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Showing 2 results for Mird.
Dr. D. Shahbazi-Gahrouei, S. Nikzad,
Volume 8, Issue 4 (3-2011)
Abstract
Background: Radioiodine therapy has proven to
be an effective method in the treatment of patients
with differentiated thyroid carcinoma after thyroidectomy.
The scope of this study is to describe a method
to obtain the dose of organs using medical internal
radiation dosimetry (MIRD) method. At the end, the
results of MIRD calculations were compared with
thermoluminescent dosimeter (TLD-100). Materials
and Methods: The study was performed on 27
patients using TLD for thyroid, sternum and cervical
vertebra. There were 5 TLDs for each organ which
they were taken after 4, 8, 12, 20 and 24 hr. To
calculate the amount of activity in the thyroid a head
and neck phantom with a source of 10 mCi of 131I
was used. A head and neck phantom was used to
determine the absorbed dose. A source of 10 mCi of
131I was putted on phantom. Several TLDs were
placed on the surface of thyroid on phantom for 24 hr
and then compared with the dose of phantom and
patients followed by calculation of the activity in
patient's thyroid. Finally, MIRD formula was used to
calculate absorbed dose in cervical vertebra and
sternum. Results: The average of measurements of
TLDs on phantom for 10 mCi of iodine was 33.3 cGy.
The absorbed activity in thyroid in three groups for
100, 150 and 175 mCi administered 131I were 94.9,
104.6 and 108.8 mCi cumulated activity in 24 hrs.
The absorbed dose obtained by MIRD calculations
was found to be 419.9, 463.2, and 481.5 for thyroid,
288.9, 252.4 and 252.4 for sternum and 288.9,
252.4 and 252.4 for cervical vertebra. Conclusions:
The results of MIRD method was similar to the results
obtained experimentally. It was shown that 75% of
absorbed dose calculated by the MIRD method is
detectable by the TLD method. Iran. J. Radiat. Res.,
2011 8(4): 249-252
H. Liu, Ph.d., C. Geng, X. Tang, L. Tang, X. Li, P. Xu,
Volume 20, Issue 2 (4-2022)
Abstract
Background: This study aims to investigate voxel-level dose calculation methods and improve its calculation efficiency in nuclear medicine that can consider animal-specific heterogeneous tissue compositions and radiopharmaceutical biodistributions simultaneously. Materials and Methods: The voxelized mouse phantom was constructed from real mouse CT images and simulated using the Monte Carlo GEANT4 code. According to the dynamic PET images of real mouse, the real distribution of radiopharmaceutical activity was set in the Monte Carlo simulation. The sampling method to improve the calculation efficiency was proposed. Two voxel-level dose calculation methods were implemented in this study. The average absorbed dose in vital target organs and the tumor was calculated by the proposed voxel-level dose calculation methods and the traditional MIRD method respectively. The results of the average absorbed dose calculated by the two methods were compared. Based on the voxel-level dose calculation method, the three-dimensional dose distribution in organs and the tumor was obtained and evaluated. Results: The relative difference of average absorbed dose between the two voxel-level dose calculation methods was mostly less than 10%. The sampling method proposed to improve calculation efficiency for the voxel-level dose calculation can decrease the calculation time by ~34% with less deviation. Conclusion: The results confirmed that the voxel-level dose calculation methods proposed in this study allow for more accurate and efficient assessment of the internal radiation dose.
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