Radiation Protection Personal Protective Equipment

Introduction: The assignment, consist of three parts including this introduction, which mentions how the assignment will take shape. Ideas and concepts taken from elsewhere for the preparation of this document will be cited appropriately within the work. The document which will be given to staff will address the issues pertaining to the appropriate use of personal protective equipment(PPE), legislations associated with their use, the principles of physics behind their use. The document will briefly delve in to issues pertaining to radiation hazards and protection, legislations relevant to radiation work in United Kingdom and use of personal protective equipment. Principles of physics behind radiation protection methods will be addressed in the document. Commonly used PPE in radiographic departments will be explained with their appropriate use along with personnel dosimetry. Local rules aiding radiation protection and defining PPE use will be also addressed in the document. Radiation protection methods and appropriate use of PPE will be given in a tabular format explaining where, when and why these protection methods and PPE should be used for those situations.

The third section of this work will include a conclusion which will include the reasoning behind the composition of the document. It will also briefly address other important radiation protection issues and methods which are not addressed in the documents and the reasoning behind it. It will demonstrate how the assignment brief has been addressed by the document. The conclusion segment of this assignment will also emphasise as to why understanding of the work produced is important.

The main factors aiding the preparation and decisions made for the preparation of the document will also be included in the conclusion. At the end of the work all references used in the preparation of this work will be laid out in the Harvard system of referencing.

Radiation Protection and the use of Personal Protective Equipment.

Introduction:

Being at the leading edge of radiation dose delivery, a radiographer has a unique professional duty towards himself and others around him for a reduction in the hazards caused by ionising radiation (Manning, 2004). Many radiation related fatalities and injuries suffered by radiation pioneers and scientific studies of the 1950s, which implicated low level doses to stochastic effects in radiation workers and patients led to the radiation protection regulations of today (Bushong, 2003).

Radiation hazards

When humans are irradiated, atomic interactions results in ionisation, this can lead to chemical and biological changes which are damaging to the cells and chromosomes. This radiation induced changes can lead to two distinct types of injuries at cellular level.

Deterministic effects: Above a certain threshold dose, effects show up and the severity of the effects increase with dose

Stochastic effects: Probability of occurrence of effects increases with increase in dose. The effects include cancer induction and hereditary effects in future generations (Martin and Harbison, 2006). These late stochastic effects, has led to the radiation protection regulations of today (Bushong 2003).

What is Radiation protection and why do it

In light of the hazards that could be caused by radiation, protection from unnecessary radiation gains paramount importance. All radiation workers and patients should be protected against these hazards by various methods and equipment, this process is called radiation protection. A system of linear non threshold (LNT) model for radiation protection is applied to all radiation practices (Martin 2004). There is also increasing opinion in favour of radiation hormesis(Carver 2006), but since there is no absolute evidence to suggest a lower threshold below which no damage occurs the LNT model as required by current legislations is considered appropriate to estimate risks at low doses(Matthews and Brennan 2008)

The patient should only be exposed if the clinical evidence suggests that the patient is likely to benefit from the procedures. The law requires the doses to be kept to as low as reasonably practicable (ALARP), so the requirement of radiation protection is laid out by various legislations (Graham et al.,2007).

The regulations relevant to radiographic work and the use of PPE in United Kingdom (UK)

Ionising Radiations Regulations 1999(IRR 1999)

Ionising Radiations (Medical Exposure) Regulations 2000 (IR(ME)R)

Management of Health and Safety at Work Regulations 1999

Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations 1995(RIDDOR 1995)

Personal Protective Equipment at Work Regulations 1992

Manual Handling Operations Regulations 1992

Control of Substances Hazardous to Health Regulations 2002 (COSHH)

(Messer, 2009)

The recommendations of The International Commission for Radiation Protection(ICRP), that radiation exposure to radiation workers and the patient should be As Low As Reasonably Achievable(ALARA) is generally accepted(Engel-Hills,2006), The recommendations of ICRP and the European union(EU) euratom directives have all had a significant impact on British law (Whitley et al., 2005)

Principles of Radiation Protection

IR(ME)R requires all medical exposures in diagnostic radiology to apply the radiation protection principles of justification, optimisation and dose limitation. (Institute of Physics and Engineering in Medicine(IPEM), 2002). These principles ensure patient dose is kept to the ALARP principle. The cardinal principles of radiation protection will be further discussed.

