Patent Description:
This invention also concerns an immobilisation mask for immobilizing a body part of a patient on a carrier, the immobilisation mask containing a sheet of a thermoplastic material for receiving the body part to be immobilized, and connection means for connecting the immobilisation mask to the carrier.

This invention further concerns a profile for connecting an immobilisation mask for immobilizing a body part of a patient on a carrier, to the carrier.

The use of masks or similar means for positioning one or more body parts of a patient in a predetermined position on the carrier and immobilizing of the body part in this position in a predetermined posture during the treatment of the patient with radiation, such as for example with Intensity Modulated Radiation Therapy (IMRT), Image Guided Radiation Therapy (IGRT), stereotactic radiation therapy or surgery and proton therapy, is well known. With such techniques, the accurate and reproducible positioning of the body part to be treated of a predetermined position in a predetermined posture is of utmost importance. As use is often made of a radiation source that has the shape and/or size of the tissue to be treated, it is therefore essential that the radiation is directed at the tumour, and to spare the surrounding healthy tissue. Deviations of a few mm may result in that not the tumour is irradiated, but the surrounding healthy tissue, which is thus destroyed or damaged. This is undesirable.

Treatment and imaging techniques that make use of charged, heavy particles such as protons, offer the advantage in comparison to other radiation sources such as electrons, photons, gamma or X-radiation that the radiation dose can be better directed to the tissue to be treated. Proton beams usually scatter less in the tissue to be treated and exhibit a low lateral dispersion, which limits the risk of lateral damage. This offers the advantage that a directed killing of tumour cells can be obtained and that the surrounding healthy tissue can be spared. In order to enable the directed killing of unwanted tissue with both more or less dispersing radiation beams, an accurate positioning of the body part to be treated in relation to the radiation source is essential. To minimize the risk of unwanted irradiation of surrounding tissue, it is not only required that the body part is accurately positioned in the desired posture in relation to the radiation source during the treatment, but also that the body part is fixated during the treatment in the intended posture and that the range of motion during the treatment is limited to a minimum. An accurate and reproducible positioning is of importance during fractionated treatment in which the patient is administered repeated radiation doses of less than optimal dose with in-between time intervals, to ensure sufficient radiation of the area to be treated and to limit the irradiation of healthy tissue to a minimum. An accurate positioning is also exceptionally important during a single treatment, in which a large radiation dose is administered once. Various tools have been designed to realize an accurate and reproducible positioning of a body part in relation to a radiation source, both with regard to the position as well as the posture, and thereby also to limit the range of motion of the body part to a minimum.

Traditionally, a patient is placed on a table, on which a base plate or carrier is located. Base plates that are used with radio therapy are often manufactured as a sandwich structure with a foam core and carbon fibre skin. Immobilizing a body part of a patient, such as for example the head or any other body part, on a particular place on the table in a predetermined posture is realized by attaching an immobilisation mask to the base plate or the table. The immobilisation mask has a shape that closely matches the body part to be immobilized, to limit the range of motion of the body part to be immobilized.

<CIT> in the name of the applicant discloses such a non invasive immobilization mask comprising a sheet of thermoplastic material for immobilizing the head of a patient in a predetermined position on a base plate or carrier, in a predetermined posture. The mask comprises a sheet of a thermoplastic material which is formed such that it matches the shape of the body part to be immobilized. To enable optimum design, a thermoplastic material is chosen with a low melting temperature, such that the material can be shaped directly onto the body part. An example of a suitable material is ε-polycaprolactone. Means are provided to at least a section of the edge of the sheet of thermoplastic material for attaching the mask to the base plate. The attachment means disclosed in <CIT> comprise a first lower lip for the attachment of the immobilization mask to the outer edge of a base plate or carrier.

To meet the special requirements set by the radiation therapy concerning the immobilisation of the patient in relation to the radiation source and, especially with proton therapy, homogeneity of the radiation that reaches the tissue to be treated, the carrier is designed such that it supports the patient well.

