Head holder for brain tomography

A head support assembly for immobilizing the head of a supine patient during brain tomography includes a mounting panel including mounting straps for securing the assembly to the patient support table of an imaging apparatus. A head frame assembly extends from one end of the panel and includes a pair of head frame elements having upstanding leg portions and horizontal head clamping portions. An adjustment screw connects the free ends of the head frame elements to permit the clamping of a patient's head therebetween. A head sling is suspended between the head clamping portions, being adjustably attached thereto by means of hook and loop fasteners. Forehead and chin restraining straps are also adjustably secured by means of hook and loop fasteners to the head frame elements. An optional neck support strap may also be attached to the head frame elements by means of hook and loop fasteners. The entire assembly is made of a non-metallic, imagable material, preferably a high strength composite, and provides a rigid immobilization of the head in a compact construction which permits close proximity of the camera to the patient's head for nuclear medicine imaging.

BACKGROUND OF THE INVENTION 
During tomographic imaging of the brain, it is essential that the patient's 
head be held motionless in an optimal position throughout the procedure. 
Since an imaging session may require the head to be immobilized for an 
hour or more, the comfort of the patient is an important factor in 
achieving a successful examination. 
Prior devices for supporting the head during tomographic imaging have 
typically comprised a trough or dish resting on or extending from a panel 
or tray on the examination table on which the patient is supported in a 
supine position. Because heads vary considerably in both size and shape, 
the trough or dish usually must be provided with a complement of foam 
pads, which are wedged under and around the head to achieve a head 
position which is optimal for the examination. The pads also serve to 
prevent head motion and provide some measure of comfort to the patient. 
The selection and placement of the pads by the technician can be a time 
consuming trial and error process which, while usually effective in 
obtaining the desired head position, is not always effective in 
immobilizing the head or providing comfortable support for the patient. 
The principal shortcoming of previous devices is the reliance on padding 
for head positioning and restraint. Due to its resilient nature, the 
padding can allow some head displacement if the patient should twitch, 
especially if it is not packed tightly enough between the head and head 
support structure. Since any head movement can blur the image produced, 
repetition of the procedure may be necessary in some cases. 
A further problem with the use of selective padding to position the head is 
the difficulty in determining whether the comfort level established 
initially for the patient will be adequate over the lengthy course of the 
examination. It may turn out, particularly for patients with spinal 
injuries, that what seemed comfortable at the beginning of the procedure 
becomes unbearably painful before its completion, necessitating the 
interruption of the procedure. 
In addition to the described problems of inadequate restraint and patient 
comfort, prior head restraint devices are generally unsuitable for nuclear 
medicine imaging due to the interference by the head support structure 
with the imaging radiation. This can create shadows on the image which 
complicate the reading of the image and could even lead to a 
misinterpretation of the image. 
It is furthermore highly desirable in nuclear medicine imaging, 
particularly with SPECT (single photon emission computed tomography), to 
have the camera as close to the patient's head as possible, and prior head 
support devices generally do not permit the close camera proximity 
desired. 
SUMMARY OF THE INVENTION 
The present invention comprises a panel adapted for attachment to the 
patient support surface of an imaging machine in a position underlying the 
shoulders of a patient. Extending from the head end of the panel is a head 
frame assembly comprising a pair of spaced, parallel, upstanding head 
frame elements which flank the neck of the patient and include 
substantially horizontal parallel portions which embrace the head of the 
patient. Adjustment means are provided connecting the free ends of the 
head frame elements which permits the selective adjustment of the 
horizontal spacing of the head frame elements to snugly grip the patient's 
head therebetween. The head frame assembly is of a non-metallic, imageable 
construction, formed preferably of a light-weight composite. 
A flexible head sling extending between the head frame elements is 
adjustably attached to at least one head frame element. The head sling 
supports the weight of the patient's head and its adjustability permits 
the desired degree of head elevation. The sling conforms to the head 
contour, and is thus extremely comfortable, there being no pressure points 
as with conventional head supports. In the preferred embodiment, the sling 
is made of a looped fabric, and a strip of hooked fabric is attached to 
the outer face of each head frame element, thus providing the infinite 
adjustment capability characteristic of a hook and loop fastener. 
To further insure the immobilization of the patient's head, a neck support 
strap may be provided extending between the head frame elements, the neck 
support strap also being adjustable such as by hook and loop attachment to 
facilitate the proper positioning of the strap. A chin restraining strap 
is provided which is adjustable in the same manner as the neck support 
strap. An adjustable forehead retraining strap is also provided, and its 
ends preferably include a strip of hooked fabric to cooperatively engage 
the looped head sling fabric which they overlie. 
It is accordingly a first object of the present invention to provide a head 
support for brain tomography which will effectively immobilize the 
patient's head in the desired position for the duration of the procedure. 
A further object of the invention is to provide a head support as described 
which may be quickly adjusted to provide the desired head position. 
Another object of the invention is to provide a head support as described 
which gives the patient a high degree of comfort for any selected head 
position. 
