Glossary · Clinical
CT scan
A CT (computed tomography) scan is a cross-sectional imaging study that uses rotating X-ray beams and computer processing to produce detailed axial, coronal, and sagittal images of bone and soft tissue. In orthopedics it is the preferred modality when plain radiographs are insufficient to characterize fracture pattern, bony architecture, or surgical anatomy.
Verified May 8, 2026 · 5 sources ↓
Definition
Source · Editorial summary grounded in 5 cited references ↓
Computed tomography acquires hundreds of X-ray projections around a single rotational axis, then reconstructs them into thin-slice cross-sectional images. Because cortical and cancellous bone absorb X-rays differently than soft tissue, CT produces sharp delineation of fracture lines, comminution patterns, articular step-off, bone loss, hardware position, and subtle cortical defects that plain films routinely miss. Modern multidetector scanners can generate isotropic voxels small enough to support three-dimensional reconstructions, which orthopedic surgeons rely on for preoperative templating in complex periarticular fractures, spinal deformity, and revision arthroplasty.
Coverage under Medicare is governed by National Coverage Determination 220.1, which requires the scan to be reasonable and necessary for the individual patient and performed on equipment meeting CMS criteria. CMS has long recognized CT as a primary diagnostic tool capable of eliminating the need for multiple other tests, reducing overall episode cost, and avoiding the complications associated with more invasive diagnostic procedures. Payer criteria for medical necessity typically require documentation of a specific clinical indication—such as inconclusive plain films, pre-surgical planning, or concern for occult fracture—rather than CT ordered reflexively.
In orthopedic coding, CT scans of the musculoskeletal system fall within CPT radiology codes 70000–79999. The correct code depends on the anatomical region, whether contrast was used, and the number of views or sequences performed. When a CT is ordered on the same date as an evaluation and management service, the ordering documentation must independently support both services; NCCI bundling edits and Medically Unlikely Edits (MUEs) govern how imaging and professional services interact on the same claim.
Why it matters
Selecting the wrong CT CPT code—most commonly confusing with-contrast versus without-contrast versus with-and-without-contrast variants—triggers automatic NCCI edits and can result in claim denial or post-payment audit recoupment. Separately, ordering a CT without a clearly documented clinical indication in the note creates a medical-necessity denial risk under NCD 220.1; payers routinely request records, and a chart that reads 'CT ordered' without a rationale linking the imaging to the clinical decision fails that review. On the clinical side, missing a CT finding such as articular incongruity greater than 2 mm or posterior wall comminution directly affects surgical planning and patient outcome, making the imaging-to-documentation pipeline a shared liability for the surgeon and the coding team.
Common mistakes
Where people most often go wrong with this concept.
Source · Editorial brief grounded in cited references ↓
- Billing the with-and-without-contrast CPT variant when only one contrast phase was actually performed, producing an NCCI edit and overpayment exposure.
- Ordering and billing a CT on the same date of service as a related procedure without documenting a separate, distinct clinical reason, risking denial of the imaging charge.
- Using an unspecified or incorrect anatomical region code—for example, billing a spine CT code for a sacral fracture that should map to a pelvis CT code—causing both a coding error and a mismatched ICD-10 link.
- Failing to append modifier 26 (professional component) when the radiologist's interpretation is billed separately from the technical component billed by the facility, leading to duplicate payment flags.
- Documenting only 'abnormal CT' in the orthopedic note without specifying the finding (e.g., degree of articular step-off, percentage posterior wall involvement), which undermines both surgical planning records and audit defense.
- Assuming preauthorization obtained for an MRI automatically covers a CT of the same body part; insurers treat them as distinct services with independent prior-authorization requirements.
Related codes
Codes commonly involved when this concept appears in practice.
CPT
- 73200 $160.66CT scan of the upper extremity (arm, forearm, wrist, elbow, or shoulder) performed without contrast material.
- 73700 $130.26CT scan of the lower extremity performed without contrast material, producing cross-sectional images of bones, soft tissue, and other structures without injected dye.
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01When should an orthopedic surgeon order a CT instead of an MRI?
02Does Medicare always cover a CT scan ordered by an orthopedist?
03What is the difference between modifier 26 and modifier TC on a CT claim?
04Can a CT scan be billed on the same day as an orthopedic office visit?
05How does contrast status affect CPT code selection for orthopedic CT?
06Is a 3D reconstruction billed separately from the CT scan?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01cms.govhttps://www.cms.gov/medicare-coverage-database/view/ncd.aspx?NCDId=176
- 02cms.govhttps://www.cms.gov/files/document/09-chapter9-ncci-medicare-policy-manual-2025finalcleanpdf.pdf
- 03cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=57215
- 04aoassn.orghttps://www.aoassn.org/wp-content/uploads/2020/12/CodingTTP.pdf
- 05cgsmedicare.comhttps://www.cgsmedicare.com/medicare_dynamic/j15/partb/ptpb/ptp.aspx
Mira AI Scribe
When Mira captures a CT scan order or result in an orthopedic encounter, it flags the following for the coding and documentation layer: 1. CONTRAST STATUS — Mira identifies whether the report header specifies without contrast, with contrast, or with-and-without contrast and maps to the correct CPT variant automatically. If the report is ambiguous, Mira queues a clarification task before claim submission. 2. ANATOMICAL SPECIFICITY — Mira cross-references the body region documented in the clinical note against the CPT code selected. If the note references the sacrum but the default code maps to lumbar spine, Mira surfaces a mismatch alert. 3. MEDICAL NECESSITY LINKAGE — Mira checks that the ordering note contains a clinical rationale (e.g., 'plain films inconclusive for posterior wall fracture extent; CT obtained for surgical planning') and pairs it with a supporting ICD-10-CM code at the highest specificity available. If only an unspecified code is present, Mira prompts the provider to confirm laterality and encounter type before the note is finalized. 4. SAME-DAY BUNDLING CHECK — When a CT is ordered on the same date as a procedure or E/M, Mira references current NCCI edits to determine whether a modifier or additional documentation is required to support separate billing. 5. PRIOR AUTHORIZATION TRACKING — Mira maintains a separate auth record for CT versus MRI for the same anatomical region and alerts the front-end team if a CT auth is missing even when an MRI auth exists.
See Mira's approachRelated terms
MRI (magnetic resonance imaging) is a non-ionizing diagnostic imaging modality that uses strong magnetic fields and radiofrequency pulses to generate high-contrast images of soft tissues, joints, and the spine. In orthopedics, it is the primary tool for evaluating cartilage, ligaments, tendons, bone marrow, and nerves when plain radiographs are insufficient.
Fluoroscopy is real-time X-ray imaging used during orthopedic procedures to guide needle placement, confirm fracture reduction, direct implant positioning, and assess joint congruency—without interrupting the surgical workflow.
Medical necessity is the standard requiring that a service or item be reasonable and appropriate for diagnosing or treating a patient's condition according to accepted clinical practice. Payers—including Medicare—use this standard to determine whether a claim will be covered and paid.