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مجال
التميز
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تميز دراسي وبحثي
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البحوث المنشورة
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البحث (1):
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عنوان البحث:
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A comparison
of the dose distributions from three proton treatment planning systems in the
planning of meningioma patients with single-field uniform dose pencil beam
scanning
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رابط إلى البحث:
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تاريخ النشر:
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08/01/2015
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موجز عن البحث:
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With the
number of new proton centers increasing rapidly, there is a need for an
assessment of the available proton treatment planning systems (TPSs). This
study compares the dose distributions of complex meningioma plans produced by
three proton TPSs: Eclipse, Pinnacle3, and XiO. All three systems were
commissioned with the same beam data and, as best as possible, matched
configuration settings. Proton treatment plans for ten patients were produced
on each system with a pencil beam scanning, single-field uniform dose
approach, using a fixed horizontal beamline. All 30 plans were subjected to
identical dose constraints, both for the target coverage and organ at risk
(OAR) sparing, with a consistent order of priority. Beam geometry, lateral
field margins, and lateral spot resolutions were made consistent across all
systems. Few statistically significant differences were found between the
target coverage and OAR sparing of each system, with all optimizers managing
to produce plans within clinical tolerances (D2 < 107% of prescribed dose,
D5 < 105%, D95 > 95%, D99 > 90%, and OAR maximum doses) despite
strict constraints and overlapping structures.
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البحث (2):
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عنوان البحث:
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Cone-Beam Computed Tomography and Deformable Registration-Based “Dose
of the Day” Calculations for Adaptive Proton Therapy
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رابط إلى البحث:
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Click here
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تاريخ النشر:
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16/10/2015
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موجز عن البحث:
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Purpose: The aim of this work was to evaluate the feasibility of
cone-beam computed tomography (CBCT) and deformable image registration (DIR)
based “dose of the day” calculations for adaptive proton therapy.
Methods: Intensity modulated radiotherapy (IMRT) and proton therapy
plans were designed for three head and neck patients that required
replanning, and hence had a replan CT (rCT). Proton plans were generated for
different beam arrangements and optimizations: intensity modulated proton
therapy and single field uniform dose (SFUD). We used in-house DIR software
implemented in our institution (NiftyReg) to generate a deformed CT (dCT), by
warping the planning CT (pCT) onto the daily CBCT. This CBCT had a similar
patient geometry to the rCT. Dose distributions on the rCT were considered
the gold standard for “dose of the day” calculations, and were compared to
doses on dCT (our method) and directly on the calibrated CBCT and
rigidly-aligned pCT (alternative methods) in terms of dose differences (DD),
by calculating the percentage of voxels whose DD was smaller than 2% of the
prescribed dose (DD2%-pp) and the root mean square of the DD distribution (DDRMS)
Results: Using a dCT the DD2%-pp within the CBCT imaging volume was
93.2±0.7% for IMRT, and 87±3% for proton plans. In a region of higher dose
gradient we found that while DD2%-pp was 94.3±0.2% for
IMRT, in proton plans it dropped to 74±4%. A larger number of treatment beams
and SFUD optimization appear to make the proton plans less sensitive to DIR
errors. For example, within the treated volume the DDRMS
was reduced from 2.6±0.6% of the
prescribed dose (%pD) to 1.0±1.3%pD when using SFUD.
Conclusions: Promising results were found for DIR and CBCT-based
proton dose calculations. Proton dose calculations were however more
sensitive to registration errors than IMRT doses, particularly in high dose
gradient regions.
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المؤتمرات العلمية:
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المؤتمر (1):
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عنوان المؤتمر:
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International
Conference on Radiation Medicine (ICRM2014)
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تاريخ الإنعقاد:
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16-20 February 2014
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مكان
الإنعقاد:
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Riyadh,
Saudi Arabia
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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Comparison
of proton therapy treatment planning systems
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ملخص المشاركة:
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Purpose/Objective:
With the potential improvement of dose conformity of protons compared to the
photon (X-Ray), the number of new proton centres is increasing rapidly. An
important decision that physicists and physicians are required to choose the
best available proton treatment planning system (TPS). The purpose is to
evaluate accuracy of dose calculation, planning tools, user friendliness and
speed for different available TPS.