A still further object of the invention is to provide a head holder as 
described which will not interfere with the clarity of the imaging 
process. 
Still another object of the invention is to provide a head holder as 
described which will permit the camera in nuclear medicine tomography to 
come extremely close to the patient's head, especially in the area of the 
brain stem. 
Another object of the invention is to provide a head holder as described 
which will permit tomographic imaging of the neck area of the patient. 
A further object of the invention is to provide a head holder as described 
which will accommodate a wide range of head sizes and shapes. 
A further object of the invention is to provide a head holder as described 
which is of a simple, economically manufactured design, and which can be 
readily attached to and detached from the patient support table of 
tomographic equipment. 
Additional objects and advantages of the invention will be more readily 
apparent from the following detailed description of a preferred embodiment 
of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to the drawings and particularly FIGS. 1, 4, 6 and 7 thereof, a 
head support assembly generally designated 10 is illustrated which 
comprises a head frame assembly 12 extending from a frame support means 
14. In the preferred embodiment, the frame support means comprises a 
mounting panel 16 curved to conform to the shape of a typical imaging 
machine patient support table 18 as shown in solid lines in FIG. 2 and in 
broken lines in FIGS. 4 and 6. A pair of straps 20 adjustable by means of 
buckles 22 extend beneath the panel 16 and permit its demountable 
attachment to the table 18, the belts passing underneath the table as 
shown in FIG. 7. The ends of the belts pass through slots 24 in the panel 
and are secured by means of pins 26 passing through loops sewn in the belt 
ends. A felt pad 28 on the bottom of the panel engages the table top, 
serving as a buffer between the two hard surfaces. The panel 16 is 
preferably made of a light weight fiber reinforced plastic material, such 
as a carbon fiber reinforced epoxy. 
Although the frame support means 14 could comprise something other than the 
illustrated panel 16, for example the table itself, the panel arrangement 
is preferred since the present head support assembly can be quickly 
mounted on or dismounted from the table simply by tightening or loosening 
the straps 20, thus freeing the table for other uses. 
The head frame assembly 12 comprises a pair of head frame elements 30 
extending from a neck portion 32 of the panel 16 which, as shown in FIG. 
2, underlies the neck of the patient. Each head frame element 30 includes 
an upstanding leg portion 34 attached at its lower end to the panel and a 
substantially horizontal head clamping portion 36 extending from the upper 
end of the leg portion. Although the leg portions 34 in the illustrated 
embodiment are angled upwardly and outwardly from the panel neck portion, 
in other embodiments having a more extended neck portion of the panel, the 
leg portions may extend more vertically since they will then clear the 
patient's shoulders. Also, the panel neck portion 32 may if desired be 
raised above the remainder of the panel and configured to conform to the 
shape of a human neck, in which case the leg portions 34 of the head frame 
elements 30 will be somewhat shorter and more nearly vertical. 
The head clamping portions 36 of the head frame elements 30 extend in 
substantially parallel spaced relation, being sufficiently spaced to 
receive the head of the patient therebetween as shown in FIG. 2. The free 
ends of the head clamping portions 36 extend beyond the patient's head and 
preferably are curved inwardly toward each other to facilitate the 
attachment of adjustment means 38 for adjusting the spacing between the 
two head clamping portions 36. In the illustrated embodiment, the 
adjusting means 38 comprises an adjusting screw 40 which is threadedly 
engaged with round nuts 42 attached to the free ends of the head frame 
elements 30 by bands 44 as best seen in FIGS. 4 and 5. One half of the 
screw 40 is a right hand thread while the other half is a left hand thread 
so that turning of the screw in one direction will bring the head clamping 
portions 36 closer together while rotation in the other direction will 
move them farther apart. 
The adjustment means 38 serves both to provide adjustment of the spacing of 
the head clamping portions as well as to structurally couple the ends of 
the head frame elements to provide rigidity to the head frame structure. 
The head frame elements are quite thin in lateral section but are 
preferably formed of a strong composite such as a structural foam 46 
sandwiched between layers 48 of carbon fiber reinforced plastic as shown 
in the enlarged view of FIG. 8. Using such materials, the frame elements 
30 can be on the order of 0.25 inches thick but still have sufficient 
rigidity so as not to deform or flex should the patient twitch. With such 
a construction, the head frame elements, which should ideally be 
positioned above the ears of the patients, do not extend laterally beyond 
the ears of the patient and thus permit a camera path very close to the 
patient's head. This is extremely important in SPECT imaging wherein the 
camera path actually follows the configuration of the patient's head to 
gain the best image resolution. The present head frame assembly minimizes 
the lateral protrusion of the head support and, being formed of an 
imageable material, is particularly well suited for nuclear medicine 
imaging techniques such as PET and SPECT. By selection of imageable 
materials for the adjustment means 38 as well as the frame elements 30, 
the frame assembly contains no metal structure which would cast shadows on 
the tomographic image. The screw 40 and nuts 42 are preferably made of a 
strong plastic material and the nuts 42 are connected to the frame element 
ends by bands 44 of a carbon fiber reinforced plastic such as an epoxy. 
