pept 0.2.1

A Python library that unifies Positron Emission Particle Tracking (PEPT) research, including tracking, simulation, data analysis and visualisation tools.

The pept Library

A Python library that integrates all the tools necessary to perform research using Positron Emission Particle Tracking (PEPT). It includes algorithms for the location, identification and tracking of particles, in addition to tools for visualisation and analysis, and utilities allowing the realistic simulation of PEPT data.

Positron Emission Particle Tracking

PEPT is a technique developed at the University of Birmingham which allows the non-invasive, three-dimensional tracking of one or more 'tracer' particles through particulate, fluid or multiphase systems. The technique allows particle or fluid motion to be tracked with sub-millimetre accuracy and sub-millisecond temporal resolution and, due to its use of highly-penetrating 511keV gamma rays, can be used to probe the internal dynamics of even large, dense, optically opaque systems - making it ideal for industrial as well as scientific applications.

PEPT is performed by radioactively labelling a particle with a positron-emitting radioisotope such as fluorine-18 (18F) or gallium-66 (66Ga), and using the back-to-back gamma rays produced by electron-positron annihilation events in and around the tracer to triangulate its spatial position. Each detected gamma ray represents a line of response (LoR).

Transforming gamma rays, or lines of response (left) into individual tracer trajectories (right) using the `pept` library. Depicted is experimental data of two tracers rotating at 42 RPM, imaged using the University of Birmingham Positron Imaging Centre's parallel screens PEPT camera.

Getting Started

These instructions will help you get started with PEPT data analysis.

Prerequisites

This package supports Python 3.6 and above. You can install it using the batteries-included Anaconda distribution or the bare-bones Python interpreter. You can also check out our Python and pept tutorials here.

Installation

You can install the latest official version of pept from PyPI:

pip install -U pept

Or you can install the development version from the GitHub repository:

pip install git+https://github.com/uob-positron-imaging-centre/pept

Example usage

A minimal analysis script using the PEPT-ML algorithm from the pept.tracking.peptml package:

import pept
from pept.tracking import peptml

# Read in LoRs from a web-hosted CSV file.
lors_raw = pept.utilities.read_csv(
    ("https://raw.githubusercontent.com/uob-positron-imaging-centre/"
     "example_data/master/sample_2p_42rpm.csv"),    # Concatenate long string
    skiprows = 16                                   # Skip file header
)

# Encapsulate LoRs in a `LineData` subclass and compute cutpoints.
lors = pept.scanners.ParallelScreens(lors_raw, screen_separation = 712)
cutpoints = peptml.Cutpoints(lors, max_distance = 0.15)

# Cluster cutpoints using HDBSCAN and extract tracer locations.
clusterer = peptml.HDBSCANClusterer()
centres = clusterer.fit(cutpoints)

# Plot tracer locations using Plotly.
grapher = pept.visualisation.PlotlyGrapher()
grapher.add_points(centres)
grapher.show()

Running the above code initialises 80,000 lines of PEPT data from an online location (containing the same experiment as before - two tracers rotating at 42 RPM), transforms lines of response into accurate tracer locations and plots them in a 3D interactive browser-based graph:

You can download some PEPT data samples from the UoB Positron Imaging Centre's Repository:

$> git clone https://github.com/uob-positron-imaging-centre/example_data

Tutorials and Documentation

A very fast-paced introduction to Python is available here; it is aimed at engineers whose background might be a few lines written MATLAB, as well as moderate C/C++ programmers.

A beginner-friendly tutorial for using the pept package is available here.

The links above point to Google Colaboratory, a Jupyter notebook-hosting website that lets you combine text with Python code, executing it on Google servers. Pretty neat, isn't it?

Full documentation for the pept package is available here.

Performance

Significant effort has been put into making the algorithms in this package as fast as possible. The most computionally-intensive parts have been implemented in C / Cython and parallelised using joblib and concurrent.futures.ThreadPoolExecutor. For example, using the peptml subpackage, analysing 1,000,000 LoRs on the author's machine (mid 2012 MacBook Pro) takes ~26 s.

Help and Support

We recommend you check out our tutorials. If your issue is not suitably resolved there, please check the issues page on our GitHub. Finally, if no solution is available there, feel free to open an issue; the authors will attempt to respond as soon as possible.

Contributing

At the moment, the subpackages in pept.tracking are biased towards PEPT-ML, as there aren't many algorithms integrated into package yet. New algorithms and/or recommendations for the package are more than welcome! pept aims to be a community effort, be it academic, industrial, medical, or just from PEPT enthusiasts - so it is open for help with documentation, algorithms, utilities or analysis scripts, tutorials, and pull requests in general! To contribute please fork the project, make your changes and submit a pull request. We will do our best to work through any issues with you and get your code merged into the main branch.

Citing

If you used this codebase or any software making use of it in a scientific publication, we ask you to cite the following paper:

Nicuşan AL, Windows-Yule CR. Positron emission particle tracking using machine learning. Review of Scientific Instruments. 2020 Jan 1;91(1):013329.

https://doi.org/10.1063/1.5129251

Licensing

The pept package is GNU v3.0 licensed. Copyright (C) 2020 Andrei Leonard Nicusan.