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This page describes products and general use; it is not medical advice.
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Short answer: an ultrasound linear probe (also written linear probe ultrasound or linear ultrasound probe) is a transducer whose piezoelectric elements sit in a straight row on a flat face, so it produces a rectangular image with strong detail close to the skin and limited depth. It is used by clinicians, sonographers and students who scan superficial structures such as blood vessels, tendons, thyroid and breast tissue.
What an ultrasound linear probe is
A linear probe is an ultrasound transducer characterised by a flat footprint that emits parallel sound waves. According to the Global Ultrasound Institute’s POCUSpedia entry on the linear probe, this design gives excellent near-field resolution and a rectangular field of view, which suits superficial structures such as blood vessels, musculoskeletal tissue and nerves (checked 2026-11-01). It connects to an ultrasound machine, which processes the returning echoes into the image.
Who uses it: clinicians and sonographers scanning near-surface anatomy, and students learning probe selection.
How a linear array is built
A peer-reviewed 2025 review of linear-array transducers describes them as composed of numerous small piezoelectric elements, typically 128 to 256, arranged in a line. The acoustic beamlines produce rectangular B-mode images with uniform beam density, and this layout gives excellent near-field resolution, particularly for superficial anatomical structures (PMC12467595, checked 2026-11-01).
Conventional linear-array imaging produces a cross-sectional two-dimensional image. The same review notes that building a three-dimensional volume requires additional scanning in the elevational direction, perpendicular to the image plane.
Linear vs convex probes
A 2024 volunteer study in Diagnostics compared a linear array (Canon i11LX3, centre frequency 7 MHz) with a convex array (i8CX1, centre frequency 4 MHz) on the same scanner. The authors report that the imaging window is much smaller with the linear probe and that its imaging depth is limited. They describe the convex probe as the one commonly used in steatosis (fatty liver) evaluation, and the linear probe as suited to more superficial tissue such as thyroid, musculoskeletal and breast measurements, where it “is in its element” (PMC11083206, checked 2026-11-01).
| Feature | Linear array | Convex array | Source |
|---|---|---|---|
| Centre frequency in the study | 7 MHz (i11LX3) | 4 MHz (i8CX1) | PMC11083206 |
| Protocol imaging depth | 6 cm | 10 cm | PMC11083206 |
| Imaging window | Much smaller | Larger | PMC11083206 |
| Typical target | Superficial: breast, thyroid, muscle | Liver (steatosis evaluation) | PMC11083206 |
The 6 cm and 10 cm figures are the depth settings of the protocol used in that study (the linear probe’s ATI-General preset and the convex probe’s setting). The study compared one named linear model with one named convex model, so the figures describe those two probes and presets, not every device. For phased and endocavitary designs see types of ultrasound probe.
Frequency and depth
Higher frequency gives finer detail but less penetration. Published frequency figures differ by what they describe (an operating range or the centre frequency of one probe), so they are shown side by side rather than merged into one number. POCUSpedia notes that linear probes use high frequencies, which allow detailed visualisation of structures close to the skin surface.
| Source | What it states | Type of source |
|---|---|---|
| Linear-array transducer review (PMC12467595) | Typical linear arrays operate across 1 to 20 MHz, with penetration of several centimetres and resolution of a few hundred micrometres | Peer-reviewed review |
| Diagnostics 2024 volunteer study (PMC11083206) | Centre frequency 7 MHz for the linear probe tested | Peer-reviewed study |
Because penetration is limited, the Diagnostics study states that imaging depth with a linear probe is limited, which is why its protocol depth was 6 cm against 10 cm for the convex probe.
Common uses
- Superficial structures: blood vessels, musculoskeletal tissue and nerves (POCUSpedia).
- Breast, thyroid, tendons and blood vessels, as routine anatomical targets (PMC12467595).
- POCUSpedia also names vascular access and nerve blocks among the procedures where near-surface detail matters; this page does not describe how those procedures are performed.
Matching probe to target
The sources describe one selection principle: match the probe to the target. The linear array suits near-surface structures, while the convex array gives a wider, deeper view (PMC11083206; POCUSpedia). Probe choice for any given exam rests with the clinicians involved and the machine maker’s documentation.
Safe handling basics
Follow the probe manufacturer’s instructions for use for cleaning, disinfection and storage, since the permitted methods are specific to each model. Protective barriers are covered in ultrasound probe covers, and the coupling medium in conductive gel.
Common mistakes
- Expecting a linear probe to image deep organs; the studies above show depth is its limit.
- Comparing frequency numbers across sources without checking whether they are a range or the centre frequency of one probe.
- Treating a result from one probe model as a rule for all linear probes.
FAQ
What is a linear probe ultrasound used for?
It is used to image structures close to the skin, such as blood vessels, nerves, tendons, muscle, thyroid and breast tissue, because it gives high near-field resolution (POCUSpedia; PMC12467595).
What is the difference between a linear ultrasound probe and a convex probe?
The linear probe has a flat face and rectangular image with limited depth; the convex probe has a wider, deeper view. In one study the linear probe was run at 7 MHz and 6 cm depth, the convex at 4 MHz and 10 cm (PMC11083206).
How many elements does a linear array have?
Typically 128 to 256 small piezoelectric elements arranged in a line (PMC12467595).
Sources
Sources checked 2026-11-01.
- Linear-array transducer volumetric imaging review, PMC12467595, https://pmc.ncbi.nlm.nih.gov/articles/PMC12467595/ (checked 2026-11-01).
- Hanni et al., Diagnostics 2024, ultrasound attenuation imaging with a linear versus convex probe, https://pmc.ncbi.nlm.nih.gov/articles/PMC11083206/ (checked 2026-11-01).
- Global Ultrasound Institute, POCUSpedia, Linear probe, https://globalultrasoundinstitute.com/pocuspedia/linear-probe/ (checked 2026-11-01).
