Radiology Coding CPT Guide: Diagnostic Imaging, Interventional & Radiation Oncology

Radiology coding presents a unique challenge for new coders because it combines anatomical knowledge, an understanding of imaging technique, and a distinct set of billing conventions that do not apply the same way to surgical or evaluation and management coding. The Radiology section of CPT, covering codes 70010 through 79999, includes diagnostic imaging, ultrasound, and nuclear medicine, and it is tested regularly on the CPC exam because of its component-billing structure and its reliance on precise reading of the radiology report. This guide covers the core concepts needed to code radiology services accurately, building on the modifier fundamentals in CPT Modifiers Guide.

The Professional and Technical Component Split

The single most important concept in radiology coding is the division between the professional component and the technical component of an imaging service. The technical component covers the equipment, supplies, and technologist labor required to perform the imaging study, while the professional component covers the radiologist’s work in interpreting the images and producing a written report. When a single facility owns the equipment and employs the radiologist who both performs and interprets the study, the full “global” code, with no modifier, is reported. When these responsibilities are split between different entities, modifiers are used to indicate which component is being billed.

Modifier -26 indicates that only the professional component is being billed — the radiologist interpreted images that were technically performed by a different entity, such as an independent imaging center. Modifier -TC indicates that only the technical component is being billed — the facility performed the imaging but a separate radiologist elsewhere provided the interpretation. Understanding when to append -26 versus -TC versus neither modifier (for a global service) is one of the most frequently tested concepts in this coding area.

Reading the Radiology Report for Coding Clues

A well-structured radiology report typically includes an indication for the study, the imaging technique used, a comparison to prior studies if available, the findings, and an impression summarizing the clinical significance of those findings. For coding purposes, the technique section is often the most important, since it specifies the exact modality, the anatomic region imaged, the number of views obtained, and whether contrast material was used — all details that directly determine the correct CPT code. Coders should always read the technique section carefully rather than relying solely on the ordering physician’s requisition, since the study actually performed may differ from what was initially ordered.

Contrast and Non-Contrast Imaging

Many radiology codes are differentiated by whether contrast material was administered, and this distinction significantly changes which code applies. Three general categories exist: without contrast material, with contrast material, and without contrast material followed by contrast material (meaning both a non-contrast and a contrast-enhanced series were obtained during the same session). This third category has its own specific codes and is not the same as coding the non-contrast and contrast studies as two separate services — when a single code exists for “without contrast followed by with contrast,” that combined code should be used rather than reporting two separate codes for the same imaging session.

Code Selection by Number of Views

For many plain radiographic studies, particularly of the spine and chest, CPT differentiates codes based on the number of views obtained during the study. A two-view chest x-ray, for example, is coded differently than a single-view chest x-ray, and a complete spine series with additional oblique or flexion-extension views is coded differently than a basic two- or three-view study. Coders must count the actual number of views documented in the report and select the code matching that specific view count, rather than assuming a “standard” view count applies to every case.

Radiological Supervision and Interpretation

Many procedures performed by other specialties — such as needle placements, injections, or catheter-based interventions — require imaging guidance to confirm correct placement, and CPT accounts for this through separate radiological supervision and interpretation (S&I) codes reported alongside the primary procedure code. These S&I codes describe the radiologist’s role in guiding and interpreting the imaging component of a procedure performed by another physician. Whether an S&I code is separately reportable, or whether imaging guidance is instead bundled into the primary procedure code, depends on the specific combination of codes involved and current National Correct Coding Initiative bundling edits, discussed generally in Bundled Codes and NCCI Edits. Many newer CPT codes for image-guided procedures already include imaging guidance within the primary code description, making a separate S&I code inappropriate for those specific procedures.

Ultrasound Coding Basics

Diagnostic ultrasound codes are organized primarily by anatomic region — abdominal, retroperitoneal, pelvic, obstetric, and others — and are further differentiated by whether the study is complete or limited. A complete ultrasound study requires documentation and imaging of all the elements specified in the code description for that anatomic region, while a limited study addresses only a specific clinical question or a subset of the required elements. Coding a limited study using a complete-study code when not all required elements were documented and imaged is a common and significant coding error, since payers frequently require documentation supporting the completeness of the study before reimbursing the complete-study code.

