FR2765487A1 - Adjustable inclined support for patient undergoing thoracic radiotherapy - Google Patents

Abstract

The support, designed for positioning and subsequent identical repositioning of a patient lying supine upon it, consists of an upper inclined panel (2) hinged to a base (3) and made with head-rest (8), dorsal (14) and buttocks (15) zones, an angle adjuster (5) and various accessories (23) to increase the patient's comfort. The dorsal zone of the panel can be adjusted in width to the right or left of its lengthwise axis by means of extensions (18), and in length by a wedge (16) for the buttocks. The support is made from a radio-transparent material such as carbon or polymethyl methacrylate manufactured under the name of 'Altuglas' (RTM), and its head rest, which is adjustable by means of strips of 'Velcro' (RTM), incorporates a thermally mouldable mask to protect the patient's face.

Description

MODULAR INCLINED PLAN FOR RADIOTHERAPY OF A PATIENT
INCLINED DORSAL DECUBITUS
The invention relates to a modular and scalable inclined plane for the iterative positioning of the thorax of a patient disposed in an inclined dorsal decubitus during radiotherapy sessions and more particularly when these must be reproduced identically several times.

 The inclined plane is intended to elevate the patient in order to bring him more comfort during the radiotherapy sessions while protecting his sternum, his lungs, his vessels and his heart, and to make radiation accessible.

 The inclined plane is also used to position the patient during radiation of the thorax, and / or the mediastinum or the chest. This positioning must be precise because bombardments of heavy particles are used for the treatment of well localized tumors; however, it is even more important to be able to reproduce the patient's position always identical during successive sessions to avoid having to repeat each time the necessarily precise adjustment of the irradiation source relative to the tumor. We know that a patient can be treated 2 to 3 times a week for periods that can range from 2 to 9 weeks.

 Finally, the inclined plane is particularly important in the treatment of breast tumors in that it makes it possible to perform tangential fields in different planes of space.

 Many devices are already known for positioning and immobilizing patients during a radiotherapy session. Generally the inclined planes available on the market include a tilting plate either by means of shims of different heights, or by more known means of racks relative to a base supporting the inclined plane and a more or less padded seat plate allowing the patient put yourself in an inclined dorsal decubitus position; fixed or snapped onto the inclined plate, various accessories allow the patient to maintain himself in a reproducible position, or ensure the maintenance or restraint of one of his members in correct positioning for radiological treatment.

Of course, the plate is made of a radio-transparent material so as not to disturb the irradiation. However, the mechanical requirements of these inclined planes make it necessary to strengthen the thickness of the material, which, due to their thickness, creates modifications in the radiation, in particular by diffraction; to reduce these harmful effects, it has been necessary to reduce the thicknesses and consequently to resort to clearly more solid materials such as carbon fiber. The disadvantages of this type of inclined planes are numerous
First of all, they are not very precise since they do not include any provision to adapt to the size of each patient, and this repeatedly. On the other hand, such plans, if we want to avoid excessive weight and significant risks of diffraction, will be made of relatively expensive materials which are, moreover, difficult to machine and have no ability to great modularity. However, such an apparatus must be light because it cannot be fixed on an X-ray table, and it must be constantly moved, put in place and removed many times a day to adapt to very different treatments both for their purpose only by their duration or by their more or less repetitive nature.

 On the other hand, we understand that it is necessary to design inclined planes capable of adapting to both children and adults while remaining as light as possible so that staff, often female, can effortlessly exaggerated, handle this type of material. It is now estimated that an inclined plane of this type should not exceed 8 kg.

 Naturally, such devices must, in breast tumors be designed to carry out tangential fields, and therefore the device should only hinder the radiation field as little as possible in order to avoid any diffraction as has been said. .

 In this regard and in accordance with the invention, there is provided a scalable modular inclined plane for the positioning and subsequent repositioning identical to the thorax of a patient in inclined dorsal decubitus, during a radiotherapy session, comprising at at least one tilting upper plate, articulated on a base successively comprising a headrest zone, a dorsal zone and a gluteal zone, angulation means with markings between said base and said plate, various accessories with markings for patient comfort , support, support and restraint of its members, remarkable in that the dorsal area of the plate can be adjusted in width to the left and / or right of its axis of longitudinal symmetry by extensions and in length by a wedge movable gluteus and in that the tray is predisposed to receive laterally to the left and / or right various support or support accessories which come to adapt p ar the same fixing means in place of one and / or the other of the lateral extensions.

