Utero-fetal unit and pregnant woman modeling using a computer graphics approach for dosimetry studies

Electroconvulsive therapy (ECT) during pregnancy: quantifying and assessing the electric field strength inside the foetal brain

Electroconvulsive therapy (ECT) is an effective treatment option for severe mental illness during pregnancy. However, there is little knowledge about the amount of electric field produced inside the foetus, which is important to understand the effects of ECT on the foetal excitable tissues. Thus, in this paper, the electric field strength inside the foetus was computed and compared to the basic restriction of the International Commission for Non-Ionizing Radiation Protection (ICNIRP). A computational human phantom representing a 30-weeks pregnant female, four types of electrode placements and a range of stimulus pulse width (0.25 ms-2 ms) and frequency (10 Hz-140 Hz) were used to compute the electric field inside the foetus. A linear relationship between the maximum electric field inside the foetal brain and the electrode current was derived. The results suggest that, considering the maximum current output, pulse width, and frequency range of constant-current ECT devices, the electric field produced inside the foetal brain is most likely below the ICNIRP basic restriction. This is based on the practical scenario of a 30-weeks foetus with a bottom-up and head-down foetal position and the mother taller than 1.62 m.

Hybrid 3D pregnant woman and fetus modeling from medical imaging for dosimetry studies

PURPOSE

Numerical simulations studying the interactions between radiations and biological tissues require the use of three-dimensional models of the human anatomy at various ages and in various positions. Several detailed and flexible models exist for adults and children and have been extensively used for dosimetry. On the other hand, progress of simulation studies focusing on pregnant women and the fetus have been limited by the fact that only a small number of models exist with rather coarse anatomical details and a poor representation of the anatomical variability of the fetus shape and its position over the entire gestation.

METHODS

In this paper, we propose a new computational framework to generate 3D hybrid models of pregnant women, composed of fetus shapes segmented from medical images and a generic maternal body envelope representing a synthetic woman scaled to the dimension of the uterus. The computational framework includes the following tasks: image segmentation, contour regularization, mesh-based surface reconstruction, and model integration.

RESULTS

A series of models was created to represent pregnant women at different gestational stages and with the fetus in different positions, all including detailed tissues of the fetus and the utero-fetal unit, which play an important role in dosimetry. These models were anatomically validated by clinical obstetricians and radiologists who verified the accuracy and representativeness of the anatomical details, and the positioning of the fetus inside the maternal body.

CONCLUSION

The computational framework enables the creation of detailed, realistic, and representative fetus models from medical images, directly exploitable for dosimetry simulations.