Radiology Billing and Coding Cheat Sheet: CPT Codes, Modifiers, and ICD-10 Pairings (2026)

What Belongs on a Radiology Billing and Coding Cheat Sheet?

A radiology billing and coding cheat sheet is a quick-reference guide covering the CPT codes, modifiers, ICD-10 diagnosis pairings, and payer rules that radiology practices and imaging centers use to bill Medicare, Medicaid, and commercial carriers correctly. As of October 2026, this guide reflects the FY 2027 ICD-10-CM code set, current CMS modifier rules for professional and technical component billing, the multiple procedure payment reduction for imaging, and prior authorization requirements for advanced imaging studies.

• Professional vs. technical split: Every radiology CPT code with a PC/TC indicator of 1 splits into two billable components. Modifier 26 represents the radiologist’s interpretation and report. Modifier TC represents the equipment, technologist, and facility. Billing global (no modifier) means the same entity performed both.
• Most common billing error: Billing a global radiology code when the practice only performed the professional read, or vice versa. This produces overpayment on one side and audit exposure on the other.
• FY 2027 ICD-10 codes are live: CMS added 190 new ICD-10-CM codes and deleted 30 effective October 1, 2026, including new flank pain codes in the R10.A series that directly affect how abdominal and renal imaging studies are coded for medical necessity.

Professional vs. Technical Component Billing

The professional and technical component split is the single most important concept in radiology billing. Nearly every diagnostic imaging code in the CPT manual carries a PC/TC indicator that determines whether it can be billed as two separate services or only as a global charge. For a complete breakdown of how the professional component modifier works in practice, see our full guide to Modifier 26 in radiology billing.

When a radiologist interprets a study but does not own the equipment or employ the technologist, the radiologist bills with Modifier 26 for the professional component. The facility that owns the scanner and employs the tech bills the same CPT code with Modifier TC for the technical component. When the same entity owns the equipment and provides the interpretation, it bills the code with no modifier, which is called a global service.

Getting this wrong is not a coding error that produces a denial. It produces an overpayment, which is worse. A practice that bills globally when it only performed the professional read collects the full fee schedule amount instead of the 26-component amount. That overpayment sits in the system until a payer audit or an OIG review catches it, at which point the practice faces a recoupment plus potential penalties. CMS audits PC/TC splits routinely, and radiology is one of the highest-volume targets.

Billing Scenario	Modifier	Who Bills	What Is Included
Practice owns equipment AND radiologist interprets	None (Global)	Practice bills globally	Full fee schedule: TC + professional bundled
Radiologist interprets only; hospital owns equipment	26	Radiologist/physician	Professional component only: interpretation + report
Facility owns equipment; no interpretation on this claim	TC	Facility/imaging center	Technical component only: equipment, supplies, tech staff

Chest X-Ray and Plain Film CPT Codes

Chest imaging is the highest-volume category in diagnostic radiology billing. The code selection depends entirely on the number of views taken. CPT code 71046 for a two-view chest X-ray is the most commonly billed plain film code in the specialty and the one that draws the most scrutiny from payers on medical necessity.

71045 covers a chest X-ray with a single view, typically a PA or AP projection. 71046 covers two views, almost always a PA and lateral. 71047 covers three views, and 71048 covers four or more. The view count must match the documentation: if the order calls for two views but only one was taken, billing 71046 instead of 71045 will fail on review.

Beyond the chest, common plain film codes include 73610 (ankle, complete with a minimum of three views), 73630 (foot, complete with a minimum of three views), and 72100 (lumbosacral spine, two or three views). Each one follows the same logic: the number of views documented determines the code.

CT Scan CPT Codes and Contrast Rules

CT coding revolves around three variables: the body region scanned, whether contrast was administered, and whether the study was performed with and without contrast as a combined protocol. The contrast status is embedded directly in the code, not handled by a modifier, so choosing the wrong contrast tier means choosing the wrong code entirely.

For CT of the abdomen and pelvis, 74176 covers the study without contrast, 74177 covers the study with contrast, and 74178 covers the combined without-then-with protocol. For CT of the chest, 71250 is without contrast, 71260 is with contrast, and 71270 is without then with.