The immobilization mask according to <CIT> may however be quite cumbersome to secure to the carrier. The person applying the mask usually stands at the head of the patient, looking down onto the patient, and would for example firstly connect a first profile at the top of the patient's head to the carrier. He would then connect the two profiles on the left and right sides of the mask to the carrier on the respective sides of the head. As the dimensions of the carrier at the location of the head are often smaller than the dimensions of the head, in order to avoid scattering and alteration of the radiation beam emitted to the patient by the radiation source, the connecting means will often be positioned behind the head of the patient in the connected state, and the visibility for the person fixing the mask will thus be bad as that person looks down onto the patient. Consequently, it may take too much time to find the right position of the connecting means on the carrier, as it may take several attempts to find the correct position of the connection means in the connected state. This may cause discomfort and stress to the patient.

Consequently, there is a need for attachment means for attaching an immobilisation mask to a carrier or base plate for the support of the patient that allows connecting the profile to the carrier more quickly.

It is known in the state of the art such as in the patent publication <CIT> or <CIT> to provide a profile for connecting a carrier to an immobilisation mask for immobilizing a body part of a patient on the carrier, wherein the profile contains at a second side first connection means for connecting the profile to the carrier, and at a first side opposite to the second side, second connection means for connecting the profile to the immobilisation mask, and wherein the first connection means are provided, in a connected state, to engage corresponding connection means of the carrier, wherein the profile comprises a swivel arm provided to cooperate with a swivel anchor point provided to the carrier. These known profiles however are cumbersome to attach to the carrier in a rapid manner, certainly when the visibility on the profile is reduced. It is thus an aim of the present invention to provide a profile that can be attached to the carrier more quickly when the visibility on the profile is reduced.

The present invention relates to a profile as set out in the claims <NUM>-<NUM>. Moreover, the present invention relates to an immobilisation mask as set out in claims <NUM>-<NUM>. Finally the present invention relates to an assembly as set out in claims <NUM>-<NUM>.

The immobilisation mask according to the invention and preferred embodiments thereof are disclosed in the attached claims, figures and figure description.

The aim of this invention consists further in connection means, in particular in providing a profile for attaching an immobilisation mask to a carrier for supporting a patient, wherein the connection means exhibit improved mechanical strength and a longer operating life as well as making the fixation of the mask on the patient's head more practicable for the practitioner and more comfortable for the patient.

The profile according to the invention and preferred embodiments thereof are disclosed in the attached claims, figures and figure description.

The invention is illustrated in the accompanying drawings which display preferred embodiments and describe the profile, the immobilisation mask provided with a profile, and an assembly of a carrier, an immobilisation mask and profile for the connection of the immobilisation mask to the carrier or base plate or carrier on which the patient rests. The invention is further illustrated in the description of the figures of these preferred embodiments. In the following figure description, the same reference numbers refer to the same elements.

A view to an upper side of a preferred embodiment of a carrier or base plate <NUM> for supporting a patient in radiation therapy is shown in <FIG>. The preferred embodiment shown in <FIG> of the carrier <NUM> contains a top support surface <NUM> for supporting the patient. With "along" is meant that the connection means are located at a distance of the edge <NUM> of the carrier <NUM> or may be provided in one piece with the carrier, dependent on the nature of the connection means <NUM> on the profile. Along the edge of the carrier <NUM>, preferably carrier connection means <NUM>, as opposed to mask connection means <NUM>, <NUM>, comprising the first and the second connection means <NUM>, <NUM>, extend at least at one position, that are provided to cooperate with the mask connection means <NUM>, <NUM> for the connection of the immobilisation mask <NUM> with the carrier <NUM>. Along the edge <NUM> of the carrier <NUM>, there is provided preferably on at least one position, an opening <NUM> for receiving connection means <NUM> for attaching the immobilisation mask <NUM> to the carrier <NUM>. Along the edge <NUM> of the carrier <NUM>, there is provided at least one swivel anchor point <NUM> for cooperation with swivel arm <NUM> extending along the connection means <NUM>. More preferably, two or more openings <NUM> are provided. The amount of openings <NUM> is usually chosen such that a sufficient amount of profiles <NUM> can be applied to enable a stable and accurate fixation of the position and posture of the body part of the patient and to allow not more than the desired range of motion. The openings <NUM> may be applied at random positions along the edge <NUM> of the carrier. However, preferably, the openings <NUM> are applied symmetrically relative to the longitudinal axis of the carrier to attain optimal distribution of the tension and tensile force over the immobilisation mask <NUM> and to enable optimal derivation thereof to the carrier <NUM> (see <FIG>). It is further possible to choose the amount of openings <NUM> such that the carrier <NUM> is suitable for immobilizing multiple body parts with varying size. Every other arrangement of openings <NUM> considered suitable by the person skilled in the art may be chosen.

