ARDMS (USA / international) — SPI physics exam + a specialty exam

The American Registry for Diagnostic Medical Sonography (ARDMS), part of Inteleos, is the dominant sonography registry in the USA and is widely recognised internationally. Its credentials sit on two pillars: the SPI (Sonography Principles & Instrumentation) physics exam, taken once, plus one or more specialty exams. The two exams may be taken in any order but must be passed within five years of each other to be awarded the credential.

The credentials

The SPI exam Everyone

• Format: roughly 110 multiple-choice questions in a 2-hour appointment at a Pearson VUE test centre. Some items are unscored pilot questions used to trial wording and difficulty.
• Pass standard: a scaled score of 555 on a 300–700 scale (a scaled score, not a raw percentage).
• Content domains (broad areas): clinical safety; physical principles; ultrasound transducers; pulse-echo instrumentation; Doppler; image optimisation and artifacts; and quality assurance / bioeffects. See the physics high-yield section for the condensed revision list.

Specialty exams

• Format: typically ~150–170 multiple-choice questions over ~3 hours (the exact count varies by specialty — e.g. OB/GYN is towards the larger end). Many include interactive image-based (“hot spot”) items.
• Retake policy: if you do not pass, you can generally reapply after a short window but must wait a defined period (e.g. ~60 days) before re-sitting — confirm the current rule per exam.

Eligibility / prerequisites

ARDMS offers several prerequisite pathways; a first-time applicant selects the one that fits their background (use the ARDMS Prerequisite Prep tool). The two most common:

• Accredited-program pathway: graduate of (or student soon to graduate from) a CAAHEP / CMA / HSO-accredited diagnostic sonography or vascular program — no additional clinical experience required.
• Allied-health + experience pathway: hold a two-year allied-health credential in a patient-care field (e.g. radiologic technology, nursing) plus ~12 months (≈1,680 hours) of full-time clinical ultrasound experience, documented on Clinical Verification (CV) forms.

Prep strategy & high-yield

• Do SPI early. It is pure physics/instrumentation and least dependent on clinical exposure — many candidates sit it while still in their program. See the Physics (SPI) high-yield section.
• Learn the calculation set cold: propagation speed & time-of-flight (13 µs/cm), wavelength, PRF/PRP, Nyquist limit and aliasing, attenuation (~0.5 dB/cm/MHz), spatial pulse length and its link to axial resolution.
• For specialty exams, drill normal measurements/values, protocol/scan-plane recognition, pathology appearance and Doppler waveforms for your organ system.
• Multi-credential (e.g. RDMS + RVT) sharply lifts employability — the SPI only has to be passed once.

ARRT(S) (USA) — sonography via the radiography registry

The American Registry of Radiologic Technologists (ARRT) offers Sonography R.T.(S) as an alternative US credential, popular with people already inside the ARRT system (e.g. registered radiographers). Unlike ARDMS, ARRT bundles physics and clinical content into a single sonography examination rather than a separate SPI.

Eligibility — the Primary Eligibility Pathway

• Education: earn an associate degree (or higher) and complete an ARRT-approved educational program in the discipline (sonography). The degree need not be in radiologic science and can be earned before or after the program.
• 2025 timing rules: as of 1 January 2025, the degree must be earned within 3 years of finishing the program, and the ARRT application must be submitted within 3 years of completing the program.
• Competencies: you must demonstrate the required didactic coursework and a defined set of clinical competencies (documented procedures) before you can test.
• Ethics: all ARRT candidates must satisfy the ARRT Standards of Ethics (including a background review).

Exam format & pass standard

• A single computer-based Sonography exam. ARRT publishes a content specification covering physics/instrumentation and clinical procedures.
• Pass: a scaled score of 75. For Sonography, ARRT also requires section minimums — ≥7.5 in Abdominal Procedures and ≥7.5 in Obstetrical & Gynecological Procedures — so you cannot pass on volume alone while failing a core clinical area.
• Attempts: up to three, all within three years of the date your first exam window opens.

Australia — ASAR accreditation (course + logbook), not a single board exam

Important correction to a common misconception: Australia does not have a single national sonography “board exam.” Accreditation is granted by the Australian Sonographer Accreditation Registry (ASAR) on the basis of completing an ASAR-accredited course (which contains its own internal university assessments) plus a supervised clinical training component logged over time. The exams that exist are the coursework assessments within the accredited program, not an external registry exam like the ARDMS SPI.

How accreditation works

• Enrol in an ASAR-accredited course (typically a Graduate Diploma of Medical Sonography, usually undertaken while employed in a training role; some combined Bachelor/GradDip routes exist).
• Register as an Accredited Student Sonographer (ASS) with ASAR while training in a patient environment, and maintain a clinical logbook.
• Complete the clinical training component: standards recommend a minimum of ~3 days/week over two years (≈2,000+ hours) of supervised clinical practice.
• On completion, register as an Accredited Medical Sonographer (AMS) — this is what allows services to attract Medicare rebates.

Eligibility & the professional body

• Entry to the Graduate Diploma usually requires an existing health-science degree (commonly medical imaging / radiography) and a training sonographer position secured first — the employed-trainee model is the norm.
• The Australasian Sonographers Association (ASA) is the professional/member body (supervision guidance, CPD, advocacy) — distinct from ASAR, which is the accreditation registry.

What to “prep” for

• There is no single mock-able board exam — success is built from coursework assessments + logbook competency sign-offs. Prep effort goes into the university’s OSCE-style clinical and written assessments and completing logbook cases across the required systems.
• The physics content (see the Physics section) is still examined within the accredited course — the science is universal even if the delivery isn’t a registry exam.

