ESTRO 36 Abstract Book

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S981 ESTRO 36
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rectum and sigmoid were contoured by a single radiation
oncologist and the contours were reviewed by all members
of the Brachytherapy team. Plan optimization was
performed according to International guidelines . Rectum
position variation, due to the presence of the rectal tube
(diameter: 8.3 mm) , attracted the attention of the team.
The treatment plan was transferred on CT scan without
rectal tube and OARs and target doses were evaluated. For
both plans, bladder and rectum DVHs were assessed
considering the near maximum dose to 2cc of each organ,
D2cc (%). Results are reported as mean (±SD). The
Wilcoxon test for pair samples was used for comparison.
Differences were considered statistically significant at p <
0.05.
Results
No significant variation was found for bladder D2cc with
and without rectal tube: (68.7±5.9)% vs (68.7±4.2)%,
respectively. D2cc for the rectum systematically increased
in all calculated plans without rectal tube: (68.9±5.7)%
vs.( 86±6.7)%. Differences were found statistically
significant (p=0.031).
Conclusion
These preliminary results show that an unexpected
advantage of the rectal tube, used for in-vivo dosimetry,
is the favorable modification of the rectal anatomy with a
consequent significant reduction in terms of D2cc.
EP-1786 Intraoperative Brachytherapy (HDR-IOBT) in
advanced or recurrence gynecologic cancer..
E. Villafranca Iturre1 , J. Muruzabal2, A. Sola1, P.
Navarrete1, M. Barrado1, S. Aguirre 2, S. La Peña2, O.
Tarrio 2, J. Jimenez3, M. Ciga 4
1 Hospital of Navarra, Radiation Oncology, Pamplona,
Spain
2 Hospital of Navarra, Gynaecology, Pamplona, Spain
3 Hospital of Navarra, Urology, Pamplona, Spain
4 Hospital of Navarra, Surgery, Pamplona, Spain
Purpose or Objective
Review our initial results in the treatment with surgery
and Intraoperative Brachytherapy (HDR-IOBT) in advanced
or recurrence gynecologic cancer.
Material and Methods
This protocol was designed in 2011 and all cases have been
approved in the Committee on Gynecologic Tumors. They
included two patient groups: Group 1: patients with
advanced cervical cancer with poor response to Radiation
and chemotherapy; group 2: patients with pelvic
recurrence of gynecological tumors of any origin. In all CT
and MRI was performed, in recurrences also PET to exclude
metastatic disease. The surgical procedure was pelvic
exenteration, enlarged cystectomy or rectal resection or
both depending on the extent of disease. After extraction
of the surgical specimen, was confirmed in all cases with
intraoperative biopsy the absence of macroscopic residual
disease. Then, put clips in the surgical bed. Subsequently
an applicator Fleipbrup Flap® (Elekta) was placed, with
an appropriate number of channels to the extension of the
bed. After intraoperative planning, a dose of 10 Gy
prescribed at 0.5 cm bed depth was administered. Finally,
the applicator was retiring to complete the surgery.
Results
In the period between October 2011 and September 2016,
22 patients have been included. In group 1, there were 11
patients with cervical cancer stage IIB in 5 p and IIIB in 6;
in group 2 were 11 recurrences of 5p cervix, 3p
endometrial carcinoma, 2 sarcoma and 1 vulva. With a
median follow-up of 22 months (1-61m), the Local DFS 2
years was 67%: Group 1: 73%; Group 2: 44%; 2 years Disease
Free Survival 54.7%: Group 1: 65%, Group 2: 32%; 2 years
Overall Survical 56%: Group 1: 76%, Group 2: 44%. The
complications were fistula: 1 intestinal, 2 bladder ,
1osteitis pubis in 1p. stenosis sigma 1p.
Conclusion
HDR-IOBT associated with pelvic exenteration offers good
results of pelvic control and overall survival in patients
with gynecologic cancer with a poor prognosis, which
usually palliative treatments are offered, although further
monitoring is required. However the number of
complications, especially fistulas has been important, so
we must take it into account for prevention. These results
are possible thanks to the multidisciplinary approach to
these patients
EP-1787 Dosimetric Implications of the organs at risk
in Vaginal Cuff Brachytherapy with ML Cylinder
N. Dumitru1, M. Shojaei1, S. Pella1,2, T. Leventouri1, J.
Pinder 1
1Florida Atlantic University, Medical Physics, Boca Raton,
USA
221st Century Oncology, Medical Physics, Boca Raton,
USA
Purpose or Objective
To develop a method to evaluate the cumulative dose of
organs of risk when using the Multi-Channel Cylindrical
Applicators in vaginal cuff brachytherapy.
Material and Methods
A retrospective analysis of 30 patients treated in 2015 with
the Multi-Lumen Cylindrical Applicator with 3 cm
diameter, were considered for this study. A total of 150
fractions was received by patients, each of them receiving
5 fractions with 5 Gy each, delivered twice a week and
prescribed to the applicator’s surface for 2/3 of the
vaginal length. The CT scans of these patients, taken for
treatment plan were separately imported into the
treatment planning system and paired with the initial CT
scan after completing the contouring. Two sets of CT
images were fused at a time together with respective to
the applicator, using landmark registration. Dosimetric
evaluations were performed. The maximum doses
received by the rectum wall, bladder wall, bowels and PTV
were analyzed and traced over the five fractions to
determine the total dose distribution over the entire
prescribed treatment.
Results
No contour of any of the OAR was exactly similar when CT
images were fused to each other. Depending on the depth
of the insertion the PTV varied minimally. Each plan was
performed independently and cumulated 2 at a time until
all 5 fractions were added to the initial fraction. There is
a difference between the doses received by the OARs
between treatments and between the points of maximum
does. The PTV volumes vary from fraction to fraction. The
maximum dose varied between 12% and 27% in rectum wall
and bladder wall. The minimum dose varied between 2%
and 7% in rectum wall and bladder wall. The average dose
varied between 9% and 21% in rectum wall and bladder
wall. The cumulative treatment does do not indicate a
total maximum dose exceeding the tolerances for the
rectum and bladder.
Conclusion
The variation in volumes of OARs and isodoses near the
OARs, indicate that the estimated doses to OARs on the
planning system may not be the same dose delivered to
the patient in all the fractions. There are no major
differences between the prescribed dose and the
delivered dose over the total number of fractions.
Variation in the length of the cylinder part implanted into
the vagina and PTV's coverage indicates an inconsistency
in the entire vaginal cuff in all five fractions. In some
cases, the critical organs will benefit if the consecutive
plans will be made after the CT scans are registered with
the initial. All the cases studied indicate the need for more
detailed study in order to establish a protocol of planning.