How to Choose an X-Ray Baggage Scanner: Tunnel Size, Resolution & Throughput Guide

Choosing an X-ray baggage scanner is one of the most significant physical security procurement decisions you will make. A scanner that is too small jams your queue. A scanner with inadequate resolution misses concealed threats. A scanner that cannot integrate with your access control system leaves your checkpoint fragmented. And a scanner without adequate local support becomes a costly liability when it needs maintenance.

This buying guide takes you through every key specification you need to evaluate — in plain language, with specific guidance for the Bangladeshi market context including customs, hotels, courts, and corporate environments.

Specification 1: Tunnel Aperture (Size)

The tunnel aperture — the opening through which items pass — is the first specification to define, because it determines what you can and cannot screen.

Understanding Aperture Dimensions

Tunnel size is expressed as width × height in centimetres. A 100×80 cm tunnel (100 cm wide, 80 cm high) accommodates standard carry-on luggage, briefcases, laptop bags, and backpacks. This is the standard specification for:

• Court and government building entrances
• Hotel lobbies
• Corporate office security checkpoints
• Bank branch screening

A 140×100 cm tunnel accommodates larger checked-luggage-sized bags, bulky sports bags, and medium-sized parcels. This is appropriate for:

• Airport check-in screening (smaller regional airports)
• Event venue bag screening
• Large hospital entrance screening
• University entrance screening with bulky student bags

A 160×120 cm or 180×150 cm tunnel handles large parcels, small boxes, and industrial items. These are used at:

• Cargo and parcel screening facilities
• Customs examination halls
• Postal sorting facilities
• Large export processing zone checkpoints

Critical procurement mistake: Buying a smaller tunnel to save cost, then finding that legitimate items (wheelchair components, medical equipment, large bags) cannot fit through and must be manually inspected, defeating the purpose of the X-ray. Always survey the largest items you will need to screen before specifying the tunnel size.

Specification 2: Image Resolution (Wire Detection)

Resolution determines how fine a detail the X-ray image can show. In X-ray screening, resolution is measured by the thinnest wire the system can detect — expressed in millimetres of wire diameter. This is the wire detection specification.

Wire Detection Standards

• 0.1 mm wire: Professional security screening standard. Detects fine wires used in detonator assemblies, thin blades, and fine wire connectors in improvised devices.
• 0.2 mm wire: Acceptable for standard commercial checkpoint applications such as hotel lobbies and corporate offices where the primary threat is bladed weapons.
• 0.3 mm wire: Entry-level specification. Suitable only for applications where the primary goal is detecting large weapons and obvious prohibited items.

For any application where the threat profile includes improvised explosive devices (IEDs), narcotics concealment, or sophisticated weapon concealment, specify 0.1 mm wire detection. For standard commercial applications, 0.2 mm wire detection is the practical minimum.

Spatial Resolution

Some vendors quote spatial resolution in line pairs per millimetre (lp/mm). This measures how closely spaced lines can be resolved as separate elements. A higher lp/mm value indicates sharper images. For professional security screening, specify minimum 28 lp/mm at standard beam penetration.

Penetration and Dynamic Range

Penetration is the material thickness the X-ray can pass through at a useful image quality level. This is typically expressed as the maximum steel thickness penetrable. A generator capable of penetrating 30 mm of steel at the 160 kV range is adequate for most airport and commercial screening. Cargo applications with dense industrial items require 40 mm or greater steel penetration.

Dynamic range — the ability to show both very dark (dense) and very light (low-density) items on the same image without losing detail in either extreme — is a critical but rarely specified parameter. A wide dynamic range (typically 8,192 grey levels or more) allows an operator to see detail inside dense luggage and also detect thin organic items. Narrow dynamic range makes one or the other difficult to see clearly.

Specification 3: Dual-Energy vs. Single-Energy vs. Multi-View

Single-Energy X-Ray: The Baseline

A single-energy scanner produces a greyscale image based on material density. Dense items (metals) appear dark; low-density items appear light. Single-energy systems cannot reliably differentiate organic material from inorganic material of similar density. They are an inadequate specification for any professional security checkpoint.

Do not procure single-energy X-ray scanners for security checkpoint applications. The additional cost of dual-energy is small relative to the detection capability gain.

Dual-Energy X-Ray: The Standard

Dual-energy X-ray (as described in our "How X-Ray Scanners Work" guide) uses two beam energies to calculate the effective atomic number of each material in the bag. This produces colour-coded images where:

• Orange = organic materials (explosives, narcotics, food, paper)
• Blue = inorganic materials (metals, ceramics, glass)
• Green = mixed-composition materials

Dual-energy is the minimum standard for all professional security checkpoint applications in Bangladesh. Specify it as a mandatory requirement, not an optional feature.

Multi-View (Dual-View) X-Ray: Enhanced Capability

Multi-view scanners use two X-ray generator/detector pairs positioned at different angles — typically 0° and 60° from horizontal. Each pair produces a separate image of the bag from a different perspective. The operator can view both images simultaneously on adjacent screens, seeing items that may be concealed behind others in the primary view.

Multi-view dual-energy scanners are the premium specification for high-security applications. They significantly reduce false negatives (missed threats concealed behind other items) because a threat item that is obscured in one view is rarely obscured in both views simultaneously.

For Bangladesh customs examination halls, major court complexes, and any facility where bag-image review time is limited, multi-view dual-energy is worth the additional investment.

Specification 4: Generator Voltage

The generator voltage directly determines the penetrating power of the X-ray beam.

