Type approvals pursuant to the X-ray Ordinance: Frequently Asked Questions

• 1. What are the characteristic radiation protection features in the individual type categories and what must be observed when operating these devices?
  • 1a. X-ray tube housing assemblies (Annex 1 and 2 no.1 RoeV)
  • 1b. Basic protection devices (Annex 2 no. 6 RoeV)
  • 1c. High protection devices
  • 1d. Full protection devices (Annex 2 no. 3 RoeV) and school X-ray devices (Annex 2 no. 4 RoeV)
  • 1e. PTB Safety Guideline, further requirements for safety systems in basic protection devices, high protection devices, full protection devices and school X-ray devices
  • 1f. Parasitic X-ray emitters (Annex 2 no. 5 RoeV)
• 2. Recurring tests (§ 18 (1) no. 5 Roev)
• 3. Testing, trial and maintenance
• 4. What is to be observed by type approval holders, if...
  • ... they wish to make modifications to type-approved devices?
  • ... company-related data or responsibilities (e.g. persons in charge) change?
  • ... the time limit of the type approval is about to expire?
• 5. What do holders (operators) of a type-approved device need to know with respect to the limitation of the type approval period?
• 6. What do holders (operators) of a type-approved device need to observe with respect to the transfer of devices?

1. What are the characteristic radiation protection features in the individual type categories and what must be observed when operating these devices?

According to the X-ray Ordinance, the operation of an X-ray device is generally subject to licensing. Such a license is granted by the competent authority of the Federal State and must be applied for.

The operation of type-approved devices can be exempted from this rule under certain conditions (pursuant to § 4 RoeV) so that the device may be operated without licensing. The radiation protection effort required for the startup and the operation of these devices varies depending on the protection level stipulated for the individual type categories. Details are laid down in §§ 3 to 5 RoeV.

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1a. X-ray tube housing assemblies (Annex 1 and 2 no.1 RoeV)

X-ray tube housing assemblies that, by definition, consist of an X-ray tube and a tube housing provide the lowest protection level among all type-approved devices due to the unshielded exiting X-ray beam.

The type approval for such devices concentrates on the shielding effect of the protective tube housing when the beam exit window is closed. This effect is evaluated by measuring the dose rate under maximum operating conditions. The requirements and the admissible dose rates are set out in Annex 1 and Annex 2 no. 1 RoeV. It has been observed that the technical development of type-approved X-ray tube housing assemblies is orientated towards a reduction of the ionising radiation penetrating the housing.

Purposes of use

Type-approved X-ray tube housing assemblies are classified by the purpose of use and the rated voltage, i.e. the corresponding acceleration voltage for the electrons. The devices are classified into the following categories:

• X-ray equipment for veterinary purposes, unless such equipment is primarily put into circulation according to the regulations of the German Medical Products Law (Annex 1 RoeV),
• X-ray tube housing assemblies for the purposes of fine structure X-ray analysis, e.g. X-ray diffraction, microradiography, X-ray spectral analysis (Annex 2 no.1.1 RoeV),
• other X-ray tube housing assemblies (Annex 2 no. 1.2 RoeV) with a maximum rated voltage of 500kV

Operation of type-approved veterinary X-ray equipment

In addition to the requirements set out in § 3 (2) RoeV, applicants notifying the competent authority of the operation of type-approved veterinary X-ray equipment must provide evidence that the applicant or the appointed qualified expert is a licensed veterinary surgeon, medical practitioner or dentist and is entitled to perform this job (pursuant to § 4 (2) no. 5 RoeV).

Operation of type-approved non-medical X-ray tube housing assemblies

If a type-approved X-ray tube housing assembly is used within an X-ray device, the entire device may be used without licensing. This is subject to the condition that the competent authority is notified of the startup of such device at least two weeks in advance and that a qualified expert has established that the requirements for the intended operation are met. More detailed provisions can be found in § 4 (1) and (2) RoeV.

However, pursuant to § 4 (4) no. 1 RoeV, operation without licensing is not possible if the X-ray tube housing assembly is used in the field of technical radiography for macrostructural analysis for the purposes of material testing (i.e. X-ray imaging). This includes e.g. the inspection of weld seams or verifying that workpieces are free of cavities, fissures or other defects. This exclusion from operation without licensing is not valid for X-ray appliances that are approved as basic protection device, high protection device or full protection devices, e.g. in the type of a shielded and protected cabin.