UK — CASE-accredited PgCert/PgDip/MSc (competency & coursework), not a national board exam

Correcting the same misconception for the UK: there is no single national board exam for UK sonographers. Instead you complete a CASE-accredited postgraduate award, and competence is judged through coursework, written assessment and — critically — assessed clinical competency at the level of a newly qualified autonomous practitioner. The “exam” is internal to the university programme.

How the CASE model works

• CASE (Consortium for the Accreditation of Sonographic Education) accredits programmes so graduates are demonstrably competent and safe to practise; CASE-accredited awards are recognised nationally and internationally.
• Award ladder (typical): PgCert in ~12 months → PgDip in ~20 months (adds named clinical modules) → MSc (adds a dissertation module).
• Assessment is set at the standard of a newly qualified autonomous ultrasound practitioner: written papers, image-interpretation assessment, and practical/clinical competency assessment in the workplace.
• Clinical placement: you must secure a satisfactory placement providing (per stage) a minimum of around 320 hours of supervised hands-on scanning (≈2 days/week over ~9 months).

Eligibility & registration context

• Most entrants qualify first as a health professional — usually an HCPC-registered diagnostic radiographer (sometimes a midwife or nurse) — then specialise via the CASE award, frequently in a funded NHS trainee sonographer post.
• There is no statutory (mandatory) register specifically for sonographers; many join the voluntary Register of Clinical Technologists (RCT) (its Accredited Registers status has been under review — confirm current status).

What to “prep” for

• Prep targets the university’s written papers, image/viva assessments and clinical competency sign-offs — plus the underpinning physics (Physics section), which is examined within the award.
• Build a strong reflective clinical portfolio; UK assessment leans heavily on evidenced competence and reflective practice, not a single multiple-choice registry test.

Sonography Canada — written exam(s) + the CCSA practical → generalist credential

Correction to a widespread naming error: Canada’s national credentials are CRGS / CRCS / CRVS (Canadian Registered Generalist / Cardiac / Vascular Sonographer) — not “Canadian RDMS/RDCS/RVS.” Certification is by Sonography Canada and combines knowledge-based written examinations with a hands-on Canadian Clinical Skills Assessment (CCSA™).

Exam structure (generalist route, current NCP 6.1 format)

• To certify as a Generalist Sonographer (CRGS) you must pass both the Core (Core Sonographic Skills) examination and the Generalist Sonographer examination.
• Generalist exam format: 240 multiple-choice questions in 240 minutes, with a 10-minute break after question 140. It integrates abdomen / superficial structures / peripheral venous and obstetrics / gynaecology content.
• CCSA™: a separate clinical skills assessment evaluating hands-on scanning competence — required in addition to the written exam(s) to earn the credential.
• Upcoming change: from January 2027 the standalone Core exam is being integrated into the Generalist / Cardiac / Vascular credentialing exams, so first-time writers will no longer sit a separate Core exam — confirm the format for your sitting.

Eligibility

• Your educational program determines eligibility for the Core exam, and you generally must have graduated from an accredited (or accredited-with-condition) program before challenging a specialist exam, with the program confirming your eligibility to Sonography Canada.
• An Alternate Pathway exists for some internationally trained / experienced applicants — check current criteria.

ARDMS partnership

• Since October 2023, Sonography Canada members in good standing can, in select specialties (Breast, Fetal Echo, Pediatric Sonography, Pediatric Echo, MSK), substitute passing scores on Sonography Canada Core exams (5.1 / 6.0 / 6.1, within 5 years) for the ARDMS SPI — a streamlined route to add ARDMS credentials without re-sitting SPI. It boosts cross-border portability.
• Provincial regulation: some provinces regulate sonography (e.g. Ontario — CMRITO); elsewhere employers require Sonography Canada certification. Check your province.

Prep strategy

• Use the official certification examination blueprints and Sonography Canada practice exams to map your revision to the actual weightings.
• The Core exam is physics-heavy — the Physics tab applies directly; the Generalist exam rewards strong normal values, protocols and OB-GYN dating/anatomy.

Physics (SPI) high-yield — the cross-cutting content everyone needs

Whether you sit the ARDMS SPI, the ARRT sonography exam, the Sonography Canada Core exam or an AU/UK course’s physics module, the underlying ultrasound physics is the same. This is the condensed, revision-ready checklist. Free

Condensed 20-point revision checklist

• Soft-tissue speed 1,540 m/s and the 13 µs/cm round-trip rule.
• c = f × λ and how frequency changes wavelength.
• PRF ↔ imaging depth relationship and duty factor.
• Damping/backing layer effects on SPL, bandwidth and Q-factor.
• Axial resolution = ½ SPL; why higher frequency improves it.
• Lateral resolution and focusing; elevational & temporal resolution.
• Near-field length ∝ diameter²/λ; far-field divergence.
• Attenuation ~0.5 dB/cm/MHz; half-value layer; decibels.
• Impedance Z = ρ × c; reflection at mismatches.
• Doppler angle effect (0° max, 90° none; keep ≤60°).
• Nyquist = PRF/2; recognise and fix aliasing.
• CW vs PW Doppler trade-offs (aliasing vs range resolution).
• Colour vs power Doppler (sensitivity vs directional info).
• Reverberation, mirror-image, shadowing, enhancement.
• Side/grating lobe, slice-thickness, speed-error, range-ambiguity artifacts.
• TI (heating) vs MI (cavitation); ALARA and OB caution.
• SPTA as the key intensity for thermal bioeffects.
• Receiver chain: amplify, compensate (TGC), compress, demodulate, reject.
• QA phantom tests (resolution, penetration, accuracy, uniformity).
• Harmonic imaging, compounding, elastography, CEUS basics.