Patent Description:
Ionizing electromagnetic radiation poses a great health hazard to those who must work around scanners, test and measurement instruments, fluoroscopes, X-ray machines and other radiation emitting equipment. Especially medical professionals such as cardiologists and radiologists are at an increased risk of contracting radiation associated diseases due to compounded radiation exposure as a result of long procedures and multiyear careers using radiation procedures. To effectively reduce exposure to the ionizing radiation, the radiation is commonly shielded by means of leaded aprons or suits and thyroid collars. As research has shown that said medical professionals have an increased risk of developing brain tumours and cataracts, there is a need for additional protection of the head and especially the eye region, as the eyes are one of the most sensitive areas of the body, and one of the most vulnerable to radiation.

<CIT> for instance discloses a radiation eye shield adapted to protect the wearer from the hazards of direct beam and scattered radiation. <CIT> discloses a metal detectable lens carrier that includes a polymeric material and metal particulate dispersed throughout the polymeric material. <CIT> describes articles, including fabrics and film layers, are disclosed which can protect against multiple hazards, including radiation, chemical, biological agents, metal projectiles and fire hazards. <CIT> describes a radiation protector for protecting a hippocampus of a user from radiation exposure. <CIT> describes an X-ray eye shield useful in protecting eye tissue from radiation during dental radiography. <CIT> discloses a radiation material made of plastic material comprising a metallic filler.

For the purpose of protecting the eyes of medical professionals against the deleterious effects of radiation, radiation safety glasses are used that are commonly provided with leaded glass lenses that reduce the amount of radiation propagating through the lenses into the eyes of the wearer. Although these glasses are able to limit exposure of the eyes to incoming radiation, they are unable to limit this exposure up to a point where the involved health risks are sufficiently mitigated. In addition, current radiation safety glasses are often cumbersome in use and uncomfortable to wear, thereby hindering the medical professional in its work.

It is therefore a goal of this invention to provide glasses that offer an improved protection against ionizing radiation, and X-radiation in particular, that at the same time are comfortable to wear and do not hinder the wearer in any way.

This object can be achieved by providing glasses according to claim <NUM>.

The use of a tungsten and plastic mixture as a material for the frame provides the frame with a high shielding effectiveness against incident ionizing radiation due to the high atomic number of tungsten. Tungsten may hereby serve as an alternative to lead, which has traditionally been used to shield healthcare practitioners. Tungsten is nontoxic and nonreactive and can be effectively blended with plastics in high concentrations (up to <NUM>% by weight) to produce a mixture or compound with a shielding effectiveness equal to or better than that of lead. A further advantage of tungsten is that it is reusable and, unlike lead, can be disposed of through normal channels. Nonetheless, it is conceivable that any metal, and in particular metals with a high atomic number including lead, may be used in the mixture, even instead of tungsten. The metal in the frame acts as absorbent of incoming radiation, thereby weakening, or even nullifying, this radiation and protecting the wearer of the frame. The higher the atomic number, the denser the metal, which increases the absorbing ability of the metal. Therefore metals with high atomic number, such as atomic number of <NUM> and above, are particularly effective in the present invention. The object of the invention can thus be achieved by providing glasses according to the preamble, wherein the frame is composed of a material comprising a mixture of at least a metal, in particular a heavy metal, and a plastic, preferably a plastic suitable to be injection moulded. Due to combining the metal with a plastic, a material (also referred to as "mixture" or "compound") is obtained that is highly formable and as such allows the glasses to be given complex shapes while retaining a consolidated design. The glasses can hence be designed to closely fit the shape of the wearer's head and be comfortable to wear for extended periods of time. In addition, the plastic provides the material with additional corrosion resistance and strength without unduly increasing the mass of the overall construction. The ability to reduce the weight of the glasses is especially important as the dense radiation shielding materials add weight to both the frame as well as the one or more lenses. For reasons of wearing comfort, it is however critical that the mass of the glasses is kept to a minimum. It is especially advantageous if the plastic applied is an injection mouldable plastic, as injection moulding allows the glasses to be given complex and intricate shapes that are otherwise too complicated and expensive to manufacture. Additionally, injection moulding is especially efficient due to the attainable high production output rates and the more or less finished appearance of the obtained product.

