Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
2000-08-11
2002-08-20
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C128S898000, C600S001000, C600S003000, C600S007000, C600S008000
Reexamination Certificate
active
06438401
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an improvement to treatment plans using brachytherapy or the like and more specifically to a technique for rapid and accurate identification and quantification of needle placement departures from such a treatment plan.
DESCRIPTION OF RELATED ART
In the treatment of prostate cancer, a method is often employed to implant numerous radioactive seeds in a carefully preplanned pattern in three dimensions within the prostate. That procedure serves to deliver a known amount of radiation dosage concentrated around the prostate, while at the same time sparing radiation-sensitive tissues, such as the urethra, the bladder and the rectum. Customarily, 60 to 120 seeds are placed through 15 to 30 needles in the inferior (feet) to superior (head) direction. Those needle positions are selected from a 13×13 grid of 0.5 cm evenly spaced template holes, which are used to achieve precise needle insertion. The number of those holes which intersect with the prostate cross section, and therefore are potentially usable, is typically about 60. The number of mathematical combinations is therefore greatly in excess of 10
16
, each of which is a potential treatment plan but is associated with different degrees of cancer control and a different likelihood of treatment complications.
In current clinical practice, the design of a suitable seed configuration which is customized to the anatomy of a patient is achieved by a highly trained medical physicist or dosimetrist by using trial-and-error manual iterations. The practitioner usually starts with an initial needle configuration based on experience or rules of thumb, and then adjusts the radioactive strength per seed or the locations of certain needles or both until the calculated dose intensity distribution satisfies a set of clinical considerations. That process requires between 15 minutes and 2 hours, depending on the experience of the treatment planner and the geometric complexity of the relationship between the prostate and the surrounding anatomical structures.
Those known treatment planning processes are typically aided by one of several available commercial computerized treatment planning systems. Such treatment planning systems enable the user to outline the prostate in relation to a template grid, to turn on or off any available needle positions and seed positions within each needle, and to examine the resultant dose distribution in two or three dimensions. Examples of such planning systems include those offered by Multimedia Medical Systems (MMS) of Charlottesville, Va., SSGI Prowess, of Chico, Calif., Nucletron Plato, from Columbia, Md., Computerized Medical Systems (CMS) Focus, of St Louis, Mo., Radiation Oncology Computer Systems (ROCS), of Carlsbad, Calif., ADAC Laboratory's Pinnacle, of Milpitas, Calif. and Theraplan, available from Theratronics International Ltd. of Kanata, Ontario, Canada.
In a number of such known commercial treatment planning systems, for example, those available from MMS and SSGI, the initial needle configuration that otherwise would have to be turned on by the human treatment planner is automatically set up by the computer system. That initial setup is based on simple rules of thumb, such as uniform loading, peripheral loading or modified peripheral loading. In a number of instances, the manufacturer claims that its planning system offers “automatic planning”, “geometric optimization”, or “real-time dosimetry”. However, none of those commercial planning systems offer true optimization in that the automatically loaded seeds are not designed based on customized dosimetric calculations. Rather, they are designed to fill the space of the prostate in some predetermined manner. Therefore, such known automatic seed loading techniques are designed to save between 15 and 30 mouse clicks by the operator (or about 1 minute of operation). However, the user is still required to apply his or her expert knowledge to iteratively improve upon that initial design in order to achieve customized planning for any individual patient. Thus, there are two significant drawbacks of the above-mentioned current techniques: First, the complete treatment planning process is under the manual guidance of a radiation planning expert using trial and error techniques; and second, the adjustment of the delivered dose is achieved by varying the radioactive strength per seed until an isodose surface with the desired shape and size is scaled up or down to the prescription dose, i.e., those techniques will suffer when the activity per seed is fixed, as at the time of surgical implantation in the operating suite.
Because of those two severe drawbacks, the currently available commercial treatment planning systems are not suitable for intraoperative treatment planning in the surgical suite, where the patient is placed under anesthesia in volatile conditions and where the cost per minute is very high. The variability of human performance, experience and stress, and the general inability of humans to manage large amounts of numerical data in 1 to 2 minutes are also factors that deter current practitioners from performing intraoperative treatment planning.
An optimization technique for treatment planning is taught by U.S. Pat. No. 5,391,139 to Edmundson. More specifically, Edmundson is intended for use with a high dose rate (HDR) source which is moved within a hollow needle implanted in a prostate or other anatomical portion. The medical personnel using the system of Edmundson select a needle location using empirically predetermined placement rules. An image is taken of the prostate with the hollow needles implanted in it, and the dwell time of the source at each dwell position in the needle is optimized. However, placement itself is not optimized, but must instead be determined by a human operator.
Another optimization technique is taught by WO 00/25865 to one of the inventors of the present invention. An implant planning engine plans implants for radiotherapy, e.g., prostrate brachytherapy. The system optimizes intraoperative treatment planning on a real-time basis using a synergistic formulation of a genetic algorithm, multi-objective decision theory and a statistical sensitive analysis.
While the above techniques allow calculation of optimized dwell time, placement or the like, they do not provide for detection and correction of errors in needle or seed placement.
SUMMARY OF THE INVENTION
It will be apparent from the above that a need exists in the art to detect and correct errors in implementation of a treatment plan.
It is therefore a primary object of the present invention to permit rapid and accurate identification and quantification of needle placement departures from a treatment plan generated prior to a brachytherapy implant based on real-time ultrasound.
It is another object of the invention to allow real-time correction to the brachytherapy dosimetry and iterative compensation of loss of dose coverage due to misplacement of the needles/catheters and seeds.
It is still another object of the invention to permit such identification, quantification and correction without the need for CT or MR imaging during the interval between needle/catheter placement in the target organ and final deposition of radioactive sources for irradiation of the target organ.
To achieve the above and other objects, the present invention is directed to a technique for identifying and quantifying needle displacement departures from a placement plan for the placement of radioactive seeds in a prostrate or other internal organ for brachytherapy or the like. The placement plan is made available to an intraoperative tracking interface which also shows a live ultrasound image of the needle or catheter placement in the prostate. The difference in the x-y plane between the planned and actual locations of the needle or catheter is calculated, and from that difference, the error in position of each seed is calculated. The seeds are moved, or the operator changes the number of seeds, and the dose is recalculated. A small
Cheng Gang
Liu Haisong
Yu Yan
Alpha Intervention Technology, Inc.
Blank Rome Comisky & McCauley LLP
Lateef Marvin M.
Qaderi Runa Shah
LandOfFree
Indentification and quantification of needle displacement... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Indentification and quantification of needle displacement..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Indentification and quantification of needle displacement... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2930263