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1b. Basic protection devices (Annex 2 no. 6 RoeV)

Features

Basic protection devices include e.g. baggage X-ray machines or food scanners. In these devices, both - the X-ray tube housing assembly and the object to be scanned - are enclosed by the protective housing. However, the openings for samples transport may not provide efficient technical protection against people reaching into dangerous areas in the device. Yet these devices ensure an increased protection level compared with X-ray tube housing assemblies and fulfil a number of requirements with respect to their design and the shielding effect provided by the protective housing. The X-ray beam does not exit from the device but is directed onto the sample to be scanned inside the device. Openings for samples transport are usually fitted with flexible shielding material, e.g. lead sheets. The existing protective measures must ensure a dose rate of a maximum of 10 microsievert per hour (10µSv/h) at a distance of 0.1 m from the touchable surface or from the openings under maximum operating conditions.

Basic protection devices may only be operated when the protective housing is completely closed. An exception is made for devices that exclusively use a sample changer or conveyor for bringing the samples in and out; in this case the dimensions of the openings must be suitable for this purpose.

In the case of basic protection devices with continuous operation of the X-ray tube housing assembly, the dose rate inside the device must also not exceed 10µSv/h under maximum operating conditions when the protective housing is opened (e.g. for servicing purposes). As in the case of high protection devices, organisational measures as part of the radiation protection regime may also be used to ensure the safe operation of the device.

Operation

The competent authority of the Federal state shall be notified according to § 4 (3) RoeV at least 14 days before a basic protection device is taken into operation. Such notification shall be accompanied by a copy of the type approval certificate as well as documents certifying safe operation and compliance with the radiation protection requirements (pursuant to § 3 (2) no. 2 to 4 RoeV). The competent authority of the Federal state decides on a case-by-case basis if further radiation protection measures have to be taken.

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1c. High protection devices

Features

A type-approved high protection device provides a high level of protection in itself. The X-ray tube housing assembly and the object to be scanned are both enclosed by the device’s protective housing. High protection devices may only be operated when the protective housing is completely closed. The dose rate must not exceed 10 microsievert per hour (µSv/h) at a distance of 0.1 m from the completely closed protective housing under maximum operating conditions. Where the protective housing is equipped with openings, the dose rate in the accessible part of the interior must not exceed 250 microsievert per hour (µSv/h) under maximum operating conditions.

In the case of high protection devices with continuous operation of the X-ray tube housing assembly, the dose rate inside the device must not exceed 10 microsievert per hour (µSv/h) under maximum operating conditions even when the protective housing is opened (e.g. for changing samples, provided that the shutter of the X-ray tube housing assembly is closed). Additionally, certain safety-related technical requirements must be fulfilled, eventually accompanied by organisational measures.

Operation

High protection devices may be operated without licensing, provided that the competent authority is notified pursuant to § 4 (3) RoeV at least two weeks before the device is taken into operation. The operation of high protection devices requires a radiation protection regime. Such notification shall be accompanied by a copy of the type approval certificate as well as documents certifying safe operation and compliance with the radiation protection requirements (pursuant to § 3 (2) no. 2 to 4 RoeV).

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1d. Full protection devices (Annex 2 no. 3 RoeV) and school X-ray devices (Annex 2 no. 4 RoeV)

Features

The type categories of full protection devices and school X-ray devices provide the highest level of radiation protection. The devices may be operated only when the protective housing is completely closed. The X-ray tube housing assembly and the object to be scanned are completely enclosed by the protective housing. The dose rate must not exceed 3 Microsievert per hour at a distance of 0.1 m from the touchable surface when the device is in operation. In the case of full protection devices with continuous operation of the X-ray tube housing assembly, the dose rate inside the device must not exceed 3 Microsievert per hour (µSv/h) under maximum operating conditions even when the protective housing is opened (e.g. for changing samples, provided that the shutter of the X-ray tube housing assembly is closed).

This must be ensured by two independent safety systems that fulfil the highest requirements and conform to the state of the art. In the case of school X-ray devices it must additionally be ensured that the maximum operating values cannot be exceeded.

Operation

Full protection devices may be operated without licensing and without radiation protection regime. It is sufficient to notify the competent authority, pursuant to § 4 (3) RoeV, at least two weeks before the device is taken into operation. Such notification must be accompanied by the type approval certificate.