CT of the head follows the same pattern: 70450 covers CT head without contrast, 70460 with contrast, and 70470 without then with.

One of the most common CT billing errors is submitting a combined study (the “without then with” code) when only one phase was actually performed. The medical record must document both the pre-contrast and post-contrast image acquisition. If only one phase is documented, the corresponding single-phase code applies, and using the combined code creates a false claim.

MRI CPT Codes

MRI codes follow the same three-tier contrast structure as CT. For MRI of the lumbar spine, 72148 covers the study without contrast, 72149 covers it with contrast, and 72158 covers the combined protocol. MRI of the brain uses 70551 (without), 70552 (with), and 70553 (without then with).

For MRI of a lower extremity joint such as the knee, hip, or ankle, CPT code 73721 covers the study without contrast, 73722 covers it with contrast, and 73723 covers the combined study. Upper extremity joint MRI mirrors this pattern with 73221 (without), 73222 (with), and 73223 (without then with).

MRI carries the heaviest prior authorization burden of any imaging modality. Over 90 percent of commercial payers require prior authorization for MRI studies, and Medicare Advantage plans have expanded their authorization requirements steadily since 2024. A claim submitted without the required authorization will be denied regardless of clinical appropriateness, and retro-authorization rules vary by payer.

Ultrasound and Guidance CPT Codes

Ultrasound coding separates into diagnostic studies and procedural guidance. On the diagnostic side, CPT code 76700 covers a complete abdominal ultrasound including the liver, gallbladder, common bile duct, pancreas, spleen, kidneys, and aorta. 76705 covers a limited abdominal ultrasound, which images one or more but not all of those structures. The distinction between complete and limited is documentation-driven: if the report does not address every required element for a complete study, the claim must use the limited code even if the tech imaged all of them.

For procedural guidance, CPT code 76942 covers ultrasound guidance for needle placement such as biopsies, aspirations, and injections. This code requires permanent documentation of the ultrasound images used for guidance, and it cannot be billed alongside a diagnostic ultrasound of the same area on the same date without a distinct-service modifier and supporting documentation.

Pelvic ultrasound has its own code set: 76856 covers a complete pelvic study, 76857 covers a limited study, and 76830 covers a transvaginal ultrasound. OB ultrasounds are coded separately under the 76801 to 76828 range and follow different payer rules.

Mammography and Breast Imaging

Mammography billing splits between screening and diagnostic studies, and the distinction matters because screening mammography has different coverage rules, cost-sharing exemptions, and frequency limits under Medicare and the ACA.

77065 covers a diagnostic mammogram of one breast (unilateral). 77066 covers diagnostic mammography of both breasts (bilateral). 77067 covers a screening mammogram, which is always bilateral. Under Medicare, screening mammography is covered once every 12 months for women age 40 and older with no cost-sharing, while diagnostic mammography applies standard Part B cost-sharing. 3D mammography, or digital breast tomosynthesis, is billed as an add-on code. CPT code 77063 covers screening tomosynthesis and is reported in addition to the base screening code 77067.

A common billing error is reporting 77067 (screening) when the study was ordered for a clinical indication such as a palpable mass or abnormal prior finding. If a clinical indication exists, the study is diagnostic by definition, and billing a screening code understates the medical necessity and may create coverage issues with the payer.

Multiple Procedure Payment Reduction

The multiple procedure payment reduction, or MPPR, is a Medicare payment rule that reduces reimbursement on the professional component of imaging studies when more than one study is performed in the same session by the same provider.

Under the current rule, the first study is paid at 100 percent of the fee schedule. The second and subsequent professional component interpretations performed during the same session are reduced to 75 percent of the professional component rate. The technical component is not reduced. This means a radiologist who reads a chest CT and an abdominal CT for the same patient on the same date will receive full payment on the first read and 75 percent on the second read for the professional component only.

The MPPR applies automatically during claim processing. Practices do not need to append a modifier or adjust the billed amount. However, understanding the reduction is essential for revenue forecasting and for evaluating whether the practice’s reimbursement matches what it should receive. Many commercial payers have adopted similar reduction policies, though the percentages and rules vary.

