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S837
ESTRO 36 2017
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EP-1573 TBI and TMI treatment comparison using
bilateral and anteroposterior delivery techniques
E. Sandrini
1
, C.M. Da Silva
1
1
Clínicas Oncológicas Integradas, Medical Physics -
Radiotherapy, Rio de Janeiro, Brazil
Purpose or Objective
Evaluate doses in organs at risk and target volume
coverage of patients undergoing total body irradiation
(TBI) or total marrow irradiation (TMI) treatment in supine
and lateral decubitus. The TBI and TMI treatment are an
old kind of treatment that normally uses 2D calculation.
This work used a 3D calculation with heterogeneity
correction as the same way of the old technique (two
opposite fields), but with a CT it’s possible to estimate the
dose in OAR and the target coverage.
Material and Methods
Five partial (3/4) total body CT image were used to plan a
TBI treatment with two different setups: supine and
lateral decubitus. The plans had two opposite fields with
6MeV and their collimator rotated by 45 degrees, the
extended SSD used was 350cm, it was used Acurus XB dose
calculation algorithm and the prescription was 12Gy in 6
fractions. For each CT it was drawn the body, bones,
lungs, heart, kidneys, liver and eyes. It was investigated
the following aspects: (A) body coverage (TBI treatment),
(B) bone coverage (TMI treatment), (C) dose homogeneity
index (DHI) defined as the ratio of dose received by 90% of
the volume (D90) to the minimum dose received by 10% of
the volume (D10), (D) mean dose of organs at risk: lungs,
kidneys, heart and liver and (E) maximum dose in eyes.
Results
It was observed that when using supine decubitus instead
of lateral decubitus the D95 of body decreases 2%, and D95
of bones didn’t change; The DHI of TBI and TMI treatment
was reduced by 10%; The crystalline maximum dose and
heart mean dose was increased by 20% and 3%,
respectively; And the mean dose of kidney, lung and liver
was reduced by 10%, 6% and 4%, respectively.
Conclusion
This work indicates that the target coverage and DHI
aren’t significantly affected by the patient positioning.
Although the bilateral technique increased the eyes and
heart dose, it was observed a decrease in lung, kidney and
liver dose. So as the pulmonary complication is renowned
as the major causes of mortality following TBI, the best
positioning for this kind of treatment is supine decubitus.
EP-1574 Helical Tomotherapy for Bilateral Breast
Cancer Patients: 3-Years Single Centre Experience
F. Ertan
1
, M. Altundag
1
, H. Abanuz
1
, S. Duzgun
1
1
Ankara Oncology Hospital, Radiation Oncology, Ankara,
Turkey
Purpose or Objective
The present study aims to evaluate dose distribution
characteristic using helical tomotherapy (HT) for patients
with bilateral breast cancer.
Material and Methods
From January 2013 to December 2015, 12 patients were
treated with tomotherapy. The target volume includes
different parts for each patient and was shown in Table-
1. During CT simulation, the patient was positioned supine
on a breast board and CT slices were obtained at 3 mm
intervals extending from the chin to the upper abdomen
during free breathing. Tomotherapy planning parameters;
the field width, modulation factor and pitch, were
assigned to 5cm, 2 and 0.287, respectively, for all plans.
To protect critic organs at maximum level, the complete
block was applied. The delivered dose was 50Gy within 25
fractions for 11 patients and, simultaneous integrated
boost technique was used within 60Gy to boost and 50Gy
to PTV in 25 fractions for 1 patient. Treatment planning
objectives were to cover at least 95% of the planning