Lesson 1Sound wave fundamentals: frequency, wavelength, propagation, acoustic impedanceIntroduces core sound wave properties relevant to ultrasound imaging, including frequency, wavelength, propagation speed, and acoustic impedance, and explains how these determine reflection, refraction, and transmission at tissue interfaces in practical settings.
Frequency, period, and clinical rangesWavelength and spatial resolution linksPropagation speed in different tissuesAcoustic impedance and reflectionRefraction and transmission at boundariesIntensity, power, and beam profilesLesson 2Basic troubleshooting: noise, probe contact problems, and cable/instrument checksProvides a structured approach to troubleshooting poor images, including recognising noise, checking probe contact and gel, inspecting cables and connectors, and identifying when equipment service is required in resource-limited environments.
Identifying electronic and speckle noiseImproving probe contact and gel useChecking cables, connectors, and portsVerifying presets and default settingsSimple on-the-spot functional testsWhen to escalate to technical serviceLesson 3Doppler basics (overview): colour vs spectral Doppler principles and limits for bedside useIntroduces Doppler physics for bedside use, comparing colour and spectral Doppler, aliasing and angle dependence, and practical limits in emergency and critical care applications where rapid, focused assessments are needed in Sierra Leonean clinics.
Principles of the Doppler frequency shiftColour Doppler flow mapping and settingsSpectral Doppler waveforms and indicesAngle dependence and aliasing limitationsPractical bedside Doppler applicationsCommon Doppler pitfalls and artefactsLesson 4Transducer types and beam formation: linear, curvilinear, phased-array characteristicsDescribes linear, curvilinear, and phased-array transducers, how beam formation differs among them, and how footprint, frequency, and field of view guide probe selection for vascular, abdominal, cardiac, and lung imaging in diverse patients.
Linear probes and high-resolution imagingCurvilinear probes and abdominal viewsPhased-array probes and cardiac windowsBeam steering, focusing, and apodizationProbe frequency ranges and applicationsSelecting probes for point-of-care examsLesson 5Attenuation and depth: effects of frequency selection on depth and image qualityExplores how ultrasound energy is attenuated with depth, how frequency choice alters penetration and resolution, and how to balance image brightness, noise, and diagnostic detail when scanning superficial versus deep structures in everyday practice.
Mechanisms of attenuation in soft tissueFrequency versus penetration trade-offsFrequency effects on axial and lateral resolutionOptimising settings for superficial targetsOptimising settings for deep structuresRecognising attenuation-related artefactsLesson 6Focusing, focal zones, and near/far field optimisationCovers how focusing and focal zones narrow the beam, improve lateral resolution, and differ in the near and far fields. Emphasises selecting and positioning focal zones to optimise target structures at varying depths for better diagnostics.
Near field, focal zone, and far field basicsElectronic versus fixed focusing methodsEffect of focus on lateral resolutionChoosing number and depth of focal zonesOptimising focus for superficial targetsOptimising focus for deep structuresLesson 7Common artefacts: reverberation, shadowing, enhancement, mirror image, comet-tail, A/B-lines, ring-downReviews key ultrasound artefacts, why they occur, and how to recognise and use or avoid them. Emphasises reverberation, shadowing, enhancement, mirror image, comet-tail, A- and B-lines, and ring-down in point-of-care exams in local settings.
Reverberation and multiple reflection patternsAcoustic shadowing and clean versus dirty shadowsPosterior acoustic enhancement mechanismsMirror image and duplication artefactsComet-tail, ring-down, and short-path artefactsA-lines, B-lines, and lung artefact patternsLesson 8Resolution and penetration: axial, lateral, and elevational resolution trade-offsDetails axial, lateral, and elevational resolution, how each depends on pulse length and beam width, and how probe choice, depth, and focusing affect the trade-off between fine detail and adequate penetration in clinical imaging scenarios.
Axial resolution and spatial pulse lengthLateral resolution and beam widthElevational resolution and slice thicknessDepth, focusing, and resolution changesProbe selection for optimal resolutionBalancing resolution against penetrationLesson 9Time-gain compensation, overall gain, and dynamic range: purpose and practical adjustmentsExplains how time-gain compensation, overall gain, and dynamic range shape image brightness and contrast. Focuses on practical knobology to correct for depth-related attenuation and to avoid over- or under-gaining structures in real-time scans.
Overall gain and global brightness controlTime-gain compensation curve shapingDynamic range and image contrast controlRecognising overgain and undergain patternsDepth-specific adjustments during scanningPreset use and manual fine-tuningLesson 10Safety and bioeffects: thermal and mechanical indices, ALARA principle, safe scanning timesOutlines ultrasound safety principles, including thermal and mechanical indices, ALARA, and safe exposure times. Emphasises practical strategies to minimise risk while maintaining diagnostic image quality in vulnerable patients in Sierra Leone.
Thermal index meaning and limitationsMechanical index and cavitation riskALARA principle in daily practiceSafe scanning times by patient groupHigh-risk scenarios and mitigationRegulatory guidelines and labelling
