HKIE Professional Assessment - Biomedical Discipline cheat sheet

Stress σ = F/A (Pa); strain ε = ΔL/L₀ (dimensionless); elastic modulus E = σ/ε in the linear region.

Hip contact force during walking ≈ 2.5–3× body weight; during stair climbing or stumbling can exceed 5–8× body weight.

Bone remodels per Wolff's law: trabecular alignment follows principal stress trajectories; cortical bone E ≈ 15–20 GPa, cancellous ≈ 0.1–2 GPa.

Poiseuille flow: Q = πΔP r⁴/(8ηL) - radius dominates (fourth power), so a 20% radius loss cuts flow ~59%.

Reynolds number Re = ρvD/η; laminar flow in arteries typically Re < 2000, turbulence occurs at stenoses and bifurcations.

Biomaterials: 316L stainless steel, Co-Cr alloys, titanium (Ti-6Al-4V), alumina/zirconia ceramics, UHMWPE, PMMA bone cement, PEEK, silicone, and biodegradable PLA/PGA/PLGA.

Host response sequence: protein adsorption (seconds) → neutrophil adhesion (minutes–hours) → macrophage fusion to foreign-body giant cells (days) → fibrous capsule (weeks).

Cardiac output CO = HR × SV; Fick principle VO₂ = CO × (CaO₂ − CvO₂); mean arterial pressure ≈ DBP + (SBP − DBP)/3.

Instrumentation chain: transducer → amplifier → anti-alias filter → ADC → digital processing; Nyquist requires fs ≥ 2× highest signal frequency.

ECG diagnostic bandwidth 0.05–150 Hz, sampling ≥ 500 Hz; EMG 20–500 Hz; EEG 0.5–70 Hz; SpO₂ uses red (660 nm) and infrared (940 nm) absorbance ratio.

Electrode half-cell potential offset can reach ±300 mV; Ag/AgCl electrodes reduce it; high input impedance (>10 MΩ) and CMRR > 80 dB are needed.

Defibrillation: monophasic 200–360 J, biphasic 120–200 J; energy stored E = ½CV²; charge time typically < 10 s.

Pulse oximetry calibration uses the empirical R = (AC_red/DC_red)/(AC_IR/DC_IR) ratio curve against arterial blood reference (SaO₂).

Patient leakage current limits (IEC 60601-1, normal condition, 50/60 Hz): type CF applied part ≤ 10 µA; type BF ≤ 100 µA; type B ≤ 100 µA.

Earth leakage current limit normal condition: ≤ 500 µA (class I); patient auxiliary current ≤ 100 µA (B/BF) and ≤ 10 µA (CF).

Isolation: 1× MOPP (means of patient protection) for applied parts; 2× MOPP for F-type applied parts; 1× MOOP for operator-accessible parts.

Lifecycle stages: needs assessment → capital planning → procurement → acceptance testing → in-service maintenance → decommissioning/disposal.

Acceptance testing verifies device against manufacturer specification and purchase order before clinical use; results filed in the equipment record.

Preventive maintenance (PM) interval set by manufacturer recommendation, risk score, and utilisation; typical 6 or 12 months.

Risk-based PM prioritisation uses equipment function, clinical criticality, incident history, and physical risk (e.g. Fennigkoh–Smith score).

Calibration traceability: verified against a standard traceable to a national metrology institute (in HK, Standards and Calibration Laboratory).

Electrical safety testing (IEC 62353) records protective earth resistance (< 0.2 Ω typically for cord plus plug), insulation resistance, and leakage currents.

Uptime KPI = (scheduled available time − downtime)/scheduled available time; MTBF = total operating time/number of failures.

Decommissioning: remove from asset register, delete patient data to PDPO/privacy requirements, and dispose of e-waste and batteries per local regulations.

ISO 13485:2016 - QMS for medical devices; requires risk-based approach, traceability, design controls, and process validation; certification by notified/accredited body.

ISO 14971:2019 - risk management: risk = severity × probability; process is identify hazards → estimate risk → evaluate → control → residual risk → overall benefit-risk.

Risk control hierarchy: inherently safe design → protective measures → information for safety.

IEC 60601-1 (3rd ed. + A1/A2) - general safety and essential performance; classification by type of protection (class I/II) and applied part (B/BF/CF).

IEC 62304 - medical device software lifecycle: safety classes A (no injury possible), B (non-serious injury possible), C (death or serious injury possible).

IEC 62366-1 - usability engineering: summative evaluation with representative users; use-related hazards included in risk file.

ISO 10993 series - biological evaluation: cytotoxicity, sensitisation, irritation, systemic toxicity, implantation, haemocompatibility; test selection by contact category and duration.

