GB2472246A

GB2472246A - Radiation shield

Info

Publication number: GB2472246A
Application number: GB0913287A
Authority: GB
Inventors: Miles William Harcourt Behan; David Hildick-Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-07-30
Filing date: 2009-07-30
Publication date: 2011-02-02
Also published as: GB0913287D0

Abstract

A device for protecting surgeons from radiation during interventional cardiology via the radial artery has a base plate to which releasably attaches a screen that blocks radiation, the screen being oriented perpendicular to the base. The screen may be made of lead glass or lead rubber and can engage with a channel in the base and be secured by adhesive, hooks, clips or releasable hook—and—loop fastener. The base may be made of fibreglass or transparent polycarbonate, can be autoclaved and preferably has at least one opening to act as a handle or to engage with a hook for storage. The base plate may have attachment points for securing a patient's arm during surgery. In use, the patient lies on the base plate and the screen is located between the patient's arm and torso.

Description

Title: Radiation protection devices and methods The invention relates to radiation protection devices and methods for protecting interventional cardiologists and their colleagues during interventional procedures using the transradial route.

Interventional cardiology is an extensive and growing field of medicine. It involves passing small tubes or catheters up to the coronary arteries under Xray guidance. From here wires and balloons can be passed into the coronary arteries that have been affected by narrowing as a result of atherosclerosis (fat deposits in the artery walls).

Interventional cardiology encompasses coronary angiograms and coronary angioplasties. A coronary angiogram is a procedure where one or more catheter ais put in the arteries and then Xrays are taken. A coronary angioplasty is where the artery is stretched (after an angiogram).

Conventional angioplasty involves expanding the lumen of arteries which have been narrowed by atherosclerosis. The narrowed, diseased arteries are stretched open by passing a balloon into the vessel and inflating the balloon to expand the artery lumen. Small metal scaffolds or stents are inserted into the newly stretched vessel which remain in the patient and keep the artery lumen open thus easing blood flow through the diseased arteries. Several hundred thousand of these procedures are carried out in Europe each year, with more in the USA.

These procedures are carried out in a catheter laboratory where a team of people work. The interventional cardiologist (the operator) stands next to the patient and normally works through a small puncture in the femoral artery, a large artery at the top of the leg. Recently many operators have been accessing the coronary art:eries through the radial art:ery which is at the wrist, rather than via the femoral artery.

The radial route has several benefits: including reduced bleeding post procedure, increased patient comfort, decreased vascular access site complications, greater ease of mobilization post operatively, reduced length of hospital stay and increased patient satisfaction compared to the femoral route.

In addition, there is now registry evidence suggesting reduced 30-day and one-year mortality with transradial intervention due to a decreased need for transfusion. Chase AJ, Fretz EB, Warburton WP, et al. Association of arterial access site at angioplasty with transfusion and mortality. The M.O.R.T.A.L. study: (Mortality benefit of reduced transfusion after percutaneous coronary intervention via the arm or leg). Heart 2008;94:1019-1025 and Hamon M, Nolan]. Should radial access be the gold standard' for PCI? Heart 2008;94: 1530-1532.

Accordingly, the number of interventional centres carrying out radial procedures is dramatically increasing and the replacement of the femoral route by the radial route seems inevitable.

A notable disadvantage of angioplasty via the radial route is that it requires a higher level of operator skill which necessarily takes longer to acquire than for the femoral route.

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A more significant disadvantage when performing angioplasty via the radial route is that the operator is subjected to a much higher radiation dose from the equipment than when doing the same procedure by the femoral route, particularly for the increasingly complex percutaneous interventions now being undertaken.

Operator exposure is a serious problem especially as most interventional operators carry out several hundred procedures a year. The higher radiation dose in comparison to the femoral route is because of the patient's position (see fig. 1) and the fact that the operator has to stand closer to the patient rendering him especially susceptible to side scatter.

A number of studies have reported that the transradial route is associated with increased operator radiation exposure, when compared to the femoral route.

