ANNEX

Product Documentation and X-ray Performance Requirements

Terms and Definitions

For the purposes of this Annex, the following terms and definitions should apply:

(1) ‘Concept of operations (CONOPS)’: document describing the equipment characteristics and correct operating procedure(s);

(2) ‘Dark alarm’: visual indication presented to the operator when X-ray equipment cannot fully penetrate a scanned item (also known as ‘shield alarm’ or ‘dark alarm’);

(3) ‘Dual energy’: the exploitation of the energy-dependent attenuation of X-rays in different materials to estimate the effective atomic number of scanned materials, typically employed to discriminate between organic and inorganic material;

(4) ‘Dual view’: X-ray equipment where X-ray detection is implemented at two different angles of at least 60° and no more than 90° rotation to give two simultaneous views of scanned objects;

(5) ‘Edge enhancement’: an image-processing filter that enhances the edge contrast of an image in an attempt to improve its apparent sharpness;

(6) ‘Effective atomic number’: real (non-integer) number describing a hypothetical single element that would exhibit very similar X-ray attenuation as the scanned object comprising different elements;

(7) ‘Inorganic material’: in the context of X-ray security screening, a material with an effective atomic number greater than 10;

(8) ‘Multi view’: X-ray equipment where X-ray detection is implemented at different angles to give different simultaneous views of scanned objects;

(9) ‘Organic material’: in the context of X-ray security screening, a material with an effective atomic number less than 10;

(10) ‘Threat image projection (TIP)’: a software function used in X-ray screening to merge a pre-recorded scan of a threat item with an operational scan to create a realistic combined image that is presented to the operator in near real-time.

1. Product Documentation

The X-ray equipment to be used for security-threat detection in public spaces should be supplied together with documentation (in paper and/or electronic form) that contains the following information:

1.1. Physical dimensions of equipment

— overall dimension should be expressed as length (L) x width (W) x height (H) in millimetres (mm);

— tunnel size should be expressed as length (L) x width (W) in mm;

— the maximum object size that can be scanned should be expressed as length (L) x width (W) in mm;

— the maximum conveyor load should be evenly distributed and expressed in kilograms (kg);

— the conveyor height (H) should be expressed in mm.

1.2. Weight of equipment

The overall weight of the X-ray equipment should be expressed in kilograms (kg). The equipment weight should only consider the X-ray hardware and not include additional elements, such as a conveyer belt.

1.3. Throughput

The throughput should be expressed as conveyor speed in meter per second (m/s).

1.4. Power supply and consumption

— the power supply of the X-ray equipment should be expressed in voltage of alternating current (VAC) with a tolerance of ± 10 %;

— power consumption should be expressed in kilovolt-ampere (kVA).

1.5. X-ray generator

— the number of generators should be indicated (e.g. single, dual, multi);

— the anode voltage should be expressed in kilovolt (kV);

— the beam current should be expressed in milliampere (mA);

— the cooling system should be described (e.g., sealed oil bath with forced air).

1.6. IP rating

The IP rating according to IEC 60529 should be reported.

1.7. Operating environment

— operating temperature should be expressed in degree Celsius (°C);

— storage temperature should be expressed in degree Celsius (°C);

— humidity should be expressed in range in % (non-condensing).

1.8. System of conveyance

It should be indicated if the equipment includes a system of conveyance.

1.9. Threat image projection

It should be indicated if the system is able to provide threat image projection (TIP) functionality.

1.10. Requirements for CE marking

The equipment should be provided with all relevant documentation to demonstrate compliance with the requirements laid down in the applicable EU legislation that would allow affixing the CE marking. It should be the responsibility of manufacturers to determine which rules apply for their products. Relevant provisions can include, for example:

— Directive 2006/42/EC on machinery

— Directive 2014/35/EU on low voltage

— Directive 2014/30/EU on electromagnetic compatibility

1.11. Radiation leakage

Equipment should be provided with a declaration signed by a legal representative of the manufacturer that it meets all requirements for occupational and public exposure to ionising radiation in accordance with Council Directive 2013/59/Euratom on basic safety standards for protection against the dangers arising from exposure to ionising radiation.

1.12. Operating instructions (concept of operations)

The system should be provided with operating instructions, also referred to as concept of operations (CONOPS).

2. X-ray Performance Requirements

The X-ray equipment to be used for security-threat detection in public spaces should meet the following performance requirements:

2.1. Image enhancement functions

The X-ray equipment should have the following functions to enhance the image deployed on the screen:

— the capability of at least two times zoom on any part of the image;

— video inversion so as to be able to display a monochrome image with white displayed as black, and black displayed as white;

— an edge-enhancement feature.

Any selected function should reset automatically when the next screened object is shown to the operator.

2.2. Dark alarms

The X-ray equipment should generate dark alarms when scanned objects cannot be fully penetrated by X-ray.

