ESTRO 36 Abstract Book

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S506 ESTRO 36 2017
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technique (orthogonal vs. CBCT and high vs. low quality)
on the doses to normal tissue was evaluated using Eclipse,
where the imaging doses were used as based plans in the
treatment planning process. For breast plans, doses to the
heart and lung were evaluated. For head/neck plans,
doses to all the normal tissues were compared.
Figure 1. Anthropomorphic phantom (CIRS) with dose
measurement points identified.
Results
Average imaging dose was measured as 1.3, 2.5, 3.7, and
7.6cGy for daily low dose MV pairs, high quality MV pairs,
low dose CBCT and high quality CBCT, respectively. Over
a 30 fraction treatment with daily IGRT, this equates to 38
- 227cGy. The average agreement between measured and
calculated tissue doses due to imaging was 0.4±0.4cGy.
The largest difference was 1.3cGy, found in the lung for
high quality CBCT imaging (~39cGy over a 30 fraction
treatment).
With imaging dose incorporated into the treatment
planning process, it was possible to create clinically
acceptable treatment plans for a range of treatment sites,
including breast, head and neck and prostate. The imaging
technique did, however, increase the heart and lung dose
for breast plans. For an example left breast treatment,
the mean heart dose in our original, clinically delivered
plan was 60cGy. With daily MV imaging included, this
increased to 140, 150, 190 and 260cGy for daily low dose
MV pairs, high quality MV pairs, low dose CBCT and high
quality CBCT, respectively. The corresponding values for
mean lung dose were 360cGy (original clinical) and 470,
490, 510 and 570cGy.
Table 1: Tissue doses(cGy/fraction) at different points in
the anthropomorphic phantom. M: Measured. C:
Calculated
Conclusion
Image-guided radiation therapy using MV imaging can be
incorporated into the treatment plan to give clinically
acceptable dose distributions. Dose to normal tissues is
increased, however, and depends on the imaging
technique, it is important to select the technique which
minimizes normal tissue dose while providing sufficient
image quality for patient setup.
Poster: Brachytherapy: Breast
PO-0922 Late toxicity and cosmetic outcome following
APBI using interstitial multicatheter HDR brachytherapy
T. Soror1,2, G. Kovács 2, N. Seibold2, C. Melchert2, K.
Baumann3, E. Wenzel 4, S. Stojanovic-Rundic5
1National Cancer Institute, Radiation Oncology
Department, Cairo, Egypt
2Interdisciplinary Brachytherapy Unit, University of
Luebeck/UKSH-CL- Germany, Lübeck, Germany
3Clinic for Gynecology and Obstetrics, University of
Luebeck/UKSH-CL- Germany, Lübeck, Germany
4Clinic for Plastic Surgery, University of Luebeck/UKSH-
CL- Germany, Lübeck, Germany
55Institute for Oncology and Radiology IORS, Radiation
Oncology Department, Belgrad, Serbia
Purpose or Objective
Accelerated partial breast irradiation (APBI) has became a
valid option in treating patients with early stage breast
cancer following breast conservation surgery (BCS). This
work reports on the late toxicity and the cosmetic
outcome following APBI using interstitial multicatheter
HDR intensity modulated brachytherapy (HDR-IMBT).
Material and Methods
Between 2006 and 2014, 114 patients received adjuvant
APBI using interstitial multicatheter HDR-IMBT. Late
toxicities were reported according to both the
RTOG/EORTC score and the LENT/SOMA score. Cosmetic
changes were documented by taking digital photographs
before the APBI and during each follow-up visit. For each
patient, we assessed two photographs, the first was taken
after surgery and before APBI (baseline image), and the
second at the last available follow-up visit. The cosmesis
was assessed through a multidisciplinary team using the
Harvard breast cosmesis scale. The clinical and the
dosimetric parameters were investigated for any potential
correlations with the cosmetic results.
Results
The median follow-up period was 3.5 years (range 0.6 –
8.5). Late skin/soft tissue toxicities at the last follow-up
visit are listed in Table1. Ten patients had grade-3 toxicity
(8.8%) and no patients showed grade-4 toxicity. The most
common toxicities were fibrosis (56.2% by LENT/SOMA
score, and 47.4% by RTOG/EORTC score) followed by pain
(42.1%).
The final cosmetic scores were 81.5% excellent/good and
18.5% fair/poor. Comparing both the baseline and the last
follow-up cosmetic scores, 59.6% of the patients had the