Brasselet C, Blanpain T, Tassan-Mangina S, et al. Comparison of operator radiation exposure with optimized radiation protection devices during coronary angiograms and ad hoc percutaneous coronary intervention by radial and femoral routes. Eur Heart J 2008;29:63-70 and Lange HW, von Boetticher H. Randomized comparison of operator radiation exposure during coronary angiography and intervention by radial or femoral approach. Catheter Cardiovasc Interv 2006;67:12-16;Yigit F, Sezgin AT, Erol T, et al. An experience on radial versus femoral approach for diagnostic coronary angiography in Turkey. Anadolu Kardiyol Derg 2006;6:229-234; Sandborg M, Fransson SG, Pettersson H. Evaluation of patient-absorbed doses during coronary angiography and intervention by femoral and radial access. Eur Radiol 2004;14:653-658; and Larrazet F, Dibie A, Philippe F, et al. Factors influencing time and dose-curve product values during ad hoc one-vessel percutaneous coronary angioplasty. Br J Radiol 2003;76:473-477.

However radiation safety is not often a major concern to interventional cardiologists even though occupational doses in PCI procedures are the highest recorded for health professionals using X-rays. Vano E. Radiation exposure to cardiologists: how it could be reduced. Heart 2003;89: 1123-1124. For interventional cardiologists, with a high yearly exposure of 5mSv, the lifetime extra risk for (fatal or non fatal) cancer after 20 years of professional life is in the range of 1 in 100. Venneri L, Rossi F, Botto N, et al. Cancer risk from professional exposure in staff working in cardiac catheterization laboratory: Insights from the National Research Council's Biological Effects of Ionizing Radiation VII ReporL Am HeartJ 2009;157:118-124. The lack of good radiation protection can increase occupational doses (and risk of cancer) by a factor of 10. Vano E, Gonzalez L, Fernandez JM, et al. Occupational radiation doses in interventional cardiology: a 15-year follow up. BrJ Radiol 2006;79:383-388 Hirshfield JW.

Standard radiation protection currently consists of 3 separate devices which can be used separately or in combination: 1. A lead apron which covers the torso and groin area from the top of the chest down to just above the knees; but leaves the arms, hands, neck, face and head exposed and unprotected.

2. A lead thyroid shield this is essentially a lead lined scarf which is placed around the neck, and covers the Adam's Apple area and protects the thyroid gland.

3. A lead shield (0.5mm thick, about 0.5m squared) which is either fixed to the ceiling, or is on wheels so that it can be moved to allow it to be positioned between the operator and the radiation source eg an Xray machine during a procedure to prevent operator exposure. However this device does not protect the operator from primary scatter (radiation emitted from the patient) or secondary scatter (radiation reflected from the walls, floor and ceiling).

Side scatter arises from Xrays that have passed into the patient which are then emitted from the side of the patient's abdomen, they are a risk to operators against which conventional radiation protection devices provide little protection.

Another problem associated with radial access is that the wrist of the patient is not as stable as the top of the leg, making manipulation of the catheters more difficult.

A need exists for a means of protecting operators from radiation exposure during interventional procedures guided by fluoroscopy via the radial route. The protection means must ensure operators are protected from primary scatter (radiation emitted from the patient) or secondary scatter (radiation reflected from the walls, floor and ceiling).

There is also a need for a means of stabilizing the patient's wrist during angioplasty via the radial route.

Summary of the invention

The invention relates to a device for protecting operators from radiation during interventional cardiology procedures via the radial artery comprising: a base plate which in use is positioned under the patient; and a screen which blocks radiation wherein the screen releasably engages with attachment means on or in the base plate and forms a 900 angle to the base plate wherein in use the screen is positioned between the patient's torso and arm.

In another aspect the invention relates to a device wherein the screen is a lead glass or lead rubber screen.

In another aspect the invention relates to a device wherein the attachment means comprise a channel into which the screen engages.

In another aspect the invention relates to a device wherein the base plate can be autoclaved for cleaning.

In another aspect the invention relates to a device wherein the base plate is formed of fibreglass, polycarbonate, Perspex� or like material.

In another aspect the invention relates to a device wherein the base plate has one or more opening which acts as a carrying handle.

In another aspect the invention relates to a device wherein the base plate has one or more opening which can engage with a hook for easy storage.

In another aspect the invention relates to a device wherein the device acts as a stabilizing support for the wrist during the surgical procedure.

In another aspect the invention relates to a device wherein the base plate has one or more attachment points for securing the patient's arm to the base plate in use.

In another aspect the invention relates to a method of protecting operators from radiation during interventional cardiology procedures via the radial artery comprising positioning the device under the patient such that the screen is located between the patient's arm and torso during the surgery.