Furthermore, the carrier <NUM> along the edge <NUM> is preferably, at least on position <NUM>, deformed for receiving a profile <NUM> for attaching the immobilisation mask <NUM> to the carrier <NUM>. The deformation <NUM> is preferably such that it is sufficiently large to receive the upper lip <NUM> of the profile <NUM> in such a way that the upper surface of the upper lip <NUM> is flush with the support surface <NUM> of the base plate or carrier <NUM> to increase the comfort of the patient. The presence of the deformation <NUM> hampers the displacement of the profile <NUM> along and relative to the edge of the carrier <NUM> and contributes in this way to the provision of a stable, accurate and reproducible connection to the immobilisation mask <NUM> with the carrier. The deformation also counteracts the possibility of rotation of the profile <NUM> relative to the carrier <NUM>. Preferably, two or more deformations <NUM> are provided. The number of deformations <NUM> is usually chosen such that a sufficient amount of profiles can be applied to enable a stable and accurate fixation of the position and posture of the body part of the patient and to allow no more than the desired range of motion. However, the presence of the deformation is not critical for the invention and can be omitted.

The dimensions and shape of the deformations <NUM>, if present, may be random. The deformation <NUM> preferably has the shape of a recess relative to the upper side of the carrier. In other words, the upper surface of the deformation <NUM> is preferably lowered relative to the upper surface <NUM> of the carrier. This is shown in <FIG>. Preferably, the dimensions of the deformations <NUM> in the longitudinal direction along the edge <NUM> of the carrier and the dimensions of the deformation <NUM> in the traverse direction on the carrier <NUM> are aligned with the dimensions of the profile <NUM> or connection means that are provided to be incorporated into this deformation. The deformation <NUM> preferably has nearly the same dimensions as the profile <NUM> or is slightly larger than the profile <NUM>, such that the profile <NUM> or at least the upper lip <NUM> of the profile can be incorporated in the deformation <NUM>. The deformation <NUM> may function, at the application of the profile, as a guide for guiding the displacement of the profile <NUM> during the establishment of the connection between the mask <NUM> and the carrier <NUM>. Since the raised edge of the deformation forms a barrier, the displacement of the profile <NUM>, once installed, is opposed, and the deformation <NUM> contributes to the stable and accurate fixation of the position and posture of the body part of the patient so as to allow no more than the intended range of motion.

A view to the lower side of a preferred embodiment of a commonly used carrier <NUM> for supporting a patient, especially in proton therapy, is shown in <FIG>. At a position between the edge <NUM> of the carrier and the opening <NUM>, a guide <NUM>, <NUM> is preferably provided at the lower side of the carrier for guiding the displacement of the profile <NUM> at the establishment of the connection of the immobilisation mask <NUM> with the carrier <NUM>, for example for guiding the displacement of the first lower lip <NUM> on the profile <NUM>. A preferred embodiment of the guide <NUM> has for example the shape of two opposite protrusions <NUM> or rails, in between which, for example, the lip <NUM> of the profile <NUM> is displaceable at the establishment of the connection. The two opposite protrusions <NUM> can however also be positioned such that in between them, two opposing side edges of a profile can be slid, as for example shown in <FIG> for a profile not comprising a swivel arm and therefore not according to the invention. In such embodiment, the guide <NUM> for example has the shape of two opposite protrusions <NUM> or rails, in between which, for example, the second and the third lip <NUM>, <NUM> are displaceable at the establishment of the connection. Otherwise, the guide <NUM> may also have the shape of a single protrusion provided to slide along an edge of the profile <NUM> according to the invention, preferably opposing the side of the profile from which the swivel arm <NUM> extends. Once the connection has been established, the protrusions counteract a displacement of the profile, for example the lip <NUM> and if present the second and the third lip <NUM>, <NUM>, in a direction along the edge and therefore contribute to a stable and accurate fixation of the position and posture of the body part of the patient. Instead of the protrusions or rails <NUM>, an alternative guide, for example a slot or any other alternative deemed suitable by the person skilled in the art, may be used that is adapted to embodiment of the lower lip <NUM> and, if present, the second and the third lip <NUM>, <NUM>.

