ESTRO 36 Abstract Book

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S966 ESTRO 36 2017
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EP-1783 Acute toxicity with Xoft Axxent Electronic
Brachytherapy (XB) in endometrial or cervical cancer
A. Mendez Villamon1 , A. Miranda Burgos1, M. Gascón
Ferrer1, M. Puertas Valiño1, S. Lozares Cordero2, A.
Gandia Martinez2, J. Font Gomez2, M. Tejedor Gutierrez1
1 H.U. Miguel Servet, RADIATION ONCOLOGY, Zaragoza,
Spain
2 H.U. Miguel Servet, MEDICAL PHYSICIST, Zaragoza, Spain
Purpose or Objective
To analyze acute toxicity outcomes after treatment with
Xoft Axxent Electronic Brachytherapy (XB) in postsurgical
endometrial or cervical cancer patients treated at our
medical centre.
Material and Methods
Prospective study in which we selected 29 patients that
received treatment with Xoft Axxent Electronic
Brachytherapy (XB) administered twice a week after
endometrial or cervical cancer surgery, with 3D
planification. The patients were selected from September
2015 to September 2016. They were divided in two groups:
Group 1 (15/29) considered high risk and group 2 (14/29)
considered intermediate risk. Group 1 received external
beam radiotherapy (46Gy) followed by XB (15Gy in 5Gy
fractions) and group 2 received exclusive XB (25Gy in 5Gy
fractions). We analyzed the median dose in bladder,
rectum and sigmoid D2cc, V50, V35 with XB comparing the
doses with Ir-192. The vaginal mucosa, gastrointestinal
(GI) and genitourinary (GU) toxicities were analyzed with
the Common Terminology Criteria for Adverse Events
(CTCAE 4.0) scale.
Results
The median dose in bladder with XB vs. Ir-192 was: 2cc
66,4% vs. 71.6%, V50 7,2 vs. 11.9 Gy, V35 14.8 vs. 26,6. In
rectum XB vs. Ir-192 was: D 2cc 68,4% vs. 73.5% , V50 9.9
vs. 16.7 Gy, V35 19.9 vs. 36. In sigmoid XB vs. Ir-192 was:
D 51.4%vs. 59.8%, V50 12.9 vs. 21.3 Gy, V35 28.8 vs. 41.5.
The median follow-up was six and a half months (range 3-
12 months).
In group 1, acute vaginal mucositis (G1) was observed in
40% of the patients, GI toxicity (G1) occurred in 13% and
GU toxicity (G1, G2, G3) was not present.
In group 2, we observed acute vaginal mucositis (G1 and
G2) in 57% of the patients, GI toxicity (G1) occurred in 7%
and GU toxicity (G1) was present in 29%. There was no
grade 3 or greater toxicity in any of the groups. At 3
months follow-up, all of the patients were asymptomatic.
Conclusion
The dose received by the organs at risk with the Xoft
Axxent Electronic Brachytherapy is less compared to Ir-
192, with a good coverage of the PTV and excellent results
as for acute toxicity. The greater toxicity was observed
immediately after the treatment was finished reducing in
an important way at the third month after treatment.
EP-1784 Needle use in cervical cancer brachytherapy
using the Utrecht applicator: a single center experience
M. Smolic1, C. Sombroek1, M. Bloemers1, B. Van Triest1,
M.E. Nowee1, A. Mans 1
1 Netherlands Cancer Institute Antoni van Leeuwenhoek
Hospital, Radiation Oncology, Amsterdam, The
Netherlands
Purpose or Objective
The Utrecht applicator (Elekta, Veenendaal, the
Netherlands) used in brachytherapy (BT) for cervical
cancer can include up to 10 interstitial needles along with
the intra-uterine and ovoid channels. The aim of this study
is to examine the clinical use of needles at our institute,
and to investigate whether the two needles with largest
discrepancy between application and use are essential to
treatment planning.
Material and Methods
The study included 22 cervical cancer patients treated
with 3 fractions of BT. The application of needles per
fraction was based on consensus amongst radiation
oncologists, medical physicists and RTTs, using the
available pre-treatment imaging, physical examination
and MRI scan made in the week before BT. We examined
how often each of the 10 possible needles (Figure 1) was
applied and the frequency of its subsequent use in
treatment planning, as well as the average intensity of
each needle’s use, given by the average ratio of needle
channel dwell time to total treatment time. We
investigated whether the two needles with lowest
frequency and intensity are essential for achieving the
planning aims while respecting OAR constraints and
yielding an acceptable conformal dose distribution. We
did this by removing these needles from the optimized
clinical plans (CP) and re-optimizing using the other
available needles, intra-uterine and ovoid channels (RP).
We aimed to obtain identical HR-CTV D90 values while still
trying to achieve similar OAR planning aims and dose
distribution conformality as achieved in the CP. We
compared RP and CP for DVH parameters (HR-CTV D90 and
OAR D2cc’s, as well as the ratio D2cc OAR to D90 HR-CTV
as a measure of DVH parameter favorability) and dose
distributions, characterized by high dose volumes HR-CTV
V200% and V300%, the dose homogeneity index (DHI = 1 –
HR-CTV V150%/HR-CTV V100%) and conformal index (COIN
= HR-CTV V100 (cc)/HR-CTV Volume (cc) x HR-CTV V100
(cc)/Implant V100 (cc)).
Results
Needles C, H, J and A are applied most often (in 89%, 89%,
71% and 67% of the cases, respectively) while the needles
with the lowest frequency of subsequent use are A (64%),
J (68%), F (68%), E (77%). Needles contributing the least to
the total treatment time are J (2.9%), E (2.9%), A (3.0%)
and F (3.5%). Needles A and J are thus applied often but
have the lowest frequency and intensity of subsequent
use. Of the 66 clinical treatment plans in this study, 25
made use of both needles A and J. Re-optimizing these
clinical plans without using needles A and J leads to
minimal differences in DVH parameters and dose
distributions between CP and RP (Table 1)
.
Conclusion
Needles C and H are applied and used most frequently and
intensely in our clinic. Needles A and J are applied often
but have the lowest frequency and intensity of subsequent
use. We managed to obtain equally clinically acceptable
plans without these needles, indicating that they are not