PyTomography: A Python Library for Quantitative Medical Image Reconstruction

Background: There is a scarcity of open-source libraries in medical imaging dedicated to both (i) the development and deployment of novel reconstruction algorithms and (ii) support for clinical data. Purpose: To create and evaluate a GPU-accelerated, open-source, and user-friendly image reconstruction library, designed to serve as a central platform for the development, validation, and deployment of novel tomographic reconstruction algorithms. Methods: PyTomography was developed using Python and inherits the GPU-accelerated functionality of PyTorch for fast computations. The software uses a modular design that decouples the system matrix from reconstruction algorithms, simplifying the process of integrating new imaging modalities or developing novel reconstruction techniques. As example developments, SPECT reconstruction in PyTomography is validated against both vendor-specific software and alternative open-source libraries. Bayesian reconstruction algorithms are implemented and validated. Results: PyTomography is consistent with both vendor-software and alternative open source libraries for standard SPECT clinical reconstruction, while providing significant computational advantages. As example applications, Bayesian reconstruction algorithms incorporating anatomical information are shown to outperform the traditional ordered subset expectation maximum (OSEM) algorithm in quantitative image analysis. PSF modeling in PET imaging is shown to reduce blurring artifacts. Conclusions: We have developed and publicly shared PyTomography, a highly optimized and user-friendly software for quantitative image reconstruction of medical images, with a class hierarchy that fosters the development of novel imaging applications.Comment: 26 pages, 7 figure

Electrochemical evaluation of ion substituted-hydroxyapatite on HeLa cells plasma membrane potential

This study reports the electrochemical activities of a novel ion substituted-Hydroxyapatite (HAp) material in contact with HeLa cells. The work was performed to evaluate the inhibitory effects of various concentrations of HAp on ion transfer mechanisms in HeLa cells. The materials (n = 2: HAp1 and HAp3) were prepared at different stirring times from Achatina achatina snail shells and phosphate-containing solution. The structure of the materials and the trace elements concentration were evaluated using x-ray diffractometry and infrared spectrometry as well as atomic absorption spectroscopy. Electrochemical studies conducted on the cells after 30 min of exposure to the materials demonstrated different responses as elucidated by cyclic voltammetry. The voltammograms revealed HAp1 to be non-redox whereas HAp3 was redox active. Minimal concentrations of HAp1 showed high anodic peak current when compared to the HeLa cells alone, indicating a hyperpolarization of the cells. The peak current gradually reduced as the concentration of HAp1 was increased, and then followed by a sudden rise suggesting inhibition of the cell action potential. HAp3 showed a wavy pattern of the anodic peak current when the material concentration was varied. Peak currents of $$0.92 \pm 0.03$$ nA and $$0.57 \pm 0.01$$ nA were recorded for HAp1 and HAp3, respectively at the highest concentration of 5 µL. The results suggest that different inhibitory mechanisms are at play on the voltage-gated ion channels of the cells, indicating the possibility of using the materials to achieve different cancer proliferation inhibition