Polypropylene (PP) is favoured as plastic, in part by offering excellent mechanical properties in terms of strength and toughness, but also by offering superior flow and easy acceptance of high metal loadings. Additionally, polypropylene is able to withstand cleaning the frame with solutions containing at least up to <NUM>% alcohol. It is however also possible to use a wide range of other plastics, including polyethylene (PE), polyamide (PA) and polyurethane (PU). In order to obtain a sufficient shielding effectiveness without unduly increasing the thickness of the material, tests have shown that the mixture or compound must at least contain <NUM> percent by weight metal, such as tungsten, and at most <NUM> percent by weight polypropylene. The shielding effectiveness of the material is hereby found to be sufficient when <NUM>% of radiation emitted by a radiation source using a maximum voltage of <NUM> kV, placed at a distance of <NUM>,<NUM> metres, is absorbed or scattered. With metals other than tungsten, different percentage may apply based on the shielding effectiveness of the particular metals used. By further increasing the percentage by weight tungsten (or metal in general), the shielding effectiveness can either be increased or kept constant while decreasing the material thickness. The maximum percentage by weight of the metal typically lies in the range of <NUM>-<NUM>% and is commonly determined by minimum percentage by weight of the plastic that is necessary for the flowability of the plastic to substantially remain intact such that the material remains mouldable.

Given the above-stated advantages of an injection moulding process, the frame is obtained by subsequently mixing and injection moulding of the tungsten and the plastic. In a commonly instance, the mixing comprises the plastic being loaded with powdered tungsten and/or another metal. The obtained mixture or compound has a high radiation shielding effectiveness due to the application of the dense metal, while still retaining a mouldability similar to that of the plastic. The subsequent moulding process allows the frame to be shaped in a single step and in high volume in a broad range of (complex) shapes. When possible due to the composition of the mixture or compound, the moulding process may be performed on standard injection moulding equipment.

In a possible embodiment of the glasses according to the invention, the plastic is polypropylene, and the mixture comprises at least <NUM> percent by weight (wt%) tungsten and at most <NUM> percent by weight (wt%) polypropylene. Polypropylene (PP) is favoured as plastic, in part by offering excellent mechanical properties in terms of strength and toughness, but also by offering superior flow and easy acceptance of high metal loadings. Additionally, polypropylene is able to withstand cleaning the frame with solutions containing at least up to <NUM>% alcohol. It is however also possible to use a wide range of other plastics, including polyethylene (PE), polyamide (PA) and polyurethane (PU). In order to obtain a sufficient shielding effectiveness without unduly increasing the thickness of the material, tests have shown that the mixture or compound must at least contain <NUM> percent by weight tungsten and at most <NUM> percent by weight polypropylene. The shielding effectiveness of the material is hereby found to be sufficient when <NUM>% of radiation emitted by a radiation source using a maximum voltage of <NUM> kV, placed at a distance of <NUM>,<NUM> metres, is absorbed or scattered. With metals other than tungsten, different percentage may apply based on the shielding effectiveness of the particular metals used. By further increasing the percentage by weight tungsten (or metal in general), the shielding effectiveness can either be increased or kept constant while decreasing the material thickness. The maximum percentage by weight of the metal typically lies in the range of <NUM>-<NUM>% and is commonly determined by minimum percentage by weight of the plastic that is necessary for the flowability of the plastic to substantially remain intact such that the material remains mouldable.

In a further embodiment of the glasses according to the invention, the at least one ionizing radiation shielding lens is non-corrective. This commonly means that no difference exists in curvature between the front and rear surface of the radiation shielding lens. The fact that the one or more radiation shielding lenses of the glasses do not (need to) have a corrective function that necessitates cutting the lens to include a spherical correction according to the particular prescription of wearer significantly simplifies the manufacturing process for the glasses, thereby reducing manufacturing costs.