Radiology Modifiers That Decide the Claim

Modifiers carry as much weight as the CPT code itself in radiology billing. Choosing the wrong modifier or omitting one entirely is the difference between a paid claim and a denial.

Modifier 26 identifies the professional component of a diagnostic service. Modifier TC identifies the technical component. Neither is appended when billing globally. Modifier 59, or one of the more specific X modifiers that CMS now prefers (XE for separate encounter, XS for separate structure, XP for separate practitioner, XU for unusual non-overlapping service), marks two services that would normally be bundled as truly distinct. Modifier 76 indicates a repeat procedure by the same physician on the same day, while Modifier 77 indicates a repeat by a different physician. Modifier 52 flags a reduced service when a study was not completed in full. LT and RT indicate laterality for paired structures. And GC indicates a service performed under the supervision of a teaching physician in a resident training program.

Any radiology billing and coding cheat sheet that does not call out the PC/TC split and the MPPR reduction prominently is missing the two rules that affect more imaging claims than any other. These are the rules this guide is built around.

Prior Authorization for Advanced Imaging

Radiology has the highest prior authorization burden of any medical specialty. The American Medical Association reports that over 90 percent of commercial payers require prior authorization for advanced imaging, including CT, MRI, PET, and nuclear medicine studies. Medicare Advantage plans have expanded their imaging PA requirements steadily, and the CMS Interoperability and Prior Authorization Rule (CMS-0057-F) introduced new payer obligations starting in 2026 that affect imaging PA workflows.

Under the CMS rule, Medicare Advantage and Medicaid managed care plans must now respond to standard prior authorization requests within 7 calendar days and expedited requests within 72 hours. Payers must also provide specific reason codes when denying a request and publicly report their PA metrics, including denial rates and appeal outcomes.

Radiology Benefit Management (RBM) companies such as eviCore, AIM Specialty Health, and Carelon process the majority of commercial imaging authorizations. Each uses its own clinical criteria and submission workflow. The most common denial reason on PA-required imaging is submitting the claim before the authorization is obtained or submitting with an authorization number that does not match the code, modality, or site actually performed.

In our experience matching providers with billing partners, practices that build PA verification into their scheduling workflow rather than their billing workflow catch mismatches before the patient arrives, not after the claim is denied. That single process change eliminates the majority of PA-related imaging denials.

FY 2027 ICD-10 Changes Radiology Practices Must Know

Effective October 1, 2026, CMS and the CDC released the FY 2027 ICD-10-CM code set, which adds 190 new billable diagnosis codes, deletes 30, and revises 4. Several of these changes directly affect how radiology practices code the clinical indications for imaging studies. Claims filed with deleted codes after October 1 will deny at the code level.

The most significant radiology-relevant update is the addition of new flank pain codes in the R10.A series. R10.A0 covers flank pain unspecified, R10.A1 covers right flank pain, R10.A2 covers left flank pain, and R10.A3 covers bilateral flank pain. Previously, flank pain was reported under the broader R10.9 (unspecified abdominal pain) or R10.30 (lower abdominal pain, unspecified), neither of which precisely described the clinical indication. For radiology, flank pain is one of the most common indications for CT abdomen and pelvis, renal ultrasound, and KUB studies, so the new codes directly strengthen the medical necessity link between the diagnosis and the imaging order.

Radiology practices should verify every ICD-10 code on their superbill and EHR favorites list against the FY 2027 deleted code list before submitting any more October claims. The superbill is the single most common source of post-transition coding errors.

Common Radiology ICD-10 Code Pairings

The top denial reason on radiology procedure claims is a mismatch between the CPT code billed and the ICD-10 diagnosis attached to it. Pairing the two correctly matters as much as getting either one right on its own. The following codes reflect the FY 2027 ICD-10-CM code set effective October 1, 2026.

