ESTRO 36 Abstract Book

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S957 ESTRO 36 2017
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6 Tata medical center, Psycho-Oncology, Kolkata, India
7 Tata medical center, Statistics, Kolkata, India
Purpose or Objective
There are no standard palliative breast radiotherapy
regimens for local control but many use the dose
equivalent as in the adjuvant setting (40Gy/15 fractions).
Within HYPORT study we are exploring a dose of 35 Gy in
10 fractions over 2 weeks prescribed to the breast and
supraclavicular fossa (SCF) to palliate advanced incurable
breast cancers
Material and Methods
A gafchromic RTQA2 film based matching of the junction
of tangents and Supraclavicular (SCF) fields (JF) is being
carried out to assess the geographical overlap or
separation during first 3 fractions. Similarly during the
first 3 fractions, in-vivo thermo luminescent dosimetry
(TLD) is being performed to confirm received dose by
placing a TLD over isocenter of the tangential fields and
another at JF. Primary objective for the study has been
set to assess the acute toxicity using CTCAE version 4 in 30
total patients
Results
Of the required 30 patients, 19 have been recruited.
Median dose planned to receive by 95% volume of the
breast PTV was 96.3% (range=95.2-98.9%). The median
dose max planned to the breast PTV was 106.4%
(range=105.4-106.9%). Breast PTV receiving ≥105% of the
prescribed dose was planned to be 1.75% (median) with no
point dose ≥107%. Organ at risks (OAR) dose constraints
were met for all patients. The junction movement range
using gafchromic RTQA2 film was between -2mm to +3mm.
TLD measured dose (median) and percentage variation of
tangential field isocenter dose and field junction dose for
first three fractions is summarized in table 1. Median
percentage variation for tangential field isocenter dose as
measured using TLD was 3 % (Range = -9.7 to 9.4%) and
similarly median percentage dose variation for JF as
measured with TLD was 1.2 %( Range= -8.5 to 8.9%). At a
median follow up of 5 months only 1patient reported grade
2 acute skin toxicity (others had grade 1). None of the
patients complained of dysphagia or acute brachial
plexopthy
Conclusion
QA measures in the HYPORT study confirm the delivery of
the prescribed two week dose schedule with no significant
over dosage at the JF. A dose of 35Gy is well tolerated
EP-1764 Implementation of a patient specific QA in-
vivo dosimetry protocol using the PerFRACTION 3D
system
F. Vinagre 1, P. Rachinhas1, P. Simões1, A. Cavaco 1, F.
Balau1, M. Borrego1
1 Centro Hospitalar e Universitário de Coimbra,
Department of Radiotherapy, Coimbra, Portugal
Purpose or Objective
The goal of this presentation is to share the experience in
implementing an EPID-based in-vivo dosimetry system
PerFRACTION™ 3D (PF) from Sun Nuclear Corporation in
our center. The results for approximately 50 patients
treated with VMAT and IMRT plans in a Truebeam 2.5,
Varian Medical Systems, included in a in-vivo dosimetry
protocol in clinical routine, are presented and discussed.
Material and Methods
About fifty patients treated with a VMAT/IMRT technique
were included in this study. In the first 3 fractions of
treatment, in-vivo EPID transit images (movie files) were
acquired during treatment for every field. After the first
3 fractions, in-vivo measurements were repeated on a
weekly basis. The PerFRACTION analysis is almost fully
automated. Treatment plans were calculated in version
10.6 of Eclipse TM TPS from Varian Medical Systems. The
plan, the structure set, the dose distribution and the CT
image set are exported to PF server. This server
continually searches in R&V and ARIATM oncology
information system, from Varian Medical Systems, for the
data of each patient. After each treatment the server gets
the recorded log files and the measured EPID Dicom files
which are processed and used for the 3D dose distribution
calculation. PerFRACTION 3D uses a
superposition/convolution type algorithm, the SDC Dose
Calculator, to calculate back the dose on the CT image set
or on the patient CBCT acquired at the treatment session.
Following AAPM TG-218 report, we adopted a tolerance
limit (treatable but further evaluation may be warranted)
of 95 % of points passing the 3%Global/2mm/10% gamma
analysis, and an action limit of 90% (requires additional
analysis and may need corrective action). Dose-volume
histograms (DVH) analysis obtained by 3D reconstructed
dose on the planning CT or CBCT scans allow a clinical
interpretation of the deviations and helps to find possible
reasons for the discrepancies. PerFRACTION also demands
goals definition for specific targets and/or organs at risk
which are used to trigger failure email notifications.
Results
PerFRACTION 3D was launched in the beginning of 2016
and is in an early stage of clinical use, with constant
software updates and corrections. In the first two months
of the in-vivo dosimetry QA protocol implementation, 30
transit EPID images were acquired during the treatment
fractions of 10 patients. PTV 3D overall gamma passing
rate was equal to 97.3% ± 1% (1 SD), with all fractions
within the adopted tolerance level of 95%.
Conclusion
The preliminary results for in-vivo dosimetry using
PerFRACTION 3D suggests it as a promising tool for
detection of treatment discrepancies and their clinical
impact. This in-vivo dosimetry approach combined with
plan pre-treatment verification can contribute to a more
robust patient specific QA as well as to identify more
clearly the possible causes of discrepancies such as
machine and/or patient related ones.
Electronic Poster: Brachytherapy: Breast
EP-1766 First experiences using the new Papillon +
TM Contact X-Ray Brachytherapy 50KVp (CXB) unit
J.P. Gérard1, C. Dejean2, M.E. Chand 1, D. Lam Cham
Kee1, J. Doyen1, K. Benezery1, J.M. Hannoun-Levi 1
1Centre Antoine Lacassagne, Radiotherapy, Nice, France
2Centre Antoine Lacassagne, Physics, Nice, France
Purpose or Objective
The Papillon 50 TM unit was designed in 2009 to perform
CXB treatment using 50 KVp X-Rays with short focus
distance (FSD <4cm) and high dose rate (> 15 Gy/mn)
aiming at replacing the Philips RT 50TM to treat
endoscopically rectal cancer. In order to treat breast
cancer using an intra-operative radiotherapy (IORT)
approach a new Papillon + TM ( P+ ) unit was designed
(Ariane cpy. UK) and the first prototype was installed in
Centre A Lacassagne in Nice during december 2016.