To enable the glasses to be used by wearers having eye conditions that necessitate the wearer to use prescription eyewear, the glasses may comprise an accessory frame placed in front of the at least one ionizing radiation shielding lens, which accessory frame is configured to enclose at least one corrective lens at least partially. Conventionally, the optical profile of the radiation shielding lens hereby differs from that of the corrective lens, wherein the radiation shielding lens preferably is non-corrective. By enabling the radiation shielding glasses to be used in concurrence with such an accessory frame, adaptation of the glasses to match the prescription of the wearer becomes possible and is significantly simplified in comparison with directly cutting the radiation shielding lens to include a spherical correction according to the particular prescription. Namely, as the refractive index of radiation shielding lenses, which in a common instance include lead, differs from that of plastic and glass lenses commonly used in prescription glasses, different cutting techniques and processes are necessary to produce these lenses. These techniques and processes are often not within the skills of ordinary opticians, meaning that changing the correction of the one or more lenses requires the skills of a specialist. With the prescription lenses being dissociated from the shielding lenses however, the corrective lenses could be easily adapted and replaced by any optician without having to alter the radiation shielding lenses.

The accessory frame may be placed on an inside of the frame turned towards the face of a wearer. An advantage of this relative position of the accessory frame is that the one or more corrective lenses held by the accessory frame can be placed at a distance from the eyes of the wearer conventional to normal prescription lenses. Moreover, as the accessory frame is place on an inside of the radiation shielding glasses, the exterior of the glasses can be kept clean without any protruding parts, which could facilitate the mounting of vision aids such as magnifying surgical loops.

In addition, the accessory frame may be detachably mounted on the frame to facilitate the removal and placement of the accessory frame from and on the radiation shielding glasses. The detachable mounting may be effectuated by means of mounting or attachment means provided on the accessory frame and/or the frame at least partially enclosing the one or more radiation shielding lenses. These mounting or attachment means may establish any connection between the respective frames such as a snap connection or a screw connection. It is however advantageous if the connection allows for quick and easy removal and placement of the accessory frame. It is also possible that the accessory frame is fixedly connected to the frame at least partially enclosing the one or more radiation shielding lenses, while the lenses held by the accessory frame are themselves detachably connected to said accessory frame. The accessory frame may be designed such that it can be used as prescription glasses independently from the radiation shielding glasses. It is even possible that the accessory frame is forms part of an ordinary pair of prescription glasses and that the radiation shielding glasses are provided with mounting means enabling the mounting of such prescription glasses to the radiation shielding glasses.

To be able to sufficiently limit radiation exposure up to a point where the involved health risks are mitigated, the frame may be configured to form an at least partially sealed interior around the eyes of a wearer. The glasses and the frame in particular may even form a substantially completely sealed interior around the eyes of the wearer. The interior around the eyes of a wearer and consequently the eyes of the wearer themselves are then protected against ionizing radiation entering the eyes not only from the front, but also from other directions possibly including the top, bottom and sides.

As a way to provide an adequate shielding around the eyes of the wearer of the glasses, the frame at opposing side ends may comprise temples for engaging either side of the wearer's head, wherein the temples comprise side panels dimensioned to form shields for shielding the eyes of a wearer from ionizing radiation entering from the side of the wearer's head. Said side panels preferably form an integrated part of the temples and therewith the frame, wherein the side panels are composed of the same material as the frame. It is possible that the side panels on their free edges connect to, and more preferably form-fit the head of the wearer to completely seal the outer sides of the eye sockets from incoming ionizing radiation.

The glasses may be configured to connect with a part of the face of a wearer, in particular below the eyes, preferably at the height of the cheekbones, to provide for additional shielding of the eyes from ionizing radiation, and especially radiation coming from below the wearer's head and propagating upwards. The connection between the glasses and the face may be achieved by providing the bottom end of the frame and/or the at least one lens with a shape that follows the shape of the face. Constituting a protruding part of the face, the cheekbones are a suitable area for the bottom end of the glasses to connect with, thereby preventing radiation to pass underneath the glasses and reach the eye area.