The connection means, more in particular the mask connection means of the connection means, preferably comprise a profile <NUM> with first connection means <NUM> at a first side of the profile along which the profile is connectable to the carrier <NUM>, and second connection means <NUM> at a second side of the profile <NUM> opposite the first side along which the profile <NUM> is connectable to the immobilisation mask <NUM>. The first connection means <NUM> are provided, in the connected state, to engage an outer edge of the carrier. Such connection means enable to establish a connection between the immobilisation mask <NUM> and the carrier <NUM>, also when the profile is subjected to high tension. The first connection means <NUM> preferably engage in the thickness direction the outer edge of the carrier. In a possible embodiment, the first connection means <NUM> exercise a clamping force onto the carrier <NUM>.

The first connection means <NUM> preferably comprise an upper lip <NUM> that is provided to extend, in the connected state, along an upper surface or side of the carrier <NUM>. Preferably, the upper lip <NUM> is incorporated in a corresponding deformation <NUM> along the upper surface <NUM> of the carrier <NUM>. To enable a greater transmission of forces between the immobilisation mask <NUM> and the carrier <NUM>, the upper lip <NUM> preferably extends in the longitudinal direction along the edge <NUM> of the carrier <NUM>. The upper lip <NUM> may, for example, be curved to optimally follow the shape of the immobilisation mask <NUM>, the upper lip <NUM> may however also be flat and rectangular or may take any other appropriate shape. The edge <NUM> of the upper lip may, for example, be curved to optimally follow the shape of the edge of the immobilisation mask as shown in <FIG>. The upper lip <NUM> increases the stability of the mask in the connected state with the carrier, since a tilting movement of the profile is counteracted.

The first connection means <NUM> preferably also comprise at least one lower lip <NUM> that is provided to extend in the connected state along a lower surface or lower side of the carrier <NUM>. More preferably, the first connection means <NUM> comprise a lower lip <NUM> that is provided on the side directed to the carrier with a protrusion <NUM> that is provided, in the connected state, to engage corresponding connection means on the lower side of the carrier <NUM>. Preferably, protrusion <NUM> engages a corresponding opening <NUM> in the carrier <NUM>. The opening <NUM> may extend throughout the entire thickness of the carrier <NUM> or over a section thereof. The first connection means <NUM> further preferably comprise on a first side of the lower lip <NUM> a second lower lip <NUM> which preferably extends in the longitudinal direction along the edge of the carrier <NUM>. The first connection means <NUM> further preferably comprise at a second side of the lower lip <NUM> opposite the first side in transverse direction of the lower lip <NUM>, a third lower lip <NUM> which preferably extends in the longitudinal direction along the edge of the carrier <NUM>. With a resiliently arranged lip <NUM>, an easily detachable connection is provided between the profile <NUM>, in particular between the profile and the carrier <NUM>. The second and third lip <NUM>, <NUM> may have the same or different shapes, but preferably have a corresponding shape. The second and third lower lips <NUM>, <NUM> may, for example, be curved to optimally follow the shape of the immobilisation mask, they may however also be rectangular or may take any other appropriate shape. The presence of the second and third lower lip <NUM>, <NUM> increases the stability of the mask in the connected state with the carrier, since a tilting movement of the profile <NUM> is counteracted.

Preferably, at least one swivel arm <NUM> is provided extending along the connecting means <NUM>, to connect with a corresponding swivel anchor point <NUM> located on the lower side of the carrier <NUM>.

