On this page
- 01Before you start
- 02How an X-ray baggage scanner works
- 03Imaging technologies
- 04Image colours and material discrimination
- 05Tunnel sizes
- 06Essential X-ray specs
- 07Walk-through metal detectors
- 08Single-zone vs multi-zone
- 09WTMD dimensions and lanes
- 10Sensitivity and alarms
- 11Handheld detectors (HHMD)
- 12Throughput and lane count
- 13Integration
- 14EMI and crosstalk
- 15Radiation safety
- 16Floor loading and delivery
- 17Application starting points
- 18Presales spec matrix
- 19Check that it works
- 20Common problems and how to fix them
- 21Frequently asked questions
- 22Talk to PSS about security screening
Screening is a checkpoint design problem, not a catalogue purchase. Airports, government buildings, corporate lobbies, hotels, campuses, industrial sites and transport hubs use it to find prohibited items and control entry to restricted zones.
Two technologies usually form the core: X-ray baggage scanners inspect bags, parcels and cases without opening them; walk-through metal detectors (WTMD) detect metallic objects on people in a screening lane. Handheld detectors cover secondary inspection. CCTV, access control, visitor management and a control-room platform often sit around the same lane. Tunnel size, image quality, detection sensitivity and realistic throughput drive the quotation — on site, clearances, EMI, radiation safety, floor loading and commissioning decide whether the lane works.
Before you start
- What is screened: hand baggage, parcels, cargo, mail?
- Peak flow per hour; largest and heaviest item?
- Penetration target; is dual-view mandatory?
- Operator count, shifts and rotation policy?
- Who holds the radiation licence; is room shielding required?
- Room size, floor loading, door widths, mains and earthing?
- HVAC load and noise at the operator desk?
- Image archive retention; CCTV and access integration?
- Who trains and certifies operators; who runs the annual radiation survey?
- Documented throughput study and EMI/site survey done?
How an X-ray baggage scanner works
A non-invasive system moves an item through a shielded tunnel while an X-ray generator irradiates it. Detectors measure transmitted radiation; software builds an image on the operator monitor. Trained staff judge shapes, concealments and materials that need a second look.
Process: place bag on belt → conveyor through tunnel → X-ray generation → detector acquisition → image processing → operator decision (pass or secondary inspection).
Unlike a camera, the scan shows internal arrangement — it is not infallible. Dense objects, overlap and odd orientations complicate interpretation. Performance = equipment + operator training.
Imaging technologies
Single-energy — one principal energy measurement. Suitable for straightforward baggage/parcel work; often lower cost and simpler workflow; less direct material differentiation than dual-energy.
Dual-energy — measurements at different energies to classify materials by attenuation; colour-coded display helps separate clothing, plastic, electronics and metal. Common for corporate, government and hotel entrances that need richer image cues.
Dual-view — two viewing directions. Helps with overlap and can cut rescan/reposition work — often a throughput feature as much as an image-quality one. Confirm two generators are actually fitted, not only listed.
CT (computed tomography) — many projections into a 3D volume; may include automated explosives algorithms on specialised systems. Different cost, footprint and ops profile from standard tunnel scanners — select for the application, not as a default upgrade.
Image colours and material discrimination
Dual-energy colour schemes vary by manufacturer. A common convention:
| Colour (typical) | Broad material cue |
|---|---|
| Orange | Predominantly organic — paper, textiles, wood, many plastics, some foods; some explosives/narcotics may fall in organic categories — colour alone does not prove a threat |
| Green / yellow | Mixed or intermediate — combinations, glass, some minerals/electronics (OEM-dependent) |
| Blue | Predominantly inorganic / metals — steel, copper; dense metal can hide items behind it |
| Very dark / black | High attenuation or insufficient penetration — thick metal, overlap, weak signal; needs further look, not automatic “weapon” |
Colours are interpretation aids, not universal IDs. Shape, density, context, overlap and processing tools still matter — and specialised explosives detection is a separate capability when required.