Unspecified abdominal pain, coded R10.9, supports a wide range of abdominal imaging but is increasingly subject to payer pushback for being too vague. Lower abdominal pain, coded as ICD-10 code R10.30, is more specific and supports CT abdomen and pelvis, pelvic ultrasound, and abdominal X-ray. The new flank pain codes (R10.A0 through R10.A3) provide the strongest medical necessity link for renal CT, renal ultrasound, and KUB studies.

Constipation, coded as ICD-10 code K59.00, supports abdominal X-ray and limited CT studies. Cough, coded R05.9, is the standard pairing for chest X-ray. Pulmonary nodule, R91.8, supports follow-up chest CT under the Fleischner Society guidelines. Low back pain, M54.5 (now M54.50 through M54.59 for laterality specificity in FY 2027), supports lumbar spine MRI and X-ray. Headache, R51.9, supports CT or MRI of the brain.

ICD-10 Code	Description	Common Imaging Pairing	Billing Note
R10.A1/A2	Flank pain, right/left (NEW FY 2027)	CT abdomen/pelvis, renal US, KUB	Replaces R10.9 default for flank complaints
R10.30	Lower abdominal pain, unspecified	CT abdomen/pelvis, pelvic US, abdominal X-ray	More specific than R10.9; preferred by payers
K59.00	Constipation, unspecified	Abdominal X-ray, limited CT	Supports KUB and limited abdominal imaging
R05.9	Cough, unspecified	Chest X-ray (71045/71046)	Standard chest imaging indication
R91.8	Other nonspecific abnormal lung finding	Follow-up chest CT (71250/71260)	Supports Fleischner guideline follow-up scans
M54.50	Low back pain, unspecified	Lumbar MRI (72148), lumbar X-ray	FY 2027 now requires laterality specificity
R51.9	Headache, unspecified	CT head (70450), MRI brain (70551)	PA often required for MRI
Z12.31	Screening mammography	Screening mammo (77067 + 77063)	No cost-sharing under Medicare; annual frequency

Across the billing companies we vet at Billing Service Quotes, the practices that handle the October code transition without revenue disruption are the ones with a billing partner that loads the FY 2027 files before the transition date and monitors claims for the first 30 days. For radiology-specific guidance on ACR standards, see our guide to guidelines from the American College of Radiology.

Denial Traps That Cost Radiology Practices

A handful of patterns account for the majority of denials in radiology billing, and nearly all of them are avoidable with the right process in place.

Billing a global code when the practice only performed the professional component, or vice versa, creates an overpayment that eventually triggers a recoupment. Submitting a combined contrast study code (such as 74178 for CT abdomen without then with contrast) when only one phase was performed is a false claim. Filing a claim for an advanced imaging study without the required prior authorization produces an automatic denial. Using an ICD-10 code that CMS deleted in the FY 2027 update on a claim with an October 2026 or later date of service denies at the code level. Billing two studies that CMS considers bundled without a proper distinct-service modifier (59 or XE/XS/XP/XU) zeroes out the second study. And submitting an incomplete diagnostic ultrasound under the complete study code fails on documentation review.

One question we hear constantly from imaging center managers is why their denial rate climbs every October. The answer is almost always the same: the annual code transition work was incomplete. The most common miss is a deleted diagnosis code embedded in a high-volume EHR template that runs for weeks before the denial pattern surfaces in reporting.

Every denial pattern listed above is something a radiology billing and coding cheat sheet should make impossible to overlook. If your current reference does not flag these traps prominently, this guide is designed to replace it.

Frequently Asked Questions

Note: CPT codes and descriptors are maintained by the American Medical Association and are provided here for reference. Coverage, frequency, and modifier rules vary by payer and by Medicare contractor, so verify against current payer policies and local coverage determinations before billing.

Next Steps

• For chest X-ray coding, see our guide to CPT code 71046.
• For CT chest without contrast billing, see our guide to CPT code 71250.
• For lumbar spine MRI coding, see our guide to CPT code 72148.
• For ACR-specific coding standards and appropriateness criteria, see our guide to guidelines from the American College of Radiology.
• Ready to hand radiology billing off? Get matched with vetted billing companies that know PC/TC splits, MPPR, prior authorization, and the modifier rules that decide whether you get paid.