Hong Kong Medical Device Administrative Control System (MDACS): voluntary listing of devices (Class I–IV) and traders with the Medical Device Division of the Department of Health; conformity assessment via a recognised body.

Digital filter types: FIR (linear phase, always stable) vs IIR (lower order, non-linear phase); Butterworth maximally flat, Chebyshev ripple, Bessel flat group delay.

Pan-Tompkins QRS detection: band-pass 5–15 Hz → derivative → squaring → moving-window integration → adaptive thresholding.

Common-mode rejection: CMRR (dB) = 20 log₁₀(A_differential/A_common); driven right-leg circuit raises effective CMRR.

Aliasing: signal components above fs/2 fold into the baseband; anti-alias filter must attenuate them before sampling.

CT reconstruction: filtered back projection with a ramp (Ram-Lak) filter; Hounsfield unit HU = 1000 × (µ_tissue − µ_water)/µ_water.

MRI: spin echo uses 90° then 180° RF pulses; T1 and T2 relaxation times differ by tissue; SNR scales with voxel volume and √(number of averages).

Image quality metrics: spatial resolution (MTF), contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR); DICOM is the standard image and metadata format.

Wavelet and time-frequency analysis (STFT, spectrogram) localise transient events in non-stationary signals such as EEG and EMG.

HL7 v2 (pipe-delimited messaging), HL7 FHIR (RESTful resources such as Patient, Observation, DiagnosticReport), and DICOM (imaging) are the main interoperability standards.

ICD-10/ICD-11 for diagnoses; SNOMED CT for clinical concepts; LOINC for laboratory observations; these are complementary terminologies.

IHE profiles (e.g. XDS, PIX/PDQ) specify integration workflows across systems using existing standards.

Data protection: Hong Kong Personal Data (Privacy) Ordinance (Cap. 486) - six Data Protection Principles, including purpose limitation and security.

Clinical decision support: sensitivity, specificity, PPV and NPV; PPV depends on prevalence, so a test with 99% specificity has low PPV in a low-prevalence population.

Audit trail requirements: record who accessed or modified a record, when, and from where; keep immutable logs for the retention period.

Data quality dimensions: completeness, accuracy, timeliness, consistency, validity, uniqueness.

De-identification: remove direct identifiers (name, HKID, address, dates) and assess re-identification risk from quasi-identifiers.

Tissue engineering triad: cells (autologous/allogeneic/stem), scaffold (porosity, pore size, degradation rate, mechanical match), and signals (growth factors, mechanical cues).

Scaffold requirements: interconnected porosity typically 70–90%, pore size ~100–500 µm for bone ingrowth, degradation matched to tissue regeneration rate.

Cell sources: mesenchymal stem cells (bone marrow, adipose), induced pluripotent stem cells (iPSC), embryonic stem cells; immunogenicity differs.

Bioreactors provide controlled perfusion, mechanical loading, and oxygen/nutrient gradients; shear stress in perfusion bioreactors promotes osteogenic differentiation.

Sterilisation of biologics: aseptic processing, gamma irradiation (may damage ECM), supercritical CO₂; terminal sterilisation often not possible.

GMP manufacturing: cell and tissue products require cleanroom (ISO 5 for open processing), validated processes, and chain of identity/custody.

Regenerative medicine regulatory pathways differ: in HK, human cell/tissue products fall under the MDACS or specific hospital ethics committee approval for clinical trials.

3D bioprinting: extrusion, inkjet, and laser-assisted; key challenge is maintaining cell viability and vascularisation of thick constructs.

Duty of care: engineer must act within competence; refer to a specialist when the task exceeds expertise.

Informed consent and patient safety override commercial or schedule pressure; escalate concerns via the appropriate clinical governance channel.

Confidentiality: patient data must not be disclosed without consent or legal authority; the PDPO and hospital policy govern access.

Conflict of interest: declare financial or personal interests in device procurement or vendor relationships.

Incident reporting: adverse events and near misses are reported to the hospital authority and, where required, to the Medical Device Division.

Whistleblowing and professional codes: HKIE Code of Conduct covers integrity, public safety, and competence; breaches may lead to disciplinary action.

Risk management is continuous: re-assess after changes to device, software, or clinical use; document residual risk acceptance.

Human factors: design out use errors; label, colour-code, and force-function to reduce confusion between similar devices.

Project phases: initiation → planning → execution → monitoring/control → closure; gate reviews at each phase.

Scope, schedule, cost triangle: change in one affects the others; change control board approves scope changes.

Earned value: EV = % complete × budget; CPI = EV/AC; SPI = EV/PV; CPI < 1 or SPI < 1 indicates overrun or delay.

