Distance to the emitter in m

Fig. 4.8. Distance square law. Decrease in radiation intensity by the distance to the emitter for punctiform free dissipation of the X-ray Ordinance, and they must hold a radiation card (7 see § 35 Para 2 and 3 of the X-ray Ordinance).

Immediate measure to be taken on exceeding the limit values. If it is possible for the dose limit value for persons with occupational radiation exposure to be exceeded for one or several persons when operating an X-ray machine as a result of »extraordinary events or circumstances« (§ 42 of the X-ray Directive), this »event«, which the old X-ray Ordinance referred to as accident, must be reported immediately to the supervisory authorities. In addition, the affected persons must consult an »authorised doctor« immediately. As a rule, the authorities will check the event or circumstances resulting in this »accident« on the spot and order further measures to guarantee compliance with the dose limit values for persons with occupational radiation exposure. Given the fact that such incidents, which also have to be reported to the responsible Professional Association, are extremely rare when operating surgical image intensifiers, they will not be given any further attention here. Helpers

§ 2 of the amended X-ray Ordinance contains a definition for »helpers« based on the rulings in the directive 97/43/Euratom. Accordingly, helpers, e.g. members of the patient's family (previously called »accompanying persons«) are persons who support and look after the patient »voluntarily outside their occupational activity« where X-rays are being used as part of medical treatment. No dose limit values apply to helpers, because their exposure always depends on the exposure of the person being helped or cared for. The demand for protective measures to restrict the radiation exposure of helpers indicates that their dose should not exceed a few milli-sievert.

In addition, the regulations of »physical radiation protection control« do not apply to helpers, i.e. the use of »official dosimeters« (film badges) is not necessary when present in the control area. The bo dy dose can be ascertained by measuring the personal dose, e.g. with dosimeters which can be read off at any time, by multiplying the period of presence with the local dose measured at the place where the helper is, or »by other suitable means«. Information and instruction procedures

The annual instruction of persons using X-rays or permitted to enter the control area as employees, »helpers« or trainees stipulated in the X-ray Ordinance is of great significance for the radiation protection of staff and patient when using radiation in surgical image intensifiers. This instruction according to § 36 of the X-ray Ordinance essentially deals with 4 the intended working methods, 4 the possible risks,

4 the safety and protection measures being used, 4 the essential contents of the X-ray Ordinance referring to the activity or presence and 4 the radiation protection instruction.

Together with persons with authorised access to the control area, instruction must also be given to those who use X-rays or are involved in the technical aspects of using radiation, without having to be present in the control area. As far as the instructions are concerned, § 36 of the X-ray Ordinance says: »Records are to be kept about the contents and time of the instructions and must be signed by the person receiving the instructions. The records are to be kept for five years (one year for helpers) and submitted to the supervisory authorities on request.«

The instructions do not have to be provided by the radiation protection manager or radiation protection of ficer: they can be delegated to another person, e.g. well qualified doctors of the department or an external expert. The radiation protection manager still remains responsible for the contents and delivery of the instructions. From the requirement to provide instruction »about the safety and protective measures to be used«, it can be deduced that »general« or »sweeping« instructions e.g. just about the radiation protection regulations in the X-ray Ordinance, are inadequate. The particular special type of radiation application and the activities of the persons being instructed must always be taken into account in the instructions. On the other hand, together with verbal instruction it is also possible to use specially elaborated instruction texts, together with including film or video recordings during the instructions.

Patient protection. Radiation protection of the patient is featured in the X-ray Ordinance in the application principles of § 25 as already mentioned above. According to these principles, X-rays must only be used on persons if 4 this is advisable resulting from a medical indication and a person with the necessary expertise has made the »justifying indication«, 4 the health benefits from using radiation on the individual outweigh the radiation risk, 4 other procedures with similar health benefit which entail no or lesser radiation exposure have already been considered, 4 it is certain that the radiation exposure can be limited to an extent which is compatible with the requirements of modern medical science.

Together with these principles, § 16 of the X-ray Ordinance demands compliance with so-called diagnostic reference values (DRW) which are published by the Federal Department for Radiation Protection, in order to guarantee good practice when performing medical and dental X-ray examinations. The diagnostic reference values do not constitute limit values for patients and do not apply to individual examinations. But the use of radiation in the various examinations should be organised and optimised so that the diagnostic reference values are not exceeded in average for an adequate number of examinations of one specific examination type.

Personal radiation protection of the patient also includes the requirement in § 25 of the X-ray Ordinance that parts of the body, which do not have to be affected by the effective radiation in the intended use of X-rays, must be protected as far as possible from radiation exposure. Here is it necessary to keep available and use suitable radiation protection accessories, such as patient protection aprons, gonadal shields and other lead rubber covers. Up to now according to the meanwhile withdrawn standard DIN 6813 issue July 1980 [10], patient protection aprons had to have a lead equivalent value of min. 0.4 mm and gonadal shields

□ Table 4.2. Radiation protection accessories

For the radiation user (doctor and assistant) with the necessary lead values in mm Pb according to DIN 6813, issue July 1980

Radiation protection apron, front

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