ESTRO 36 Abstract Book

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S762 ESTRO 36
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sinusoidal movement with changeable motion amplitude
and frequency. To simulate target motion during a normal
breathing to the sphere it was applied a movement of ± 5
mm in antero-posterior and lateral direction, ± 10 mm in
superior-inferior direction. The frequency of respiratory
cycles was set to 1 cycle/3 seconds. A planning CT of the
CIRS phantom was performed using a 3 mm slice thickness.
CT images were exported to the Oncentra Masterplan (OM)
version 4.3. Planning target volume (PTV) was obtained by
adding an isotropic expansion of 0.8 cm to sphere (gross
tumor volume, GTV) delineated on CT “lung” window and
without inclusion of blurring effect. A test VMAT
treatment plan with identification of the isocenter at the
center of the PTV was created. A verification of the target
sphere position by means of Symmetry TM was performed.
4D-CBCT was acquired and subsequently sent to the OM to
verify the correspondence between volumes planning CT-
based and volumes obtained on CBCT 4D and to obtain ITV-
4D. GTVs were delineated on all phases of 4D-CBCT to
define ITV.
Results
Simmetry XVI software appeared able to follow organ
movements. It was found from this study that ITV4D-CBCT
and PTV4D-CBCT were overlapped. The margin applied to
obtain CTV was reliable.
Conclusion
The 4D-CBCT with Simmetry XVI was adequate in providing
imaging-guidance for treatment of lung cancer and other
tumors occurring in site influenced by organ motion.
Simmetry XVI is a valid instrument to perform a
respiratory-gated radiation therapy when 4D planning CT
is not available. Actually, in our department, the
applicability of this procedure on patients continues to
be under investigation.
EP-1427 Peer reviewed radiation treatment planning
process at a university hospital in a developing country
B.M. Qureshi 1, A.N. Abbasi1, N. Ali1, A. Hafiz1, M.U.
Karim1, A. Mansha1
1 Aga Khan University Hospital, Radiation Oncology
Section- Dept. of Oncology, Karachi, Pakistan
Purpose or Objective
The study aimed to evaluate if peer review in weekly
simulation review meeting impacts the radiation therapy
treatment planning process in a resource limited setting.
Material and Methods
The study was done at the Radiation Oncology facility of
Aga Khan University, Karachi Pakistan for a period of 2
months. Simulation review meeting (SRM) was held
weekly during the study to discuss all the patients being
planned for radiation therapy in the presence of
consultants and residents. Each patient's contour of organ
at risk and treatment volumes or fields, total dose, dose
per fraction, number of phases etc are discussed after
being planned by primary radiation oncologist.
In this study, data was recorded for patients being planned
for radiation in weekly SRM in the presence of at least 2
radiation oncologist. Intent was recorded as radical or
palliative and discussion for all the patients including 2-D,
3D-CRT and IMRT was noted. The study included patients
of primary malignancies of different anatomic regions,
treated with external beam radiation therapy at our
institute except those who were planned and treated on
the same day. Impact of peer reviewed SRM was recorded
as 'no change', 'minor change' or major change in contour,
dose, field size or intent of treatment. This data was
recorded after approval of institutional ethical review
committee.
Results
Data was collected for a total of 116 patients, out of which
96 we planned with radical intent and 20 for palliation.
61% patients were planned with 3D-CRT technique & 26%
with IMRT. Major primary sites included head and neck
(40%), thorax (26%), pelvis (51%) and brain (12%). At least
three radiation oncologists were present in two third
meetings and changes were mostly made in with gross
tumor volume or clinical target volume. It was observed
that minor changes were made in 13% patients and major
change was done in the plans of 9% of patients.
Conclusion
In this modern era of precision radiation therapy
treatment planning, peer review of the planning process
has a vital role. Peer review of treatment plans among
radiation oncologist improves the process and
recommended changes can be incorporated in the the
treatment plans in a timely manner. The study shows that
the review of treatment plans is a necessary quality step
in radiation therapy and can be done on a weekly basis for
all the patients. Hence, the quality of planning is improved
in a resource limited university hospital.
EP-1428 Stereotactic body radiotherapy for isolated
metastasis from different primitive tumors
A. Lancia1, G. Ingrosso 1, A. Carosi1, L. Di Murro 1, E.
Giudice1, S. Cicchetti1, P. Morelli1, C. Bruni1, D. Di
Cristino1, A. Murgia1, A. Cancelli1, I. Turturici1, A.
Iadevaia1, R. Santoni1
1Tor Vergata University Hospital, Department of
Diagnostic Imaging- Molecular Imaging- Interventional
Radiology and Radiotherapy, Roma, Italy
Purpose or Objective
The oligometastatic state identifies a subset of patients
who might be amenable to curative therapy. In this
specific group of patients, Stereotactic Body Radiation
Therapy (SBRT) has been shown to reach high levels of
local tumor control through the delivery of high doses of
radiation in few fractions, without the development of
significant toxicity. Any meaningful improvement in
survival remains debatable.
Material and Methods
From July 2007 to March 2016, 78 patients were treated
at our Department with Stereotactic Radiotherapy for
isolated body metastasis. The most frequent primary
tumor was prostate cancer (28.2%), followed by colorectal
cancer (23.1%), and lung cancer (20.5%). All patients
received a radical treatment to the primary tumor site .
Median time from primary tumor treatment to SBRT for
oligometastatic disease was 30.3 months (range 1.07-
232.3). No patient had synchronous metastases at the time
of SBRT. Median age at diagnosis of oligometastatic
disease was 70 years (range 47-88). Median Karnofsky
Performance Status (KPS) was 90 (range 70-100). Patients
were also evaluated in terms of Charlson Comorbidity
Score (CCS). The most used SBRT dose fractionation
scheme was 35 Gy in 5 fractions. Overall Survival (OS),
Cancer-Specific Survival (CSS), and Local Control (LC)
were calculated from the end date of SBRT to the end of
follow-up; Progression-Free Survival (PFS) was calculated
from the end date of SBRT to the first clinical progression.
Treatment related toxicity was evaluated using the CTCAE
version 4.0.
Results
Median follow-up was 22.68 months (range 1.9-95.73).
One year and 2 years LC were 91% and 89%, respectively.
At the time of analysis, thirty-one patients (39.7%) were
free from local and systemic progression: one and 2-year
PFS were 85% and 72%, respectively. CSS at one year was
93% and it was 85% at two years. One and 2-year OS were
92% and 82%, respectively . At the univariate analysis, we
found that KPS ≥ 80 was a statistically significant
prognostic factor for OS, and PFS (p=0.001 for both). OS
was also influenced by the primitive tumor (p=0.006). 8