2024-03-29T17:01:36+03:30
http://ijrr.com/browse.php?mag_id=28&slc_lang=en&sid=1
28-577
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Prostate Helical Tomotherapy: A semi-empirical estimation of the scaling factor based on 2D approximating field
G.
Grigorov
grigorovgn@yahoo.ca
J.C.L.
Chow
Background: In Helical Tomotherapy (HT), the
scaling factor (SF) is the time in seconds that each
leaf viewing a target would need to be open to deliver
the prescribed dose. The SF is patient-specific and is
used to calculate the rotational period of the gantry,
and the total treatment time (TTT) of the HT. The SF is
generally difficult to estimate. Currently, it takes
about one hour to fully optimize a prostate HT plan
and to calculate the corresponding TTT. The aim of
this study is to develop a method for estimation of
the SF directly using a patient-specific approximating
function. Materials and Methods: The SFs of ten
randomly selected patients were used to build the
approximation model. For the entire group of patients
the PTV1 ranged from 57 to 396 cm3 for PTV1 margins
from 2 to 10 mm. The discrete data for every patient
is represented by an individual function, SF=f (k×
PTV1). The values of the function were rescaled to a
special unit which represents the target volume irradiated
with the prescribed dose per second. The values
were normalized with two “geometric” parameters,
namely, the target-to-target and the body-to-body
ratios. After the normalization, the function for every
patient was ordered in the file by the volume of the
prostate and seminal vesicles. Results: For prostate
HT planning, it was found that the planning target
volume (PTV1) has a higher impact on the SF values
than the size of the patient's bodies. The function
SF=f (k×PTV1) was found smooth and continuous over
the given interval. The rescaled and normalized
functions for all patients were represented as delimiters
of a 2D field. Conclusion: The method proposed
for determination of the SF and TTT for HT prostate
planning covers PTV1 of four margins and a volume of
prostate and seminal vesicles ranging from 42.8 to
161 cm3. Using these approximations, the TTTs for a
second group of patients were determined in several
minutes with deviation ranging from −2.8% to +7.1%
compared to that of the TTTs calculated using the HT
planning system. Iran. J. Radiat. Res., 2010 7 (4): 177-185
Helical tomotherapy
prostate treatment
scaling factor.
2010
3
01
177
185
http://ijrr.com/article-1-577-en.pdf
28-578
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Ameliorating effects of genestein: Study on mice liver glutathione and lipid peroxidation after irradiation
A.
Gaur
ajay_gaur11@yahoo.com
Background: Genistein is a soya isoflavone,
which is found naturally in legumes, such as
soybeans and chickpeas. Radiation–induced free
radicals in turn impair the antioxidative defense
mechanism, leading to an increased membrane lipid
peroxidation that results in damage of the membrane
bound enzyme and may lead to damage or death of
cell. Hence, the lipid peroxidation is a good biomarker
of damage occurs due to radiation and the inhibition
of lipid peroxidation is suggestive of radioprotective
action. Glutathione has been shown to protect cells
against oxidative stress by reacting with peroxides
and hydroperoxides and determines the inherent
radiosensitivity of cells. Materials and Methods: For
experimentation, healthy Swiss Albino male mice of 6
-8 weeks old were selected from inbred colony.
Genistein was dissolved in dimethyl sulfoxide and
then prepared different concentration solutions so
that the volume administered intraperitoneally was
0.5 ml. Lipid peroxidation was estimated by the
method of Ohkawa and GSH was estimated by the
method of Moron. Results: The intraperitoneal
administration of optimum dose (200 mg/kg body
weight) of Genistein before 24 hrs and 15 minutes of
irradiation (8 Gy at a dose rate of 1.02 Gy/min)
reverted the increase in lipid peroxidation (by 18.01%
± 3.05) and decrease of Glutathione (by 62.05% ±
21.58) caused by irradiation in liver of Swiss albino
mice. Statistically analyzed survival data produced a
dose reduction factor (DRF) = 1.24. Conclusion: The
results indicate that Genistein against radiation effect
may pave way to the formulation of medicine in
radiotherapy for normal tissue and possible against
radiomimetic drug induced toxicity. Iran. J. Radiat.