 We understand all the important advantages of the inclined plane according to the invention and in particular the fact of being able to be adaptable to all morphologies since the plane can be adjusted in width and / or in length. On the other hand, one also understands all the advantage of the extensions which can be modular in width to allow to predispose the inclined plane according to the morphology of the patient, thus bringing him maximum comfort; it is in fact possible to give the subject a maximum width of support by removing only the parts of the support, liable to hinder the radiation during the treatment.

 In this respect and according to another characteristic of the invention, the width of the dorsal region of the tray is in the basic version narrowed with respect to the width of the headrest and the gluteal region, obtained by lateral cuts normally and advantageously symmetrical with respect to the longitudinal axis of the plate giving the dorsal area a general shape of I, particularly effective for allowing tangential fields in particular for the irradiation of the breast tumor.

 It is obvious that, incidentally, provision can be made in the inclined plane in accordance with the invention for extensions to exactly compensate for the lateral cuts on either side of the I.

Other characteristics and advantages will emerge more clearly from the description which will be given of an execution of a modular inclined plane in accordance with the invention, given below by way of nonlimiting example with reference to the appended drawings in which
FIG. 1 is a general perspective representation of the inclined plane in accordance with the invention showing some characteristic accessories and their adaptation to the inclined plane,
- Figure 2 is a sectional view along the line
II-II of FIG. 1 showing in particular some remarkable positions of the gluteal wedge according to the invention, as well as a view on a larger scale and in perspective torn away from the same wedge,
FIG. 3 is a rear half-view of the inclined plane in accordance with the preceding figure,
FIGS. 4 show on a larger scale some examples of typical accessories of the invention coming to be adapted on the inclined plane for example in place of one or the other of the lateral extensions (FIGS. 4a, b, c) or on the headrest area (Figure 4d).

 In accordance with FIG. 1, the inclined plane 1 in accordance with the invention comprises a tilting plate 2 on which the patient, who is subjected to a radiotherapy session of the thorax, will be installed in the supine position.

The plate 2 is articulated to a base 3 ensuring the inclined plane its horizontal stability.

 According to a preferred variant of the invention, the inclination of the plate 2 relative to the base 3 along a hinge 4 (Figure 2) is obtained by at least one stand 5 articulated at 6 (Figure 2) to the plate 2 by its upper end and locked on a movable stop 7 embedded in holes arranged on the rear part of the base 3 so that the resulting inclination of the plate 2 relative to the base 3 is adjustable from zero (horizontal plane) to 30 corresponding to a classic inclination in radiotherapy. Of course and preferably, the stand 5 can be split in order to increase the general stability of the plane when it is tilted. In this case, two movable stops 7 are provided on either side of the base 3.

According to a first essential characteristic of the invention, the plate 2 comprises three well-differentiated zones
- A headrest area 8 arranged at the raised end of the plane 1; in this headrest zone 8 are advantageously provided recesses 9 capable of positioning in the plane of the plate 2 a headrest 10 previously mounted on a support part 11 forming a longitudinal slide for the headrest 10 whose longitudinal positioning is obtained by means of two non-slip strips 12 (for example of the type sold under the trademark VELCRO); the support piece 11 comprises two pins (not shown in the figures) which are fitted into the holes 9 ensuring correct positioning and above all the subsequent repositioning of the headrest 10.

In the headrest area 8 are also provided other through cuts elsewhere; an upper cutout 13 to ensure good grip of the plate 2 when it is tilted and later when it is desired to move all of the equipment; in the latter case another handle is provided in the lower part (hinge side 4 of the inclined plane); of course, the hand passages provided in the plate 2 are found in total correspondence on the base 3 so as to ensure total grip of the assembly, in particular during the transport of the inclined plane 1.

- a dorsal zone 14 having in a preferred variant of the invention a general shape of I, that is to say a narrowing in width with respect to the headrest zone 8 mentioned previously and with respect to the gluteal region 15 detailed below ; this narrowing in width, which is not, moreover, essential for the proper functioning of the inclined plane 1, nevertheless constitutes an important advantage when it is desired to perform tangential fields in particular in the irradiation of breast tumors,
- a gluteal region 15 of width advantageously identical to the width of the headrest zone 8, is constituted, according to an essential characteristic of the invention, by a gluteal wedge 16 collaborating in a manner which will be detailed below with the tray 2, either directly or indirectly by means of an elongated piece 17, providing a capacity for extending the length of the plate 2, giving the assembly a range of use for treating subjects of very different size, for example, adults and children.