As can be seen in the figures, the swivel arm <NUM> and the swivel anchor point <NUM> can engage each other. In the embodiment shown in the figures, the engagement of the swivel arm <NUM> and the swivel anchor point <NUM> has substantially a single degree of freedom, in this case the angle of rotation of the swivel arm <NUM> around the swivel anchor point <NUM> during swivelling of the swivel arm <NUM>. As can be seen in <FIG>, the swivel arm <NUM> comprises a gripping part <NUM> provided to grip at least partly around the swivel anchor point <NUM>. The gripping part <NUM> shown is in the form of a semi-circular shape provided to grip around a corresponding swivel anchor point <NUM>. In the figures, the swivel gripping point <NUM> is in the form of a cylindrical protrusion provided to be surrounded at least partly by the gripping part <NUM> when it grips at least partly around the swivel anchor point <NUM>. Such a connection can be provided in the form of a hinge joint allowing a single degree of freedom, in this case begin the angle of swivelling.

As can be seen in <FIG>, the swivel arm extends along the first connection means <NUM> and the second connection means <NUM>. Other embodiments are however possible, according to the desired configuration and depending on the specific use situation.

In <FIG> it can be seen that the body part to be immobilized is a head and the swivel anchor point <NUM> is provided below the mandible of the patient positioned on the carrier <NUM>, more in particular, although not shown in <FIG>, the swivel anchor point is provided below the mental protuberance of the mandible of the patient, even more in particular the swivel anchor point is provided at the height of the Adam's apple of the patient. It can further be seen that the body part is a head and the swivel anchor point <NUM> is located along the neck of a patient positioned on the carrier <NUM>, more in particular above the clavicle of the patient.

<FIG> further shows the relative difficult position of the different connection means <NUM>, <NUM> in light of attaching the connection means <NUM>, <NUM> to the carrier <NUM>.

Preferably, the outer surface of lip <NUM> further contains a second lip <NUM> that counteracts or even prevents a movement of the lip <NUM> that is directed away from the space <NUM>. The presence of such lip however is not critical for the invention and the lip <NUM> can therefore be omitted.

The opening <NUM> can be arranged centrally in the deformation <NUM>, if present, or asymmetrically.

The at least one upper lip <NUM> and at least one lower lip <NUM>, <NUM>, <NUM>, of the first connection means <NUM> are preferably arranged at a distance from one another and are connected to each other at a connection position <NUM>. Thereby, the first distance between the at least one upper lip <NUM> and at least one lower lip <NUM>, <NUM>, <NUM>, is preferably chosen such that, at one first side of the connection position <NUM>, it is sufficiently large for receiving a section of the carrier <NUM> that extends along the edge <NUM> thereof. The second connection means <NUM> preferably contain also an upper and a lower lip <NUM>, <NUM> that are connected to each other at the connection position <NUM>. The upper and lower lip <NUM>, <NUM> are preferably arranged at a second distance from each other that is sufficiently large for the inclusion of the material along the edge of the immobilisation mask. The first distance can be equal to the second distance, or may be different from it. Connection position <NUM> connects the first <NUM> and second connection means <NUM>.

The first connection means <NUM> for connecting the profile to the carrier <NUM>, preferably extends in a first direction relative to the connection position <NUM>, in particular in the direction of the carrier <NUM>. The second connection means <NUM> that connect the profile <NUM> to the immobilisation mask preferably extend in opposite direction relative to the first connection means <NUM> and the connection position <NUM>, in particular in the direction of the immobilisation mask.

The carrier <NUM> may be provided in every material deemed suitable by the person skilled in the art. The carrier is for example conducted as a plate of carbon fibres impregnated with epoxy resin. However, other materials may be used.