Risk register: likelihood × impact scoring; mitigation, transfer, acceptance, avoidance strategies.

Healthcare facility interfaces: medical gas (HTM 02-01/NFPA 99), electrical supply (essential/non-essential), HVAC (pressure regimes, air changes), and IT network segregation.

Equipment planning: room data sheets, structural loading, shielding (lead for radiology), and services (oxygen, vacuum, data, power).

Procurement: tender evaluation on whole-life cost, clinical requirements, and service support, not only purchase price.

Handover and commissioning: integrated systems test, staff training, and documented as-built records before clinical occupation.

Whole-life carbon: embodied carbon (manufacture, transport, disposal) plus operational carbon (energy, consumables); single-use devices often dominate.

Circular economy: reprocessing of single-use devices is regulated; remanufacturing and take-back schemes reduce waste.

Energy efficiency: standby power of medical devices can be significant; power management and equipment scheduling reduce consumption.

Emerging: AI/ML-based software as a medical device (SaMD), requiring a predetermined change control plan and post-market monitoring.

Digital health: wearables, remote monitoring, and telehealth raise cybersecurity and data governance requirements (IEC 62443, IEC 81001-5-1).

Cybersecurity: vulnerability management, patch policy, network segmentation, and incident response for connected devices.

CPD: HKIE requires continuing professional development; log hours, reflect on learning, and cover technical, managerial, and ethical areas.

Technology assessment: HTA evaluates clinical effectiveness, safety, cost-effectiveness, and organisational impact before adoption.

Material selection matrix: metals for load-bearing (high E, fatigue resistance), polymers for flexibility and wear surfaces, ceramics for wear and bioinertness.

Corrosion: galvanic corrosion between dissimilar metals (e.g. stainless steel screw with titanium plate) must be avoided; crevice and pitting corrosion common in implants.

Fatigue: S-N curve; implants designed for >10⁷ cycles; surface finish and notch geometry dominate fatigue life.

Viscoelasticity: creep, stress relaxation, hysteresis; modelled by Maxwell (fluid-like) or Kelvin-Voigt (solid-like) elements.

Diffusion: Fick's law J = −D dC/dx; drug-eluting stents rely on controlled release kinetics.

Haemodynamics: Bernoulli and Poiseuille relations; shear rate affects platelet activation and thrombosis on device surfaces.

Biocompatibility testing selection depends on contact nature (surface, external communicating, implant) and duration (<24 h, 24 h–30 d, >30 d).

Sterilisation methods: steam (121 °C/134 °C), ethylene oxide (residual limits), gamma, electron beam, hydrogen peroxide plasma.

Pulse oximeter accuracy stated as A_rms (typically ±2–3% for 70–100% SpO₂); motion and low perfusion degrade accuracy.

NIBP: oscillometric method measures mean pressure from cuff oscillations; auscultatory uses Korotkoff sounds.

Infusion pumps: flow accuracy typically ±5%; free-flow protection and occlusion alarms are essential performance.

Ventilators: tidal volume, PEEP, FiO₂, and inspiratory pressure monitored; alarms for high/low pressure and apnoea.

Patient monitors: ECG, SpO₂, NIBP, temperature, capnography (ETCO₂ normal 35–45 mmHg).

Electrical safety: class I relies on protective earth; class II on double/reinforced insulation; applied parts B, BF, CF denote isolation level.

EMC: IEC 60601-1-2 - emissions (CISPR 11) and immunity; keep devices away from RF sources such as mobile phones.

Battery management: lithium-ion cells require protection circuits; test capacity and replace per manufacturer schedule.

Asset register fields: unique ID, manufacturer/model, serial number, location, acquisition date, warranty, maintenance history.

Work order lifecycle: request → triage → assign → repair → verify → close; record parts, labour, and root cause.

Spare parts strategy: critical spares held on site; vendor service contracts for high-value imaging.

Training: competency records for operators and biomedical technicians; refresher intervals per policy.

Recall and field safety corrective action (FSCA): track manufacturer notices, identify affected units, and confirm action.

Downtime cost: include clinical impact, cancelled procedures, and backup equipment deployment.

Document control: controlled copies, revision history, and retention periods for maintenance records.

Key performance indicators: PM completion rate, first-time fix rate, mean time to repair (MTTR), and equipment availability.

ISO 13485 design controls: design input → output → review → verification → validation → transfer → changes.

ISO 14971 risk file: hazard identification, risk estimation, risk evaluation, risk control, residual risk evaluation, production/post-production monitoring.

IEC 60601-1 collateral and particular standards: 60601-1-2 (EMC), 60601-1-6 (usability), 60601-1-8 (alarm systems), 60601-1-11 (home healthcare).

