Surgery – Radioactive substance applied to body for therapy – Radioactive substance placed within body
Reexamination Certificate
1999-06-04
2003-10-21
Kearney, Rosiland S. (Department: 3739)
Surgery
Radioactive substance applied to body for therapy
Radioactive substance placed within body
C600S001000, C600S007000, C250S497100
Reexamination Certificate
active
06635008
ABSTRACT:
BACKGROUND
1. Technical Field
The present disclosure relates to remote afterloading devices used to position radioactive treatment source wires inside patients afflicted with cancer or other diseases, and more particularly to a system and method for delivering a medical treatment to a treatment site of such patients.
2. Background of Related Art
Radiation is used to treat cancer and other diseases of the body. Brachytherapy, is a general term for the radiation treatment of cancer at close distances inside the body. During brachytherapy, a radioactive source or sources are positioned in the area needing treatment. Depending on the type of therapy, the radioactive sources are placed permanently inside the body during surgery, or transport tubes (treatment catheters) are placed in the body which are later temporarily loaded with radioactive sources. This temporary afterloading of radioactive material either involves a human handling the radioactive material and receiving radiation exposure, or a machine called a “remote afterloader” that will load and unload the radioactive material into and from the transport tubes. Such remote afterloaders are operated by an individual from a remote location so that the individual will not receive any radiation exposure.
Existing remote a afterloaders are generally used in the cancer field to accurately advance and retract a flexible drive member containing a radioactive source over a specified distance for a specified time period. A remote afterloader generally consists of a flexible simulation drive member, a flexible drive member containing a radioactive element, controllers and drive mechanisms to operate both types of flexible members, a shielding safe for the radioactive element, an internal timer, and an exit port attached to a rotating wheel that allows multiple transport tubes (previously placed into the patient) to be attached to device at the same time.
It is known to use a simulation member for checking the patency of the transport tube without subjecting the patient to undue radiation exposure. After the patency is confirmed, the afterloader sends out the radioactive source. Upon completion of treatment in a first transport tube, the afterloader retracts the source into the shielding safe inside the afterloader, a wheel turns and aligns a slot containing a second transport tube to an exit port. The remote afterloader then repeats its function sending and retracting the simulation member and radioactive source through this second tube. The procedure is repeated until the function is carried out through all the specified transport tubes. Existing remote afterloaders use a fixed, short length radioactive source and multi-step this source many times inside each transport tube to cover the diseased area.
Currently available remote afterloaders require the following complicated procedures before any treatment can take place:
Initially, by hand, physical measurements must be made of each transport tube after it has been positioned inside the body using a simulation member, fluoroscopy, and a calibrated ruler. These measurements must accurately relate the physical distance the radioactive source needs to travel from the distal end of each tube to the inside of each transport tube to treat the disease inside the body.
Secondly, two 90 degree X-Rays showing all the transport tubes inside the body must be made and digitized into a treatment planning computer. The physical measurements taken prior to the X-rays, must be matched up with each digitized transport tube in the treatment planning computer and the physical length measurements along with other treatment data must be entered for each transport tube.
The computer then compiles all the data and a treatment plan is formed and stored on a magnetic computer disk. This computer disk containing the treatment plan is then entered into a treatment computer that programs and operates the remote after-loader. Finally, the treatment takes place.
In most cases, the above setup steps take thirty minutes or more. Existing remote afterloaders were primarily designed for the treatment of cancer but can be used in other treatments of diseases. There are critical factors that will not allow the previously available remote afterloaders to be used in the treatment of certain types of diseases. One main limiting factor is the long setup time required for treatment. In treatments where time is of the essence, such as in the treatment of heart patients, a long setup time could be unacceptable. The present disclosure allows a specially designed remote afterloader to perform its duty in a much shorter time period, eliminating many of the time consuming steps.
Other limiting factors of previous treatment afterloaders are the physical size and amount of equipment necessary to operate a remote afterloader. In many treatment facilities there is not enough room for the amount and size of equipment. Lack of certain safety features (for example, an indirect but not a direct transport tube sensing device to ensure that the transport tube is properly connected to the afterloader, human error when measuring and translating treatment distance, no control of the speed in which the drive members move, no means to fine tune the position of the drive members once they reach their target area) along with the lack of other safety features make the previously available remote afterloaders limited in use and effectiveness.
Various techniques have been developed to treat many different conduits in the body when these conduits have become reduced in size due to the existence of a stenosis or have been completely occluded. These techniques include introducing a deflated balloon catheter to the site of an occlusion or constriction, such as a stenosis, inflating the balloon one or more times to reduce the size of the stenosis, deflating the balloon and then removing the balloon catheter from the treatment site.
With respect to the vascular pathways, angioplasty is used to open an artery or blood vessel in the region where the stenosis or the occlusion has occurred. A typical angioplasty procedure consists of making a small incision through the body and into a blood vessel and then maneuvering a guide wire through the vascular system to a point beyond the stenosis or occlusion. A hollow catheter with a declarable balloon near its distal end is threaded over the guide wire and advanced to the point of stenosis or occlusion. The balloon is then inflated and deflated several times to widen the constricted area, and is then withdrawn from the body.
Unfortunately, although the angioplasty procedure does markedly reduce the area of stenosis or occlusion, many patients exhibit a reoccurrence of the stenosis within a few months of the original procedure.
Although the original stenosis occurs by means of the build up of plaque over a relatively long period of time, experimentation has led many to believe that the reoccurrence of the stenosis after the original angioplasty procedure is unrelated to the cause of the original stenosis. It is believed that the inflation of the balloon catheter used in the angioplasty procedure or the placement of a sent in the area of the stenosis causes irritation to the blood vessel. This irritation produces a mechanism of action called hyperplasia, inducing the inner layer of the blood vessel cells to rapidly reproduce, thereby causing restenosis. It has been proposed that if the blood vessel is irradiated at the point of the stenosis with a radioactive dose, the mechanism that causes hyperplasia would be destroyed without harming the blood vessel itself.
During this procedure, it is important to precisely control the amount of radiation which is directed to the blood vessel wall, since too much radiation could actually induce hyperplasia as well as destroying a portion of the blood vessel, making it possible for an aneurism or rupture to occur.
U.S. Pat. No. 5,213,561 issued to Weinstein et al and U.S. Pat. No. 5,199,939 issued to Dake et al, as well as PCT Application PCT/US92/07447 to Shefer et al, describe
Cantor & Colburn LLP
Interventional Therapies LLC
Kearney Rosiland S.
LandOfFree
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