Full-Spine and Long-Leg X-Ray: Stitching or Single Exposure?

What long-format radiography is used for

A whole spine X-ray is the standard way to document the curvature in scoliosis and to measure the Cobb angle, while a long leg X-ray shows the mechanical axis of the limb. Orthopaedic teams use these images to plan corrective osteotomies and total knee arthroplasty, and paediatric services use them for follow-up of growing patients.

Because a standard detector covers only part of the body, a long-format examination has to extend the image in some way. The two approaches are image stitching and a single large-format exposure.

The request form should state the clinical purpose, such as deformity assessment, limb axis or post-operative follow-up, because it determines the protocol and the measurement tools needed.

How image stitching radiography works

In stitching, the tube and detector move together along the patient, acquiring two to four overlapping images, and the software merges them into one. Modern DR rooms perform this automatically, with the patient standing against a chest stand or lying on the table. The great advantage is that no special detector is needed: a normal 43 x 43 cm panel is enough.

The limitation is that the patient must stay completely still during the whole series, and the merged image can show small seams or magnification differences. Good protocols use a fixed patient support, a calibrated reference marker and verified distance, and quality assurance should check that stitched lengths are reproducible.

• Works with a standard flat panel and a suitable stand or table
• Several exposures, so patient movement is a risk
• Overlap zones need correct processing and calibration
• Typical for multipurpose DR rooms

Single-exposure whole spine X-ray

Single-shot systems use one very large detector. The Perlove PLX8600, for example, has a dynamic flat panel with a field of view of up to 0.43 x 1.2 m, and the manufacturer states that full-spine and full-lower-limb images are captured in one shot without stitching artefacts. See our model overview of the Perlove PLX8600 for its published specifications.

The benefits are no seam artefacts and a single exposure time, which suits children and patients who cannot hold still. The cost is a dedicated and larger system, so the investment is justified mainly by volume. Whatever method you choose, ask for sample images with measured Cobb angle and mechanical axis, and for dose values.

Equipment you need and how to choose

For a stitching workflow, look for a chest stand that integrates a retractable patient support. Villa's Moviplan iC DR room, for example, is described with a Tele iC SR chest stand that integrates a retractable patient support for full-leg and full-spine stitching, controlled with auto-tracking and auto-positioning functions. The same function is offered in Villa's U-arm Armonicus.

For a single-exposure workflow, plan around the large detector and gantry, as in the PLX8600. When choosing, compare four things: the number of long-format exams you expect per year, patient mix (children, adults, mobility), the room available and the measurement software. The article on DR room configurations adds context on space and throughput.

Dose, quality assurance and next steps

Radiation dose should be reviewed for each method with your medical physicist, particularly for paediatric scoliosis follow-up that is repeated over years. Calibrate the system, check geometric accuracy of measured lengths and angles, and keep records. Requirements for facility registration and licensing should be confirmed with FANR and your health authority (MOHAP, DHA or DOH).

If you are planning a new room for spine or limb alignment imaging, Beckfinity can help you compare stitching and single-exposure options for your site. Request a quote or a demonstration of the relevant Villa and Perlove systems.