Materials
and Methods: A meningioma case was planned on four proton treatment-planning
systems (Eclipse, XiO, Pinnacle, & RayStation; of which the first two are
available commercially and the latter two are still in development). Two
plans were made with each of the four TPS for the case, a 2-beam Intensity
Modulated Proton Therapy Plan (IMPT) and a 3-beam IMPT plan. An additional
two-arc Volumetric Modulated Arc Therapy photon plan with 6MV energy was
planned with Eclipse® TPS. All 9 plans were subject to identical dose
constraints, both for the target coverage and organ at risk (OAR).
Results: All
TPSs were within clinical tolerances, however their algorithms differ and so
there were slight differences in the calculated results for the target and
OAR. The DVH of the PTV for the 9 different plans, namely a VMAT-photon and
IMPT plans with two and three beams, repeated using the 4 systems. The IMPT
plans show a more homogenous dose to the target relative to the photon plan.
In addition, RayStation and XiO TPSs has more homogenous dose compared to the
others.
Summery/Conclusions:
All systems produce dose within clinically-accepted tolerances, however the
differences in algorithms lead to dose differences. Perhaps the planning
tools can improve the output as well.
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المؤتمر (2):
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عنوان المؤتمر:
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NPL PPRIG
Proton Therapy Physics Conference and Workshop
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تاريخ الإنعقاد:
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12-13 March 2013
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مكان
الإنعقاد:
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Middlesex,
UK
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طبيعة المشاركة:
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Poster
presentation
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عنوان المشاركة:
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Evaluation
of Commercial Proton Therapy Planning Systems
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ملخص المشاركة:
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Purpose/Objective:
With the potential improvement of dose conformity of protons compared to the
photon (X-Ray), recently the number of new proton centres is increasing
rapidly also various proton treatment planning systems (TPSs) have become
commercially available, and their development is continuing.
The purpose
of this work is to evaluate the pencil beam scanning (PBS) proton treatment
planning of four commercially available proton TPSs to compare TPS
functionality during treatment planning.
Materials and
Methods: A pediatric brain case (glioma) was planned on four proton
treatment-planning systems (Eclipse, XiO, Pinnacle, & RayStation; of
which the first two are available commercially and the latter two are still
in development). Two plans were made with each of the four TPS for the case,
a 2-beam Intensity Modulated Proton Therapy Plan (IMPT) and a 3-beam IMPT
plan. The paediatric case used for this study is a female patient with
low-grade glioma of the optic tract who was previously treated at our institution
with a two-arc Volumetric Modulated Arc Therapy (VMAT) technique using 6MV
photons. All the plans were subject to identical dose constraints, both for
the target coverage and organ at risk (OAR).
Results: The
results show that All TPSs produce doses within clinically acceptable
tolerances, but differences exist in plan quality, dose coverage, dose
distribution and homogeneity, despite dose constraints used for optimization
being identical. However, the differences in algorithms, number of layers, layer
spacing and number of spots lead to the dose variations.
The IMPT
plans show a more homogenous dose to the target relative to the photon plan.
In addition, RayStation and XiO TPSs has more homogenous dose compared to the
others.
Summery/Conclusions:
All systems produce dose within clinically acceptable tolerances, however the
differences in algorithms lead to dose differences. The choice of planning
tools can affect the output as well.
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المؤتمر (3):
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عنوان المؤتمر:
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4D Treatment Planning Workshop 2014
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تاريخ الإنعقاد:
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28 – 29/11/2014
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مكان الإنعقاد:
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Berkshire, UK
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طبيعة المشاركة:
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Poster presentation
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عنوان المشاركة:
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CBCT and deformable registration based dose calculations for adaptive
proton radiotherapy
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ملخص المشاركة:
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Purpose/Objective: The aim of this work is to
evaluate the feasibility of a cone-beam computed tomography CBCT and
deformable image registration (DIR) based dose calculations for adaptive
proton therapy.