 According to another fundamental characteristic of the inclined plane 1 according to the invention, provision is made to be able to have on the left and / or right of the dorsal zone 14 of the plate 2 an extension 18 capable according to a first variant of filling the narrowing in width of the dorsal zone 14 then giving it a rectangular surface or according to another variant of enlarging the surface of the same dorsal zone 14 to increase for example the comfort of the patient, in particular during its installation on the plate 2.

 According to another essential characteristic of the invention, the means for fixing each extension 18 to the plate 2 are obtained by two recesses 19 provided in the thickness of the plate 2, and preferably arranged at the top and bottom of the back region 14 ; these recesses 19 open onto the lateral edge 20 of the plate 2 to come to cooperate with two correspondingly shaped tongues 21 which snap into said recesses 19 so that once in place, said tongues 21 cannot come out in a movement lateral withdrawal or vertical support towards the base 3.

 Each recess 19 is also obtained by machining a counterbore on the upper face of the plate 2; preferably, the machining of the counterbore will be operated from the lateral field 20 of the plate 2 in an advantageous form, although not necessary, of square section consequently determining three stops 191,192,193 between the upper surface of the plate 2 and the vertical drops d 'machining; the bottom of the recess 19 after machining is parallel to the upper face of the plate 2 and the innermost stop 192 is parallel to the longitudinal axis L of the plate 2 gives rise to a notch 194 extending the counterbore in the thickness even of the plate 2 over a sufficient distance to embed the end of the corresponding shaped tab 21 therein.

Of course, each tongue 21 is for this purpose provided on its face which normally comes into contact with the notch 194 with a longitudinal projection 211, capable of fitting very exactly into the notch 194; on the other hand, there is provided in the center of each recess 19 a stud 195 emerging at a height a little less than the machining height of the recess 19 capable of cooperating with a through bore 212 provided in correspondence on the shaped tongues 21.

 In this way, when it is desired to mount, for example, an extension 18 on the left side of the plate 2 of the inclined plane 1, it suffices to come to embed the two tongues 21 equipping, on either side the extension 18, in the recesses 19 on the left and at the upper and lower ends of the dorsal part 14, taking care to tilt the extension 18 slightly upwards in order to first embed the two projections 211 at the ends of the tongues 21 in the notches 194 corresponding recesses 19; by a slight downward movement of rotation, the pins 195 will progressively become embedded in the two bores 212 of the tongues 21 which are then in total coincidence with the two recesses 19 of the plate 2; at this time, it is no longer possible for the extension 18 to be removed from the housings by a lateral movement parallel to the surface of the plate. Indeed, the play of the nipples inside the bores prohibits any withdrawal; in the same way, any vertical pressure on the extension 18 in the direction of the base 3 is immediately balanced by the play of the projections 211 in the notches 195 here playing fully the classic role of a tenon and a mortise.

 On the other hand, to release the extension 18, it suffices to reverse it by a slight vertical rotation and an oblique lateral withdrawal to release the extension 18 and replace it for example with a plug 22 to erase the hollows due to the embedding 19 .

 We now understand all the interest of this mode of connection by embedding advantageously distributed to the four vertices of the dorsal zone 14 of the plate 2. In fact, and in accordance with a complementary arrangement of the invention, it is particularly advantageous to use each recess for fixing various accessories very generally used in addition to the inclined plane 1 during a radiotherapy session. There is, for example, shown in Figure 1, an accessory 23 for the shoulder restraint which is in position to be embedded in the upper left of the inclined plane in place of the extension 18 shown on the same side in figure 1.

 In this regard and in accordance with FIG. 4a on which the shoulder restraint accessory 23 is shown on a larger scale, it is clear that this accessory can evolve towards other accessories of the same type insofar as the thermoformable part 24 can be of any desired shape since it suffices to apply a thermoformable plate previously heated on the limb of the patient to produce a particular compression element corresponding exactly to the morphology of the patient. This compression piece 24 comprising at one of its ends holes 25 which cooperate with a key device 26 or equivalent, securing the compression piece 24 to the support of the accessory 23; the latter in reality comprising a tongue 21 provided terminally with a projection 211 and a bore 212 allowing mounting quite similar to that which has been described for the extension elements 18.

