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control and the D
90
CTV
HR
and CTV
IR
(p=0.08 and 0.025
respectively) were observed, no significant relationship
between point A dose and local control probability could
have been established (Figure). Moreover, a trend towards
an inverse relation was observed. After sorting patients
according to 3 levels of doses, highest local control rates
werereported in patients with D
90
CTV
HR
≥85 Gy, whereas
the patients with point A doses ≥ 70 Gy had the worst
outcomes.
Conclusion
In patients treated with IGABT, point A dose is not
predictive of local control, and nor correlated to D
90
. It
tends to be inversely related to D
90
and therefore to be a
surrogate of the irradiated volume. The pertinence of
reporting point A dose should be questioned.
PO-0939 Comparison of brachytherapy sources of
endometrial cancer: Electronic brachytherapy source
and 192Ir
S. Lozares
1
, J.A. Font Gómez
1
, A. Gandía Martínez
1
, A.
Miranda Burgos
2
, A. Méndez Villamón
2
1
Hospital Universitario Miguel Servet, Medical Physics
and Radiation Protection Department, Zaragoza, Spain
2
Hospital Universitario Miguel Servet, Oncologic
Radiotherapy Department, Zaragoza, Spain
Purpose or Objective
To compare 29 endometrial cancer patients treated in our
center with cylindrical applicators and Axxent (Xoft Inc.)
electronic brachytherapy with an equivalent planning
made for Ir-192 source.
Material and Methods
29 patients previously treated with Axxent (50 kV source)
have been replanned with Ir-192 source. The calculation
for both types of sources were performed on BrachyVision
(Varian Inc.) treatment planning system.
The prescription was 5 Gy per fraction applied in 3
fractions or 5 fractions depending on previous
radiotherapy treatment.
The planning parameters of the planning target volume
(PTV) countoured from the cylinder surface to 5 mm along
the active length were evaluated. V150 and V200 data for
PTV and D2cc, V50% and V35% for organs at risk (OAR) were
evaluated, the percentage of the volume receiving 35%
and 50% of the prescription dose, respectively, and D2cc,
highest dose to a 2 cubic centimetre volume of an OAR.
Results for bladder, rectum and sigmoid are
showed.
Results
We may observe a reduction in dose at V35% and V50% in
all OAR and also a reduction in D2cm
3
occurs (Table 1).
PTV parameters increase in the case of Axxent, as
reported previously, but very few cases of vaginal
mucositis have been reported in our center as is showed
in another clinical abstract. All patients were treated
between 2015 and early 2016, enough time to develop
early problems.
Conclusion
Preliminary results are very optimistic about the adequacy
of Xoft equipment for treatment of endometrial cancer
with a clear reduction of the physical dose in organs at risk
and very few development of acute mucositis despite the
considerable increase V150 in the treatment volume.
Further studies will be necessary to take into account the
RBE in treatments with such sources.
PO-0940 3D mapping for precise definition of GTV,
CTV and their correlation in cervix cancer BT
(EMBRACE)
S. Banerjee
1
, R. Pötter
2
, C. Kirisits
2
, K. Majercakova
2
,
M.P. Schmid
2
, S.K. Shrivastava
3
, U. Mahantshetty
3
1
Medanta The Medicity, Radiation Oncology, Gurgaon,
India
2
Vienna General Hospital- Medical University of Vienna,
Departmentof Radiation Oncology, Vienna, Austria
3
Tata Memorial Hospital, Department of Radiation
Oncology, Mumbai, India
Purpose or Objective
Image Guided adaptive Brachytherapy (BT) for cervix
cancer is based on MRI and gynaecologic examination (GE)
at diagnosis (D) and at BT to define the HR CTV. For
documentation of disease at D and at BT schematic
mapping diagrams (SMD) are used indicating values for
maximum dimensions of GTV at D and at BT. For
comprehensive assessment of available volumetric
information through MRI at D and at BT an advanced
schematic 3D mapping diagram (3DMD) was developed to
provide precise reproducible topographic and quantitative
information (Fig1). This was used to evaluate the
topographic and quantitative relation between GTVD, HR
CTV and IR CTV.
Material and Methods
42 proven cervical cancer FIGO IIB-IIIB patients from
Vienna and Mumbai were selected, mean age was 52
years. All were enrolled in the EMBRACE study and
completed the planned treatment with MRI at D and at BT.
SMDs from GE with individual tumour contours and
dimensions as prescribed for EMBRACE were available.
A 3DMD in axial, coronal and sagittal orientation was used
with a scale (grid with 10 mm distance) for the precise
documentation of available volumetric information