Tunnel sizes
Manufacturers name classes by approximate tunnel width × height in cm. A 6040 is roughly 600 × 400 mm opening — not the machine’s external size.
| # | Class | Approx. opening | Typical use |
|---|---|---|---|
| 1 | 5030 | 500 × 300 mm | Small parcels, handbags, compact bags |
| 2 | 6040 (also ~620 × 420) | 600 × 400 mm | Backpacks, briefcases, carry-on, general visitor screening |
| 3 | 6550 | 650 × 500 mm | Larger bags, medium parcels |
| 4 | 7555 | 750 × 550 mm | Larger luggage, bulky packages |
| 5 | 8065 | 800 × 650 mm | Large parcels / selected baggage |
| 6 | 10080 | 1,000 × 800 mm | Oversized packages, specialised inspection |
| 7 | 100100 | 1,000 × 1,000 mm | Tall large parcels / light cargo |
| 8 | 150165 class | ~1,500 × 1,650 mm | Selected large-item/cargo — verify pallet, weight, conveyor; not every wooden pallet |
Classes are illustrative; naming varies by OEM. Size to the largest real item, not the average bag. High-volume airport hold-baggage or cargo often needs a dedicated system, not “the biggest lobby tunnel.”
5030 vs 6040: 5030 for compact handbags/parcels and tight lobbies; 6040 is the usual starting point for offices, hotels, government and commercial visitor screening. 6550/7555 when bags regularly exceed 6040. 8065+ for bulky cases and freight envelopes.
A 600 × 400 mm tunnel machine may still exceed 2 m in overall length. Plan space for in/out rollers, load/unload, operator console, queues, maintenance access, power, adjacent WTMD and secondary inspection. Use the OEM dimensional drawing before freezing the layout.
Essential X-ray specs
Generator voltage (kV). Influences penetration energy. Categories may quote ~80, 100, 140, 160, 200 or 320 kV. Baggage units commonly sit around 140–160 kV; cargo/vehicle systems often well above 200 kV. Higher kV ≠ better detection alone — detectors, processing, penetration, resolution and geometry matter.
Steel penetration. Thickness of steel imaged under stated test conditions (e.g. 34 or 40 mm). A 160 kV unit in the 600 × 400 class often quotes ~30–40 mm steel; larger tunnels may quote differently. Confirm typical vs guaranteed vs max and comparable test methods.
Wire resolution (AWG). Higher AWG = thinner wire. 38–40 AWG (~0.08–0.10 mm copper) is a common quote on compact dual-energy units; larger tunnels may quote 36–38 AWG at given steel. Detail spec — not a guarantee every small metal threat is found.
Spatial resolution. Ability to separate small/close features; horizontal and vertical may differ (e.g. 1.0 mm H / 2.0 mm V). Contrast, noise, orientation and overlap still limit interpretation.
Conveyor speed. Often ~0.20–0.30 m/s for general-purpose units. Faster belt ≠ more people through the checkpoint if the operator cannot read the image.
Max conveyor load. Some units ~150–200 kg evenly distributed — not a licence to drop that mass at one point. Check item weight, distribution and mechanical limits.
Image tools. Zoom, brightness/contrast, inverse/grayscale, high-penetration mode, organic/inorganic highlight, storage/retrieval, training modes, Threat Image Projection (TIP), auto-highlight — verify what is included vs licence/option.
Radiation (cabinet). Dose per inspection is typically a few µGy. External leakage is often specified as a dose rate at a stated distance (e.g. < ~1 µSv/h near the cabinet — model-specific). Film safety to about ISO 1600 matters if photographic film passes. In Egypt, the radiation licence, certified operator and dosimetry are project deliverables — not paperwork after handover.
Walk-through metal detectors
A WTMD monitors an electromagnetic field; metal in the passageway changes the signal and can trigger audible/visual alarms. Designs differ (pulse induction, continuous-wave / phase discrimination, etc.) — do not treat labels as interchangeable. WTMD does not image the person or bag contents; it flags metal for assessment.
Common sites: government, courts, HQ lobbies, airports/transport, industrial restricted areas, events, public institutions.
| # | Aspect | Pulse induction (PI) | Phase discrimination / CW (PD) |
|---|---|---|---|
| 1 | Environment | More robust near difficult metal floors | Needs a more stable EM environment |
| 2 | Discrimination | Limited | Stronger, with multiple programs |
| 3 | Fit | Tough structural sites, moderate traffic | High-security gates needing fine programs |
NIJ Standard-0601.02 is a common test reference: detection at 1.0 m/s over 50 consecutive trials with probability of detection 1.00, and false alarms on innocuous items below 20% — verify the supplier’s documented test method for the chosen model.
Single-zone vs multi-zone
Single-zone — metal detected, little or no location cue; secondary search with HHMD or procedure.
Multi-zone — passageway split into regions; side LEDs/graphics can show height and lateral area. Common counts: 6, 18, 33, 60+. A 33-zone unit typically subdivides vertical and lateral regions for faster targeted secondary checks.
Zone count ≠ sensitivity. Compare layout with sensitivity, uniformity, repeatability, false-alarm behaviour and documented tests.