For standard checkpoint applications at courts, hotels, banks, and government buildings in Bangladesh, a 160 kV generator is the appropriate specification. For parcel and cargo screening at customs or logistics facilities, specify 320 kV or above and consult the Bangladesh Atomic Energy Regulatory Authority (BAERA) for compliance requirements applicable to higher-voltage systems.

Specification 5: Conveyor Speed and Throughput

Conveyor speed determines how quickly bags pass through the tunnel and therefore how long the operator has to analyse each image. Most scanners have adjustable conveyor speed; the rated throughput is typically given at maximum conveyor speed.

Throughput Calculation

Throughput (bags/min) = Conveyor speed (m/min) ÷ Average bag length (m)

A conveyor speed of 0.22 m/s (13.2 m/min) with an average bag length of 0.6 m yields a theoretical maximum of 22 bags/min. Real-world throughput is 70–80% of theoretical due to spacing between items and belt stop/start events.

For your specification, match the required throughput to your peak demand. A government ministry entrance with a peak demand of 150 persons in 30 minutes requires: 150 ÷ 30 = 5 bags/min (assuming one bag per person). A standard scanner handles this easily on a single lane. A major court building entrance with 800 visitors in a 90-minute morning session needs: 800 ÷ 90 = 9 bags/min sustained — still a single lane with capacity to spare.

Important: Do not spec purely for theoretical throughput. The operator's image interpretation time is the real bottleneck. An operator cannot reliably assess more than 15 images per minute under sustained conditions. Higher-throughput requirements mean more lanes, not faster conveyors.

Specification 6: Image Enhancement and Analysis Software

The software interface is where image interpretation happens. Key software features to specify:

Zoom and pan: The operator must be able to zoom into any area of the image with a single click. A minimum 8× zoom is standard.

Colour inversion: Reverses image polarity for alternative visual interpretation.

High-penetration mode: Increases apparent penetration for dense items, revealing detail inside opaque masses.

Organic stripping: Digitally removes organic material from the image, leaving only inorganic (metal) items visible. Reveals hidden weapons concealed inside food or organic mass.

Inorganic stripping: The reverse — removes metals from the image, leaving only organic material. Useful for detecting organic explosives hidden among metal objects.

Edge enhancement: Sharpens boundaries between objects of different density.

Threat Image Projection (TIP): Randomly overlays threat item images onto real bag scans. Measures operator detection rate. Specify TIP as a mandatory requirement for any professional security application.

Audit trail: Records every image, operator ID, and enhancement tool use. Mandatory for regulated environments.

Specification 7: Total Cost of Ownership

Purchase price is not the full cost of an X-ray scanner. Calculate total cost of ownership (TCO) over a 10-year operating period:

When comparing two products at different price points, a USD 5,000 difference in purchase price is often offset within 3 years by lower tube replacement costs, better software licensing terms, or lower maintenance frequency. Request a 10-year TCO estimate from every vendor you evaluate.

Bangladesh Application Context

Customs and Bangladesh Customs Authority

Bangladesh Customs operates X-ray screening at all major ports of entry — Hazrat Shahjalal International Airport, Chittagong Port, Benapole Land Port, and others. Customs applications require large-aperture (140×100 cm or larger), high-penetration (200–320 kV) dual-energy systems with audit trail software that integrates with customs management systems. BAERA registration is mandatory for all customs X-ray equipment.

Hotels

International standard hotels in Dhaka — particularly those along Airport Road, Gulshan, and Banani — deploy 100×80 cm dual-energy scanners at driveway security checkpoints. The hotel brand security standard (IHG, Marriott, Hilton) typically specifies the minimum scanner performance. Hotel scanners operate in a high-aesthetic environment — specify stainless steel or premium-painted finish to meet interior design requirements.

Courts and Government Buildings

The Bangladesh Supreme Court complex and major divisional courts operate multiple scanner lanes at public entrance gates. Government procurement for courts is typically conducted through DPP (Development Project Proposal) processes. Scanner specifications for government procurement should reference international standards (ECAC, TSA, or EN 50131 security requirements as applicable) to ensure competitive and verifiable procurement.

Corporate and Banking Sector

Corporate scanners are purchased through direct procurement. Banking sector clients typically reference Bangladesh Bank's physical security guidelines and any applicable audit requirements from their parent or correspondent bank. A 100×80 cm dual-energy scanner with TIP capability, 0.2 mm wire detection, and access control integration is the standard corporate specification.

Vendor Evaluation Checklist

Before committing to any scanner purchase, verify:

• [ ] Dual-energy colour display with organic/inorganic/mixed colour coding
• [ ] Wire detection specification: 0.1 mm or 0.2 mm as required
• [ ] BAERA product registration documentation
• [ ] CE marking and IEC 60950 electrical safety compliance
• [ ] TIP software capability (verify with a live demonstration)
• [ ] Audit trail and operator login features
• [ ] Local service support with documented response time SLA
• [ ] Spare parts availability in Bangladesh (or guaranteed import lead time)
• [ ] Training programme for operators (included or costed separately)
• [ ] References from comparable installations in Bangladesh

Get Expert Help

Procuring an X-ray baggage scanner is a significant investment with long-term operational implications. Choosing poorly costs you in detection capability, operational disruption, and maintenance expenses for a decade or more. SSAL has procured and installed X-ray scanning systems across Bangladesh's courts, government buildings, hotels, banks, and industrial facilities.

We advise on the right specification for your application, manage BAERA compliance documentation, and provide operator training as part of every installation. Our after-sales support team is based in Bangladesh — no international escalation for routine service needs.

Get Free Consultation — contact SSAL today to discuss your scanner requirement and receive a specification and quotation tailored to your site.