calcRfPower¶

Calculates the relative power of an RF pulse. It returns the relative energy of the pulse in units of Hz^2s (which simplifies to Hz), where the units represent RF amplitude squared multiplied by time. The mean_pwr output is closely related to relative SAR. The function also returns the peak power (in Hz^2) and the RMS B1 amplitude (in Hz). The power and amplitude values are relative; to convert the RF amplitude to Tesla (T), divide by the gyromagnetic ratio (γ). Similarly, to convert the power to mT^2s, divide by γ^2. Note that absolute SAR calculation requires additional coil and subject-dependent scaling factors.

Syntax¶

function [mean_pwr, peak_pwr, rf_rms, total_energy]=calcRfPower(varargin)

Calling Pattern¶

seq.calcRfPower(...)

Parameters¶

Optional Parameters¶

Name	Type	Default	Description	Example
`blockRange`	double	`[1 inf]`	Specifies the range of blocks in the sequence for which to calculate the power. Defaults to the entire sequence. Valid values: A two-element numeric vector [start_block, end_block]	`[10, 20]`
`windowDuration`	double	`NaN`	Specifies the time window for calculating total_energy, mean_pwr, and rf_rms. If provided, the function returns the maximum values over all time windows. The window duration is rounded up to a certain number of complete blocks. Valid values: A positive numeric scalar (Units: seconds)	`0.005`

Returns¶

Output	Type	Description
`mean_pwr`	double	Mean power of the RF pulse (relative, in Hz).
`peak_pwr`	double	Peak power of the RF pulse (relative, in Hz^2).
`rf_rms`	double	RMS B1 amplitude of the RF pulse (relative, in Hz).
`total_energy`	double	Total energy of the RF pulse (relative, in Hz).

Examples¶

seq.calcRfPower()
seq.calcRfPower('blockRange', [10, 20])
seq.calcRfPower('windowDuration', 0.01)