Patent Description:
The present invention relates to an immobilization system, for persons whose bodies or body parts are required to be retained in a particular position or attitude. In particular, a need exists for a simple and easy to use immobilization system that allows repetitive patient positioning with a high degree of accurate repeatability across time, for example, wherein radiation treatments must be directed at a certain anatomical point across different times. Such precise positioning of the head and neck area, as might be required for radiotherapy of that region, is particularly problematic due to difficulty in immobilizing the area, while maintaining the patient's ability to breath, and with a reasonable degree of patient comfort.

The use of low-temperature thermoplastics for patient positioning is well-known and dates back to splinting devices invented in the <NUM>'s (Larson, <CIT>). Splints are heated, usually in hot water, to a temperature of about <NUM>° F, whereupon they become pliable and can be molded by hand directly on the patient's body part. These devices are well known in the field of occupational therapy and include splints with padding or cushioning material laminated to the thermoplastic to provide comfort against the patient's skin.

Plastic materials have been successfully used in the past for making splints, casts and the like. <CIT>describes the use of thermoplastic polydienes like transpolyisoprene and transpolychloroprene, which melt between <NUM>° F (<NUM>° Celsius) and <NUM>° F (<NUM>° Celsius), and which harden by crystallization at about <NUM>° F (<NUM>° Celsius), such that these plastics can be formed for use as a body supporting member. Poly (epsilon-caprolactone) (PCL) has also been found to be an excellent splint or cast material (<CIT>). Polyurethanes based on prepolymers of poly (epsilon-caprolactone) have also been used (<CIT>).

As described in earlier patents, the polymers can be heated in hot water at a temperature usually exceeding <NUM>° F (<NUM>° Celsius) and up to about <NUM>° F (<NUM>° Celsius), whereby they become soft, self-adherent and sufficiently pliable to be deformed and shaped as a cast, splint or protective device. When allowed to cool in air to about <NUM>° F (<NUM>° Celsius), the materials will remain pliable, moldable and cohesive for a period of several minutes, exhibiting a hysteresis, as described in <CIT>. During this time the splint, cast or device can be molded directly to the patient without discomfort, and the shaped plastic sets hard by crystallization to assume a rigid form as a useful body support member or protective device.

In the field of radiation therapy, precise patient positioning is essential for treatment accuracy. An additional requirement is that patients be precisely re-positioned for repeated radiation treatments. Repositioning to an accuracy within millimeters, or even less, is generally desirable. This requires the positioning to be reproduced accurately each time the patient undergoes a treatment. Low-temperature thermoplastic masks in conjunction with other positioning methods are often used for such positioning. Masks are heated to a temperature of about <NUM>° F (<NUM>° C), and formed directly on to the patient's head or other body part. The masks may be affixed to a table supporting the patient and cooled to form a firm mask holding the patient steady for treatment. After treatment, the mask may be removed. When the patient returns for the next treatment, the mask is releasably reattached, holding the patient in a reproduced position for treatment.

Various masks are used for radiation therapy treatments, including stereotactic head masks holding the top and bottom of the patient's head (Vilsmeier, <CIT>). In the field of moldable head and neck masks, a particular problem is holding the mask, when heated, to conformance around the patient's facial and head area for the short period of time required for the mask to cool and assume a stable shape. A tension exists between holding the mask accurately to conform to these features, while maintaining a reasonable degree of patient comfort.

Another goal of patient immobilization systems for radiation therapies is the avoidance of as much mass surrounding the patient's body as possible, as the mass tends to attenuate a radiotherapy beam. Therefore, the avoidance of unnecessary bulk in the immobilization system confers an advantage over more bulky systems. However, at the same time, systems have found it difficult to achieve adequate stabilization without using relatively high-mass immobilization devices.

<CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> further disclose relevant information.

The disclosed invention relates to methods to for making an immobilization system. Especially for those systems intended for use on the human head and neck area, there may be a retention mask, molded to the face or head contours of the patient, holding the desired body parts firmly to the formable support. This allows for high reproducibility in positioning.

The system includes a bite block immobilization system having a bite block with a dental interface releasably engageable with a plurality of teeth of a patient. The dental interface may be supplied with the system, or may be added at the time of use by a user. The dental interface releasably engages the teeth of a patient and allows very highly accurate repositioning during multiple procedures. In some embodiments, the bite block may have an integral bite block airway passage, allowing a patient to have unobstructed breathing both during molding of the retention mask and during subsequent use of the system.

