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

The Radiology section of CPT (70000–79999) accounts for approximately 4–6% of the CPC exam. Codes cover diagnostic imaging, ultrasound, radiation oncology, and nuclear medicine. Understanding the component coding model and the technical vs. professional distinction is essential for exam success. This guide covers the key radiology CPT codes, coding rules, modifiers, and exam-tested scenarios.

Radiology Code Structure

Radiology CPT codes are divided into several subsections, each covering a different imaging modality or treatment category:

• Diagnostic Radiology (70010–76499): X-rays, CT scans, MRI, fluoroscopy. Organized by body region (head/neck, chest, spine, abdomen, extremities).
• Diagnostic Ultrasound (76506–76999): Ultrasound imaging by body region. Includes OB ultrasound, vascular duplex studies, and abdominal/pelvic imaging.
• Radiologic Guidance (77001–77022): Fluoroscopic, CT, and MRI guidance for procedures. These are guidance-only codes used when imaging directs a separate procedure.
• Breast Mammography (77065–77067): Screening and diagnostic mammography.
• Bone/Joint Studies (77071–77086): Bone density scans (DEXA), bone age studies, and osseous surveys.
• Radiation Oncology (77261–77799): Treatment planning, radiation delivery, brachytherapy, and related services for cancer treatment.
• Nuclear Medicine (78012–79999): Diagnostic and therapeutic nuclear medicine studies using radiopharmaceuticals.

Technical vs. Professional Components

This is one of the most important radiology coding concepts tested on the CPC exam. Every radiology service has two components:

• Technical component (TC): Covers the equipment, supplies, technologist, and facility costs for performing the imaging study. Reported with modifier TC.
• Professional component (PC): Covers the physician’s work in supervising, interpreting, and writing the report. Reported with modifier 26.
• Global service: When the same provider owns the equipment AND interprets the study, report the code without any modifier (global). The global fee equals TC + 26 combined.

Exam Tip: Hospital-based radiologists typically report modifier 26 only, because the hospital bills the TC. Independent imaging centers that employ their own radiologists report the global code. Office-based physicians with their own X-ray equipment who read their own films also report the global code.

Common Exam Trap: Not all radiology codes have TC/26 splits. Some codes are inherently professional-only (e.g., consultation codes for second opinions on imaging) and some are inherently technical-only. Check the code description to determine if component billing applies.

Commonly Tested Diagnostic Imaging Codes

X-Ray (Plain Radiography)

X-ray codes are selected based on two factors: body region and number of views.

• 71045–71048: Chest X-ray. 71045 = single view, 71046 = 2 views (PA and lateral — the most common), 71047 = 3 views, 71048 = 4+ views. The 2-view chest X-ray (71046) is the most frequently ordered and most commonly tested.
• 73560–73564: Knee X-ray. 73560 = 1-2 views, 73562 = 3 views, 73564 = complete (4+ views). Number of views determines the code.
• 73030: Shoulder X-ray, complete, minimum 2 views.
• 72100–72114: Lumbar spine X-ray. 72100 = 2-3 views, 72110 = minimum 4 views (complete), 72114 = complete with bending views.
• 73610: Ankle X-ray, complete, minimum 3 views.
• 73630: Foot X-ray, complete, minimum 3 views.

Coding Tip: Always count the number of views documented in the report. The view count is the primary differentiator between X-ray codes for the same body part. “AP and lateral” = 2 views. “AP, lateral, and oblique” = 3 views.

CT Scan (Computed Tomography)

CT codes are organized by body region and whether contrast is used:

• Without contrast: The baseline scan performed without IV contrast injection.
• With contrast: Scan performed after IV contrast administration.
• Without contrast followed by with contrast: Two separate acquisitions — one before and one after contrast. This is the most comprehensive and highest-valued CT code for each body region.

Key CT codes to know:

• 70450: CT head/brain without contrast. One of the most commonly ordered CT scans — used for acute stroke, head trauma, and headache evaluation.
• 70460: CT head/brain with contrast.
• 70470: CT head/brain without contrast followed by with contrast.
• 71250: CT chest without contrast.
• 71260: CT chest with contrast (CT pulmonary angiogram for PE evaluation uses this code).
• 71270: CT chest without then with contrast.
• 74176: CT abdomen and pelvis without contrast.
• 74177: CT abdomen and pelvis with contrast.
• 74178: CT abdomen and pelvis without then with contrast.