The profile <NUM> may be provided in one piece with the immobilisation mask <NUM> or as a separate component. Preferably, it is provided in one piece with the mask <NUM> in order to absorb higher tensile forces on the mask with minimal risk of releasing the profile <NUM>. The profile <NUM> may be provided in another material than the mask, such that for both components the material may be chosen that is optimally adapted to the selected function it performs. This offers, for example, the possibility to choose the material for the mask such that it may directly be shaped to the patient, and to choose the material of the profile <NUM> such that it exhibits an optimal mechanical strength and minimal deformation to ensure an accurate and reproducible positioning.

Suitable materials for manufacturing the immobilisation mask are for example thermoplastic elastomers, thermoplastic polyurethane, thermoplastic polyisoprene, thermoplastic polyesters, thermoplastic polyolefins, polyvinyl chloride, polystyrene, or a blend of two or more of these materials. Preferred are these polymers that have a relatively low softening temperature wherein the material is deformable, such that these are exceptionally suitable for the manufacturing of immobilisation mask that can directly be formed onto the body part to be immobilized. The body part to be immobilized then serves as a mould for shaping the immobilisation mask. Examples of suitable thermoplastic polyolefins comprise polyethylene, polypropylene or ethylenepropylene co-polymers. Examples of suitable thermoplastic polyesters comprise polyethylene vinyl acetate, polyacrylates or polymethacrylate, polymeric fatty acid esters, in particular poly-C-caprolactone, for example poly-ε-caprolactone such as available at Perstorp (UK) under the trade name Capa®. Preferred are the polymers of the group of thermoplastic polyurethane, isotactic polypropylene, copolymers of ethylene with <NUM> -butene, a copolymer of ethylene with <NUM>-octene, poly-ε-caprolactone, poly-ε-caprolactone containing thermoplastic polyurethane, as well as mixtures of two or more of these materials. Poly-C-caprolactone is especially preferred because it has a low melting point and is deformable at temperatures that the human body can tolerate.

Suitable materials for manufacturing the profile are ABS, polyoxymethylene, polyamide or other equivalent materials.

This invention also concerns an immobilisation mask for immobilizing a body part of the patient in a previously determined posture of the carrier <NUM>, wherein the immobilisation mask is provided with a profile <NUM> as described above, for connecting the mask <NUM> to the carrier <NUM> for supporting the patient. Preferably, the profile <NUM> is attached to the mask <NUM> along the edge of the mask <NUM>, by incorporating the edge <NUM> of the mask in the second space <NUM> at the second connection means <NUM>. Attachment can be done, for example, by gluing, by welding, by means of a mechanical connection or by any other connection deemed suitable by the person skilled in the art. Preferably, the connection is established by gluing or welding. Preferably, the profile <NUM> is as described above. To enable an optimal positioning and immobilizing along the edge of the mask, usually multiple profiles <NUM> will be applied.

This invention further concerns the profile <NUM> for connecting an immobilisation mask <NUM> to the carrier <NUM>, wherein the mask <NUM> is provided for immobilizing a body part of a patient in a predetermined posture on the carrier. Preferably, the profile <NUM> is as described above.

Claim 1:
Profile for connecting a carrier (<NUM>) to an immobilisation mask for immobilizing a body part of a patient on the carrier (<NUM>), wherein the profile (<NUM>) contains at a second side first connection means (<NUM>, <NUM>, <NUM>) for connecting the profile (<NUM>) to the carrier (<NUM>), and at a first side opposite to the second side, second connection means (<NUM>) for connecting the profile to the immobilisation mask, and wherein the first connection means (<NUM>, <NUM>) are provided, in a connected state, to engage corresponding connection means (<NUM>) of the carrier (<NUM>), wherein the profile (<NUM>) comprises a swivel arm (<NUM>) provided to cooperate with a swivel anchor point (<NUM>) provided to the carrier (<NUM>), wherein the swivel arm (<NUM>) and the swivel anchor point (<NUM>) being provided to cooperate such that when swivelling the swivel arm (<NUM>) around the swivel anchor point (<NUM>) towards the carrier (<NUM>), the first connection means (<NUM>) are guided to the connected state where they engage the corresponding connection means of the carrier (<NUM>), characterized in that the swivel arm (<NUM>) comprises a gripping part (<NUM>) provided to grip at least partly around the swivel anchor point (<NUM>).