WTMD dimensions and lanes
Illustrative passageway: ~700–800 mm wide × ~1,900–2,100 mm high; external frame is larger. Use OEM drawings. Wider openings may support wheelchairs/mobility aids — confirm accessibility rules; width alone is not compliance. High volume often needs more lanes, not one ultra-wide portal — plan EMI, queues and secondary staffing.
Sensitivity and alarms
Set sensitivity from risk assessment and screening policy, not from a generic “hotel vs prison” label. Higher sensitivity can raise nuisance alarms from permitted metal or EMI. Balance detection with manageable alarm rates; demand demonstrated performance with agreed test objects.
Useful features: sensitivity profiles, alarm sound/light/duration, people and alarm counters, event logs/network reporting, sync for adjacent detectors where supported. Record the program setting in handover — an undocumented sensitivity cannot be defended or repeated.
Handheld detectors (HHMD)
Portable secondary search after a WTMD alarm. Select for sensitivity, ergonomics, battery life, alarm modes, durability and spares. Easy to deploy; performance depends on technique; they do not replace a properly sited WTMD for throughput.
Millimetre-wave body scanners may be justified on selected high-security sites — separate from standard WTMD/X-ray.
Throughput and lane count
Separate bags/hour (X-ray) from people/hour (WTMD). They run together but are not the same rate.
Example: belt at 0.22 m/s → 0.22 × 3,600 = 792 m/h of belt travel — not bags/hour. Bags/hour depend on bag length, spacing, load/unload, image time, alarm resolution and operator skill. A supplier may quote several hundred bags/hour under stated conditions — validate against workflow.
Rough operator reality: theoretical bags/hour from speed and spacing often land near 60–70% of that theory once humans interpret images. Do not staff for the brochure maximum.
Lane estimate: peak people/hour ÷ realistic people/hour per complete lane. Example: 2,000 peak ÷ 500/lane → 4 lanes as a first sketch — then validate visitor/bag ratio, WTMD time, alarm %, secondary capacity, staffing and surge patterns. Add resilience for queues and downtime; finish with a documented throughput study.
Space rule of thumb: ~3–4 m queue before X-ray, ~2 m after for bag reclaim, ~900 mm oversize path where needed. Rotate image operators about every 20–30 minutes — fatigue is the real bottleneck; price headcount into the offer.
Throughput drivers: bags per visitor, image time, loading layout, secondary %, WTMD alarm rate and spacing, officers per lane, separate secondary area, arrival surges. A dedicated secondary area stops one hard alarm from blocking the whole lane.
Integration
Possible stack: X-ray + WTMD + HHMD + CCTV + access control + visitor management + VMS. Control room watches the lane while access governs the next barrier. Define shared events, alarm export, time sync and correlation. Not every scanner/WTMD talks directly to VMS — confirm interfaces, licences, network and scope before contract.
EMI and crosstalk
WTMDs are sensitive to nearby steel doors/gates, reinforced structure, motors, transformers, high-current cables, RF sources and adjacent detectors. Crosstalk is mutual interference between close WTMDs without sync/management.
There is no universal clearance. Some manuals cite ~0.5 m from stationary metal and more from moving metal — treat as examples. Site practice: follow the exact OEM manual; map metal and interference; keep clearances; enable frequency sync where supported; test in the final environment; document commissioning. Confirm multi-lane support if lanes are tight. Do not assume a fixed X-ray–WTMD distance always suffices.
A WTMD beside a steel door frame or moving metal gate will nuisance-alarm all day.
Radiation safety
Cabinet baggage scanners use shielding, lead curtains at openings, interlocks, warning indicators/labels, key control and access-panel controls. Leakage specs are model-specific (dose/exposure rate at a stated distance). Some jurisdictions reference cabinet emission limits around 0.5 mR in one hour at 5 cm under defined conditions; others use different units — follow the applicable standard and local authority.
Before commissioning: conformity and radiation docs; curtain integrity and position; interlocks and warnings; no unauthorised shield mods; OEM maintenance path; required radiation measurements by qualified staff. Never tie back, remove or bypass curtains in normal use. Retain test results in handover.
Floor loading and delivery
A compact 6040-class unit may weigh several hundred kilograms; large units can exceed one tonne. Tunnel size does not predict weight — use the datasheet. Raised floors often allow less load than a structural slab; concentrated foot loads matter as much as total mass.
Pre-delivery: net/operating weight; feet/wheels/load points; structural capacity; raised-floor panel/pedestal limits; load-spreading only if a structural engineer and OEM require it; door/lift/corridor route; level final position. Flexing floors jitter the image.