Nuclear Medicine Coding

Nuclear medicine codes cover studies using radioactive tracer materials, such as bone scans, thyroid uptake studies, and cardiac perfusion imaging. These codes are typically reported for the imaging and interpretation component, while the radiopharmaceutical (the tracer substance itself) is frequently reported separately using an appropriate HCPCS Level II code, discussed further in HCPCS Level II Coding Guide. Recognizing that the imaging procedure and the radioactive tracer substance are billed with two different types of codes — one CPT, one HCPCS — is an important distinction in nuclear medicine coding specifically.

Mammography Coding

Mammography codes are differentiated by whether the study is a screening mammogram, performed on an asymptomatic patient as a preventive measure, or a diagnostic mammogram, performed to evaluate a specific sign, symptom, or abnormal finding. This distinction mirrors the general screening-versus-diagnostic principle that also governs many ICD-10-CM Z-code decisions, and coding a diagnostic mammogram with a screening code (or vice versa) misrepresents the clinical reason for the encounter and can affect both reimbursement and patient cost-sharing under many insurance plans.

Common CPT Modifiers Used in Radiology

Beyond -26 and -TC, several other modifiers appear frequently in radiology coding. Modifier -59, or the more specific X-modifiers, may be needed when a distinct imaging procedure is performed that would otherwise be bundled with another service on the same date. Modifier -76 indicates a repeat procedure by the same physician, used when the same imaging study must be repeated during the same session or day, such as a repeat x-ray to confirm hardware placement after an adjustment. Modifier -77 indicates a repeat procedure by a different physician, used in similar circumstances but when a different radiologist performed the repeat study.

CT and MRI Coding Considerations

Computed tomography (CT) and magnetic resonance imaging (MRI) codes are organized by anatomic region and, like many other radiology codes, are differentiated by contrast status. A distinguishing feature of CT and MRI coding compared to plain radiography is that these studies are not differentiated by view count, since the imaging technology itself generates a full three-dimensional data set regardless of how many reconstructed images are ultimately reviewed. Instead, code selection depends primarily on the anatomic region scanned and whether contrast material was used. When multiple anatomic regions are scanned during the same session — for example, a CT of the chest, abdomen, and pelvis performed together — each region typically has its own code, and coders must verify whether combination codes exist for commonly paired regions before defaulting to reporting each region as a fully separate service.

Coding Multiple Views or Studies of the Same Region on the Same Day

When a patient returns for a repeat study of the same anatomic region on the same day — for example, an initial x-ray followed later by a repeat x-ray to confirm hardware alignment after a closed reduction — modifier -76 identifies the repeat service by the same physician, allowing both studies to be reported despite covering the same anatomic region. Without this modifier, claims-processing systems may flag the second study as a duplicate billing error and deny it. Recognizing when a second study represents a legitimate repeat procedure, rather than a duplicate claim submission error, and applying the correct repeat-procedure modifier is an important practical skill beyond simply selecting the correct base code.

How the CPC Exam Tests Radiology Coding

Pattern 1 — Selecting Between -26, -TC, and a Global Code

A scenario describes a radiology service where either the professional or technical component was performed by a separate entity, testing whether you select the correct modifier or recognize when no modifier (global billing) is appropriate.

Pattern 2 — Counting Views for Code Selection

A scenario describes a plain radiographic study with a specific number of views documented, testing whether you select the code matching the actual view count rather than assuming a standard view count.

Pattern 3 — Contrast Sequence Recognition

A scenario describes a study performed without contrast followed by a contrast-enhanced series, testing whether you recognize the combined code for this sequence rather than reporting two separate contrast and non-contrast codes.

Pattern 4 — Complete vs. Limited Ultrasound

A scenario describes an ultrasound study, testing whether you correctly determine if all required elements for a complete study were documented, or whether the limited-study code applies instead.

Common Mistakes

Confusing the professional and technical components. Appending -26 when the technical component was actually performed by the same entity, or omitting a needed modifier entirely, misrepresents which portion of the service is being billed.

Assuming a standard view count without reading the report. Plain radiograph codes differ based on the actual number of views obtained, which must be verified in the report rather than assumed.

Reporting separate contrast and non-contrast codes when a combined code exists. When a single code describes a without-contrast-then-with-contrast sequence, that combined code should be used instead of two separate codes.

Using a complete-study ultrasound code without documentation supporting all required elements. A limited-study code should be used when not every element specified in the complete-study code description was imaged and documented.

Failing to separately report the radiopharmaceutical in nuclear medicine studies. The tracer substance is typically billed with a separate HCPCS code in addition to the CPT imaging code.

Miscoding screening versus diagnostic mammography. These represent different clinical reasons for the encounter and require different codes even when the imaging technique performed is identical.

Frequently Asked Questions