Res., 2009 7 (4): 187-199
Genistein
tyrosine kinase inhibitor
radiation
liver
oxidative stress.
2010
3
01
187
199
http://ijrr.com/article-1-578-en.pdf
28-579
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Individual virtual phantom reconstruction for organ dosimetry based on standard available phantoms
F.
Babapour Mofrad
farshid.mofrad@yahoo.com
R.
Aghaeizadeh Zoroofi
A.
Abbaspour Tehrani Fard
Sh.
Akhlaghpoor
Y.W.
Chen
Y.
Sato
Background: In nuclear medicine application
often it is required to use computational methods for
evaluation of organ absorbed dose. Monte Carlo
simulation and phantoms have been used in many
works before. The shape, size and volume in organs
are varied, and this variation will produce error in
dose calculation if no correction is applied. Materials
and Methods: A computational framework for
constructing individual phantom for dosimetry was
performed on five liver CT scan data sets of Japanese
normal individuals. The Zubal phantom was used as
an original phantom to be adjusted by each individual
data set. This registration was done by Spherical
Harmonics (SH) and Thin-Plate Spline methods.
Hausdorff distance was calculated for each case.
Results: Result of Hausdorff distance for five individual
phantoms showed that before registration ranged
from 140.9 to 192.1, and after registration it
changed to 52.5 to 76.7. This was caused by index
similarity ranged from %56.4 to %70.3. Conclusion: A
new and automatic three-dimensional (3D) phantom
construction approach was suggested for individual
internal dosimetry simulation via Spherical Harmonics
(SH) and Thin-Plate Spline methods. The results
showed that the individual comparable phantom can
be calculated with acceptable accuracy using
geometric registration. This method could be used for
race-specific statistical phantom modeling with major
application in nuclear medicine for absorbed dose
calculation. Iran. J. Radiat. Res., 2010 7 (4): 201-206
Dosimetry
individual phantom
thin-plate spline
Monte Carlo simulation
spherical harmonics.
2010
3
01
201
206
http://ijrr.com/article-1-579-en.pdf
28-580
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Activity concentrations of natural radionuclide levels in well waters of Ago Iwoye, Nigeria
O.O.
Fasunwon
sfasunwon@yahoo.co.uk
S.K.
Alausa
R.K.
Odunaike
I.M.
Alausa
F.M.
Sosanya
B.A.
Ajala
Background: Natural Radioactivity, though
natural requires concentration monitoring, especially
for the health/ environmental checks of the
populace. Materials and Methods: The activity
concentrations of 40K, 238U and 232Th in the waters
from wells with depths ranging between 141.0 -
214.0 feet were randomly sampled and determined
from 20 locations in Ago-Iwoye town in South
Western, Nigeria. Results: The activity concentrations
obtained were in the ranges of (9.9-50.9)Bq/kg with
mean value of (25.1± 10.7) Bq/kg for 40K, (BDL-15.0)
Bq/kg with mean value of (1.2 ± 3.2) Bq/kg for 238U
and (BDL-6.2) Bq/kg with mean value of (1.6 ± 1.7)
Bq/kg for 232Th. Conclusion: According to the results
obtained for the activity concentrations from 20 well
water samples in Ago Iwoye, Southwestern, Nigeria it
was observed that the v40K, 238U and 232Th values
were still within the tolerance level indicating minimal
radiological health burden on the human populace
and the environment. Iran. J. Radiat. Res., 2010 7 (4):
207-210
Well water
depth
locations
activity concentration
health hazard
Ago Iwoye.
2010
3
01
207
210
http://ijrr.com/article-1-580-en.pdf
28-581
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Evaluation of combination effects of 2- methoxyestradiol and methoxyamine on IUdRinduced radiosensitization in glioma spheroids
A.
