urx.probe - moduleus/urx GitHub Wiki

Generic ultrasound probe formed by a collection of elements.

Parameter	Datatype	Description
description	string	User description.
elements	Array of element	Array of elements in the probe.
element_geometries	Array of element_geometry	Array of unique element_geometry in the probe.
impulse_responses	Array of impulse_response	Array of unique electromechanical impulse responses of the elements in the probe.
transform	transform	Attitude of the probe in 3D space.
type	probe_type	Type of probe.

Note that the elements in element_geometry and impulse_response are referred by the fields inside each member in element, avoiding unnecessary replication of information.

If the probe.type is not UNDEFINED, then some assumptions can be made depending on the value of probe.type:

• All probe.elements share the same element_geometry and impulse_response.
• All probe.elements.transform.translation have $y=0$ and $z=0$.
• All probe.elements.transform.translation have an equal x-spacing.
• Elements in the array probe.elements are ordered from the most negative-x to the most positive-x.
• The probe is centered on the origin of the : probe.elements(first).transform.translation.x == -probe.elements(last).transform.translation.x.

The next figure shows an example of a linear probe with 64 elements, the first and tenth elements are highlighted:

The probe.element_geometries contains a single geometry:

$$[(x_1, y_1, z_1), (x_2, y_2, z_2), ...] = \left[ (-0.00013, -0.003, 0), (0.00013, -0.003, 0), (0.00013, 0.003, 0), (-0.00013, 0.003, 0) \right]$$

The position of the i-th element, in probe.elements(i).transform.translation.x is:

$$x = \frac{pitch \times (n-1)}{2} + i \times pitch$$

• All probe.elements share the same element_geometry and impulse_response.
• Elements in the array probe.elements are ordered from the most negative-x to the most positive-x.
• The probe is centered: probe.elements(first).transform.translation.x == -probe.elements(last).transform.translation.x
• Let $R$ be the radius of curvature of the curvilinear probe. The transform of the elements is defined by: $TODO$

• All probe.elements share the same element_geometry and impulse_response.
• All probe.elements.transform.translation have and $z=0$.
• All probe.elements.transform.translation have an equal x-spacing: pitch_x = probe.element(i+1).transform.translation.x - probe.element(i).transform.translation.x.
• All probe.elements.transform.translation have an equal y-spacing: pitch_y = probe.element(i+1).transform.translation.y - probe.element(i).transform.translation.y.
• Elements in the array probe.elements are ordered from the most negative-x to the most positive-x, then from the most negative-y to the most positive-y.
• The probe is centered on the origin in the x and y direction.

The next figure shows an example of a matrix probe, elements (1, 2, 20, 21) are highlighted to show the ordering regarding x and y axis:

• All probe.elements share the same element_geometry and impulse_response.
• All probe.elements.transform.translation have and $z=0$.

The following figures show example of sparse arrays:

Given an N-by-M RCA probe:

• All probe.elements point to one of two possible element_geometry and impulse_response. The row's elements (resp. column's) can have a different element_geometry and impulse_response, but don't have to.
• All probe.elements.transform.translation have $z=0$.
• The probe is centered on the origin in the x and y direction.
• All probe.elements.transform.rotation are null, ie $(0, 0, 0)$. Rows and columns elements are not $\pi/2$ rotation from one another, instead they have different element_geometry and transform.translation. Rows (resp. column's) elements have translation.x == 0 (resp. translation.y == 0).
• Elements in the array probe.elements are ordered in the following manner:
  1. Elements with y=0, from negative-x to positive-x.
  2. Elements with x=0, from negative-y to positive-y.
  • When the number of elements in x (resp. y) direction is odd, the center element has its y (resp. x) coordinate equal to 0. Yet it is ordered in the probe.element array with its siblings, in order not to mix row's and column's elements.

The next figure shows an example of a RCA probe:

Other types of probes can be defined using the special probe_type = UNDEFINED. For example the following probe does not fit any aforementioned types of probes:

element | element_geometry | impulse_response | probe_type | receive_setup | transform | transmit_setup