In the invention, the bite block releasably cooperates at a tongue diverter receiver with a tongue diverter, that may, by way of example only and not limitation, be used to divert the tongue away from a therapeutic radiation beam. Unclaimed steps for employing the system are further described below.

The invention is defined by appended independent claim <NUM>, a preferred embodiment is defined by appended dependent claim <NUM>.

Without limiting the scope of the as disclosed herein and referring now to the drawings and figures:.

These illustrations are provided to assist in the understanding of the exemplary embodiments of the method of forming an immobilization system having a bite block stabilization feature and materials related thereto described in more detail below and should not be construed as unduly limiting the specification. In particular, the relative spacing, positioning, sizing and dimensions of the various elements illustrated in the drawings may not be drawn to scale and may have been exaggerated, reduced or otherwise modified for the purpose of improved clarity. Those of ordinary skill in the art will also appreciate that a range of alternative configurations have been omitted simply to improve the clarity and reduce the number of drawings.

What is claimed then, as seen in <FIG>-<NUM>, is an immobilization system (<NUM>) for highly reproducible patient positioning. In the invention, seen well in <FIG>, <FIG>, <FIG> and <FIG>, the system (<NUM>) may include a bite block immobilization system (<NUM>) having a bite block (<NUM>) having a dental interface (<NUM>) releasably engageable with a plurality of teeth of a patient, and a bite block-retention mask interface (<NUM>) releasably engageable with a retention mask (<NUM>). The dental interface (<NUM>) may include a moldable dental impression putty in some embodiments, while in others, may include a moldable thermoplastic ring. The dental interface may be supplied with the system (<NUM>), or may be added at the time of use by a user. The dental interface (<NUM>) releasably engages the teeth of a patient and allows very highly accurate repositioning during multiple procedures.

The retention mask (<NUM>), seen well in <FIG>, is releasably and memorably moldable to the contours of a face of the patient. According to the invention, seen well in <FIG> and <FIG>, has a retainer means (<NUM>) cooperating with the bite block (<NUM>) and the retention mask (<NUM>) to releasably secure the bite block (<NUM>) and the retention mask (<NUM>). As would be known to one skilled in the art, the retention mask (<NUM>) may be secured to a backing board by any feasible releasable securing means for greater stability and reproducibility.

According to the invention, seen well in <FIG> and <FIG>, the retention mask (<NUM>) has a plurality of mask fenestrations (<NUM>). In other embodiments, seen well in <FIG>, the bite block (<NUM>) may have an integral bite block airway passage (<NUM>). This allows a patient to have unobstructed breathing both during molding of the retention mask (<NUM>) and during subsequent use of the system (<NUM>).

In the invention, the bite block (<NUM>), seen well in <FIG> and <NUM>, releasably cooperates at a tongue diverter receiver (<NUM>) with a tongue diverter (<NUM>), and, as seen well in <FIG>, the tongue diverter receiver (<NUM>) is releasably engageable with a tongue diverter retainer (<NUM>) to releasably engage the tongue diverter (<NUM>) and the bite block (<NUM>).

The tongue diverter (<NUM>) may further include as seen well in <FIG>, a diverter airway (<NUM>) and includes, as seen well in <FIG>, a lingual interface (<NUM>). The lingual interface (<NUM>), as would be known by one skilled in the art, diverts the tongue of a patient in a lateral, cephalic, or caudal direction, or in some combination of multiple directions.

In the invention, seen by way of example and not limitation only in <FIG>, the retainer means (<NUM>) is releasably engageable with bite block (<NUM>) and the retention mask (<NUM>) by means of an interface retainer (<NUM>) releasable securing the bite block (<NUM>) to the retention mask (<NUM>). Such an interface retainer (<NUM>) is a humanly releasable digital manipulator (<NUM>). In the invention, seen well in FIGS. <NUM>-<NUM>, a tongue diverter removal tool (<NUM>) is releasably engageable with the tongue diverter receiver (<NUM>) to releasably disengage the tongue diverter (<NUM>) and the bite block (<NUM>).