Methods: We used the in-house DIR software implemented
in our institution (NiftyReg) to map the Hounsfield units from the CT to the
geometry of the CBCT. Intensity modulated radiotherapy (IMRT) and proton
therapy (IMPT) plans were designed for three head and neck patients. For each
plan the doses were recalculated on a calibrated-CBCT and deformed CT, and
then compared with the dose recalculated on a replan CT (gold-standard). Dose
distributions were compared in terms of dose differences (DD), by calculating
the percentage of voxels whose DD was smaller than 2% of the prescribed dose
(DD2%-pp) and the mean square root value of the DD (DDRMS).
Results: Using a deformed CT, the DD2%-pp within the
CBCT imaging volume was 93.5
0.6% for IMRT, and 89.5
3.2% for IMPT. The high gradient region (i.e, region
where 50 to 95% of the pD was delivered) was defined as region of interest,
and we found that while DD2%-pp was 94.3
0.2% for IMRT, in IMPT it dropped to 78.2
3.2%. This corresponded to a DDRMS of 2.0
0.2%pD and 6.0
0.5%pD, respectively. The absolute improvement in DD2%-pp
between using a deformed CT and a calibrated-CBCT was 15% and 29% for IMRT
and IMPT, respectively.
Conclusions: We have presented a feasibility study investigating the
use of CBCT and DIR based dose calculations. IMPT dose calculations were more
sensitive to registration errors than IMRT doses, particularly in high dose
gradient regions. However, using a deformed CT instead of calculating doses
directly on CBCT resulted in larger improvements in IMPT versus IMRT.
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المؤتمر (4):
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عنوان المؤتمر:
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The 8th Saudi Students Conference
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تاريخ الإنعقاد:
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01/02/2015
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مكان الإنعقاد:
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London, UK
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طبيعة المشاركة:
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Poster presentation
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عنوان المشاركة:
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Evaluation of Commercial Proton Therapy Planning Systems with IMPT and
SFUD planning for pediatric glioma and meningioma cases
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ملخص المشاركة:
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Purpose/Objective: The purpose of this work is to compare
intensity-modulated proton therapy (IMPT) plans from four commercially
available treatment planning systems (TPS).
Materials and Methods: Two paediatric brain cases (glioma and
meningioma) were planned on four proton TPS (Eclipse, XiO, RayStation &
Pinnacle), of which the first three are available commercially and the latter
is still in development. An Intensity-Modulated Proton Therapy (IMPT) and
Single Field Uniform Dose (SFUD) plans using 2-beams were calculated with
each of the four TPS. All plans used the same spot spacing and plan target
margin. The paediatric cases used for this study treated at our institution with
a two-arc Volumetric Modulated Arc Therapy (VMAT) technique using 6MV photons
and the prescription was 54Gy in 30 fractions for the glioma, and 50Gy in 28
fractions for the meningioma. All the plans were subject to identical dose
objectives and constraints.
Results: All four TPS produced clinically acceptable plans.
Differences existed in plan quality, dose coverage, dose distribution and
homogeneity, despite dose constraints used for optimization being identical.
These variations were attributed to differences in algorithms, number of
energy layers, layer spacing and number of spots.
The IMPT plans show better homogeneity relative to the VMAT plan. XiO
showed more conformity than other TPS.
Summary/Conclusions: All systems produced clinically acceptable IMPT
plans. However the differences in algorithms lead to dose differences. An
understanding of these is required to mitigate their impact on plan quality.
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المؤتمر (5):
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عنوان المؤتمر:
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The 14th Annual
British Thoracic Oncology Group BTOG Conference
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تاريخ الإنعقاد:
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27-29
/01/ 2016
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مكان
الإنعقاد:
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Dublin, Republic of
Ireland
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طبيعة المشاركة:
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Poster presentation
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عنوان المشاركة:
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Planning study
comparing the use of photon radiation therapy to proton therapy for superior
sulcus tumours (SSTs)
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ملخص المشاركة:
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Background:
SSTs represent 5% of
bronchogenic carcinomas and present a unique treatment challenge due to
characteristic local invasion of the apical chest wall and thoracic
inlet. Target volume (TV) coverage
using radical photon therapy (PT) is often compromised due to close proximity
to the spinal cord.