2.3. Colour mapping behaviour

The X-ray equipment should differentiate between inorganic and organic materials by displaying them in different colours. The X-ray equipment should have the following image functions to differentiate between inorganic and organic materials:

— inorganic function to highlight inorganic materials.

— organic function to highlight organic materials.

The colour mapping behaviour specifications that the X-ray equipment should meet is indicated in Table 2.1.

Table 2.1

Colour mapping behaviour

Effective atomic number of material no image function enabled organic function enabled inorganic function enabled 0 < Zeff ≤ 10 orange orange none 10 < Zeff ≤ 17 green orange blue/green Zeff > 17 blue none blue

When organic and inorganic material are stacked on top of each other, the X-ray equipment should display the organic material when the organic function is enabled, as indicated in Table 2.2.

Table 2.2

Colour mapping behaviour (stacked organic/inorganic)

Effective atomic number of material no image function enabled organic function enabled inorganic function enabled organic material under aluminium plate green orange blue/green organic material under steel plate blue orange blue

2.4. Image quality tests

The image quality tests for the X-ray equipment should be performed by using the human perception (HP) test piece described in the following international standard:

— ASTM F792-17e1, Standard Practice for Evaluating the Imaging Performance of Security X-Ray Systems, ASTM International, West Conshohocken, PA, 2017, www.astm.org

The image quality of the X-ray equipment should be assessed by using the following nine tests:

2.4.1. Test 1: wire display

— the ability of an X-ray equipment to display images that can be used by an operator to identify metal wires.

2.4.2. Test 2: useful penetration

— the ability of an X-ray equipment to produce an image that allows for the detection, by an operator or algorithm, of wires that are hidden by different thicknesses of blocking material.

2.4.3. Test 3: spatial resolution

— the ability of an X-ray equipment to display closely spaced, high-contrast items as separate.

2.4.4. Test 4: simple penetration

— the ability of an X-ray equipment to display images that can be used by an operator to identify lead numerals that would otherwise be hidden by steel blocking material.

2.4.5. Test 5: thin organic imaging

— the ability of an X-ray equipment to display images that can be used by an operator to identify thin pieces of organic material.

2.4.6. Test 6: steel contrast sensitivity

— the ability of an X-ray equipment to display images that can be used by an operator to identify shallow circular recesses in steel.

2.4.7. Test 7: materials discrimination

— the ability of an X-ray equipment to display images that can be used by an operator to discriminate between materials with different effective atomic numbers.

2.4.8. Test 8: materials classification

— the ability of an X-ray equipment to display images that can be used by an operator to consistently identify a particular material over a range of different thicknesses.

2.4.9. Test 9: organic differentiation

— the ability of an X-ray equipment to display images that can be used by an operator to differentiate between organic materials of different effective atomic numbers.

2.5. Image quality thresholds

With reference to the human perception (HP) test piece in ASTM F792-17e1, the minimum thresholds for each image quality test should be as described in Table 2.3 below. To qualify for a specific standard, the X-ray equipment should reach the respective minimum thresholds for all image quality tests.

Table 2.3

Thresholds for image quality

Image quality Test Standard 1 Standard 2 1 wire display: wire thickness in air AWG 30 (0,255 mm) AWG 34 (0,160 mm) 2 useful penetration: wire thickness under aluminium (Al) of specified thickness AWG 24 (0,511 mm) behind 16 mm Al AWG 24 (0,511 mm) behind 20 mm Al & AWG 30 (0,255 mm) behind 12 mm Al 3 spatial resolution: perpendicular line-pair gauges (4 slots, horizontal & vertical, in 1018, 1010 or 1008 steel) 2 mm wide slots with 2mm spacing 1,5 mm wide slots with 1,5 mm spacing 4 simple penetration: lead numerals (thickness 3,0 ± 0,2 mm) attached to steel of specified thickness; 24 mm thick steel 28 mm thick steel 5 thin organic imaging: steps in polyoxymethylene with thicknesses of 0,25, 0,5, 1, 2 and 5 mm. Each step has holes of 2, 5 and 10 mm diameter. 4 holes visible (*) 7 holes visible (*) 6 steel contrast sensitivity: steel steps with thicknesses of 0,5, 1, 2, and 5 mm. Each step has holes of 2, 5 and 10 mm, all of depth 0,1 mm. 4 holes visible (*) 7 holes visible (*) 7 materials discrimination: a grid of square attenuators (varying amounts of steel & plastic varying effective atomic number and attenuation (**)). hues of 10 neighbouring squares can be differentiated hues of 12 neighbouring squares can be differentiated 8 materials classification: a test that the system consistently identifies a given material over a range of thicknesses (**). 4 columns are classified as the same material per column 6 columns are classified as the same material per column 9 organic differentiation: the observer records if he/she perceives a difference in hue between four different squares (**). squares 1 through 4 displayed as organic material squares 1 through 4 displayed as organic material

(*) A hole is considered visible if it at least half of its area or edge can be discerned.

(**) See ASTM F792-17e1 for a more detailed description of the human perception test piece.