Exam Tip: The contrast status (without, with, or both) is the most important differentiator for CT codes. Read the operative or radiology report carefully for contrast documentation. “CT abdomen pelvis with IV contrast” = 74177, NOT 74178 (which requires scans both with and without).

MRI (Magnetic Resonance Imaging)

MRI codes follow the same pattern as CT — organized by body region and contrast status:

• 70551: MRI brain without contrast.
• 70552: MRI brain with contrast.
• 70553: MRI brain without then with contrast.
• 73721: MRI knee or lower extremity joint without contrast. Very commonly ordered for ACL, meniscus, and cartilage evaluation.
• 73723: MRI knee without then with contrast.
• 72141: MRI cervical spine without contrast.
• 72148: MRI lumbar spine without contrast. One of the most commonly ordered MRI studies overall.

Fluoroscopy

• 76000: Fluoroscopy (separate procedure), up to 1 hour physician or other qualified healthcare professional time. Used when fluoroscopy is the primary procedure, not just guidance for another procedure.
• 77002: Fluoroscopic guidance for needle placement (e.g., joint injection, biopsy). This is a guidance code that is reported in addition to the procedure code.
• 77003: Fluoroscopic guidance for epidural or subarachnoid needle placement.

Diagnostic Ultrasound

Ultrasound codes are organized by body region and whether the study is limited or complete:

• 76700: Complete abdominal ultrasound. Must include visualization of the liver, gallbladder, common bile duct, pancreas, kidneys, spleen, and abdominal aorta.
• 76705: Limited abdominal ultrasound. Fewer than all required organs are imaged — commonly used for right upper quadrant pain (focused on gallbladder).
• 76856: Complete pelvic ultrasound (transabdominal). Includes uterus, adnexa, and bladder.
• 76857: Limited pelvic ultrasound.
• 76830: Transvaginal ultrasound. A separate code from transabdominal pelvic US — both may be reported if both approaches are performed and documented.

OB Ultrasound

• 76801: OB ultrasound, first trimester (less than 14 weeks 0 days), single or first gestation. Includes measurement of crown-rump length, evaluation of uterus and adnexa.
• 76805: OB ultrasound, after first trimester, single or first gestation. A complete fetal anatomic survey — the standard “anatomy scan” performed around 18-20 weeks.
• 76811: Complete fetal anatomic evaluation, detailed. More comprehensive than 76805 — used for high-risk pregnancies.
• 76815: Limited OB ultrasound. Used for follow-up of a specific concern (e.g., fetal heartbeat check, amniotic fluid assessment).
• 76817: Transvaginal OB ultrasound.

Radiologic Guidance

Guidance codes are used when imaging is used to direct a separate procedure (injection, biopsy, catheter placement). These are reported in addition to the procedure code:

• 77002: Fluoroscopic guidance for needle placement.
• 77003: Fluoroscopic guidance for epidural/subarachnoid needle placement.
• 77012: CT guidance for needle placement.
• 77021: MRI guidance for needle placement.
• 76942: Ultrasound guidance for needle placement (e.g., biopsy, aspiration). Includes permanent documentation (image storage).

Important: Many procedure codes now include imaging guidance in the code description (e.g., many interventional radiology codes state “including imaging guidance”). When guidance is bundled into the procedure code, do not separately report the guidance code. Always check the procedure code description for language like “including radiological supervision and interpretation” or “including imaging guidance.”

Mammography

• 77065: Diagnostic mammography, including CAD, unilateral. Used for a specific clinical indication (lump, pain, nipple discharge) on one breast.
• 77066: Diagnostic mammography, including CAD, bilateral. Both breasts imaged for a diagnostic indication.
• 77067: Screening mammography, bilateral, including CAD. Routine screening for asymptomatic patients — no symptoms or clinical findings.

Key Distinction: Screening (77067) is for asymptomatic patients; diagnostic (77065-77066) is ordered when there is a clinical indication. If a screening mammogram identifies an abnormality and additional diagnostic views are taken during the same session, report only the diagnostic code — the screening is bundled.

Radiation Oncology

Radiation oncology codes cover the planning, simulation, and delivery of radiation therapy for cancer treatment. These are divided into several service categories:

Treatment Planning

• 77261: Therapeutic radiology treatment planning; simple.
• 77262: Therapeutic radiology treatment planning; intermediate.
• 77263: Therapeutic radiology treatment planning; complex. The complexity level depends on the number of treatment areas, number of ports, and use of custom blocking.