In a possible embodiment of the glasses according to the invention, the frame is provided with at least one flexible sealing element configured to connect on a first end with the face of a wearer, in particular below the eyes, and at a second end with a rim of the frame enclosing the ionizing radiation shielding lens. The sealing element may hereby be composed of a material comprising a similar mixture to that of the frame, possible added with a suitable elastomer or plasticizer to provide the sealing element with a degree of elasticity. The sealing element is flexible in order to closely adhere to the shape of the wearers face for increased protection. Moreover, the sealing element improves the fit of the glasses, which increases wearing comfort. Although radiation originating from below poses a predominant treat to medical professionals, as radiation emitting equipment conventionally targets part of a human body lying down wherein the radiation source is positioned at a lower level than the medical professional's eyes, similar flexible sealing elements may be applied on other parts of the glasses, and especially the edges of the frame where a gap is present between the glasses and the wearer's head.

The at least one sealing element may be provided with at least one reinforcing member, wherein the reinforcing member is deformable to at least partially form-fit the shape of the wearers face. The reinforcing member may for this purpose be made of a bendable material with good fatigue strength and plasticity. By deforming (bending) the one or more reinforcing members to attain a desirable shape for the sealing element, a customizable fit can be created without the need for customized glasses.

As the interior around the eyes of a wearer is sealed in an increased degree, fogging or steaming up of the lenses may occur due to exhaling or moisture and/or heat coming from the eyes and/or the skin. The at least one sealing element may therefore be provided with at least one ventilation channel connecting the inside to the outer side of the glasses to lead moist air away from the eye region and counteract this steaming or fogging up. The ventilation channel may hereby be configured to prevent propagation of ionizing radiation though the channel towards the inside of the glasses, wherein the channel in particular extends at an angle compared to direction of propagation of incoming ionizing radiation. As radiation propagates in a straight line, providing the channel with a large enough angle is an effective way in ensuring that the rays of radiation do not pass straight through the channel but instead pass through the sealing element, thereby being at least partly absorbed by said sealing element.

To further increase the fit and wearing comfort of the radiation shielding glasses, the glasses may comprise at least one nose pad, wherein the nose pad is moveably connected to the frame. The moveable connection between the frame and the nose pad allows the nose pad to move relative to the frame. This lets the nose pad adapt to the position of the nose, independent on the specific wearer. Moreover, the nose pad may accommodate for placement of the glasses in various positions (e.g. more forward or more backward placed) on the nose. The nose pad may additionally seal any existing gap between the glasses and the nose and/or other parts of the face. Moreover, the nose pad may be composed of a material with a high ionizing radiation shielding effectiveness.

In yet another embodiment of the glasses according to the invention, the glasses comprise a headband connected to the frame, wherein the headband is configured for fixing the glasses to the face of the wearer. The headband, preferably connected to the ends of either temple of the frame and placed around the back of the head allows for a secure fixation of the glasses to the wearer's face, even when hanging over a patient.

To ensure the medical professional with an unobstructed view looking through the glasses, the at least one ionizing radiation shielding lens may have a minimum light transmittance of <NUM>%. This specified minimum light transmittance value is also preferred to meet various standards for eye protection, including the European norm EN166, which is considered the baseline for safety eyewear.

The invention further relates to a frame for use in a pair of glasses for shielding against ionizing radiation as described in any of the above-described embodiments, the advantages of which have been already discussed in the foregoing.

The invention will now be elucidated into more detail with reference to non-limitative exemplary embodiments shown in the following figures. In the figures:.

