Sequence and system limits

The sequence container, the system limits a sequence is designed under, and the geometry transforms applied to a finished sequence. Gradient amplitude limits are in Hz/m, slew-rate limits in Hz/m/s and rasters in s; Pulseq representation describes the format these objects represent.

Sequence container

Object	Input	Returns	Purpose
Sequence	System limits	Sequence holding libraries, blocks, definitions, system limits	Block construction, file I/O, waveform, k-space and timing analysis.

Field-of-view transforms

Object	Input	Returns	Purpose
TransformFOV	Rotation, translation (m), per-axis gradient scale, or 4-by-4 transform	TransformFOV; apply_to_sequence returns the transformed sequence	Prescription geometry: a rotation composed after each block’s own, a translation along the channel or logical axes.

System limits

apply_system_derates() and cap_system() return copies and do not modify their argument.

Object	Input	Returns	Purpose
Opts	Gradient and slew limits with units, rasters, dead times, gamma, B0	Opts holding limits in Hz/m, Hz/m/s and rasters in s	System limits and rasters.
default_system	Opts or None	The argument, or the shared default Opts	Default-system resolution.
apply_system_derates	Opts, gradient and slew fractions	Opts copy, limits scaled from base values	Derated design limits.
cap_system	Opts, gradient and slew ceilings with their units	Opts copy, limits lowered to the ceilings	Capped design limits.
MAX_GRAD_DERATE	—	float	Default grad_derate of apply_system_derates.
MAX_SLEW_DERATE	—	float	Default slew_derate of apply_system_derates.