Pencil beam
proton beam therapy (PBPBT) is an attractive alternative as its Bragg peak
results in a sharp dose fall-off, enabling minimal deposition to surrounding
normal tissue.
This is a
retrospective radiotherapy planning study comparing conformal PT with
volumetric arc therapy (VMAT) and PBPBT for patients with SSTs to see if the
therapeutic ratio improves with protons.
Methods:
Patients with SSTs
treated with radical PT in the last 5yrs are identified. Tumour motion is assessed using 4D
CT planning scans, and conformal PT, VMAT and PBPBT plans are generated for
each patient. Proton and photon plans are reviewed independently by 2
physicists experienced their respective fields. Verification plans are
created to assess dose distribution on the extreme breathing phases. PBPBT
plans undergo robustness analysis to quantify dosimetric uncertainty due to
motion and range uncertainty. TV coverage and sparing of normal tissue is
compared for each plan.
Results:
Preliminary
results show that TV coverage is best achieved with PBPBT. Verification plans
show the clinical target volume (CTV) is consistently covered by the 95%
isodose. Robustness analysis shows that in the worst case scenario, 95% of
the CTV receives 95.3% dose and no organ at risk (OAR) tolerances are
exceeded. PBPBT most significantly spares low dose to the lungs (50.1% and
41.7% reduction in lung V5 and V10 respectively) as well as a 27.4% reduction
in mean lung dose, and 57.3% reduction in oesophagus V35 compared to VMAT.
Conclusions:
Preliminary results
show that PBPBT achieves robust TV coverage that is comparable, if not
superior, to VMAT and conformal PT plans whilst sparing OARs.
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المؤتمر (6):
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عنوان المؤتمر:
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The European Society
for Radiotherapy & Oncology ESTRO 35 congress
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تاريخ الإنعقاد:
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29
April – 3 May 2016
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مكان
الإنعقاد:
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Turin, Italy
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طبيعة المشاركة:
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Poster & Oral
presentation
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عنوان المشاركة:
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Benchmarking computed
integral depth dose curves for four proton treatment planning systems against
measured data
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ملخص المشاركة:
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Purpose/Objective:
Accurate beam
modelling is an essential function of a treatment planning system (TPS) to
ensure that plans can be calculated that are deliverable within clinically
acceptable tolerances. The purpose of this work is to evaluate the computed
integral depth dose (IDD) curves of four commercially available proton TPSs,
benchmarked against measured data. The four TPSs (EclipseTM, XiO®, Pinnacle3,
RayStation®) were commissioned using pencil beam scanning data from the
University of Pennsylvania (UPenn) facility.
Materials and
Methods:
A water cube phantom
(40cm3) was created in each TPS for calculation of IDD curves. Calculation
grid size set to 1mm in all TPSs. Individual IDDs for 27 nominal energies,
ranging from 100 to 226.7MeV, were calculated by integrating the calculated
depth dose distributions. These were all benchmarked against measured data
from UPenn, comparing the clinical range at 80% distal dose (D80), Bragg peak
width between distal and proximal 80% (D80-P80), range at 0.5% (R0.5), and
distal penumbra between D80 and R0.5. Gamma-index analysis with pass criteria
of 1mm/1% was also used to compare computed and measured IDDs.
Results:
Mean percentage of
IDDs with >95% pass rate for 1mm/1% criteria were 96.7% (SD 4.9) for XiO®,
94.1% (SD 8.9) for EclipseTM, 95.4% (SD 8.6) for RayStation®, and 49.2 (SD
26.0) for Pinnacle3. Maximum differences between computed and measured IDD
data are shown below. No correlation with nominal energy was observed.
Conclusions:
Characteristics of
computed IDDs were compared to measured data for four commercially available
TPSs. All were within clinically acceptable tolerances, with XiO showing the
closest agreement. Differences observed were attributed to TPS specific beam
modelling. Further investigation will assess the cumulative impact of these
discrepancies on verified clinical treatment plans.
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