In another series of embodiments, a bite block immobilization system (<NUM>) may include a bite block (<NUM>) having an integral bite block airway passage (<NUM>), and a dental interface (<NUM>) releasably engageable with a plurality of teeth of a patient. The bite block (<NUM>) may be releasably cooperating at a tongue diverter receiver (<NUM>) with a tongue diverter (<NUM>) having a lingual interface (<NUM>) and a diverter airway (<NUM>). Such a tongue diverter receiver (<NUM>) may be releasably engageable with a tongue diverter retainer (<NUM>) to releasably engage the tongue diverter (<NUM>) and the bite block (<NUM>). Such embodiments may also include a bite block-retention mask interface (<NUM>) releasably engageable with a retention mask (<NUM>), and such a retention mask (<NUM>) may be being releasably and memorably moldable to the contours of a face of the patient. Further, there may be a retainer means (<NUM>) cooperating with the bite block (<NUM>) and the retention mask (<NUM>) to releasably secure the bite block (<NUM>) and the retention mask (<NUM>).

In the invention, the tongue diverter (<NUM>) further includes a lingual interface (<NUM>) that diverts the tongue of a patient in a lateral, cephalic, or caudal direction, or allow a diversion in multiple axes of direction. In other embodiments, the retainer means (<NUM>) releasably engageable with a bite block (<NUM>) and the retention mask (<NUM>) by means of an interface retainer (<NUM>) releasable securing the bite block (<NUM>) to the retention mask (<NUM>), and the interface retainer (<NUM>) is a humanly releasable digital manipulator (<NUM>). This obviates the need for a user to maintain pressure over the retention mask (<NUM>) while the retention mask (<NUM>) is converted from a more flexible, to a less flexible, state, most commonly by allowing the retention mask (<NUM>) to thermally cool.

One skilled in the art would recognize the most optimal methods of using the immobilization system. Steps for use might include; placing a bite block (<NUM>) between the maxilla and mandible of a human patient, and then placing a thermally moldable retention mask (<NUM>), in a moldable state, over at least a portion of the face of the human patient. Next, a user might secure the retention mask (<NUM>) to the bite-block (<NUM>) with a releasably engageable retainer means (<NUM>). Lastly, a user might observe or facilitate the conversion of the retention mask (<NUM>) to a fixed state, which could occur by any known method of converting the retention mask (<NUM>) from a flexible to a more rigid state, such as thermal hardening, and then, disengaging the releasably engageable retainer means (<NUM>).

Claim 1:
A bite block immobilization system (<NUM>) comprising:
a bite block (<NUM>) having a dental interface (<NUM>) releasably engageable with a plurality of teeth of a patient, and a bite block-retention mask interface (<NUM>) releasably engageable with a retention mask (<NUM>);
the retention mask (<NUM>) being releasably and memorably moldable to the contours of a face of the patient, so that the retention mask (<NUM>) converts from a flexible to a more rigid state, such as by thermal hardening and
a retainer means (<NUM>) cooperating with the bite block (<NUM>) and the retention mask (<NUM>) to releasably secure the bite block (<NUM>) and the retention mask (<NUM>), wherein the retention mask (<NUM>) has a plurality of mask fenestrations (<NUM>), further wherein the bite block (<NUM>) releasably cooperates at a tongue diverter receiver (<NUM>) with a tongue diverter (<NUM>), wherein
- the dental interface (<NUM>) further comprises a dental impression putty or comprises a moldable thermoplastic ring, and wherein
- the retainer means (<NUM>) is releasably engageable with the bite block (<NUM>) and the retention mask (<NUM>) by means of an interface retainer (<NUM>) releasable securing the bite block (<NUM>) to the retention mask (<NUM>), wherein the interface retainer (<NUM>) is a humanly releasable digital manipulator (<NUM>), and wherein
- wherein a tongue diverter receiver (<NUM>) is releasably engageable with a tongue diverter retainer (<NUM>) to releasably engage the tongue diverter (<NUM>) and the bite block (<NUM>), and further wherein
- the tongue diverter (<NUM>) further comprises a lingual interface (<NUM>), wherein the lingual interface (<NUM>) adjustably diverts the tongue of a patient in a direction selected from a lateral, cephalic, caudal, and a combination of such directions, relative to the patient, and further wherein
- a tongue diverter removal tool (<NUM>) is releasably engageable with the tongue diverter receiver (<NUM>) to releasably disengage the tongue diverter (<NUM>) and the bite block (<NUM>.