The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [446]
In accordance with the Medical and Dental Guidance Notes, for women known or likely to be pregnant, where the examination has been justified on the basis of clinical urgency and involves irradiation of the abdomen, operators must optimize the technique to minimize irradiation of the foetus (IPEM 2002). Radiography of areas remote from the foetus, for example chest, skull or hand, may be carried out safely at any time during pregnancy as long as good beam collimation and proper shielding equipment are used.
Legal and professional issues
The Ionizing Radiation (Medical Exposure) Regulations (2000) set out the legal roles and responsibilities of all duty holders related to medical exposures to X-rays.
In accordance with the Ionizing Radiation (Medical Exposure) Regulations (IR(ME)R) (2000), the completed request form for a medical exposure must be clear and legible and the following information must be supplied.
(a) Unique patient identification – to include at least three identifiers from name, date of birth, hospital number or NHS number.
(b) Sufficient details of the clinical problem to allow the IR(ME)R practitioner to justify the medical exposure, and indication of examination thought to be appropriate.
(c) If applicable, information on the patient’s possible pregnancy status.
(d) Signature uniquely identifying the referrer as it is important that the referrer is qualified to order an X-ray.
Blank request cards, pre-signed by a referrer, are a breach of the regulations and any entries on the request form made by others should be checked and initialled by the referrer prior to signing the form.
Preprocedural considerations
Pharmacological support
For some types of X-ray such as the barium swallow or enema, the patient is usually required to drink the contrast or have it administered via an enema and a series of X-ray pictures taken at various intervals. Afterwards the patient will be advised to drink plenty of fluids to clear their system of the contrast as quickly as possible.
Specific patient preparations
The radiology department will inform the patient of any requirements prior to the booked procedure such as being nil by mouth. For most examinations, the patient will be asked to remove some of their clothing and change into a hospital gown, to ensure that no artefacts (any feature in an image which misrepresents the object in the field of view) (McRobbie 2007) are caused in the area of clinical interest on the X-ray image. It is advisable for the patient not to wear jewellery at the time of the appointment as in most cases this will have to be removed, again to prevent the presence of artefacts on the image. For all X-rays the patient will be required to keep still to prevent any blurring of the images. Some procedures are performed on inspiration/expiration, and the patient will be given the appropriate breathing instruction by the operator performing the procedure.
Magnetic resonance imaging (MRI)
Definition
Magnetic resonance imaging provides cross-sectional images of the body. The patient lies inside the bore of a very strong magnet, typically 1.5 tesla. Protons in the body’s water molecules spin or ‘precess’ when exposed to such a strong magnetic field. Radio waves are transmitted into the patient at the same frequency at which the protons are precessing and the patient transmits a signal that is detected by a receiver coil. This signal contains specific information or ‘weighting’ about the individual tissues that can be mapped to form a two- or three-dimensional image (Weishaupt et al. 2006).
Evidence-based approaches
Rationale
Soft tissue structures such as the brain, spinal cord, musculoskeletal system, liver and pelvic structures are particularly well demonstrated using MRI. It is possible to scan the whole body but MRI tends to be a more targeted scan, and they take longer with scan times of 20–60 minutes. MRI does not use ionizing radiation