and patient are also monitored
continuously for possible collision risks.
Additionally, the patient’s vital signs can also
be monitored to make sure that the patient is at
good health during treatment delivery.
TECHNOLOGY
Optical Triangulation
Measurement in the Catalyst™ system is based on the principle of optical triangulation. A
rapid and near-invisible sequence of patterns
is projected onto the surface of the object to
be measured. At the same time, images are
captured by a camera, which is mounted at
an angle from the projector. By analyzing the
recorded image sequence, a high resolution
3D surface model can immediately be reconstructed. Thanks to the speed and stability of
the system´s components and mechanics, a
complete surface can be captured in fractions
of a second, with an accuracy of a few tenths of
a millimeter – measured at a distance of several
meters away.
Re-projection and Visual Guidance
While near-invisible light is employed for measurements, the Catalyst™ is also capable of
projecting a high-resolution multicolor light
field onto the measured surface (so called reprojection). Measurement and re-projection
can be done in parallel which enables a fully
interactive feedback loop where misalignment
and required corrections are clearly indicated
and continuously updated.
Marker Tracking
Apart from being a high-performance surface
scanning system, the Catalyst™ platform
also features direct, real-time identification
and tracking of markers. This is useful where
some objects to be detected are very similar
in shape but still need to be uniquely identified (this is likely to be the case with e.g. immobilization devices). It can also be a benefit
in cases where an object´s color, surface pro-
High-performance measurement and computation allows the patient motion to be tracked and applied to a deformable volumetric model in real-time. Information on any set-up errors as well as the required couch shift to
bring the target (red sphere) to the treatment position (blue sphere) is continuously re-projected directly on the
patient’s skin, thus forming a complete feedback loop.
perties or shape makes it difficult to locate
reliably based on surface registration only.
Non-rigid Registration
The highly optimized non-rigid surface registration algorithms in the Catalyst™ system enable the real-time and continuous tracking of
any motion of the patient’s skin surface, without requiring the presence of any markers or
tattoos. This allows any setup errors to be immediately detected and provides information
on any movement during treatment delivery.
patient positioning and intra-fraction motion
detection, where there is an interest in acting
on the target position as well as the detected
motion on the skin surface. By aggregation
of the data collected during each complete
respiratory cycle, the clinically relevant timeweighted average target position is modeled.
Deformable Models
With knowledge of the surface movements, a
volumetric deformable model is used to predict the influence on the actual target position.
This is useful for many applications such as
AN INTERACTIVE SOLUTION
WITH ADAPTATION
TO PATIENT ANATOMY
^
^
^
Works in progress. Not for sale in the US.
SP-002-110429-001-01
C-RAD AB
Bredgränd 18
SE-753 20 Uppsala
Sweden
www.c-rad.se