Wahyu Edy Wibowo
Abstrak :
[Telah dilakukan penelitian dalam mengevaluasi pengaruh material homogen dan inhomogen pada teknik IMRT (Intensity Modulated Radiotherapy) menggunakan modalitas Fan Beam CT (FBCT) dan Cone Beam CT (CBCT) terhadap Gamma Index (GI). Perencanaan ulang dilakukan untuk 5 pasien kanker paru kanan pada modalitas FBCT dan CBCT menggunakan TPS Phillips Pinnacle energi foton 6 MV. Menggunakan Teknik IMRT 30 segmen, 50 segmen, dan 70 segmen untuk perencanan terapi. Calculation Grid Resolution (CGR) 0.2 cm dan 0.4 cm digunakan sebagai resolusi dalam perhitungan dosis. Serta kalibrasi bilangan CT (KBC) FBCT, CBCT, dan linear dipergunakan sebagai koreksi CT density number. Pengukuran plannar dose untuk evaluasi Gamma Index (DD 2% / DTA 2 mm, passing rate 90%) dilakukan pada SAD 100 cm dengan material homogen dan inhomogen pada kedalaman 1.5 cm, 5 cm, dan 10 cm. Didapatkan deviasi nilai rata-‐rata GI antara CGR 0.2 cm dengan 0.4 cm material homogen modalitas FBCT dan CBCT berturut-‐tutut ≤1.46% dan ≤ 1.13%. Serta deviasi pada material inhomogen sebesar ≤ 2.54% (FBCT) dan ≤ 1.74% (CBCT). Deviasi Nilai rata-rata GI antara FBCT dengan CBCT dengan CGR 0.2 cm berturut-turut ≤ 1.95% (homogen) dan ≤ 2.36% (inhomogen). Dan deviasi Nilai rata-‐rata GI antara material homogen dan material ekuivalen homogen sebesar ≤ 0.80%. Dari hasil penelitian yang didapat, bahwa evaluasi Gamma Index dapat dipengaruhi oleh jumlah segmen, modalitas CT, kalibrasi bilangan CT, Calculation Grid Resolution, dan kedalaman material.
......These Studies have been carried out to evaluate the effect of a homogeneous and inhomogeneous material on IMRT Technique (Intensity Modulated Radiotherapy) using Fan Beam CT (FBCT) and Cone Beam CT (CBCT) for the Gamma Index (GI). The Phillips Pinnacle treatment plan was used to replan 5 patients on right side of lung cancer. Photon 6 MV was applied to this technique with 30 segments, 50 segments, and 70 segments, repectively. Using Calculation Grid Resolution (CGR) 0.2 cm and 0.4 cm for resolution in the calculation of the dose. As well as the calibration of CT numbers (CCN) FBCT, CBCT, and the linear density are used as a correction CT number. The planar measurement for the evaluation of Gamma Index (DD 2% / DTA 2 mm, the passing rate of 90%) carried out at 100 cm SAD with the homogeneous and inhomogeneous material at a depth of 1.5 cm, 5 cm, and 10 cm, respectively. We obtained deviation average value of GI between CGR 0.2 cm and 0.4 cm using the homogeneous material on FBCT and CBCT modality ≤1.46% and ≤ 1:13%, respectively. As well as the material inhomogeneous deviation of ≤ 2.54% (FBCT) and ≤ 1.74% (CBCT). The deviation of the average GI value between FBCT with CBCT with CGR 0.2 cm respectively ≤ 1.95% (homogeneous) and ≤ 2.36% (inhomogeneous). Finally, the deviation of the average GI value between homogeneous and equivalent of homogeneous material is ≤ 0.80%. From the results obtained, that the Gamma Index can be influenced by the number of segments, modalities of CT, calibration of CT numbers, calculation grid resolution and depth of material.
, These
Studies
have
been
carried
out
to
evaluate
the
effect
of
a
homogeneous
and
inhomogeneous
material
on
IMRT
Technique
(Intensity
Modulated
Radiotherapy)
using
Fan
Beam
CT
(FBCT)
and
Cone
Beam
CT
(CBCT)
for
the
Gamma
Index
(GI).
The
Phillips
Pinnacle
treatment
plan
was
used
to
replan
5
patients
on
right
side
of
lung
cancer.
Photon
6
MV
was
applied
to
this
technique
with
30
segments,
50
segments,
and
70
segments,
repectively.
Using
Calculation
Grid
Resolution
(CGR)
0.2
cm
and
0.4
cm
for
resolution
in
the
calculation
of
the
dose.
As
well
as
the
calibration
of
CT
numbers
(CCN)
FBCT,
CBCT,
and
the
linear
density
are
used
as
a
correction
CT
number.
The
planar
measurement
for
the
evaluation
of
Gamma
Index
(DD
2%
/
DTA
2
mm,
the
passing
rate
of
90%)
carried
out
at
100
cm
SAD
with
the
homogeneous
and
inhomogeneous
material
at
a
depth
of
1.5
cm,
5
cm,
and
10
cm,
respectively.
We
obtained
deviation
average
value
of
GI
between
CGR
0.2
cm
and
0.4
cm
using
the
homogeneous
material
on
FBCT
and
CBCT
modality
≤1.46%
and
≤
1:13%,
respectively.
As
well
as
the
material
inhomogeneous
deviation
of
≤
2.54%
(FBCT)
and
≤
1.74%
(CBCT).
The
deviation
of
the
average
GI
value
between
FBCT
with
CBCT
with
CGR
0.2
cm
respectively
≤
1.95%
(homogeneous)
and
≤
2.36%
(inhomogeneous).
Finally,
the
deviation
of
the
average
GI
value
between
homogeneous
and
equivalent
of
homogeneous
material
is
≤
0.80%.
From
the
results
obtained,
that
the
Gamma
Index
can
be
influenced
by
the
number
of
segments,
modalities
of
CT,
calibration
of
CT
numbers,
calculation
grid
resolution
and
depth
of
material.
Key
words
:
Calculation
Grid
Resolution,
Calibration
of
CT
Numbers,
Cone]
Depok: Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2016
T45207
UI - Tesis Membership Universitas Indonesia Library
