986 / 1096
S970
ESTRO 36
_______________________________________________________________________________________________
demand). MR acquisition was also designed to allow for
collection of data needed for CT+MR as well MR-only (or
synthetic CT) workflows. This is expected to facilitate
access to the in-house adaptive RT implementation in
RayStation (RaySearch, Stockholm, Sweden). All MR image
data was validated for RT use by means of comprehensive
testing for global image quality and correction of spatial
distortions. In particular for liver, the management of
motion was adapted for the MR environment in the case of
potential subjects undergoing either breathhold or
abdominal compression (AC). Breathhold was evaluated
using Medspira (Minneapolis, MN) whereas AC was
implemented using pneumatic pressure belts. Staff
requirements and safety for in-room operations was
evaluated via simulations and dry runs.
Conclusion
Workflows for MR guidance in prostate and liver were
designed and preliminary tested. The next step is to
enable imaging-only clinical trials in patients. Based on
feedback the workflows will be refined to allow for the
full implementation of MR-guidance studies.
EP-1762 A Comparative Study of 4D and 3D
CTSimulation in Esophageal Carcinoma
J. Li
1
, G. Lai
1
1
Fujian Cancer Hospital, radiation oncology, Fuzhou-
Fujian, China
Purpose or Objective
To compare the internal gross target volume (IGTV) and
its displacement of primary esophageal carcinoma (EPC)
on the base offour-dimensionaland three-dimensional
computed tomography (4D-CT and 3D-CT) simulation
technology.
Material and Methods
Twenty-two esophageal cancerpatients with pathological
proved diagnosiswererecruited in this prospectively study.
Every patient sequentially received contrast enhancement
free-breathing 3D-CT and respiration-synchronized4D-CT
simulationchest.Then the target volume and the
displacement on three orthogonal directionsof three
different
IGTV
planningmethods
(including
IGTV
4D,
IGTV
4D'
and IGTV
3D
. The dice similarity coefficient
(DSC) and overlap index (OI) between IGTV
4D
and IGTV
4D'
,
between IGTV
4D
and IGTV
3D
for different segments of
esophagus were calculated. Statistical analysis included
theFriedman test, analysis of variance on the base of
repeated measurement data and paired-samples student t
test and the
P
<0.05 was set as statistically significant.
Results
There were statistical significance of displacement at left-
right, anterior-posterior, and superior-inferior directions
of primary esophageal tumor GTV of the ten phases
originated from medium-thoractic segments and medium-
lower-thoractic segments (
P
= 0.005 and
P
= 0.001). There
presented a significant differences of primary tumor
volume where appeared IGTV
3D
> IGTV
4D
> IGTV
4D'
(
P
<0.05).In
other words, the implementation of GTV by means of
extending position error from based of 3D-CT wouldlead
to unnecessary radiation of the surrounding normal tissues
(about 9~24%); However, the application of GTV only by
means of integrating end-inhalation and end-exhalation
phases would result in uncover target area (about
10~34%).
Conclusion
4D-CT simulation technology is superior to 3D-CT
simulation technologyfor IMRT in esophageal cancer.
EP-1763 Acute toxicity and in-vivo dosimetry of a two
week hypofractionated schedule within the HYPORT
study
A. Saha
1
, G. Goswami
2
, S. Mandal
2
, A. Mahata
2
, D.
Midha
3
, R. Ahmed
4
, S. Agarwal
4
, S. Ray
5
, J. Das
5
, S.S.
Datta
6
, S. Sinha
7
, S. Chatterjee
2
1
Tata medical center, Radiotherapy, Kolkata, India
2
Tata medical center, Radiation Oncology, Kolkata, India
3
Tata medical center, Oncopathology, Kolkata, India
4
Tata medical center, Breast Surgery, Kolkata, India
5
Tata medical center, Nuclear Medicine, Kolkata, India
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. Rachinhas
1
, P. Simões
1
, A. Cavaco
1
, F.
Balau
1
, M. Borrego
1
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