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Pre-treatment Group: Treatment Planning and Mould Room... |
Treatment Planning and Mould Room
(by Dr. Jaap Vaarkamp)
The pre-treatment group consists of the treatment planning section and
mould room with currently a staffing level of three radiotherapy
physicists, four dosimetrists and one mould room technician. The
planning work is done on three CMS XIO workstations and three Focal
contouring dose review PCs, providing external beam clinical treatment
planning for about 2200 new patients a year. The group provides advise
on planning issues and is continuously reviewing its planning techniques
being actively involved in writing radiotherapy protocols. Our
workstations are fully networked with a simulator and a dedicated CT
scanner using a dicom link, and three Varian linacs using Varis. In the
near future we upgrade to PC based planning workstations and will have
floating licenses for contouring and dose review. We are further
expecting a wide bore CT scanner that will further modernise workflow
and techniques. Our mould room produces tailor made patient
immobilisation devices, mainly with thermoplastic shells, and electron
cut outs.
Last year the group has completed and initiated several projects to
further improve the service, work towards challenging targets defined by
Cancer Standards, Clinical Governance and ISO 9000 Quality Standards.
Examples are:
-
 Planning
Workflow
Workload in treatment planning is managed using a spreadsheet
acquiring the relevant information regarding booked patient
appointments from Varis. Various members of the planning group have
been involved in developing this tool for monitoring planning
progress to tailor it to our flexible approach without scheduling
activities. Planning work is ready in time, with rare exceptions,
usually because of circumstances beyond the direct control of
treatment planning staff and planning times are decreasing.
- Breast Planning
The treatment for most of our breast patients is designed on
simulator and based on a 2D breast contour obtained using a camera
based system, OSIRIS. When introducing OSIRIS through inter
disciplinary work we streamlined the simulator visit and treatment
technique.
Breast patients participating in the SUPREMO trial and patients
requiring more homogenous doses than can be achieved on simulator
are CT scanned. This extends the role of treatment planners to
define the Supra clavicular field and fully designing the breast
treatment. Since September 2003 we are treating breast IMRT patients
with the emphasis on reducing the maximum breast dose.
Fig. 1.
Conventional 3D breast treatment and 3D breast treatment adding 1
segment in both tangential beams to improve dose homogeneity.
- Projects
Dose calculations are performed with a recently commissioned
convolution algorithm. As part of the commissioning we looked at
off-axis wedge factors and developed a technique for independent
checking off-axis wedge factors. We further have put a large effort
into image matching to DRRs, rather than simulator verification
images, and using oblique treatment beams for this purpose rather
than cardinal imaging fields. All this work has allowed us to do
more asymmetric planning to use CT defined tattoos as the isocentre,
thus avoiding daily patient moves at treatment. This work has also
allowed us to develop more complicated plans for prostate and pelvic
node treatments and head and neck. In selected cases we use IMRT.
Fig. 2. Beam arrangement for treating
prostate and pelvic nodes.
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