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Showing 3 results for Fetal Dose
M. Atarod, Dr. P. Shokrani, A. Pourmoghadas,
Volume 10, Issue 3 (12-2012)
Abstract
Background: In most cancer cases, the treatment
choice for a pregnant patient is radiotherapy. In these
patients, the abdomen is usually not exposed
therefore fetus exposure is due to peripheral dose
(PD). The purpose of this study was to estimate the
fetal dose (the maximum PD in each pregnancy
stage) for modalities available and to fabricate and
evaluate a generally applicable fetal shield. Materials
and Methods: PD values were measured for brain,
breast and mediastinum irradiation in a whole body
anthropomorphic phantom using a NE 2571
ionization chamber. An external shield was then
designed to reduce the fetal dose to the standard
dose limit, 5 mSv. Results: The range of PD values as
a function of distance from the field’s edge were as
follows 1) 9.4-259 cGy for Mantel field 2) 6.5-95 cGy
for chest wall irradiation with 10 MeV electrons, 3)
8.5- 52.5 cGy for tangential field with Co-60 and 4)
4.8-7.8 cGy for brain radiotherapy with 9 MV photon.
PD values for the same setups using the fetal shield
were as follows: 1) 1.4-22 cGy, 2) 0.5-4 cGy, 3) 1.5-5
cGy and 4) under 1 cGy. Conclusions: The measured
PD data sets can be used to estimate fetal dose for
specific treatment setups and pregnancy stages. The
use of external shield designed in this research
reduced the fetal dose effectively to under the threshold
(a 70-90% reduction), except for the final stages
of pregnancy in Hodgkin’s patients. Iran. J. Radiat.
Res., 2012 10(3‐4): 151‐156
N. Ahmadi, A. Karimian, Dr. M.n. Nasrabadi, A. Rahmim,
Volume 17, Issue 4 (10-2019)
Abstract
Background: Clinical application of PET imaging for diagnosis, staging, re-staging treatment planning and treatment response assessment have become a major focus of studies in the past decades. Fetus is more sensitive to ionizing radiation, consequently, radiation absorption risks need to be assessed carefully. The objective of this article is to accurately estimate the absorbed dose during pregnancy in PET examinations. The method adopted in this article is simulative-analytic. Materials and Methods: The absorbed dose from administrating 18F-FDG during pregnancy is estimated through the BodyBuilder anthropomorphic mathematical phantom (inexpensive) together with Monte Carlo simulations in order to obtain a reliable and feasible methodology. In this simulation, the Specific Absorbed Fractions (SAF) is estimated for organs of 3, 6 and 9-months fetal. Results: The obtained results indicate that the absorbed dose of 18F-FDG PET imaging the fetal is 2.50×10-2 mGy/MBq early; 2.04×10-2 mGy/MBq first three months of pregnancy, 1.80 ×10-2 mGy/MBq second three months, and 1.50 ×10-2 mGy/MBq in the third three months of pregnancy. Maternal absorbed dose estimation here is (R2=0.965) which perfectly corresponds to ICRP publication. Conclusion: The results from Monte Carlo code with BodyBuilder anthropomorphic phantoms and ICRP recommendation are of acceptable correlation. Applying the pure BodyBuilder anthropomorphic phantoms in this simulation, which yields agreeable results in addition to its low time consumption, corresponds to the available finding by other researchers while reducing calculation times. Moreover, the fetal & maternal absorbed doses remain however well below the threshold for any deterministic effects.
H.r. Masjedi, H. Zamani, G. Perota, R. Omidi, E. Razavi, Ph.d., M.h. Zare,
Volume 20, Issue 1 (1-2022)
Abstract
Background: This study aimed to assess the risks of exposure-induced death (REID) in patients and embryos during CT examinations in Yazd province (Iran). Materials and Methods: Data on the exposure parameters were retrospectively collected from six imaging institutions. In total, 932 patients were included in this study and for each patient, organ doses were then estimated using ImpactDose software. The REIDs were calculated by BEIR VII risk model and using PCXMC software. In the case of gestational irradiation, excess cancer risk of 0.006% per mSv was taken into account in terms of the ICRP 84 recommendations, to calculate the excess childhood cancer risk imposed on the embryo. Results: The highest estimated organ doses for abdomen-pelvis, routine chest, chest HRCT, brain, and sinus examinations were obtained as 12.82 mSv for kidneys, 12.09 mSv for thymus, 13.16 mSv for thymus, 29.71 mSv for brain, and 11.70 mSv for oral mucosa, respectively. Across all procedures, abdomen-pelvis CT scan induced the highest excess REID to the patients (240 deaths per million). The highest delivered dose to the fetus was roughly 35 mSv, which was lower than the threshold dose proposed by ICRP (100 mSv) for the induction of malformations. However, the associated excess fatal childhood cancer risk of 2122 incidence per million scans can be a subject of concern for public health experts. Conclusion: Based on the results, although death risks related to induced cancer from CT scans were negligible, this risk can be relatively significant for children exposed during the fetal period.
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