Simulation

• 77280: Therapeutic radiology simulation-aided field setting; simple.
• 77285: Simulation; intermediate.
• 77290: Simulation; complex.
• 77295: 3-dimensional radiotherapy plan, including dose-volume histograms.

Treatment Delivery

• 77385: Intensity-modulated radiation therapy (IMRT), simple. Delivery of complex radiation with modulated beam intensity.
• 77386: IMRT, complex. More treatment fields and greater modulation complexity.
• 77401: Radiation treatment delivery, superficial and/or ortho voltage. Lower energy radiation for skin lesions.
• 77402: Radiation treatment delivery, >= 1 MeV; simple. Standard external beam radiation for a single treatment area.

Brachytherapy

• 77750: Infusion or instillation of radioelement solution. Liquid radioactive material administered into a body cavity.
• 77761: Intracavitary brachytherapy; simple (1-4 sources). Placement of radioactive sources inside a body cavity (e.g., uterus for cervical cancer).
• 77762: Intracavitary brachytherapy; intermediate (5-10 sources).
• 77763: Intracavitary brachytherapy; complex (over 10 sources).

Nuclear Medicine

Nuclear medicine uses radiopharmaceuticals (radioactive tracers) injected into the patient to image organ function. Unlike X-ray and CT (which show anatomy), nuclear medicine shows physiology and function.

• 78451–78454: Myocardial perfusion imaging (cardiac stress test with nuclear imaging). 78451 = single study, 78452 = multiple studies (rest and stress). Commonly tested.
• 78300–78320: Bone scan. 78300 = limited area, 78305 = multiple areas, 78306 = whole body. Used for detecting bone metastases, fractures, and infections.
• 78579–78580: Pulmonary perfusion and ventilation imaging. Used for suspected pulmonary embolism (V/Q scan).
• 78800–78804: Tumor imaging (oncologic nuclear medicine). Used for cancer staging and recurrence detection.

Real-World Coding Examples

Example 1: CT Abdomen and Pelvis

Report: CT abdomen and pelvis performed with IV contrast for evaluation of acute abdominal pain. Interpreted by a hospital-employed radiologist.

Correct Code: 74177-26 — CT abdomen/pelvis with contrast, modifier 26 for professional component only (hospital bills TC).

Example 2: Screening vs. Diagnostic Mammogram

Report: Patient presents for annual screening mammography. During the screening exam, a suspicious mass is identified. Additional diagnostic views and spot compression are performed.

Correct Code: 77066 — Diagnostic bilateral mammography only. When a screening exam converts to diagnostic during the same visit, report only the diagnostic code. The screening is bundled.

Example 3: Fluoroscopic-Guided Joint Injection

Report: Left knee joint injection performed under fluoroscopic guidance in the physician’s office. The physician owns the fluoroscopy equipment and performs both the injection and the imaging.

Correct Codes: 20610 + 77002 — Joint injection (major joint) + fluoroscopic guidance. Report both codes without modifiers since this is a global service (physician owns equipment and interprets).

CPC Exam Tips for Radiology Coding

• TC vs. 26 vs. Global: Always determine who owns the equipment and who interprets. Hospital-based = modifier 26. Office-based with own equipment = global (no modifier). TC is reported by the facility.
• Count the views for X-rays: The number of views is the primary differentiator for X-ray codes of the same body part.
• Contrast status for CT/MRI: Without, with, or without-then-with are three separate codes. “Without then with” is not the same as “with” — it requires two acquisitions.
• Check for bundled guidance: Many procedure codes include imaging guidance. If the procedure code says “including imaging guidance,” do not separately report a guidance code.
• Screening vs. diagnostic mammography: Screening = asymptomatic. Diagnostic = symptoms or clinical finding. If screening converts to diagnostic, report only diagnostic.
• Complete vs. limited ultrasound: Complete requires visualization of all specified organs. If any are missing, it is limited.
• Radiation oncology is multi-component: Planning, simulation, and delivery are coded separately. Treatment management (weekly reviews) uses separate codes.

Summary

Radiology coding requires understanding the technical vs. professional component distinction, contrast status for CT and MRI, view counts for X-rays, and the bundling rules for imaging guidance. Always identify who performs the service and who owns the equipment to determine the correct modifier. For the CPC exam, focus on the TC/26/global distinction, contrast coding for CT and MRI, X-ray view counts, screening vs. diagnostic mammography, and the difference between complete and limited ultrasound studies. These high-yield topics account for the majority of radiology questions on the exam.