Detailed description of the invention:

An embodiment of the invention will now be described with reference to the accompanying drawings in which:

Description of the drawings:

Figure 1: shows the position of the operator and the patient during surgery via the radial artery.

Figure 2: shows a schematic representation of a preferred embodiment of the invention With reference to figure 2 which shows a transradial radiation protection board (TRPB) according to the invention.

The device comprises a planar, lightweight base plate 1 which in use is positioned posteriorly underneath the patient's torso for stability; and anteriorly underneath the patient's arm such that the arm is stabilized and supported during the transradial puncture and subsequent catheterisation and angioplasty procedure.

In use the base plate also acts as an equipment support during the transradial puncture, catheterisation and angioplasty procedure.

Preferably the base plate is transparent.

Preferably the base plate is made of a single piece of fiberglass, polycarbonate, Perspex� or like moulded or extruded plastic material.

Preferably the base plate is autoclavable to enable it to be easily cleaned and sterilized after each use.

Preferably the base plate has one or more openings 4 which act as carrying handles. Optionally the openings 4 can also be used to allow, one or more base plate, to be hung on a hook for easy storage.

The base plate is provided with connecting means 3 for releasably receiving a screen 2.

Preferably the connecting means 3 comprise an open ended channel into which the screen engages so as to be retained in an upright substantially vertical position such that the screen is held at a 900 angle to the base plate.

Preferably the connecting means form an integral part of the base plate 1.

Alternatively the connecting means 3 may comprise one or more of a range of fixings such as by way of example only adhesives, slots, hooks, clips, velcro� etc. In use the device is positioned so that the base plate 1 sits under the patient's arm and torso with the screen 2 is located between the patient's arm and torso.

Preferably the screen consists of a 20cm high vertical plane of 0.5mm leaded glass or lead rubber to provide operator protection.

Screens of different sizes may be inserted in the same connecting means. The size of screen used can be varied depending on the size of the patient, and the ease of access to the radial artery. For example when working on very large patients or patients with a high BMI the operator may favour a larger screen as the range of the side scatter is likely to be greater than if the procedure were being performed on a particularly small patient. Alternatively if a patient is disabled such that access to the radial artery is restricted the operator may favour a smaller screen.

The device of the present invention has the additional advantage that it stabilises the patient's arm and wrist during the procedure.

Optionally holes 5 are provided in the base plate through which fixings can be applied to secure the patient's arm to the base plate to restrict movement of the wrist during the procedure.

Optionally the screen is covered with a protective layer of fabric or like material which serves to protect the screen and may also provide some additional radiation protection.

After each procedure the screen 2 is removed from the connecting means 3 to allow the base plate to be cleaned and sterilized.

Optionally the screen 2 may have one or more opening or loop to enable it to be hung on a hook for easy storage.

The invention is furt:her illustrated by the following examples which should not be construed as further limiting the subject invention.

Exam IDles: Investigation of the effect of a transradial radiation protection board (TRPB), in addition to standard radiation Drotection, on oDerator radiation exDosure durinci coronary ancjiocjraphy and percutaneous coronary intervention (PCI).

109 patients were randomly assigned by time period to undergo radial coronary procedures either with or without a TRPB.

Patients presenting for coronary angiography (CA), CA with ad hoc PCI and planned PCI between July and December 2008 were randomly allocated by cohort to have their procedure either with or without the TRPB. There were no exclusion criteria for the study. For the patients allocated to use of the TRPB, the device was put into position as the patient lay down on the catheterisation table.

Patients were prepared and draped with their right arm abducted and the wrist extended on the TRPB. The radial artery was punctured with either a dedicated 21-gauge radial needle or a 20-gauge cannula according to operator preference.

A Terumo� short hydrophilic sheath (11cm) was inserted and intra-arterial nitrate (250pg) was given. Coronary catheters were introduced over a 0.035' guidewire. Angiography was undert:aken using Judkins-shaped catheters by preference (JL3.5; JR4); intervention was undert:aken using extrabackup guides or Judkins guides according to operator preference (XB3; JR4). Heparin was given in the aort:ic root (2500 i.u. for angiography, 5000 i.u. for PCI).

All procedures were performed by one of two cardiology consultants or two interventional fellows in the same catheterization laboratory in a high-volume radial centre. All operators were experienced in transradial intervention.