 With reference to FIGS. 4b and 4c, it is easy to understand that these are specific examples and in no way limitative of accessories capable of being mounted in the same way as the shoulder compression accessory 23 which has just been mentioned. instead of the extensions 18 in the recesses 19 of the plate 2. In FIG. 4b it is a holding handle 27 provided with its tongue 21 and a vertical rod 28 serving as support for the patient. Of course, this handle 28 can be adjusted in any desired direction by a simple groove 29 having marks 30 along which the handle 28 can move parallel to itself and be fixed by a simple set of screws / bolts.

 FIG. 4c shows a complex accessory comprising a first base of the same type as the accessory 27 in FIG. 4b where the handle 28 has been replaced by a handle of different shape 31 constituting for example an armrest support, the assembly allowing positioning with X and Y location of the handle 31; it will be observed that the two grooves 29 and 32 can be held together by the same screwing 33 in any position, that is to say perpendicular to each other or at any angle as desired, in order to adapt the accessories as closely as possible. maintaining or supporting the patient's morphology.

 Finally and in accordance with a particular arrangement of the extension 18, the latter comprises at least one longitudinal groove 34 which is advantageously millimetered, although not necessarily, disposed parallel to the longitudinal axis L of the plate 2 on which accessories for holding the device slide. support or restraint; like what has been described with reference to FIGS. 4b or 4c, a rapid clamping means is here again conventionally used to fasten the accessory 28,31 to the extension 18 at the desired location. According to a variation preferred of the invention, provision is made to have grooves 34 on each extension 18 extending practically in line with the tongues 21 and parallel to the longitudinal axis L of the plate, in accordance with the representation of FIG. 1.

 The inclination a of the plate 2 relative to the base 3 can be adjusted as follows with reference to the diagram which is shown in FIG. 2.

 As has been said before, the inclination a of the plate 2 is provided by at least one crutch 5, and preferably two, as shown in the half-view of FIG. 3 corresponding to a right view of FIG. 2 that is to say a rear view of the inclined plane in maximum position. The stand 5 articulated to the lower part of the plate 2 by a hinge 6 disposed substantially at right and at the bottom of the headrest zone 8 allowing its rotation in a plane parallel to the plane of symmetry S of the plate 2 from a zero position, - that is to say stand 5 against plate 2 -, its end 51 being directed towards the upper end 201 of plate 2 to a maximum position usually corresponding to a = 30 where the stand 5 comes to bear on a movable stop 7 , consisting of a cylindrical axis which can be moved on the rear part 301 of the base 3 from a position A on the right of FIG. 2 to a position B of the same FIG. 2. The displacement of the stop 7 forwards 302 of the base 3, that is to say from A to B, amounts to increasing the value a of the inclination of the plate 2.

 According to a particularly advantageous variant allowing fine adjustment, for example from degree to degree, of the inclination a of the plate 2, it is provided that the crutches 5 normally arranged symmetrically with respect to the plane of symmetry S of the plate 2, have a width sufficient to cooperate with two rod stops 7 which can be embedded in holes arranged in parallel spans 35,36,37 on the base 3 so that their center is offset not only longitudinally but also transversely; for this purpose and in accordance with FIGS. 2 and 3, a first series of holes 35 will be provided for each stand 5, arranged regularly from a position A to a position B in FIG. 2; all the centers are here arranged on the same line parallel to the axis of symmetry of the base 3 it is clear that the spacing of a hole relative to the next hole is at least equal to the diameter of the rod forming the stop 7; this is why, in order to obtain an intermediate adjustment, it is necessary to provide several spans 35, 36, 37 arranged parallel to one another and sufficiently offset so that two neighboring holes can be offset in length without overlapping. In order to perform an efficient wedging, the previous device will be completed by providing at the end 51 of the stand (s) 5, notches 52 of semi-cylindrical shape in a number equivalent to the number of spans of holes 35,36,37 for complete the blocking in position of each stand against each stop 7 whatever its arrangement on said spans. It goes without saying that each of the holes, regardless of their belonging to the spans 35, 36, 37, will be correctly located so as to be later found and thus reproduce identically a particular inclination at each radiotherapy session.