Neshasteh-Riz
neshastehriz@yahoo.com
S.
Babaloui
S.
Khoei
Background: Glioblastoma is the most common
and most malignant cancer of central nervous
system. Targeted radiotherapy is an effective method
toward its treatment. Iododeoxyuridine (IUdR) is a
halogenated thymidine analogue known to be
effective as a radiosensitizer in human cancer
therapy. In this study we have evaluated the combination
effects of 2-Methoxyestradiol, an inhibitor of
hypoxia inducible factor 1α (HIF-1α) and
Methoxyaminem, an inhibitor of base excision repair
(BER) pathway on radiosensitization of IUdR in
glioblastoma spheroid culture. Materials and
Methods: The cytotoxic damages of DNA in U87MG
cell line were compared using colony formation assay.
Experiments were performed in large spheroids with
a diameter of approximately 350μm. Results:
Evaluation of the effects of IUdR with 2ME2 and MX
pretreatment on spheroid cultured cell followed by
ionizing irradiation showed more enhancemented
(p≤0.001) IUdR induced-radiosensitization. These
results introduced a key role for 2ME2 in IUdR related
studies. Conclusion: Pretreatment of tumor cells with
IUdR, MX and 2ME2 before irradiation enhances
tumor radiosensitization and may improve therapeutic
index for IUdR and 2ME2. Iran. J. Radiat. Res.,
2010 7 (4): 211-216
Hypoxia-inducible factor-1α
IUdR
radiosensitization
spheroid
methoxyamine
2-methoxyestradiol.
2010
3
01
211
216
http://ijrr.com/article-1-581-en.pdf
28-582
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Comparison of dosimetry parameters of two commercially available Iodine brachytherapy seeds using Monte Carlo calculations
M.
Zehtabian
mehdizehtabian@yahoo.com
R.
Faghihi
S.
Sina
Background: Iodine brachytherapy sources with
low photon energies have been widely used in
treating cancerous tumors. Dosimetric parameters of
brachytherapy sources should be determined
according to AAPM TG-43U1 recommendations
before clinical use. Monte Carlo codes are reliable
tools in calculation of these parameters for brachytherapy
sources. Materials and Methods: Dosimetric
parameters (dose rate constant, radial dose function,
and anisotropy function) of two I-125 brachytherapy
sources (models LS-1 and Intersource) were
calculated with MCNP4C Monte Carlo code following
task group #43 (TG-43U1) recommendations of
American Assossiation of Physicists in Medicine. The
simulations were done inside a spherical water
phantom because of its tissue equivalent properties.
The Monte Carlo simulations for radial dose function
were performed at distances ranging from 0.25 to 10
cm from the source center. The anisotropy functions
F(r, θ), for both sources, were calculated at distances
of 1, 2, 3, 5 and 7 cm from the source center for
angles ranging from 15 to 90 degree. Results: The
results of the Monte Carlo simulation indicated a
dose rate constant of 0.952 cGyh -1U-1 and 0.986
cGyh -1U-1 for models LS-1 and Intersource,
respectively. The tabulated data and fifth order
polynomial coefficients for radial dose functions
along the source are described in this paper. The
results indicated that the anisotropy in dose
distribution increased along the source axis.
Conclusion: The obtained results were in good agreement
with measurements and calculations of other
investigators, using other Monte Carlo codes. Iran. J.
Radiat. Res., 2010 7 (4): 217-222
Brachytherapy
radial dose function
Monte Carlo
TG-43.
2010
3
01
217
222
http://ijrr.com/article-1-582-en.pdf
28-583
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
A Monte Carlo simulation and dosimetric verification of physical wedges used in radiation therapy
M.
Momennezhad
M.T.
Bahreyni Toosi
R.
Sadeghi
H.
Gholamhoseinian
Sh.