Procedures were carried out on using two digital single plane cineangiography units (GE Systems) with an undertable 10-ray tube. A film speed of 12.5 frames/s was used both for fluoroscopy and acquisition. Standard radiation protection was used by all operators consisting of a lead apron and collar, low leaded flaps and leaded glass (0.5mm equivalent for each, see Figure 2).

Radiation exposure was measured for each operator using an electronic personal dosimeter (EPD) attached to the upper left pocket of the standard issue lead apron. Patient height, weight, calculated body mass index (BMI), contrast dose, diamentor, total screening time and procedure duration were recorded. Procedure duration was calculated as the time between the patient entering and leaving the catheter lab. Patient demographics and procedural data were electronically collected on a dedicated data management database (PATS; Dendrite Clinical Systems�).

Statistical analysis Statistical analysis was performed using Stata 10.1 (StataCorps, Texas, USA).

Categorical data were presented as absolute values and percentages whereas continuous data were presented as mean � standard deviation. Continuous data were compared using Student's t test. Categorical data were compared using x2 with appropriate degrees of freedom. Regression modelling was used to correct individual operator exposure for total radiation dose. Statistical significance was considered forp values <0.05.

Results During the study period 109 patients underwent a transradial procedure. 51 patients were in the initial cohort who underwent the procedure with standard protection alone. 58 patients subsequently underwent angiography � intervention with the TRPB in addition to standard protection. There were no differences between the two groups in terms of age, sex, height weight or BMI. There were significantly more coronary angiograms carried out in the TRPB group (56.7% vs 32.8%, p<0.05). Despite this there was a higher total patient X-ray dose in the TRPB group (4054.4 � 3259.1 CGycm2 vs 3201.4 � 2598.9 CGycm2, p=0.15).

Patient and procedural characteristics are shown in Table 1.

For all procedures there was significantly decreased operator radiation exposure when using the TRPB (31.2 � 37.4 vs 48.2 � 43.6pSV, p=0.03), with no significant difference in total fluoroscopy time, procedure duration or contrast load between the groups (see Table 2). When corrected for total patient X-ray exposure, the difference was more marked with a significant decrease of 20 � l7% in operator radiation exposure (p<0.OOl).

Splitting procedures up into type, for coronary angiography there was a trend toward decreased radiation exposure when using the TRPB (19.0 � 24.3 vs 28.1 � 19.4 pSV, p=0.08), with no significant difference for total fluoroscopy, total screening time, procedure duration or contrast load between the groups (see

Table 3).

For ad hoc PCI cases, there was a significantly lower radiation exposure when using the TRPB (33.1 � 23.8 vs 84.2 � 57.5 pSV, p=O.O1), with no significant difference for total fluoroscopy, total screening time, procedure duration or contrast load between the groups (see Table 4).

For elective PCI, there was a significantly decreased radiation exposure when using the TRPB (39.2 � 48.8 vs 73 � 51.8 pSV, p=O.04), with no significant difference for total fluoroscopy, total screening time, procedure duration or contrast load between the groups (see Table 5).

The TRPB decreased individual radial operator radiation exposure in addition to standard radiation protection. In contrast to the femoral approach, with the transradial route it is possible to use the space between the patient's abducted right arm and their side to place a lead screen, without adversely affecting any aspects of the procedure itself. The device led to a relative reduction in X-ray exposure to the operator of up to 2O%.