 According to yet another configuration of the inclined plane 1, the support plate 11 carrying the headrest wedge 10 can be replaced by a frame 38 as shown in FIG. 4 ~. This frame 38 fits over the headrest area 8 of the tray 2 in recesses 13 which can also be used as handle passages for transporting and handling the inclined plane 1. This frame 38 positioned in its recesses 13 is provided as the 'accessory 23 of shoulder compression of two side keys 39.40 coming to counter an ENT mask 41, thermoformed around the head of the client for a perfect compression during consecutive radiotherapy sessions of the face. Naturally, the thermoformable ENT mask 41 as well as the thermoformable parts 24 intended for the shoulder compression for example, are made of radiolucent materials.

 Finally, according to a last essential characteristic of the invention, provision is made to have at the lower end 202 of the plate 2 close to the articulation of the latter to the base 3, a gluteal wedge 16 capable of extending the inclined plane 1 in length. in order to adapt it to the size of the patient. With reference to FIGS. 1 and 2 and according to a particularly advantageous variant of the invention, the gluteal wedge 16 consists of a hollow semi-cylindrical part, obtained for example from the diametrical slitting of a hollow cylinder, taken in a radiolucent material, for example analogous to that of the other parts constituting the inclined plane 1. It is understandable that this hollow semi-cylindrical shape of the wedge 16 is particularly suitable for forming the gluteal setting of the patient disposed in inclined dorsal decubitus; the length of the wedge 16 is in principle close to the length of the gluteal region 15 of the plate 2, moreover comprising at least one transverse groove 203 advantageously extending over the central third of the extreme part 202 of said plate 2. On one of the longitudinal edges of the gluteal wedge 16 is extended by a projection 161 in the circular movement of the wedge 16 over a sufficient distance to be embedded in the groove 203 or the set of transverse grooves 203 of the plate 2 which are for this purpose offset parallel to each other by a distance capable of allowing an adjustment of the length of the dorsal zone 14 of the plate 2.

 According to a particular and unexpected characteristic resulting directly from the shape of the gluteal wedge 16, it is planned to use the latter, sometimes in one direction, sometimes in the other; in fact, due to its cylindrical shape and the arrangement of the projection 161, it is possible to engage the projection 161 in the same groove 203 of the plate 2 to maintain the wedge 16, its free stop being either turned towards the plate 2, or , on the contrary by a rotation in the plane of the plate, towards the outside of said plate thus creating two geographic adjustment positions for the same groove 203; it will also be noted that the projection 161 which actually results from the extension of the material forming the wedge 16 is therefore completely symmetrical, which makes it capable of cooperating in both directions with a groove 203, for its attachment to the plate 2 .

 To obtain an effective location of the length suitable for such or such patient, it suffices to wear on one of the two edges of the wedge 16 a mark (A in FIG. 1) allowing in combination with the number assigned to such groove 203, to code the length suitable for such or such patient during such or such session of radiotherapy.

 Of course, the system can be further improved by adding if necessary a generally flat intermediate extension 17 which can be inserted, as shown in FIGS. 1 and 2, between the last groove 203 provided on the gluteal region 15 of the plate 2 and the gluteal wedge 16 to extend the dorsal region 14 in length; of course, grooves identical 171 to the grooves 203 of the plate 2 and arranged in their extension, are provided on said intermediate extension 17 to allow complementary movements of the wedge 16 which can naturally, here again, be arranged at the place or at the upside down by rotation on itself in the horizontal plane as said above; it is obvious that the part 17 will be shaped in its part coming to dock the inclined plane 1, to constitute a natural extension of the plate 2 while avoiding any relief or any difference in height between said plate and said extension 17; for its attachment to the plate 2, it is therefore planned to give its end portion a slight inclination and to provide the docking area of the part with a hook-shaped protrusion which quite naturally fits into the last groove 203 of tray 2.

In Figure 2 there are shown several characteristic arrangements of the wedge 16
The schematic representations of the wedge 16 on the right of FIG. 2 correspond to an adjustment using the wedge 16 in the same direction but in two successive grooves 203 of the plate 2. The third position of the wedge corresponds to an inversion of the latter, the protrusion being in the first groove of the intermediate piece extending the plate 2, the wedge here being reversed with respect to the previous representation.