IEC 60601-1-8 alarm categories: high, medium, low priority; alarm signals must be distinguishable and prioritised.

ISO 14155 - clinical investigation of medical devices; ISO 10993 for biological evaluation.

MDR (EU 2017/745) and FDA 510(k)/PMA are common reference frameworks; HK MDACS uses a four-class risk system.

Post-market surveillance: complaint handling, vigilance reporting, and trend analysis feed back into risk management.

Audit types: internal audit, supplier audit, and certification surveillance; findings classified major/minor and closed with CAPA.

Sampling and quantisation: ADC resolution (bits) sets quantisation noise; SNR ≈ 6.02N + 1.76 dB for an N-bit converter.

Frequency-domain analysis: FFT gives spectrum; windowing (Hamming, Hanning) reduces spectral leakage.

Filter design: cutoff frequency, order, ripple, and phase response; bilinear transform maps analog to digital.

ECG features: P wave, QRS complex, T wave; RR interval variability reflects autonomic tone.

EEG bands: delta (<4 Hz), theta (4–8 Hz), alpha (8–13 Hz), beta (13–30 Hz), gamma (>30 Hz).

Image registration: rigid vs affine vs deformable; used for multi-modal fusion and radiotherapy planning.

Segmentation: thresholding, region growing, active contours, and deep learning (U-Net) for organ delineation.

Compression: lossless (PNG, JPEG 2000 lossless) vs lossy (JPEG); medical images often require lossless for diagnosis.

EHR vs EMR: EHR is shared across care settings; EMR is within one organisation.

Interoperability layers: transport (HTTP, MLLP), syntax (HL7, XML, JSON), semantics (terminologies, FHIR profiles).

FHIR resources: Patient, Encounter, Observation, Condition, MedicationRequest, DiagnosticReport; RESTful CRUD operations.

Security: authentication, authorisation (role-based access), encryption in transit (TLS) and at rest.

Clinical coding: ICD-10 for morbidity/mortality statistics; procedure coding (e.g. CPT) for billing.

Data governance: data ownership, stewardship, retention, and secondary use for research with ethics approval.

Telehealth: store-and-forward vs real-time; bandwidth, latency, and privacy requirements.

AI in health: model validation, bias assessment, explainability, and regulatory classification as SaMD.

Scaffold fabrication: electrospinning (nanofibres), freeze-drying, salt leaching, 3D printing, and hydrogels.

Hydrogels: high water content, biocompatible; crosslinking by chemical, physical, or photo-initiation.

Growth factors: BMP-2 for bone, VEGF for angiogenesis, TGF-β for cartilage; dose and delivery kinetics matter.

Cell seeding efficiency and uniform distribution affect tissue quality; perfusion seeding improves uniformity.

Mechanical conditioning: cyclic stretch for tendon, compression for cartilage, perfusion for bone.

Vascularisation: diffusion limit ~100–200 µm; thicker constructs need pre-vascularisation or perfusion.

Sterility and endotoxin testing are critical for cell-based products.

Scale-up: from bench to GMP manufacturing requires process validation and quality control release testing.

Competence boundaries: recognise limits and seek expert advice; document decisions.

Safety culture: report errors without blame; learn from near misses.

Ethical principles: beneficence, non-maleficence, autonomy, justice.

Consent: ensure patients understand risks and benefits; document consent for research and novel devices.

Conflict of interest: disclose gifts, hospitality, and financial interests; follow employer policy.

Data privacy: minimum necessary access; secure storage and transmission of patient data.

Environmental responsibility: reduce waste, energy, and hazardous materials.

Continuing professional development: maintain a reflective record and plan for skill gaps.

Stakeholder management: identify clinical users, estates, IT, finance, and infection control.

Requirements management: capture functional and non-functional requirements; trace to verification.

Contract management: define deliverables, acceptance criteria, service levels, and penalties.

Change management: assess impact on schedule, cost, risk, and clinical workflow.

Quality assurance: design reviews, testing, and audits throughout the project.

Communication plan: regular progress reports and escalation routes.

Handover: training, documentation, and warranty start dates.

Post-implementation review: lessons learned and benefits realisation.

Life cycle assessment (LCA): goal and scope, inventory, impact assessment, interpretation.

Carbon footprint: scope 1 (direct), scope 2 (energy), scope 3 (supply chain).

Circular design: modularity, repairability, recyclability, and take-back.

AI/ML: training data quality, validation, drift monitoring, and transparency.

Cybersecurity: threat modelling, patch management, and incident response.

Wearables: sensor accuracy, battery life, and data privacy.

HTA: cost-effectiveness, budget impact, and equity considerations.

CPD: technical, managerial, and ethical learning; reflect and record.