Table 1 Patient and Procedural Characteristics Characteristics Standard Standard P value Protection protection Alone +TRPB n=51 n=58 Male, n (%) 40 (78.4) 40 (70.0) 0.26 Mean age � SD 64.5 � 11.9 66.7 � 13.4 0.37 (years) Mean height � SD 169.6 � 9.3 170.1 � 11.0 0.60 (cm) Mean weight � SD 82.2 � 20.5 81.4 � 16.1 0.82 (kg) Mean BMI � SD 28.6 � 5.6 27.7 � 5.6 0.37 (kg m 2) CA alone, n (%) 29 (56.7) 19 (32.8) 0.02 CA + ad hoc PCI, 7 (13.7) 14 (24.1) 0.17 n(%) Planned PCI (%) 15 (29.4) 24(43.1) 0.19 Table 2 Operator radiation exposure, total fluoroscopy dose, total screening time, procedure duration and contrast dose for all procedures Standard Standard P value Protection Alone protection +TRPB n=51 n=58 Mean operator 48.2 � 43.6 31.2 � 37.4 0.03 exposure � SD (pSV) Mean total 3201.4 � 2598.9 4054.4 � 3259.1 0.15 fluoroscopy dose � SD (cGycm) Mean total 10.7 � 9.2 14.1 � 10.2 0.09 screening time � SD (mm) Mean total 54.9 � 31.5 66.1 � 31.0 0.09 procedure duration � SD (mm) Mean total 148.2 � 75.9 177.8 � 75.9 0.07 contrast load � SD (ml) Table 3 Operator radiation exposure, total fluoroscopy dose, total screening time, procedure duration and contrast dose for coronary angiograms Standard Standard P value Protection Alone protection +TRPB n=28 n=19 Mean operator 28.1 � 19.4 19.0 � 24.3 0.08 exposure � SD (pSV) Mean total 1537.5 � 909.2 2133.3 � 1465.3 0.11 fluoroscopy dose � SD (cGycm) Mean total 4.7 � 1.8 5.4 � 3.6 0.4 screening time � SD (mm) Mean total 36.5 � 8.0 35.3 � 7.6 0.63 procedure duration � SD (mm) Mean total 102.2 � 18.6 103.3 � 18.4 0.85 contrast load � SD (ml) Table 4 Operator radiation exposure, total fluoroscopy dose, total screening time, procedure duration and contrast dose for coronary angiograms with ad hoc PCI Standard Standard P value Protection Alone protection +TRPB n=7 n=14 Mean operator 84.2 � 57.5 33.1 � 23.8 0.01 exposure � SD (pSV) Mean total 5813.9 � 3245.1 5231.5 � 3301.7 0.7 fluoroscopy dose � SD (cGycm) Mean total 21.1 � 11.9 16.6 � 8.6 0.33 screening time � SD (mm) Mean total 85.1 � 24.1 78.8 � 19.1 0.53 procedure duration � SD (mm) Mean total 228.6 � 78.8 207.3 � 58.4 0.5 contrast load � SD (ml) Table 5 Operator radiation exposure, total fluoroscopy dose, total screening time, procedure duration and contrast dose for elective PCI Standard Standard P value Protection Alone protection +TRPB n=15 n=25 Mean operator 73.0 � 51.8 39.2 � 48.8 0.04 exposure � SD (pSV) Mean total 5143.8 � 2020.7 4725.3 � 3638.6 0.36 fluoroscopy dose � SD (cGycm) Mean total 17.0 � 7.5 18.8 � 10.6 0.60 screening time � SD (mm) Mean total 75.8 � 41.1 80.3 � 31.5 0.36 procedure duration � SD (mm) Mean total 193.2 � 83.5 212.6 � 74.4 0.50 contrast load � SD (ml)

Claims

Claims: 1. A device for protecting operators from radiation during interventional cardiology procedures via the radial artery comprising: a base plate which, in use is positioned under the patient; and a screen which blocks radiation wherein the screen releasably engages with attachment means on or in the base plate to form a 900 angle to the base plate wherein in use the screen is positioned between the patient's torso and arm.
2. A device as claimed in claim 1 wherein the screen is a lead glass or lead rubber screen.
3. A device as claimed in claim 1 or claim 2 wherein the attachment means comprises one or more of: a channel into which the screen engages; adhesives, slots, hooks, clips, and velcro�.
4. A device as claimed in any preceding claim wherein the base plate can be autoclaved for cleaning.
5. A device as claimed in any preceding claim wherein the base plate is formed of fibreg lass, polycarbonate, Perspex� or like material.
6. A device as claimed in any preceding claim wherein the base plate has one or more opening which acts as a carrying handle.
7. A device as claimed in any preceding claim wherein the base plate has one or more opening which can engage with a hook for easy storage.
8. A device as claimed in any preceding claim wherein the device acts as a stabilizing support for the wrist during the surgical procedure.
9. A device as claimed in any preceding claim wherein the base plate has one or more attachment points for securing the patient's arm to the base plate in use.
1O.A method of protecting operators from radiation during interventional cardiology procedures via the radial artery comprising positioning a device as claimed in any one of claims 1 to 9 under the patient such that the screen is located between the patient's arm and torso during the surgery.
11. A device substantially as hereinbefore described or as shown in figure 2.
12.A method substantially as hereinbefore described.