<FIG> shows a perspective view of an embodiment of the glasses <NUM> for shielding against ionizing radiation according to the invention, wherein the glasses <NUM> are shown being worn by a wearer <NUM>. The glasses <NUM> comprise a frame <NUM> that holds two ionizing radiation shielding lenses <NUM>. It is however also possible that the frame <NUM> holds a different number of lenses, such as a single lens that covers both eyes. As a result of its particular shape, the frame <NUM> forms a sealed interior around the eyes of a wearer <NUM>, in part by connecting with the face <NUM> of the wearer <NUM> in the cheekbone region <NUM>, and in part by side panels <NUM> provided on the temples <NUM> of the frame <NUM>. Due to the enclosure of the eyes created by the frame <NUM> and the lenses <NUM>, the eyes are effectively shielded from ionizing radiation entering from all side of the wearer's head. Namely, the lenses <NUM> are typically made from a radiation shielding material such as leaded glass, while the frame <NUM> is composed of a material comprising a mixture of at least tungsten and a plastic, wherein especially the tungsten has a high radiation shielding effectiveness. An accessory frame <NUM> is placed on the inside of the frame <NUM> to hold two corrective lenses <NUM> that enable wearers with prescription eyewear to also use the radiation shielding glasses <NUM>. The accessory frame <NUM> is optionally mounted to the frame <NUM> in a detachable manner.

<FIG> shows a front perspective view of another embodiment of the glasses <NUM> for shielding against ionizing radiation according to the invention. These glasses <NUM> again comprise a frame <NUM>, composed of a radiation shielding material comprising a mixture of at least one metal and a plastic, wherein one of the at least one metal is preferably tungsten. The opposing side ends of the frame <NUM> comprise temples <NUM> that are configured to engage either side of the wearer's head. The temples <NUM> are widened to integrally form side panels <NUM> that shield the eyes of a wearer from ionizing radiation entering from the sides. At their back end, the temples <NUM> are mutually connected by means of a headband <NUM> that is configured to wrap around the head of a wearer and securely keeps the glasses <NUM> in place. At a lower end of the frame <NUM>, flexible sealing elements <NUM> (clearly visible in <FIG>) are connected to the rims <NUM> of the frame <NUM> enclosing the ionizing radiation shielding lens <NUM>. The sealing elements <NUM> are provided with reinforcing members <NUM> that may be deformed to follow the contours of the face, thereby realising a close connection between the wearer's face and the glasses <NUM>. The glasses <NUM> also comprise nose pads <NUM>, which nose pads <NUM> are preferable moveably connected to the frame <NUM> and may at their bottom ends connect to the sealing elements <NUM>. In addition, the nose pads <NUM> may be made out of a similar flexible material as the sealing elements <NUM> and may be provided with deformable reinforcing members <NUM> to create a custom fit. The frame <NUM> holds two ionizing radiation shielding (leaded) lenses <NUM>, which in this case are non-corrective. To facilitate using the glasses <NUM> despite having eye conditions that necessitate the use of prescription eyewear, an accessory frame <NUM> is provided on an inside of the glasses <NUM>, which accessory frame <NUM> is configured to enclose one or more corrective lenses <NUM>.

<FIG> shows a rear perspective view of the embodiment of the glasses <NUM> shown in <FIG>. Elements corresponding to the ones shown and discussing in the <FIG> are herein indicated with corresponding numbers. Shown from behind, mounting means <NUM> are visible that are provided on the frame <NUM> and the accessory frame <NUM> configured to hold the corrective lenses <NUM>. These mounting means <NUM> connect the accessory frame <NUM> to the outer frame <NUM> in a detachable manner. Although the mounting means <NUM> may establish any connection between the respective frames <NUM>, <NUM>, it is advantageous if the connection allows for quick and easy removal and placement of the accessory frame <NUM>. The sealing elements <NUM> are furthermore provided with ventilation channels <NUM> connecting the inside to the outer side of the glasses <NUM> to prevent the lenses <NUM>, <NUM> from steaming up.

Claim 1:
Glasses (<NUM>, <NUM>) for shielding against ionizing radiation, in particular X-radiation, comprising:
- a frame (<NUM>, <NUM>), and
- at least one ionizing radiation shielding lens (<NUM>, <NUM>), such as a leaded glass lens, which lens (<NUM>, <NUM>) is at least partially enclosed by the frame (<NUM>, <NUM>),
wherein the frame (<NUM>, <NUM>) is composed of a material comprising a mixture of at least tungsten and a plastic, characterized in that the plastic is polypropylene, polyethylene, polyamide or polyurethane, and the mixture comprises at least <NUM> wt% tungsten and at most <NUM> wt% plastic.