The ARDMS Sonography Principles and Instrumentation (SPI) exam tests ultrasound physics and instrumentation across five domains. Prepare with the current content outline, check your application pathway, and practise explaining the physics behind your answers. Passing SPI is one requirement toward the associated sonography credentials.
How does SPI fit into certification?
To earn RDMS, RDCS, RVT or RMSKS, you must pass SPI and the corresponding specialty examination within five years of each other, in either order.
After passing SPI once, you do not need to repeat it for additional ARDMS certifications while you maintain active status. Passing SPI alone does not award one of those credentials.
Use the SPI outline for the shared physics examination and the separate outline for your specialty. They cover different assessment content.
Can you take SPI before graduation?
A limited early-entry pathway allows you to apply for SPI using a qualifying physics course or accepted continuing medical education (CME). It does not establish eligibility for every specialty examination.
The current prerequisite document lists a graded college, post-secondary or higher-education physics course with a grade of C or above, or at least 12 ARDMS-accepted physics CME credits earned within the two years before application. Check the document for the required course titles, transcript details and foreign-education evaluation rules.
No clinical experience or Clinical Verification form is required for that SPI-only pathway. If you qualify under a full prerequisite pathway, Inteleos recommends applying through it to make future processing faster. Use its Prerequisite Prep Tool and read all conditions for the pathway you select.
What should you expect on exam day?
The issuer lists approximately 110 multiple-choice questions over two hours. It also lists a five-minute survey.
A score of at least 555 on a 300–700 scale passes. This is a scaled standard, not 555 correct answers or a raw percentage. A practice-test percentage cannot be converted directly into an official SPI score.
Applications and exam windows are open year-round; the listed fee is USD 275. Review identification, scheduling and accommodation instructions before booking. You receive a score report at the test center, with results also available through Pearson and posted to the Inteleos portal within one week.
After an unsuccessful attempt, you may reapply after three days, but must wait 60 days before retaking the examination. These are different waiting periods.
Use the five domains to check your coverage
The current SPI content outline is version 24.1. Doppler carries the largest weighting, but all five domains belong in your preparation.
Use the detailed knowledge, skill and ability statements beneath each domain to find gaps. The outline identifies what to review; your course materials and appropriate technical references supply the explanations and supervised application.
| Domain | Weight | Topics to review |
|---|---|---|
| Perform ultrasound examinations | 23% | Patient care, ergonomics, sound–matter interaction, artifacts, bioeffects and documentation |
| Manage ultrasound transducers | 7% | Transducer selection, frequency and array concepts |
| Optimize sonographic images | 26% | Resolution, gain, pulse repetition, output power and image-processing concepts |
| Apply Doppler concepts | 34% | Angle, filters, aliasing, Doppler modes, waveforms, measurements and gain/scale |
| Provide clinical safety and quality assurance | 10% | Infection control, equipment integrity, phantom testing and statistical parameters |
Physics practice: calculate wavelength
Wave speed equals frequency multiplied by wavelength. Rearranging gives wavelength = speed ÷ frequency. Keep the units consistent before calculating.
OpenStax explains this relationship for sound waves. The exercise supplies a hypothetical medium and speed; it does not assume a universal speed for all human tissues or tell you which clinical equipment settings to choose.
Practice example
In a hypothetical medium, sound travels at 1,500 meters per second. A wave has a frequency of 3,000,000 hertz (3 MHz). What is its wavelength in millimeters?
Show answer
0.5 millimeter.
Wavelength = 1,500 m/s ÷ 3,000,000 per second = 0.0005 m. Multiplying by 1,000 converts meters to millimeters: 0.5 mm. Substituting 3 for the frequency before converting MHz to Hz would introduce a million-fold error. Under the same stated speed, doubling the frequency would halve the wavelength; that relationship alone does not determine clinical image quality.
Sources: Sonography Principles and Instrumentation Examination Content Outline v24.1 — inteleos.org/wp-content/uploads/2026/05/SPI-Content-Outline_v24.1.pdf; 14.1 Speed of Sound, Frequency, and Wavelength - Physics | OpenStax — https://openstax.org/books/physics/pages/14-1-speed-of-sound-frequency-and-wavelength
Understand what ALARA means for ultrasound
ALARA means “as low as reasonably achievable.” FDA guidance calls for minimizing ultrasound exposure while maintaining diagnostic quality.
Ultrasound does not use ionizing radiation, but it introduces energy into the body. FDA describes possible physical effects, including mechanical effects and temperature rise, and recommends regular equipment quality-control testing.
Study the outline’s safety and quality-assurance topics alongside your training and applicable procedures. A general safety principle does not establish a universal control-setting sequence for every image problem.
Sources: Sonography Principles and Instrumentation Examination Content Outline v24.1 — inteleos.org/wp-content/uploads/2026/05/SPI-Content-Outline_v24.1.pdf; Ultrasound Imaging | FDA — https://www.fda.gov/radiation-emitting-products/medical-imaging/ultrasound-imaging
Build a study plan that reveals your gaps
After a practice set, identify the concept you misunderstood and check its explanation before trying a related question.
For calculations, write the quantities, units and formula before substituting numbers. For imaging questions, identify the information given and the assumptions required. A familiar symptom or cue word may not establish one cause.
Use each domain in the official outline as a coverage check. Give additional attention to your weak topics, and practise timed sets once you can explain your answers. Treat forum discussions as leads for questions about resources or exam arrangements; verify technical answers against reliable references.
- Confirm the correct application pathway and documents.
- Review all five domains and the specialty-exam requirements separately.
- Practise with complete questions, explanations and explicit units.
- Check identification and scheduling instructions before exam day.
Sources: SPI Exam | Sonography Principles and Instrumentation Exam — inteleos.org/exam/sonography-principles-and-instrumentation/; Sonography Principles and Instrumentation Examination Content Outline v24.1 — inteleos.org/wp-content/uploads/2026/05/SPI-Content-Outline_v24.1.pdf; Inteleos SPI and specialty prerequisites, August 2026 — https://www.inteleos.org/wp-content/uploads/2026/08/SPI_Specialty_Prerequisites_Final-082026.pdf
Sources
Facts checked:
- SPI Exam | Sonography Principles and Instrumentation Exam
- Sonography Principles and Instrumentation Examination Content Outline v24.1
- SPI Exam | Sonography Principles and Instrumentation Exam (ARDMS URL)
- Communities - ARDMS - Inteleos
- SPI Practice Analysis 2022
- Certification & Exam Finder - Inteleos
- MSKS Exam for ARDMS Certification | Musculoskeletal Sonography Exam
- Musculoskeletal Sonography Examination Content Outline v24.1
- Ultrasound Imaging | FDA
- 14.1 Speed of Sound, Frequency, and Wavelength - Physics | OpenStax
- Inteleos SPI and specialty prerequisites, August 2026