The contributions of source regions to organ doses from incorporated radioactive iodine

Hoseinian-Azghadi, Elie; Rafat-Motavalli, Laleh; Hakimabad, Seyyed Hashem Miri

doi:10.1051/radiopro/2014014

Cited by 6 publications

(8 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the S factors for the ICRP reference phantoms could be estimated using SAF data provided by ICRP publication 133, 24 we directly calculated S factors for the ICRP adult female (AF) phantom as the standard data, using Monte Carlo method [25][26][27][28] to avoid possible uncertainties associated with the interpolation of SAF data. These standard values could be corrected for self-S factors when the organ mass is known for each patient.…”

Section: B2 Methods Ii: Available Standard S Factorsmentioning

confidence: 99%

Patient‐specific anatomical models for radioiodine dosimetry in treatment of hyperthyroidism: is it necessary?

2020

View full text Add to dashboard Cite

Purpose: To investigate the necessity of patient-specific dosimetry calculations using individualized models for hyperthyroid patients treated with radioactive iodine (RAI). This treatment modality was considered to be safe and effective; however, a recent publication indicated associations between greater organ-absorbed doses of RAI and risk of cancer death. Methods: Ten patient-specific models which ranged in size were used (from 152.5 to 184 cm in height and from 44 to 88 kg in mass). The time-integrated activity coefficients (TIAC) were evaluated from the 2017 Leggett's model assuming 24 h radioactive iodine uptakes (RAIU) of 30, 50, 70, and 90% and two intake routes for normal uptake (ingestion and injection). A set of 131 I S factors (mGy MBq-1 h-1) from the patient-specific phantoms including 12 source regions were provided in this study. These S factors were used together with the new TIACs to present dose coefficients. Results: The MC-based patient-specific S factors were compared with the ICRP standard data and the variation ranges (%) of (−65, +210) and (−57, +193) were reported for self and cross S factors, respectively. However, for self S factors, those intervals were reduced to (−8.3, +4.6) when mass correction was applied. Moreover, variations on organ dose coefficients were evaluated and the thyroid contributions were also assessed for 24 h RAIU of 30, 50, 70, and 90%. Considering that the thyroid contribution to adjacent normal organs is high and the variations on cross dose coefficients are also considerable, variations (%) on normal organ doses were estimated to be up to (−63, +132), with a planned thyroid absorbed dose of 150 Gy. Conclusion: Given the large variations on organ doses, the standard data are not an appropriate substitute for patient-specific data. Particularly, when accurate patient-specific dose estimation is a serious concern in RAI treatment (RAIT) for nuclear medicine practitioners. However, acquiring computed tomography (CT) images for patient-specific modeling will impose additional radiation dose to patients. It was concluded that CT imaging limited to the region from skull base to mid thorax (i.e., for organs with RAIT doses of >~50 mGy with a dose of 150 Gy prescribed to the thyroid) may be suggested and is clinically relevant because the normal organ dose increments are not greater than 10%.

show abstract

Section: B2 Methods Ii: Available Standard S Factorsmentioning

confidence: 99%

Patient‐specific anatomical models for radioiodine dosimetry in treatment of hyperthyroidism: is it necessary?

2020

View full text Add to dashboard Cite

show abstract

“…To explain the variations in fetal doses at different stages of pregnancy, we computed chord lengths between point pairs in a region of interest (as source) and the fetus (as target). The amount of points in each region was sampled randomly and the distributions of the resulting chord lengths were attained . Considering that internal scattering has the most contribution (almost 98%) in the absorbed doses of organs located outside of the scanned area (i.e., fetal organ in a chest scan), the distance between the fetus and the scan region affects the fetal dose.…”

Section: Methodsmentioning

confidence: 99%

“…The amount of points in each region was sampled randomly and the distributions of the resulting chord lengths were attained. 37 Considering that internal scattering has the most contribution (almost 98%) in the absorbed doses of organs located outside of the scanned area (i.e., fetal organ in a chest scan), 24 the distance between the fetus and the scan region affects the fetal dose. Therefore, the distribution of the CLD between fetus and CT scan region was also estimated by the mentioned method.…”

Section: D Calculation Of Cldsmentioning

confidence: 99%

See 1 more Smart Citation

Pulmonary embolism in pregnant patients: Assessing organ dose to pregnant phantom and its fetus during lung imaging

et al. 2017

View full text Add to dashboard Cite

show abstract

“…For this purpose, 10 4 point pairs have been sampled randomly in the organ of interest, and the distributions of the resulting chord-lengths were evaluated [11]. The process of calculating CLDs is described in more detail in [12][13][14][15][16].…”

Section: Chord Length Distributionsmentioning

confidence: 99%

Dosimetric factors for diagnostic nuclear medicine procedures in a non-reference pregnant phantom

Rafat-Motavalli

Hakimabad²,

Hoseinian-Azghadi³

2018

J. Radiol. Prot.

View full text Add to dashboard Cite

This study evaluates the impact of using non-reference fetal models on the fetal radiation dose from diagnostic radionuclide administration. The six-month pregnant phantoms including fetal models at the 10th and 90th growth percentiles were constructed at either end of the normal range around the 50th percentile and implemented in the Monte Carlo N-Particle code version MCNPX 2.6. This code has then been used to evaluate the Tc S factors of the target organs of interest, as this is the most commonly used radionuclide in nuclear medicine procedures. Substantial variations were observed in the S factors between the 10th/90th percentile phantoms from the 50th percentile phantom, with the greatest difference being 38.6%. When the source organs were in close proximity to, or inside the fetal body, theTc S factors presented strong statistical correlations with fetal body habitus. The trends observed in the S factors and the differences between various percentiles were justified by the source organs' masses, and chord length distributions. The results of this study showed that fetal body habitus had a considerable effect on fetal dose (on average up to 8.4%) if constant fetal biokinetic data were considered for all fetal weight percentiles. However, a smaller variation on fetal dose (up to 5.3%) was obtained if the available biokinetic data for the reference fetus were scaled by fetal mass.

show abstract

The contributions of source regions to organ doses from incorporated radioactive iodine

Cited by 6 publications

References 15 publications

Patient‐specific anatomical models for radioiodine dosimetry in treatment of hyperthyroidism: is it necessary?

Patient‐specific anatomical models for radioiodine dosimetry in treatment of hyperthyroidism: is it necessary?

Pulmonary embolism in pregnant patients: Assessing organ dose to pregnant phantom and its fetus during lung imaging

Dosimetric factors for diagnostic nuclear medicine procedures in a non-reference pregnant phantom

Contact Info

Product

Resources

About