Application starting points
| Application | Starting point | Watch |
|---|---|---|
| Small office | 5030 or 6040 + WTMD if needed | Space, moderate flow |
| Corporate HQ | 6040 dual-energy + multi-zone WTMD | Experience, image quality, integration, peak |
| Government | 6040 or larger + WTMD to policy | Compliance, documented tests, controlled access |
| Hotel / commercial | 5030 or 6040 by luggage | Flow, luggage handling, space |
| Event venue | Scanner + enough lanes | Short concentrated arrivals |
| Postal / parcels | 6040–7555+ by size | Loading, parcel rate |
| Cargo / logistics | Large-tunnel or cargo system | Pallet, load, penetration |
Preliminary only — final selection follows risk assessment, ops needs and regulations.
Presales spec matrix
Explain why the kit fits — not only model names.
X-ray matrix: tunnel W×H; single/dual/dual-view/CT; kV and penetration; wire/spatial resolution; conveyor speed and load; image tools and storage; network/integration; radiation docs; power and install dimensions; warranty, training, service.
WTMD matrix: passageway size; zone layout; sensitivity; uniformity/repeatability; alarms/counters; interference management; accessibility/install; network; power, warranty, support.
Mark standard vs option vs licence. Agree FAT/SAT: model/config, dimensions, detection/imaging tests, alarms/safety/interfaces, software/integration, training and documentation — criteria before purchase.
Check that it works
- Tunnel class and conveyor load match the largest real item on site.
- Image tools, TIP (if ordered) and archive retention verified with operators.
- WTMD program, zone layout and alarm behaviour recorded in handover.
- EMI clearances and multi-lane sync tested in the final environment.
- Radiation curtains, interlocks, licence and dosimetry documents complete.
- Throughput study matches peak visitor/bag ratios and secondary capacity.
Common problems and how to fix them
Tunnel too small for the largest bag
Bags jam or force open-bag inspection. Size to the largest real item, not the average visitor bag.
Compared by kV alone
Higher kV does not equal better detection. Compare penetration, resolution, detectors and geometry under the same test method.
Colour coding treated as threat ID
Orange/blue are cues, not proof. Train operators on shape, overlap and secondary procedure.
WTMD bought by zone count alone
Zone count ≠ sensitivity. Demand uniformity, repeatability and documented tests for the chosen program.
Brochure bags/hour used for staffing
Real throughput often lands near 60–70% of theory. Staff from a workflow study, not the maximum quote.
Dual-view on paper, one generator on site
Confirm two generators are fitted. A dual-view claim without hardware is a specification gap.
EMI and floor loading ignored
Steel doors and adjacent WTMDs cause nuisance alarms; flexing floors jitter the image. Survey both before install.
No radiation licence at handover
In Egypt the licence, certified operator and dosimetry are project deliverables. Plan them before commissioning.
Operator desk facing a window
Screen unreadable at noon. Place the console away from glare and control desk noise/HVAC.
No tray return
Queue collapses at the first peak. Design reclaim and tray return into the lane layout.
No image archive
Evidence export fails when needed. Agree retention, export format and access in the contract.
Lifecycle ignored
Weak support, parts or recurring software fees break the lane later. Price warranty, training and service into the offer.
Frequently asked questions
Is a 6040 enough for most lobbies?
Often yes for offices, hotels and general visitor screening — size up when bags regularly exceed the opening.
Does higher kV mean better detection?
No. Penetration, detectors, processing and resolution matter as much as generator voltage.
Does colour coding identify threats automatically?
No. Colours are material cues; operators still interpret shape, density and context.
Does more WTMD zones mean higher sensitivity?
No. Zone count helps locate metal; sensitivity and test performance are separate.
Can one ultra-wide WTMD replace several lanes?
Usually not for high volume. More lanes with workable EMI and secondary staffing perform better.
What is crosstalk?
Mutual interference between close WTMDs without sync or management — survey and commission in the final layout.
Do X-ray cabinets need a radiation licence in Egypt?
Yes — licence, certified operator and dosimetry are project deliverables, not afterthoughts.
Can screening integrate with access control and CCTV?
Yes when interfaces, licences, time sync and scope are defined before contract.
What inputs does a quotation need?
Items screened, peak flow, largest/heaviest bag, tunnel/imaging needs, WTMD policy, room/floor data, radiation ownership, integration scope and throughput/EMI surveys.
Talk to PSS about security screening
PSS designs, installs, and maintains access control checkpoints with X-ray, WTMD and related screening equipment sized from real baggage and peak flow. Contact the PSS team to book a first site survey.
