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opts.py
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Sun, Jun 2, 11:54

opts.py
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from pypulseq.convert import convert
class Opts:
"""
System limits of an MR scanner.
Attributes
----------
grad_unit : str
Unit of maximum gradient amplitude. Must be one of Hz/m, mT/m or rad/ms/mm.
slew_unit : str
Unit of maximum slew rate. Must be one of Hz/m/s, mT/m/ms, T/m/s or rad/ms/mm/ms.
max_grad : float
Maximum gradient amplitude.
max_slew : float
Maximum slew rate.
rise_time : float
Rise time for gradients.
rf_dead_time : float
Dead time for radio-frequency pulses.
rf_ringdown_time : float
Ringdown time for radio-frequency pulses.
adc_dead_time : float
Dead time for ADC readout pulses.
rf_raster_time : float
Raster time for radio-frequency pulses.
grad_raster_time : float
Raster time for gradient waveforms.
gamma : float
Gyromagnetic ratio. Default is 42.576 MHz for Hydrogen.
"""
def __init__(self, grad_unit: str = None, slew_unit: str = None, max_grad: float = None, max_slew: float = None,
rise_time: float = None, rf_dead_time: float = 0, rf_ringdown_time: float = 0,
adc_dead_time: float = 0, rf_raster_time: float = 1e-6, grad_raster_time: float = 10e-6,
gamma: float = 42.576e6):
valid_grad_units = ['Hz/m', 'mT/m', 'rad/ms/mm']
valid_slew_units = ['Hz/m/s', 'mT/m/ms', 'T/m/s', 'rad/ms/mm/ms']
if grad_unit is not None and grad_unit not in valid_grad_units:
raise ValueError(f'Invalid gradient unit, must be one of Hz/m, mT/m or rad/ms/mm. You passed: {grad_unit}')
if slew_unit is not None and slew_unit not in valid_slew_units:
raise ValueError(f'Invalid slew rate unit, must be one of Hz/m/s, mT/m/ms, T/m/s or rad/ms/mm/ms. You '
f'passed: {slew_unit}')
if max_grad is None:
max_grad = convert(from_value=40, from_unit='mT/m', gamma=gamma)
else:
max_grad = convert(from_value=max_grad, from_unit=grad_unit, to_unit='Hz/m', gamma=gamma)
if max_slew is None:
max_slew = convert(from_value=170, from_unit='T/m/s', gamma=gamma)
else:
max_slew = convert(from_value=max_slew, from_unit=slew_unit, to_unit='Hz/m', gamma=gamma)
if rise_time is not None:
max_slew = None
self.max_grad = max_grad
self.max_slew = max_slew
self.rise_time = rise_time
self.rf_dead_time = rf_dead_time
self.rf_ringdown_time = rf_ringdown_time
self.adc_dead_time = adc_dead_time
self.rf_raster_time = rf_raster_time
self.grad_raster_time = grad_raster_time
self.gamma = gamma
def __str__(self):
s = "System limits:"
s += "\nmax_grad: " + str(self.max_grad) + str(self.grad_unit)
s += "\nmax_slew: " + str(self.max_slew) + str(self.slew_unit)
s += "\nrise_time: " + str(self.rise_time)
s += "\nrf_dead_time: " + str(self.rf_dead_time)
s += "\nrf_ring_time: " + str(self.rf_ringdown_time)
s += "\nadc_dead_time: " + str(self.adc_dead_time)
s += "\nrf_raster_time: " + str(self.rf_raster_time)
s += "\ngrad_raster_time: " + str(self.grad_raster_time)
s += "\ngamma: " + str(self.gamma)
return s

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