Physicians (MDs and DOs) can order any type of diagnostic imaging, but they aren’t the only ones. Nurse practitioners, physician assistants, dentists, podiatrists, optometrists, chiropractors, and in some states even physical therapists can order imaging studies, though each has different limitations on what they can request and for what body parts. The rules vary by state, by imaging type, and by insurance plan.
Physicians Have the Broadest Authority
Medical doctors and doctors of osteopathy can order the full range of diagnostic imaging: X-rays, CT scans, MRIs, PET scans, ultrasounds, and nuclear medicine studies. No restrictions apply based on body region or imaging type. Physicians can also open their own imaging centers or purchase equipment like MRI and CT machines for their offices under federal self-referral exceptions.
For Medicare purposes, physicians who order imaging must have an individual National Provider Identifier (NPI) and be enrolled in Medicare with either “approved” or “opt-out” status. An organizational NPI doesn’t count. These requirements exist to create a traceable chain between the provider who ordered the test and the facility that performs it.
Nurse Practitioners and Physician Assistants
Nurse practitioners (NPs) and physician assistants (PAs) can order diagnostic imaging, and CMS lists both as eligible “ordering and certifying” provider types for Medicare. In practice, though, the scope of what they can order depends heavily on state law. Some states grant NPs full independent practice authority, which includes ordering any imaging study. Others require a collaborative agreement with a physician or limit the types of advanced imaging an NP can request without physician involvement.
Despite having legal authority in most states, NPs and PAs still account for a small share of all imaging. Between 1994 and 2015, imaging services billed by non-physician practitioners grew dramatically (increasing nearly 150-fold among Medicare beneficiaries), yet they still represented only about 1.3% of all Medicare imaging by 2015. The vast majority of imaging these providers order is basic: radiography and fluoroscopy made up 94% of their imaging services in both 1994 and 2015.
Clinical nurse specialists and certified nurse midwives also appear on the CMS list of eligible ordering providers, along with interns, residents, and fellows working under supervision.
Dentists and Oral Surgeons
Doctors of dental surgery and doctors of dental medicine can order imaging that falls within their scope of practice. This includes intraoral X-rays, panoramic X-rays, and cone-beam CT scans of the jaw and surrounding structures. CMS recognizes both dental degrees as eligible specialty types for ordering and certifying imaging under Medicare Part B. Dental imaging follows standards set by the American Dental Association and the National Council on Radiation Protection, and the ordering dentist is responsible for ensuring each X-ray is clinically justified rather than routine.
Podiatrists and Optometrists
Doctors of podiatric medicine can order imaging of the foot and ankle, including X-rays, MRIs, and CT scans of the lower extremity. They are recognized by CMS as eligible ordering providers. Podiatric imaging devices and services follow the same accreditation standards as general medical radiology.
Optometrists have more limited authority. CMS allows them to order laboratory tests, X-ray services, and durable medical equipment payable under Medicare Part B. They cannot order advanced imaging like CT or MRI through Medicare, though state scope-of-practice laws may allow broader ordering in certain clinical situations outside the Medicare framework.
Chiropractors and Physical Therapists
Chiropractors can order X-rays in most states as part of their scope of practice, particularly for spinal imaging. Their authority for advanced imaging like MRI or CT varies significantly by state. In many cases, a chiropractor who believes a patient needs an MRI will refer to a physician who then places the order.
Physical therapists have historically needed to go through a physician to get imaging for their patients, but that’s changing. U.S. military physical therapists have had direct imaging referral authority for roughly 50 years. On the civilian side, North Dakota, Rhode Island, Utah, and Wisconsin now have practice act language authorizing physical therapists to refer patients directly to radiologists for musculoskeletal imaging. Colorado, the District of Columbia, Maryland, New Jersey, and West Virginia allow it through state board rules or decisions. In states without direct referral authority, physical therapists can recommend imaging but must route the actual order through a primary care physician or other qualified provider.
What Insurance Requires
Even if a provider has the legal authority to order imaging, insurance adds another layer of requirements. For advanced outpatient imaging like CT scans, MRIs, MRAs, PET scans, and nuclear cardiology studies, many insurers require prior authorization before the test can be performed. UnitedHealthcare, for example, requires prior authorization for all of these modalities regardless of which provider type places the order. The authorization process typically involves submitting the clinical reason for the test, the specific body part, and the requested imaging type.
For Medicare patients specifically, a federal law called the Protecting Access to Medicare Act (PAMA) requires providers to consult a clinical decision support tool when ordering advanced diagnostic imaging. These tools are built around the American College of Radiology’s Appropriateness Criteria, which are evidence-based guidelines that help determine whether a particular imaging study is warranted for a given clinical situation. The provider enters the patient’s symptoms and suspected condition, and the tool indicates whether the requested scan is appropriate, possibly appropriate, or unlikely to be useful. This consultation must happen through a CMS-qualified digital tool before the order is placed.
The goal of these requirements isn’t to block imaging but to ensure that the test ordered actually matches the clinical question. A knee MRI for a patient with two days of mild soreness after exercise, for example, would likely flag as not yet appropriate, while the same MRI for a patient with locking, swelling, and suspected meniscus tear would pass easily.
State Laws Are the Deciding Factor
The single most important variable in who can order imaging is the state where the provider practices. Imaging regulation falls under each state’s professional practice laws, which define scope of practice for every licensed provider type. A nurse practitioner in one state may have full authority to order a brain MRI independently, while the same provider in a neighboring state may need a physician’s co-signature. A physical therapist in Utah can send a patient directly for a musculoskeletal X-ray, while one in California cannot.
If you’re unsure whether your provider can order the imaging you need, the simplest path is to ask the provider’s office directly. They deal with these rules daily and will know whether they can place the order themselves or need to coordinate with another provider. In most cases, if your provider can’t order the test, they can refer you to someone who can without requiring a separate office visit.