Minimising Time: As the dose is directly proportional to duration of exposure, minimising the time of exposure results in reduced dose. Minimising the time spent near a radiation source also reduces exposure. This protection method finds its use in fluoroscopy. Other methods used in fluoroscopy, using this protection method to reduce exposure is pulsed progressive fluoroscopy and the regular interval reset timers (Bushong, 2001).

Maximising Distance: The cheapest form of radiation protection is afforded by the inverse square law, which states that the radiation intensity varies to the inverse of the square of the distance (Farr and Allisy-Roberts 1997). This law holds true for the primary beam which is considered a point source of radiation. While using mobile x-ray units a radiographer can avail this principle of physics to get maximum protection by standing as far away from the source as possible with the aid of the long cable which should be at least 2metre from the x-ray tube during exposure (Bushong 2001). Dowd (1991) considers distance to be the simplest and most effective of radiation protection measures.

Maximising Shielding: Maximising shielding between the radiation source and exposed personnel reduces radiation exposure considerably. The effectiveness of the shielding material is estimated in terms of its half-value layer(HVL), which is the amount of material needed to reduce radiation exposure in to half, and tenth-value layers(TVLs); which is the amount of material needed to reduce exposure to one tenth of its original amount. The preferred material for shielding is lead (Pb). The physics behind the usage of lead for protection is its high atomic number (82). This high atomic number ensures that a majority of scatter photons gets absorbed due to its high attenuation.

PPE used in radiography departments:

Lead Aprons: They are made from powdered lead incorporated in a binder of rubber or vinyl. They come in various lead equivalencies. If used as a secondary barrier to absorb scattered radiation an apron with lead equivalency of at least 0.25mm should be used. Lead aprons shall be at least 0.5mm of lead equivalent for fluoroscopy but can be higher to the range of 1mm of lead equivalence. The downside of greater lead equivalent aprons is the greater weight. Now manufacturers make aprons with composite materials-a combination of lead, barium and tungsten. They have reduced weight and provide better attenuation of radiation.

Lead Gloves: They provide at least 0.25mm or more of lead equivalent protection. Used mainly in fluoroscopy or by people holding patients during examination.

Thyroid Shields: Mainly for use while performing fluoroscopy, these offers protection to thyroid.

Mobile Shields: These could be moved around and are sometimes used in angiography.

Protective Eyewear: Protective glasses are used mainly in fluoroscopy to protect against the cataractogenic effect of radiation(Dowd and Tilson 1999).

The concept used for radiation-protection practices is the effective dose(E). Effective dose considers the relative radio sensitivity of various tissues and organs.

Effective Dose(E) =Radiation weighting factor(Wr) x Tissue weighting factor(Wt) x Absorbed dose

(Bushong, 2001)

Personnel Dosimetry:

All classified radiation workers are routinely monitored for radiation exposures using personnel monitors. Though they do not provide any radiation protection on their own, they offer the quantity of radiation to which the person using the monitor was exposed. The commonly used dosimeters in diagnostic radiology are film badges, Thermoluminescent dosimeters(TLD) and the pocket dosimeter (Thompson et al.,1994).

Local Rules which will include working procedures and protocols for the department should be always followed for the appropriate use of PPE

Protective Methods/PPE usedng 2001,Bushong 2003)

Conclusion:

Writing an assignment about the appropriate use of PPE for radiation protection, the need to highlight radiation hazards was considered important and so the assignment started with a brief outlook of radiation hazards and subsequently radiation protection concept was discussed with emphasis on why staff and patients must be protected. The LNT dose response model for radiation protection and new concept favouring lower doses such as radiation hormesis was briefly addressed. The justification for using the LNT model for radiation protection was also emphasised.

The legal requirement for radiation protection of patients and staff was discussed and legislations relevant to radiographic work in UK and other organisations influencing British law on radiation safety was discussed.

Recommendations of ICRP, as low as reasonably achievable( ALARA) concept and the IR(ME)R requirements of radiation protection of patient through the principles of justification, optimization and limitation was also addressed.