 Finally and to the left of the drawing, the same wedge 16 is shown, disposed in the same groove 171 of the intermediate piece 17. This example clearly shows that by simple inversion (indicated in FIG. 2 by the reference pffi does indeed provide an offset of the part operating the wedge 16 when only one groove is used, so this device can be generalized by providing as many grooves on the end of the plate 2 and / or on the elongated part 17 lengthening the latter, as those skilled in the art will know. perfectly distribute in order to provide a length adjustment of the tray 2 capable of accommodating any size of patient.

 The inclined plane 1 according to the invention can be entirely made from a radiolucent synthetic material of the type of a polymethyl methacrylate or even using materials such as carbon or a combination of the two for example.

As regards materials such as polymethyl methacrylate (known under the trade name ALTUGLAS), it is obvious that the thicknesses which it is advisable to provide for guaranteeing on the inclined plane a resistance and a rigidity in conformity with the standards and in any case with the destination of the product, are necessarily more important than manufacturing carried out for example in carbon. This is the reason why the inclined plane according to the invention has recesses 42 in the plate 2 as shown in dotted lines in FIG. 1.

Under these conditions, it is clear that the inclined plane produced in ALTUGLAS 8 is particularly efficient, both because of the weight comparable to carbon constructions and mainly because of the cost, which is much lower.

Finally, the inclined plane according to the invention is remarkable in that it supports without creating an artifact, the computed tomography scanner and the magnetic radiation.
MRI.

Claims (15)

