General aspects and X-ray Ordinance, radiation generation and radiation protection

4.1 Radiation protection in the operating suite - 20

4.1.1 Introduction - 20

4.1.2 Legal principles for the use of X-rays in medicine - 21 X-ray Ordinance, Atomic Energy Law, Euratom Directives, ICRP recommendations - 21 Radiation protection manager, radiation protection officer - 24 Obligations when operating an X-ray machine - 24 Occupational exposure to radiation, personal dosimetry - 25 Information and instruction procedures - 27 Quality assurance according to the X-ray Ordinance - 29

4.1.3 Generating X-rays - 30

4.1.4 The image receiver system for surgical image intensifiers - 32

4.1.5 The main components in surgical image intensifiers - 32

4.1.6 Technical minimum requirements for examination with surgical image intensifiers - 32

4.1.7 Application-related radiation protection in the operating suite - 32

4.1.8 Correct positioning of the image receiver system - 34

4.1.9 Correct use of the automatic dose control (ADR) - 34

4.2 Surgical image intensifier systems - 35

4.2.1 Expert inspection - 36

4.2.3 Radiation protection - 36

4.2.4 Structure and technique of a surgical image intensifier - 37

4.2.5 Application - 38

4.2.6 Use of the surgical image intensifier - 38

4.2.7 Tips and tricks for daily routine - 38

References - 39

4.1 Radiation protection in the operating suite

H. Kreienfeld, H. Klimpel 4.1.1 Introduction

In 1895, the physicist Wilhelm Conrad Röntgen in Würzburg discovered a »new type of ray« which was later called X-ray or »Röntgen« in Germany in recognition of his pioneering discovery (O Fig. 4.1).

In physical terms, X-rays are attributed to ionising radiation (O Fig.4.2).

The possibility of using this radiation successfully in human medicine for diagnostic purposes or also for therapy in certain diseases led to a dramatic development in the following decades, both in examination techniques and also in the corresponding equipment required for this purpose. X-rays could be used for both short-term exposure for X-ray pictures, and also for so-called radiography for continuous exposure. During the 1950's, the development of X-ray image intensifiers had progressed to such an extent that radiography was also possible in the operating theatre for support or documentation of surgical

Radiation n first

non-ionising radio and microwaves electromagnetic fields optical radiation ionising

X-rays gamma rays particle radiation of radioactive substances

O Fig. 4.1. First handwritten message from Röntgen about his discovery

D Fig. 4.2. Attributing X-rays to ionising radiation procedures, without the room having to be darkened accordingly for this purpose. This technical development -initially the pictures were viewed through a monocular or binoculars - and the subsequent addition of television cameras and monitors paved the way for the versatile applications of mobile surgical image intensifiers (»mobile C-arm units and C-arm units on the ceiling mount in the operating theatre«).

The principle of these X-ray scanning machines has remained the same through to today, even though technical refinements have been introduced with developments in microelectronics in newly developed machines. These include for example the CCD camera (charge-coupled device - light-sensitive chip camera) together with digital image storing and processing.

Mobile C-arm X-ray machines are not shielded from leakage radiation in the design of the machine because of the special aspects of their use, so that the user has to pay special attention to radiation protection. But it is also possible for radiation protection for the patient to be impaired quite considerably, for example by unacceptable positioning and use of the emitter/image receiver system. As a result, it is absolutely mandatory for all users of surgical image intensifiers to be well instructed in correct use of the equipment (► § 18 of the X-ray Ordinance [RoV]) and in addition, they also have to possess the qualification »special knowledge in radiation protection« according to the regulation »special knowledge according to the X-ray Ordinance/Medicine« which is anchored in the X-ray Ordinance [1]. The assistants working under the medical staff must have »knowledge of radiation protection« if they are expected to trigger X-rays under the instruction of a doctor with special knowledge in radiation protection (specialised doctor) or to assume the »technical execution« of the radiation application.

Although the application techniques for X-ray examinations and surgical image intensifiers have undergone further development, X-ray diagnosis in the operating theatre still differs in character from »classical X-ray diagnosis« in the X-ray department of hospitals, which is geared to differentiated »X-ray diagnosis«. »Surgical X-ray diagnosis« differs on account of the following features: ™ In the operating theatre, the X-ray examination is an indispensable aid for supporting and documenting surgical procedures.

4 Surgeons, anaesthetists, surgical nurses and assistants are also present during perioperative radiation application in the operating theatre and thus also within the stipulated control zone.

4 Given the necessary wide range of applications of surgical image intensifiers, it is not possible to fix any radiation protection shielding for the operating staff to the C-arm machines, which have to be able to turn and swivel to all sides, in contrast for example to the close-control scanning machines used in the X-ray diagnosis department.

4 The room brightness required for the operation can possibly impair viewing and evaluation of the monitor picture.

4 The necessary presence of several doctors and assistants in the operating theatre can make it more difficult for the individual to stay for any length of time in places with low local dose or local dose rate.

4 Operations under sterile conditions and special positioning of the patient, particularly for procedures to the trunk, can considerably impair or even prevent optimum radiation protection precautions.

4 For simple issues and pictures for documentation purposes, e.g. after the removal of implants, it is possible to accept less than optimum image quality in the interests of low radiation exposure.

4.1.2 Legal principles for the use of X-rays in medicine X-ray Ordinance, Atomic Energy Law, Euratom Directives, ICRP recommendations

In Germany, the medical use of X-rays has been regulated since 1973 in the X-ray Ordinance (RoV). This legal provision was issued as an ordinance on account of the authorisation provisions in the Atomic Energy Law (AtG). The X-ray Ordinance was amended in 2002 [2] because of the stipulations in the directive 96/29/EURATOM »laying down basic safety standards for the protection of the health of workers and the general public against the dangers of ionising radiation« [3] and in the patient protection directive 97/43/EURATOM »on health protection of individuals against the dangers of ionising radiation in relation to medical exposure« [4] and came into effect on 1 July 2002.

The new X-ray Ordinance gives special priority to the radiation protection principles 4 justification, 4 dose limitation,

4 prevention of unnecessary radiation exposure and 4 dose reduction together with the newly worded Radiation Protection Directive (StrlSchV).

To this end, the new X-ray Ordinance contains clearer regulations of the medical and technical requirements for the use of X-rays on people than before. These regulations include in particular new definitions: 4 »use of X-rays« (for X-ray examinations with a differentiation between »technical implementation« and »evaluation«),

4 »image quality« (»diagnostic image quality« and

»physical image quality«), 4 »diagnostic reference values« (DRW), 4 »justifying indication«.

The sub-section »use of X-rays on people« in the new X-ray Ordinance contains above all specifications for »justifying indication«, on the »authorised persons« and »application principles« together with »documentation obligations«.

The new X-ray Ordinance also includes two important, updated implementing regulations (O Fig. 4.3): 4 the »ordinance on expert inspections according to the X-ray Ordinance (SV-RL)« dated 27 August 2003 [5] and

4 the »ordinance for performing quality assurance with X-ray equipment according to §§ 16 and 17 of the X-ray Ordinance (QS-RL)« dated 20 November 2003 [6].

Both ordinances stipulate the technical radiation protection requirements and the corresponding tests and the requirements for »physical image quality« with the corresponding intended quality assurance (quality tests) for the various medical X-ray diagnosis equipment, also for surgical image intensifiers.

For surgical image intensifiers, i.e. for »mobile C-arm units (including C-arm units on the ceiling mount in the operating theatre), these requirements for radiation protection and for quality control are featured essentially in the test positions according to section 2.2.4 of the SV-RL.

X-ray Ordinance y

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