Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2001-12-20
2004-11-30
Mercader, Eleni Mantis (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C606S130000, C600S426000, C600S417000, C600S414000
Reexamination Certificate
active
06826423
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention (Technical Field)
The present invention relates to medical equipment and methods, more particularly to equipment and methods for radiation therapy including stereotactic localization and immobilization systems and methods.
2. Background Art
Fractionated radiation therapy to a target lesion within the body is the primary method used for radiation therapy. This method requires precise immobilization and repositioning of the patient for other treatment sessions. Stereotactic localization and procedures on cranial and extra-cranial body parts have a similar requirement.
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
The need for effective patient immobilization techniques for radiation therapy has recently inspired the development and use of many immobilization devices in that field. The ability to reposition the patient and the patient's ability to maintain the position during treatment may be improved with the use of immobilization devices (see Bentel 1999). Immobilization reduces “normal tissue” complication rate, allows increased irradiation, and improves tumor control rate. “A modest increase of the treatment and isodose margin can have a significant effect on the volume of normal tissue exposed” (see Bentel 1999). Historically, skin marks, or marker systems (see U.S. Pat. No. 4,583,538, to Onik, et al.), have been used to aid in target localization and repositioning. Skin marks used for patient repositioning may migrate as they are re-marked and markings can shift with respect to underlying deeper tissues. They also tend to smear and fade. Markings on a body immobilization device do not move with respect to the target, they do not smear or fade, hence the problems of re-marking and migration are eliminated (see Bentel 1999). Markings on the immobilization device may also be matched to skin markings (see Bentel 1999).
Patient comfort, ability to easily maintain the position for extended periods of time, reproducibility of the patient's “prescription” position, and anticipated beam orientation are essential in successful repeat radiotherapy treatments (see Bentel 1999). Comfort allows the patient to relax in a position throughout the treatment period, discouraging body movement caused by fatigue or discomfort. Patient movement could invalidate target localization and expose healthy tissue to unwanted radiation. Some patients, especially children, may move as much as 5 mm (or more) during treatment (due to pain or an uncomfortable position or because they are uncooperative, demented or restless) (see Bentel 1999). Goitein and Busse studied the theoretical effect of under dosage at the perimeter of the treatment field caused by random immobilization errors. They found that as much as a 12% improvement of tumor control probability could be achieved by good Immobilization techniques (see Bentel 1999). In addition, a cost reduction is realized over traditional radiation therapy because the number of port films as well as setup time is reduced which allows for more patient throughput (see Bentel 1999).
Because body fixation is essential for controlled radiation therapy during cancer treatment (Lederman, et al. 1998), emphasis has been placed on non-invasive and comfortable means of body immobilization and repositioning (see Bentel 1999). New techniques for precision radiation to extracranial targets of the body have been developed for highly successful treatment of lesions. External fixation systems are used to localize the body for exact repositioning during repeat treatments. The concept of stereotactic localization has been used to localize and aid in the target positioning for radiotherapy (see Lax, et al. 1994 and Hamilton, et al 1995).
Bentel (Bentel 1999) references a concept of three-dimensional localization (stereotactic localization) when she states that “The coordinate system allows one to describe the location of any point with respect to another known point (origin). Three axes (x,y,z) transect this known point. The location of any point with respect to the origin is described by the distance measured along each axis and by indicating on which side of the axis the point is located.” These concepts are fundamental to the principles of stereotactc localization, which is to determine the location of deep body structures which are invisible from the surface but their location can be determined by a knowledge of their three-dimensional coordinates in space relative to known anatomical and topographical landmarks in a volumetric space defined by a stereotactic instrument. The stereotactic technique seeks to avoid disturbance to surrounding structures during therapeutic interventions by the use of minimally invasive precision localization Instruments. Guiot, G. and Derome, P., “The principles of stereotactic thalamotomy”,
Correlative Neurosurgery
, edited by Kahn, E J et al., Springfield, Ill., 2
nd
Edition, Chapter 18, pp. 376-401, 1969.
As noted by Bentel and Marks (Bentel, et al. 1997) and Bentel (Bentel 1999), a number of methods have been historically used for patient immobilization during radiation therapy. More recently the concept of stereotactic localization, which has previously been successfully applied to radiotherapy/radiosurgery of the brain (see Lutz, et al. 1988), has been applied to extracranial radiotherapy target areas. (Lax 1994, Lederman 1998, and Hamilton, et al., 1995 and 1997).
This method of patient immobilization and stereotactic localization has been found to be more effective than previous localization methods for radiation therapy. Lax, et al. (Lax, et al. 1994), found a high degree of target reproducibility when using a stereotactic body frame. They found, from repeat CT examinations of patients in the body frame, a 5 mm range (i.e., a 2-7 mm range of error) of target volume positioning for targets in the liver and lungs. In addition, local tumor control of 90% was possible using this technique (see Blomgren, et al. 1995). The clinical use of a stereotactic body frame is increasing because it can be used to treat lesions over a wide variety of body areas (see Lederman, et al. 1998a-g).
Additional references providing important background to the present invention include the following U.S. Pat. No. 3,783,251, to Pavkovich, et al.; U.S. Pat. No. 4,583,538, to Onik, et al.; U.S. Pat. No. 4,638,798, to Shelden, et al.; U.S. Pat. No. 4,341,220, to Perry; U.S. Pat. No. 4,608,977, to Brown, et al.; U.S. Pat. No. 4,618,978, to Cosman, et al.; U.S. Pat. No. 5,099,846, to Hardy, U.S. Pat. No. 5,553,112, to Hardy, et al.; U.S. Pat. No. 5,143,076, to Hardy, et al.; U.S. Pat. No. 5,176,689, to Hardy, et al.; U.S. Pat. No. 5,398,684, to Hardy, et al.; U.S. Pat. No. 5,354,314, to Hardy, et al.; and U.S. Pat. No. 6,011,828, to Hardy, et al. Other background publication include: Bentel, G. C., “Central Nervous System,”
Patient Positioning and Immobilization in Radiation Oncology
, New York: McGraw-Hill, 1999, pp. 71-92; Bentel, G. C., “General Consideration of Positioning and Immobilization,”
Patient Positioning and Immobilization in Radiation Oncology
, New York: McGraw-Hill, 1999, pp. 23-38; Bentel, G. C., “Treatment Accuracy and Precision,”
Patient Positioning and Immobilization in Radiation Oncology
, New York: McGraw-Hill, 1999, pp. 11-22; Bentel, G. C., “Treatment Geometry,”
Patient Positioning and Immobilization in Radiation Oncology
, New York: McGraw-Hill, 1999, pp. 1-10; Bertolina, J. A., et al., “Quality Assurance Testing for An Extracranial Stereotactic Device: Methods and Results,” Poster No. 129, Intl Stereotactic Radiosurgery Society, 1997, p. 233; Blomgren, H., et al., “Radiosurgery for Tumors
Deming Laura R.
Hardy Tyrone L.
Mantis Mercader Eleni
MIDCO-Medical Instrumentation and Diagnostics Corporation
Peacock Myers & Adams
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