 1 - Modular and scalable inclined plane for positioning and subsequent repositioning identical to the thorax of a patient in inclined dorsal decubitus, during a radiotherapy session, comprising at least one tilting upper plate (2) articulated to a base (3) successively comprising a head rest zone (8), a dorsal zone (14) and a gluteal zone (15), angulation means (5,6,7) with markings between said base (3) and said tray (2), various accessories (23,27,31,38) with markings for patient comfort, support, support and restraint of its members, characterized in that the dorsal area (14) of the tray can be adjusted in width to the left and / or right of its longitudinal axis of symmetry (L) by extensions (18) and in length by a movable gluteal wedge (16) and in that the plate (2) is predisposed to receive laterally on the left and / or on the right various accessories (23,27) for support or support which are adapted by the same fixing means (19,21) in place of one and / or the other of the lateral extensions (18).  2 - Inclined plane according to the preceding claim characterized in that the width of the dorsal area (14) of the plate (2) is narrowed relative to the width of the area of the headrest (8) and the gluteal area (15 ), thanks to advantageously symmetrical lateral cutouts with respect to the longitudinal axis (L) of the plate (2), giving the dorsal area (14) a general shape of I, in particular making it possible to perform tangential fields.  3 - Inclined plane according to the preceding claim characterized in that the width of the extensions (18) precisely compensates for the lateral cuts.  4 - Inclined plane according to any one of the preceding claims, characterized in that the extensions (18) comprise at least one millimeter longitudinal groove (34) forming a conventional marking system on which slide support or support accessories (27 ) or compression (23), a rapid clamping means such as a screw, secures the desired location the accessory (23,27) to the extension (18).  5 - Inclined plane according to the preceding claim characterized in that various accessories such as in particular an arm support (31) comprising a sole provided with a millimeter groove (32) capable of cooperating with the longitudinal groove of an extension either by extending it, either by crossing it at any identifiable angle, a single rapid clamping means (33) counterpressing the accessory (31) to the extension (18) at the desired location.  6 - Inclined plane according to any one of the preceding claims, characterized in that the means for fixing each extension (18) to the plate (2) are obtained by two recesses (19) provided in the thickness of the plate preferably arranged in top and bottom of the dorsal zone (14) and opening onto the lateral edge of the plate (2) to come to cooperate with two correspondingly shaped tabs (21) which snap into said recesses so that once in place , the tabs (21) cannot come out in a lateral movement of withdrawal or vertical support towards the base (3).  7 - Inclined plane according to the preceding claim, characterized in that each embedding (19) is obtained by a counterbore made on the upper face of the plate (2) and parallel to this, of advantageously square section opening onto the edge 20 of the plate, consequently determining three stops (191,192,193) with the same plate (2), the innermost stop (192) and parallel to the axis of the plate L, gives rise to a notch (194) extending the counterbore in the thickness of the plate (2) over a distance sufficient to embed the end of the tongue of corresponding shape (21) which, for this purpose, is provided on its face coming into contact with the notch (194) with a longitudinal projection (211) which fits exactly there, preventing any vertical movement towards the base (3), a stud (195) being arranged in the center of the counterbore to cooperate with a bore (212) provided in correspondence on the tongue (21) when 'she comes in coincidence idence with recess (19) to block any lateral withdrawal parallel to the plate (2).  8 - Inclined plane according to any one of the preceding claims, characterized in that the plate (2) which is articulated to the base (3) by a hinge element (4) at the end of the gluteal region (15), is adjustable angularly (a) by means of at least one crutch (5), itself articulated to the lower part of the plate (2) by a hinge (6) disposed substantially at right and at the bottom of the headrest area (8) allowing its rotation in a plane parallel to the plane of symmetry S of the plate (2) from a zero position, that is to say the stand (5) against the plate (2) its end (51) being directed towards the 'upper end (201) of the plate (2), to a maximum position usually corresponding to a = 30 "tilt where the stand (5) comes to rest on a movable stop (7) suitably embedded on the rear part of the base (3), the displacement of the stop (7) forwards (302), that is to say towards the hinge (6) of the stand (5), increasing the value of the inclination (a) and vice versa.  9 - Inclined plane according to the preceding claim characterized in that two crutches (5) are arranged symmetrically with respect to the plane of symmetry (S) of the plate (2), their width being sufficient to come to cooperate with two rod stops (7) embedded in holes marked and arranged on the left and right on the base (3), in parallel spans (35,36,37) so that their center, offset not only longitudinally but also transversely, provides a fine adjustment of inclination (a), the wide end (51) of each stand (5) comprising notches (52) capable of coinciding with each rod stop (7) whatever its place on a span (35,36,37) .  10 - Inclined plane according to any one of the preceding claims, characterized in that the gluteal wedge (16) consists of a hollow semi-cylindrical piece of length close to the width of the gluteal region (15) of the plate (2) , comprising on the third approximately of one of its longitudinal edges a projection (161) extending from said edge according to the circular movement of the wedge (16), over a distance sufficient to fit into a set of transverse grooves (203) of the plate (2) provided for this purpose and offset parallel to each other by a distance allowing the length of the dorsal zone (14) of the plate (2) to be adjusted, the inversion of the block (16) by rotation on itself in the plane of the plate (2), that is to say that the other stop, not having the projection (161), is sometimes turned upwards sometimes turned downwards for a embedding of the projection (161) in the same groove (203), thus providing if two possible length adjustments per transverse groove (203).  11 - Inclined plane according to the preceding claim characterized in that an intermediate extension (17) generally planar is interposed between the last groove (203) on the gluteal region (15) of the plate (2) and the gluteal wedge (16) to extend in length the dorsal zone (14), grooves identical (171) to those of the plate and arranged in their extension being provided on the intermediate extension (17) for the displacement of the wedge (16) at the place or at the 'upside down, the attachment of said extension being obtained by a slight terminal inclination to dock the plate (2) without unevenness thanks to a projection forming a hook which fits into the last groove (203) of the plate (2).  12 - Inclined plane according to any one of the preceding claims, characterized in that plugs (22) for obscuring the embedments (19) and various accessories for restraining the shoulders (23), handles (27), armrest supports (31 ), are configured to fit on one or the other of the recesses (19) of the plate (2) for the extensions and according to the same mounting means (211,194,195,212).  13 - Inclined plane according to any one of claims 1 to 11 characterized in that in the headrest area (8) of the plate (2), at least one and preferably two circular counterbores (9) are provided to receive a support plate (11) forming a slide with millimeter marks carrying at least one non-slip strip (12) on its upper face to limit the longitudinal movement of a headrest (10).  14 - Inclined plane according to any one of claims 1 to 11 characterized in that on the headrest area (8) of the plate (2), a frame (38) is fitted which fits into recesses (13) also providing handle passages for transport to receive and maintain a thermoformable ENT mask (39) conforming to the facial morphology of the patient.  15 - Inclined plane according to any one of the preceding claims, characterized in that it is made of radiolucent material such as carbon and / or polymethyl methacrylate, recesses (42) on the inner face of the components of the inclined plane (1 ) being intended to reduce mass while retaining the necessary rigidity.