Nasseri
NaseriSh801@mums.ac.ir
Background: The presence of a wedge filter in
the beam trajectory can modify the beam quality and
cause some changes in the dosimetry parameters
which are usually difficult to be measured directly and
accurately. Material and Methods: In this study the
MCNP-4C Monte Carlo code was used to simulate the
9 MV photon beam generated by a linear accelerator.
Upon getting a good agreement between the Monte
Carlo simulated and measured dose distribution in
open fields, the model was used to simulate the
physical wedges. The steel wedges with angles from
15º-60º were modeled and the primary and the
secondary photon beams were calculated. The beam
profiles and wedges factors were calculated for each
wedge. The output factors were determined for 45 wedge. The calculated data were compared with the
measured values of the same parameters. Results:
The results showed that the use of wedges reduced
the fluencies of the primary and scattered photons
and also increased the average energy of the primary
and the scattered photons. The agreement between
the calculated and the measured data was better
than 2% for all wedges. The results also showed that
as the wedge angle increased, the electron contamination
of photon beam decreased. Conclusion: The
presence of a wedge in a 9 MV photon beam alters
the primary and the scattered components generated
by a linear accelerator. The simulated linac machine
and its associated data can be used to predict the
dose distribution in other complex fields. Iran. J.
Radiat. Res., 2010 7 (4): 223-227
Monte Carlo
photon spectra
physical wedge
MCNP4c code
simulation.
2010
3
01
223
227
http://ijrr.com/article-1-583-en.pdf
28-584
2024-03-29
10.1002
International Journal of Radiation Research
Int J Radiat Res
2322-3243
2345-4229
10.61186/ijrr
2010
7
4
Production of 177Lu and formulation of Ethylene diamine tetramethylene phosphonate (EDTMP) kits as a bone-seeking radiopharmaceutical
F.
Johari Daha
S.
Shafiei
Sh.
Sheibani
Y.H.
Tavakoli
M.
Mazidi
M.H.
Mirfalah
M.H.
Babaei
mbabaei@aeoi.org.ir
Background: Owing to its favourable decay
characteristics 177Lu [T1/2= 6.71 d, Eβ(max)= 497
keV] is an attractive radionuclide for various
therapeutic applications. Ethylene diamine tatramethylene
phosphonate (EDTMP) is one of the most
widely used ligands which form stable complexes with
various radionuclides and all the complexes.
Materials and Methods: Enriched 176Lu2O3 was
dissolved in 0.1 N HCl and evaporated several times
and 176LuCl3 target was irradiated at 2.6×1013 n.Cm-
2.S-1 thermal neutron flux for 14 days.177LuCl3 was
dissolved in 1N HCl. EDTMP was dissolved in double
distilled water at pH=7.5-8.5 and freeze-dried kits
was radiolabeled with 177LuCl3. Distribution studies
were done in healthy mice. Results: The yield of 177Lu
was (~220 TBq/g 6000 Ci/g), the radionuclidic purity
was ~99%.The radiolabeling yield of EDTMP kits at
37°C after 30 min and 4 hours was 98±0.5% and
after 72 hours was 90±2.1%, the in vitro stability in
human serum at 37°C up to 72 hours post radiolabeling
was 85±1.8%.The biodistribution studies of
177Lu-EDTMP and 177LuCl3 in normal mice showed
skeleton uptake and low soft-tissue concentration.
Conclusion: In this study, we produce ~220 TBq/g
(6000 Ci/g) of 177Lu by neutron activation of 176Lu in
the Tehran Research Reactor. Our results showed
177Lu-EDTMP as a bone-seeking radiopharmaceutical.
Due to its suitable nuclear characteristics 177Lu
appears to be worthwhile for palliative therapy of
bone metastasis. Iran. J. Radiat. Res., 2010 7 (4): 229-234
DTMP
Bone-seeking radiopharmaceuticals
177Lu.
2010
3
01
229
234
http://ijrr.com/article-1-584-en.pdf