# diffct > Differentiable projectors and matched adjoints for computed tomography in PyTorch: native NVIDIA CUDA kernels and a portable backend for CPU, ROCm and Apple Silicon (MPS). Parallel, fan, cone and helical geometries, arbitrary trajectories, curved detectors, multi-GPU. ## Docs - [diffct](https://sypsyp97.github.io/diffct/_sources/index.rst.txt) - [Getting Started](https://sypsyp97.github.io/diffct/_sources/getting_started.rst.txt) - [Installation](https://sypsyp97.github.io/diffct/_sources/installation.rst.txt) - [Quickstart](https://sypsyp97.github.io/diffct/_sources/quickstart.rst.txt) - [User Guide](https://sypsyp97.github.io/diffct/_sources/user_guide.rst.txt) - [Trajectories and Geometry](https://sypsyp97.github.io/diffct/_sources/trajectories.rst.txt) - [Precision, training and reconstruction](https://sypsyp97.github.io/diffct/_sources/execution.md.txt) - [Large Volumes and Chunked Execution](https://sypsyp97.github.io/diffct/_sources/chunking.rst.txt) - [Multiple GPUs and Nodes](https://sypsyp97.github.io/diffct/_sources/multi_gpu.rst.txt) - [Performance](https://sypsyp97.github.io/diffct/_sources/performance.rst.txt) - [Differentiable analytical reconstruction](https://sypsyp97.github.io/diffct/_sources/analytical_learning.rst.txt) - [Migrating from diffct 1.x to 2.0](https://sypsyp97.github.io/diffct/_sources/migration.md.txt) - [Examples](https://sypsyp97.github.io/diffct/_sources/examples.rst.txt) - [Parallel Beam Filtered Backprojection (FBP)](https://sypsyp97.github.io/diffct/_sources/fbp_parallel_example.rst.txt) - [Fan Beam Filtered Backprojection (FBP)](https://sypsyp97.github.io/diffct/_sources/fbp_fan_example.rst.txt) - [Cone Beam Feldkamp-Davis-Kress (FDK)](https://sypsyp97.github.io/diffct/_sources/fdk_cone_example.rst.txt) - [Gradient-Based Iterative Reconstruction](https://sypsyp97.github.io/diffct/_sources/gradient_reconstruction.rst.txt) - [Cone Beam Iterative Reconstruction](https://sypsyp97.github.io/diffct/_sources/iterative_reco_cone_example.rst.txt) - [Measured Walnut](https://sypsyp97.github.io/diffct/_sources/walnut_example.rst.txt) - [Clinical Helical CT](https://sypsyp97.github.io/diffct/_sources/clinical_helical_example.rst.txt) - [Native Curved Detector](https://sypsyp97.github.io/diffct/_sources/curved_detector_example.rst.txt) - [API Reference](https://sypsyp97.github.io/diffct/_sources/api.rst.txt) - [Projector](https://sypsyp97.github.io/diffct/_sources/generated/diffct.Projector.rst.txt) - [fbp](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.fbp.rst.txt) - [fdk](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.fdk.rst.txt) - [fbp_into](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.fbp_into.rst.txt) - [fdk_into](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.fdk_into.rst.txt) - [helical_fdk](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.helical_fdk.rst.txt) - [helical_view_weights](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.helical_view_weights.rst.txt) - [helical_weighted_backproject](https://sypsyp97.github.io/diffct/_sources/generated/diffct.reconstruction.helical_weighted_backproject.rst.txt) - [SolverResult](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.SolverResult.rst.txt) - [cgls](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.cgls.rst.txt) - [sirt](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.sirt.rst.txt) - [tv_reconstruction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.tv_reconstruction.rst.txt) - [cgls_into](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.cgls_into.rst.txt) - [total_variation](https://sypsyp97.github.io/diffct/_sources/generated/diffct.solvers.total_variation.rst.txt) - [circular_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.circular_trajectory_3d.rst.txt) - [circular_trajectory_3d_parallel](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.circular_trajectory_3d_parallel.rst.txt) - [random_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.random_trajectory_3d.rst.txt) - [spiral_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.spiral_trajectory_3d.rst.txt) - [sinusoidal_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.sinusoidal_trajectory_3d.rst.txt) - [saddle_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.saddle_trajectory_3d.rst.txt) - [custom_trajectory_3d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.custom_trajectory_3d.rst.txt) - [circular_trajectory_2d_parallel](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.circular_trajectory_2d_parallel.rst.txt) - [sinusoidal_trajectory_2d_parallel](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.sinusoidal_trajectory_2d_parallel.rst.txt) - [custom_trajectory_2d_parallel](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.custom_trajectory_2d_parallel.rst.txt) - [circular_trajectory_2d_fan](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.circular_trajectory_2d_fan.rst.txt) - [sinusoidal_trajectory_2d_fan](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.sinusoidal_trajectory_2d_fan.rst.txt) - [custom_trajectory_2d_fan](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.custom_trajectory_2d_fan.rst.txt) - [transform_trajectory](https://sypsyp97.github.io/diffct/_sources/generated/diffct.geometry.transform_trajectory.rst.txt) - [TensorStore](https://sypsyp97.github.io/diffct/_sources/generated/diffct.TensorStore.rst.txt) - [NpyStore](https://sypsyp97.github.io/diffct/_sources/generated/diffct.NpyStore.rst.txt) - [ParameterizedSurface](https://sypsyp97.github.io/diffct/_sources/generated/diffct.ParameterizedSurface.rst.txt) - [detector_coordinates_1d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.detector_coordinates_1d.rst.txt) - [angular_integration_weights](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.angular_integration_weights.rst.txt) - [fan_cosine_weights](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.fan_cosine_weights.rst.txt) - [cone_cosine_weights](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.cone_cosine_weights.rst.txt) - [parker_weights](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.parker_weights.rst.txt) - [ramp_filter_1d](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.ramp_filter_1d.rst.txt) - [parallel_weighted_backproject](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.parallel_weighted_backproject.rst.txt) - [fan_weighted_backproject](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.fan_weighted_backproject.rst.txt) - [cone_weighted_backproject](https://sypsyp97.github.io/diffct/_sources/generated/diffct.analytical.cone_weighted_backproject.rst.txt) - [ParallelProjectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.ParallelProjectorFunction.rst.txt) - [ParallelBackprojectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.ParallelBackprojectorFunction.rst.txt) - [FanProjectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.FanProjectorFunction.rst.txt) - [FanBackprojectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.FanBackprojectorFunction.rst.txt) - [ConeProjectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.ConeProjectorFunction.rst.txt) - [ConeBackprojectorFunction](https://sypsyp97.github.io/diffct/_sources/generated/diffct.ConeBackprojectorFunction.rst.txt) - [Changelog](https://sypsyp97.github.io/diffct/_sources/changelog.md.txt) - [Moved](https://sypsyp97.github.io/diffct/_sources/iterative_reco_fan_example.rst.txt) - [Moved](https://sypsyp97.github.io/diffct/_sources/iterative_reco_parallel_example.rst.txt)