School X-ray devices may only be operated under a radiation protection regime. The notification to the competent authority shall be accompanied by documents certifying safe operation and compliance with the radiation protection requirements (pursuant to § 3 (2) no. 2 to 4 RoeV). Further regulations by the German states in the field of education may apply, too.

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1e. PTB Safety Guideline, further requirements for safety systems in basic protection devices, high protection devices, full protection devices and school X-ray devices

The committee of the German states for the X-ray Ordinance (LA Roev) at the Federal Ministry for the Environment decided on 27/28 March 2001, that further requirements for safety systems in the above type categories had to be stipulated. The used device protection equipment at full protection devices and School X-Ray devices have to comply with the requirements of the X-Ray Ordinance and the PTB Guideline PTB-DOS 49 (see below). Furthermore, the relevant regulations set out in DIN 54113 part 2 must be complied with.

These requirements ensure that the failure of one safety component will not result in a failure of the entire safety systems. The safety systems must be able to recognize and display errors during operation or, at the latest, during the next start-up. It must be ensured that the radiation cannot be switched on again until the error has been resolved. Furthermore, the devices have to be fitted with a time delay so that they cannot be opened before the acceleration voltage of the X-ray tube has fallen below 5kV.

In the case of basic protection and high protection devices a comparable level of safety can also be reached by introducing organisational measures as part of the radiation protection regime, such as regular controls conducted by competent operators or error detection by manually triggering the blocking mechanism.

PTB uses specific detailed requirements for determining the state of the art in type testing. These requirements are laid dwon in the PTB report as of December 2005, PTB-Dos-49, entitled „Sicherheitsvorrichtungen von Hochschutzgeräten, Vollschutzgeräten und Schulröntgeneinrichtungen –Anforderungen für die Bauartprüfung nach der Röntgenverordnung“, Leitfaden für Hersteller und Gutachter (ISSN 0172-70), referred to here as PTB Safety Guideline. The requirements include fundamental design principles needed to avoid systematic errors as well as guidelines for choosing appropriate components and circuit structures, considering all potential operational situations, avoiding undue interference and avoiding errors resulting from a common cause. The document also contains requirements for avoiding random errors and examples of how to implement these requirements.

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1f. Parasitic X-ray emitters (Annex 2 no. 5 RoeV)

Parasitic X-ray emitters are devices that produce X-rays although they are not operated for this purpose, which is the case, e.g., in electron beam exposure systems or vacuum interrupters. Parasitic X-ray emitters with an acceleration voltage for the electrons of more than 30 kV may only be operated without licensing if the device is type approved. Because of the restrictive requirements for this category pursuant to Annex 2 no. 5 RoeV, i.e. a dose rate of 1 microsievert per hour at a distance of 0.1 m from the touchable surface, type-approved parasitic X-ray emitters may be operated without licensing and without notification to the competent authority of the Federal state.

Type approval of vacuum interrupters in their capacity as parasitic X-ray emitters

The evaluation of vacuum interrupters focuses on the rated voltage peak value, which is taken as the reference value for the maximum acceleration voltage for the electrons. This procedure is based on the BfS communication as of 9 August 2005 on the type approval and operation of vacuum interrupters pursuant to §§ 5, 8 and Annex 2, no. 5 of the X-ray Ordinance (RoeV).

Pursuant to this method only vacuum interrupters with a rated voltage peak value exceeding 30 kV are subject to type approval as parasitic X-ray emitters. This means for practical purposes that vacuum interrupters with a rated voltage (RMS) of 24 kV or higher need a type approval in order to be operated without licensing. (24 kV_eff is a standard value for the rated voltage according to DIN EN 60694, item 4.1.1, corresponding to a peak value of 33.9 kV). The type tests will also be based on the RMS rated voltage and not on the “short-duration power-frequency withstand voltage”.

Pursuant to Annex 2 no. 5.1 RoeV the type tests must verify, that the dose rate at a distance of 0.1 m from the touchable surface of the device does not exceed 1 microsievert per hour under maximum operating conditions. When determining the distance of 0.1 m, the actually touchable surface of the device has to be taken into account. Any other existing electrotechnical safety appliances and safety installations may be taken into account in this respect. It is part of the type approval procedure for the relevant device to prove, that the electrotechnical safety appliances and safety installations effectively ensure the safety distance. In case that such a proof fails, the original surface of the vacuum interrupter will be used in order to determine the required safety distance of 0.1 m.

