ESTRO 36 Abstract Book

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S971 ESTRO 36
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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. Chand1, D. Lam Cham
Kee 1, J. Doyen1, K. Benezery1, J.M. Hannoun-Levi1
1 Centre Antoine Lacassagne, Radiotherapy, Nice, France
2 Centre 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.
Material and Methods
The P+ unit is a battery powered mobile X-Ray generator
producing an X-Ray beam with a peak energy of 30 or 50
KVp. A tungsten transmission anode is liquid cooled to
produce a dose rate of 8-18 Gy/ minute depending on
distance and added filtration. The useable beam angle is
310° x360° and is well adapted to breast IORT. The tube
incorporates a radiation delivery rod that is 22 cm long
and 1.7 cm in diameter. The X ray tube and integrated
high voltage generator are mounted on an articulated arm
that incorporates electromagnetic brakes on all
movements. A separated work station is used to remotely
control the system using a wireless connection. Various
applicators can be mounted on Treatment Application
Adaptors to treat skin, breast and rectal tumors.