Surgery – Instruments – Means for marking animals
Reexamination Certificate
2000-04-19
2003-04-01
Dvorak, Linda C. M. (Department: 3739)
Surgery
Instruments
Means for marking animals
C606S132000, C040S300000, C033S018100, C033S027030
Reexamination Certificate
active
06540756
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the medical art and, more particularly, to a tool for assisting in accurately establishing and marking a treatment portal on the skin surface of a patient undergoing radiation therapy or the like.
BACKGROUND OF THE INVENTION
The administration of radiation energy is in widespread use as an effective means of treating malignant and benign conditions. Such radiation therapy is generally administered by large, complex machines called linear accelerators. Although the linear accelerators administer specific dosages of radiation to precise locations inside the human body, it must be realized that operation of these machines is highly dependent on human interaction to ensure that the treatment regimen is successful.
One important area where human interaction is necessary is in identifying the precise location on the skin surface of the patient where radiation must be administered to produce an effective treatment outcome. This area is commonly referred to as the treatment “portal.” Prior to administering the actual radiation energy doses, it is first necessary for a team of scientists, including a treating oncologist and medical physicist, to view the internal anatomy of the patient and determine the precise locations where treatment is necessary. This is done when the patient is first brought in for radiation therapy by using a simulator, which is basically a scale model of the actual linear accelerator used during treatment without the radiation administering capabilities. To perform the simulation, the subject patient is laid on the treatment couch of the simulator below a gantry and raised vertically to the optimal imaging range. The oncologist and treating staff view the internal anatomy of the patient and locate the treatment site using fluoroscopy and reviewing pictures taken during internal imaging procedures, such as computerized axial tomography (CAT) scanning, magnetic-resonance imaging (MRI), or the like. The couch and gantry are movable to provide the oncologist with the best view of the anatomy he or she has determined needs treatment. Based on the positioning of the patient, who is normally laying down in a supine position, a sagittal laser is projected down the length of the patient's torso, a transverse laser is projected across the sagittal laser, and laterally extending lasers are projected running up and down the left and right sides of the body that intersect with the transverse laser. As any radiation therapist skilled in the art recognizes, the three areas where the lasers cross represent the triangulation points, which are marked. For some procedures, these triangulation points identify the treatment portals (i.e., the locations where radiation must be precisely administered to effectively eradicate a centralized diseased tissue mass), but it is also known to mark the triangulation points to ensure that the patient setup is the same for every treatment. For example, while a four field pelvic treatment will use triangulation points for both a setup point and a treatment portal, a two-field lung treatment would not but the lung still needs to be triangulated for accuracy and reproducibility.
Marking these locations with extreme precision is important, as small deviations from the treatment location can result in the irradiation of healthy tissue surrounding the targeted diseased tissue. In addition to failing to eradicate the diseased tissue, missing the target treatment area can result in the impairment of organs or other internal body structures, thus placing the already ill patient in perhaps a worse condition. Of particular concern is the use of such radiation near the spinal cord, where precision is especially critical, as any excessive or improper destruction of nerve tissue can result in severe paralysis.
To ensure that radiation is administered in a proper manner, professional medical practitioners known as radiation therapists or technologists are employed to, among other things, assist in designing, locating, and marking the treatment sites, or portals, on the skin surfaces on the body of the patient. To denote the treatment portal, conventional practice is to simply use a standard writing implement, such as a marker or pen, and draw the portal on the skin in a free-handed manner. Of course, it should be appreciated that such free hand markings are subject to variation based on application by different individuals, even when rulers or other conventional line drawing instruments are used. As imprecise lines can affect the course of treatment, a standard of quality assurance in applying such markings is desirable.
In an attempt to provide such precision portal markings, others have proposed the use of adhesive markers as an alternative to actually drawing the portal on the skin. For example, U.S. Pat. Nos. 5,306,271, 5,407,440, and 5,743,899, all to Zinreich et al. teach the use of various shapes and sizes of detachable, adhesive skin markers for placement at the treatment portal in place of the permanent tattoos that are presently used to permanently mark the center of the portal. Although such adhesive markers ostensibly provide greater precision than the conventional method of freehanded drawing described above, several limitations remain. First of all, radiation therapy patients generally undergo a multiple stage regimen of treatment sessions which can occur over the course of several days or even weeks. The light duty, skin-safe adhesives proposed in the above-referenced patents simply do not stay in place over the course of an extended treatment session. If an adhesive marker inadvertently falls from the predetermined treatment location, it is necessary to carefully reapply the marker or, if no permanent mark was made on the skin, to revisit the simulator for relocation of the treatment portal. Of course, this results in a waste of resources and additional discomfort for the patient.
Additionally, such markers are particularly troublesome for patients with excessive amounts of body hair or where sweat and other fluids can come into contact with and degrade the adhesive, which of course weaken the ability of the marker to remain adhered on the body. Again, if the marker is inadvertently removed, re-application or re-simulation becomes necessary, which as noted above results in a significant waste of valuable professional time and also serves to extend the already uncomfortable experience of the patient undergoing therapy.
The troublesome nature of these adhesive markers is explicitly recognized in the most recently issued '899 patent, which proposes the improvement of imbuing the adhesive backing with transferable ink. This ink is supposed to transfer to the skin at some finite time after application of the marker, thereby providing a landmark that facilitates replacement if inadvertent detachment occurs. It must be appreciated that even with the use of such ink imbued markers, limitations still remain. First of all, the markers do not eliminate the requirement of locating the central axis point of the treatment portal on the body of the patient. Precisely placing the marker oversuch an axis is difficult and may require several attempts to achieve the proper positioning. In addition, the ink blot provided by the backing simply cannot define the portal with the precision necessary for an accurate treatment regimen. Also, where excessive hair or sweat is present, the ink may not sufficiently penetrate the skin to leave a readily distinguishable mark. Finally, as with all the adhesive markers, the use of multiple markers to define a treatment portal is time consuming. The excessive application time and associated cost is simply not worth the limited benefit provided by such adhesive markers.
Thus, a need is identified for a device that facilitates the precise marking of a treatment portal upon the skin surface of a patient undergoing radiation therapy or a similar procedure. The device would be of simple construction and, thus, easy and inexpensive to manufacture. Moreover, the devi
Dvorak Linda C. M.
Farah Ahmed
King & Schickli PLLC
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