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2. Recurring tests (§ 18 (1) no. 5 Roev)

Unless determined otherwise by the competent authority of the Federal state, each X-ray device must have to be technically evaluated by an independent qualified expert in periods of at least every 5 years. The qualified expert is determined by the competent authority of the Federal state pursuant to § 4a RoeV. The evaluation will consider aspects of general safety and radiation protection as well as safety-related functions in particular. A copy of the resulting test report shall be sent to the authority without delay. Type-approved parasitic X-ray emitters are exempt from this requirement.

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3. Testing, trial and maintenance

The generation of X-rays in connection with the commercial testing, trial, service and maintenance of type-approved X-ray devices is not considered as "operation" of the device, pursuant to § 2 no. 4 RoeV. The above cited activities are subject to the regulations set out in § 6 RoeV and must only be performed by competent and approved personnel having an appropriate license.

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4. What is to be observed by type approval holders, if...

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... they wish to make modifications to type-approved devices?

Modifications to the radiation protection relevant features of type-approved devices require an amendment to the type approval certificate to be applied for at BfS.

The applicant shall submit a free-form application for a modification of the type approval to the BfS as well as documents (form sheets), which provide a sufficient and unambiguous description of the designated modifications, conforming to the standards of technical documentation. In most cases, BfS will commission the PTB with tests in order to determine whether the device with the designated modifications will still comply with the regulations set out in the X-ray Ordinance. If the requirements are fulfilled, BfS will issue an amendment to the type approval certificate.

Technical modifications, that do not affect the radiation protection relevant features of the device will be registered by the competent authority without granting an amendment to the type approval certificate.

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... company-related data or responsibilities (e.g. persons in charge) change?

Company related data in the type approval certificate must always be up to date. Modifications to the company name or registered offices of the type approval holder as well as changes of important positions, e.g. the director or the person in charge, have to be reported to the competent authority without undue delay. The type approval holder shall submit documents confirming these modifications to BfS, together with a form-free application for a modification of the type approval. Such documents include in most cases a copy of the excerpt from the commercial register, official or notarised documents confirming any relevant changes as well as a Certificate of good conduct to be presented to public authorities pursuant to § 30 (5) of the Federal Central Register Act, issued for the responsible manager. The BfS will issue an amendment to the type approval certificate, as the case may be, on the basis of these documents.

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... the time limit of the type approval is about to expire?

The type approval is valid for a maximum of ten years. Once the approval period has expired, devices must not be put into circulation as “type-approved” devices. However, the type approval period may be extended on request. The free-form application for an extension shall be submitted to the BfS at least three months before expiration of the time limitation of the type approval. Such application must be accompanied by the administrative and technical details form sheets as well as by a set of type drawings in their current version (in duplicate).

The purpose of limiting type approvals is to have the approval (granted 10 years before) evaluated according to the latest technical know-how and experience. If an approval holder applied for the extension of the type approval period, the relevant devices are evaluated as to their compliance with the state of the art and current regulations of the X-ray Ordinance. It may be necessary to have a prototype of the device to undergo a technical examination at PTB. If the requirements are fulfilled, BfS will extend the type approval.

The type approval becomes invalid with expiration of the approval period. A renewed type approval can only be granted on application with a new type approval procedure.

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5. What do holders (operators) of a type-approved device need to know with respect to the limitation of the type approval period?

The operation of a type-approved device may be continued without limitation even after the approval period has expired. According to § 8 (5) RoeV a type-approved device that was put into circulation before the approval period had expired may continue to be operated independently of such limitation provided that the requirements of the granted type approval are met, unless the approval authority has announced, pursuant to § 11 RoeV, that sufficient radiation protection is not ensured and that the device must no longer be operated.

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6. What do holders (operators) of a type-approved device need to observe with respect to the transfer of devices?

The operator of a device is entitled to transfer (sell) the device to third parties. A copy of the type approval certificate has to be handed over to the customer together with all relevant documents.

The new owner of a type-approved device that may be operated without licensing but with notification to the competent authority of the Federal state, has to take such a device into operation with respect to the the same conditions valid during the approval period (§ 4 (1) to (4) RoeV).

Type-approved parasitic X-ray emitters may be operated without licensing and notification to the competent authority. However, all other conditions valid during the approval period have to be met, if such devices are transferred to third parties.