These introductory explanations, was considered important as they were the basis for the subject for radiation protection and highlighted the need for radiation protection in diagnostic imaging departments.

Preparing the core of the work was not possible without addressing the cardinal principles of radiation protection, hence they were all discussed briefly, where these protection principles find its application for radiation protection in radiographic departments. Time, Distance, Shielding concepts of radiation protection was discussed.

Distance and Shielding concept of radiation protection was discussed in detail as they find their use quite often in imaging departments. Material commonly used for shielding with the principles of physics behind its usage was also addressed. Concepts such as half -value layer(HVL) and tenth value layers (TVLs), used to define the effectiveness of the shielding material was also detailed.

Personal protective equipment generally used in imaging departments such as lead rubber aprons, lead rubber gloves, thyroid shield, protective eye wear, mobile shield was discussed. Their appropriate usage in specific areas was also considered.

Concept of effective dose was also briefly discussed as this was considered an important concept in radiation dose.

Personnel dosimetry was discussed with a brief on the various types of personnel dosimeters used in diagnostic imaging departments, as these dosimeters play an important role in dose regulation and monitoring radiation exposure in staff.

Radiation protection methods to reduce patient dose has not been elaborated and special arrangements for pregnant radiographer such as rotating out of high exposure areas such as mobile x-ray and fluoroscopy and wearing a secondary badge under the apron at waist level when involved in such examinations to measure foetal dose(Dowd and Tilson 1994) has not been addressed in the document, so as to keep the assignment within its permissible constraints.

With all this being presented, it was decided to summarize the use of PPE and protection methods in various areas of a radiographic department; x-ray room, while using mobile x-ray equipment in wards and theatres, Fluoroscopy which is a major contributor of staff dose(Bushong 2001) and CT was considered.

It was decided to project these points in a tabular format within the document for simplicity and to meet the assignment brief within the imposed limitations. It also demonstrates the appropriate usage of PPE and radiation protection methods.

Adequate shielding in diagnostic imaging departments both primary and secondary shielding as required by legislations, means that a radiographer is sufficiently protected from the scatter, as long as they position themselves behind the protective barrier during exposure. This point is stressed within the tabular column in the document as this is considered an important radiation protection practice. X-ray tube incorporates lead shielding to attenuate the radiation travelling in any other direction other than the useful beam. The housing of the tube have a lead equivalent of typically 2.5mm (Farr and Allisy-Roberts 1997). This greatly reduces scatter or leaked radiation exposure to staff and patient. These and other protection measures incorporated with in modern x-ray machines such as collimation, beam alignment, filtration and other manual protective measures to reduce patient dose-including specific area shielding, such as contact shields and shadow shields which provide gonadal protection to patients have not been discussed in the document due to the scope and constraints of the assignment. All radiation protection methods employed to reduce patient dose bring down staff exposure as well, so good radiographic practice helps achieve reduced dose to both patient and staff (Graham et al., 2007)

Local rules as required by IRR 1999, to be a part of all departments which involves working with ionising radiation has been addressed in the document briefly, but they are an important resource towards radiation protection as these rules include written systems of work, including protocols and procedures for the imaging department. Details of contingency plans and the names of Radiation protection advisers(RPA) and Radiation Protection Supervisors(RPS) are contained within the rules(Graham et al.,2007)

Principles of physics, pertaining to the use of lead in the preparation of shielding materials have been discussed in the assignment.

Reading the document will inform the reader about the appropriate use of PPE, as to where, when and why to use these PPE. It also informs the reader the various legislations associated with radiation protection and the use of PPE in UK. It also highlights the hazards caused by ionising radiation and the need for radiation protection. Hence the assignment brief has been addressed.

Radiation protection is an important subject to be considered in the diagnostic radiography department (Moores, 2006) and hence a clear understanding of radiation protection issues is important. Ionizing radiation can cause real damage to current and future generations if not dealt with carefully, hence understanding radiation protection and the correct usage of PPE in aiding radiation protection through this work is considered important.

Together with a wide range of resources, the valuable experience gained during the clinical placement in a radiography department, observing the safety practices and usage of PPE in the imaging departments and critical self evaluation of methods and practices using the aid of published works has helped me arrive at the key decisions which are addressed in the document.

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