The thin composite construction described is utilized throughout the frame 
assembly and this allows continuous imaging beyond the head area, i.e. 
neck and upper spin, without image degradation. 
The inner surfaces of the frame element head clamping portions 36 are lined 
with strips 50 of a relatively dense resilient foam to provide some 
cushioning between the head and the head frame elements. These strips are 
quite thin, on the order of 0.25 inches, so as to prevent patient movement 
and also to minimize the bulk, particularly the lateral protrusion, of the 
head frame. 
The weight of the patient's head is supported by a head sling 52 which is 
adjustably supported between the head frame element head clamping portions 
36. In the preferred embodiment, the sling 52 is adjustably attached to 
each head frame element by means of hook and loop fasteners, the sling 
comprising a looped fabric, and the outer surface of each head frame 
element 30 being covered by a strip 54 of hooked fabric adhesively secured 
thereto as illustrated in the greatly enlarged view of FIG. 9. The sling 
will conform to the shape of the patient's head, eliminating the 
possibility of hard spots that could become painful during a long 
procedure. By providing ample sling length, adjustment of the height of 
the head can be readily accomplished from either side of the head frame by 
simply lifting the overhanging sling end to disengage the sling loops from 
the frame hooks and then raising or lowering the head to the desired 
height, following which the sling end is simply pressed against the frame 
element to reengage the looped sling fabric with the frame element hooks. 
The technician can perform this adjustment with one hand, leaving the 
other hand free to support the patient's head. 
To prevent upward head movement, a forehead restraining strap 56 is 
provided which extends across the patient's forehead and is secured to the 
head frame elements 30 by attachment to the head sling 52. The restraining 
strap 56 is made of hooked webbing and the head sling is looped on both 
sides as shown in the enlarged view of FIG. 3 to permit the strap 56 to be 
secured to it in any desired position. A resilient pad 58 of high density 
foam is provided centrally on the strap 56 for patient comfort. 
A chin restraining strap 60 is also provided to supplement the forehead 
restraining strap 56 in preventing vertical head motion as well as pivotal 
head motion about a lateral axis. The strap 60 is preferably made of a 
foam material having a looped fabric surface and sold under the name 
Velafoam by Velcro, Inc. The strap 60 can be positioned as desired and 
attaches to the head frame element hooks in the same manner as the head 
sling. 
A neck supporting strap 62 may be used if desired to tilt the head to the 
desired attitude or to provide additional comfort to the patient. The 
strap 62 is preferably made of the same material as the chin restraining 
strap and attaches to the head frame elements in the same manner. 
For use of the present head holder, the panel is placed on the table of an 
imaging machine and the straps are tightened to secure it in place. The 
head frame adjusting screw is then turned to separate the head clamping 
portions 36 of the head frame elements 30 sufficiently to receive the head 
of the patient. With the patient lying in a supine position on the table 
with his shoulders on the panel, the patient's head is introduced into the 
head holder between the head frame elements 30. The head sling is adjusted 
to provide the optimal elevation and angle of the head for the particular 
imaging process involved, and the neck support strap added and adjusted if 
needed to supplement the head sling in providing the desired attitude of 
the head. The frame adjusting screw is then tightened to a firm but 
comfortable degree of tightness to clamp the head against lateral 
movement. The forehead restraining strap and the chin restraining straps 
are then applied to complete the immobilization of the patient's head. 
The removal of the head from head support is quickly accomplished by 
removal of the chin and forehead restraining straps and the loosening of 
the adjusting screw to allow the head to be lifted from the head frame 
assembly. 
Although hook and loop attachment is the preferred arrangement for 
adjustable connection of the head sling, neck supporting strap, and chin 
and forehead restraining straps, other arrangements might be used, such as 
straps and buckles. However, the simplicity and ease of use of the hook 
and loop system are important factors which favor its use. 
The adjusting means for connecting the ends of the head frame elements 30 
could optionally comprise a strap and buckle or possibly a hook and loop 
arrangement. However, as mentioned, it is important to provide structural 
rigidity to the assembly, and if such optional adjusting means were 
employed, some additional means would be necessary to join the frame 
element ends, such as a tubular member for receiving the ends. The use of 
a large screw with large nuts provides this needed rigidity and also 
provides a positive positioning of the frame element ends whether or not a 
head is positioned in the head holder assembly. 
For nuclear medicine imaging, the preferred materials for the head frame as 
described are a low density foam, carbon fiber reinforced epoxy composite. 
This provides very high strength, light weight, permits a very thin wall 
structure and casts virtually no shadow on the image. Such a construction 
is also suitable for use with CT and X-ray imaging. 
For MR imaging, the carbon fiber cannot be used because of its 
conductivity, but other reinforcing fibers such as Kevlar, S-2 fiberglass, 
or Spectra could be employed in its place. 
Manifestly, changes in details of construction can be effected by those 
skilled in the art without departing from the invention.