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Showing 3 results for Absorbed Dose.
Dr. I.r. Ajayi,
Volume 5, Issue 4 (3-2008)
Abstract
Background: The equivalent dose in the human body due to the natural gamma-emitting radionucides (238U, 232Th and 40K) in the surface soil surrounding the Consolidated Tin mine site in Bukuru-Jos, Nigeria has been determined in this study. Materials and Methods: Measurements of the soil natural radioactivity were made using a multi-channel pulseheight analyzer (Canberra Series 10 plus) coupled to a 76 mm×76 mm Nal (Tl) scintillation detector. Results: The mean concentrations obtained for each of the radionuclides is 35.4±17.6 Bq/kg for 40K 776.0± 158.0 Bq/kg for 238U and 2.72±0.58 kBq/kg for 232Th. The mean absorbed dose rate due to natural radioactivity calculated at a height of 1.0 m above the ground is 2.16 µGy/hr which converts to an equivalent dose of 3.0 mSv/y. Conclusion: The results obtained in this study are far above the world average equivalent dose of 0.41 mSv/y but lower than the annual limit of 20 mSv/y for radiation workers but still represents a health risk to workers on the site.
M. Allahverdi, M. Zabihzadeh, M.r. Ay, S.r. Mahdavi, M. Shahriari, A. Mesbahi, H. Alijanzadeh,
Volume 9, Issue 1 (6-2011)
Abstract
Background: The electron contamination may
reduce or even diminish the skin sparing property of
the megavoltage beam. The detailed characteristics
of contaminant electrons are presented for different
field sizes and cases. Materials and Methods: The
Monte Carlo code, MCNPX, has been used to
simulate 18 MV photon beam from a Varian
Linac-2300 accelerator. All dose measurements
were carried out using a PTW-MP2 scanner with an
ionization chamber (0.6 CC) at the water phantom.
Results: The maximum electron contaminant dose at
the surface ranged from 6.1 % for 5 × 5 cm2 to 38.8
% for 40 × 40 cm2 and at the depth of maximum
dose was 0.9 % up to 5.77 % for the 5 × 5 cm2 to the
40 × 40 cm2 field sizes, respectively. The additional
contaminant electron dose at the surface for the field
with tray increased 2.3 % for 10 × 10 cm2, 7.3 % for
20 × 20 cm2, and 21.4 % for 40 × 40 cm2 field size
comparing to the standard field without any
accessories. This increase for field with tray and
shaping block was 5.3 % and 13.3 % for 10 × 10 and
20 × 20 cm2, respectively, while, the electron
contamination decreased for the fields with wedge,
i.e. 2.2 % for the 10 × 10 cm2 field. Conclusion: The
results have provided more comprehensive knowledge
of the high-energy clinical beams and may be
useful to develop the accurate treatment planning
systems capable of taking the electron contamination
in to account. Iran. J. Radiat. Res., 2011 9(1): 15-28
Ph.d., H.m.h. Zakaly, M.y.a. Mostafa, M. Zhukovsky,
Volume 18, Issue 4 (10-2020)
Abstract
Background: Monoclonal antibodies have confirmed their merit as biotherapeutics across a wide spectrum of diseases, including cancer, heart disease, infection, and immune disorders. Materials and Methods: The dynamics of 89Zr-labelled monoclonal antibodies (MAb) after injection into the human body are modelled. This modified biokinetic model can be used for dose assessment not only for 89Zr-labelled MAb tumour visualization but also for diagnostic and radiation therapy with other MAb-labelled radionuclides. The created modified biokinetic model is based on experimental data from the literature. The cumulative 89Zr activity in organs and tissues per Bq of administered activity is calculated with the WinAct program. Results: For the organs receiving the highest radiation exposure, the average absorbed doses were estimated with IDAC 2.1 software. The results from the modelled calculations are compared with new published experimental diagnostic results from real patients. The calculations reveal that the organs which received the highest dose were the spleen, liver, kidneys, and red bone marrow (doses of 1.54, 1.33, 0.81 and 0.82 mGy/MBq, respectively). In the modified biokinetic model, the organs exhibiting the highest dose were the liver, gallbladder wall, spleen, pancreas, and kidneys (at 1.07, 0.77, 0.70, 54 and 0.44 mGy/MBq, respectively), when the injection was associated with monoclonal antibodies. Conclusion: The developed biokinetic model is in good agreement with direct measurements and can be considered a first step for simulating the radiopharmaceutical dosimetry of the 89Zr isotope.
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