Patent Publication Number: US-2006014997-A1

Title: Device for radiation treatment of proliferative tissue surrounding a cavity in an animal body as well as a method for controlling the performance of radiation treatment of proliferative tissue surrounding a cavity in an animal body

Description:
The invention relates to a device for radiation treatment of proliferative tissue surrounding a cavity in an animal body comprising: 
          at least one inflatable balloon system having a balloon wall for placement in said cavity;     inflation means for inflating and deflating said balloon system with a pressurized medium;     radiation delivering means for placing at least one energy emitting source within said cavity for performing said radiation treatment.        

      The invention also relates to a method for controlling the condition of a radiation treatment being performed on proliferative tissue surrounding a cavity in an animal body, wherein for performing said radiation treatment an inflatable balloon system having a balloon wall is placed in said cavity, said balloon system is inflated with a pressurized medium, and at least one energy emitting source is placed within said cavity for performing said radiation treatment.  
      Such device is for example known from European patent application no. 1 402 922 A1 in the name of the present applicant, Nucletron B. V.  
      The one major advance that has had the greatest influence on the re-emergence of brachytherapy in recent years has been the introduction of remote afterloaders. A remote afterloader (or afterloading apparatus) enables the insertion of energy emitting sources through a catheter tube towards a specific location within a patient&#39;s body without the risk of exposing unnecessary radiation doses to the radiotherapy staff.  
      In addition to this development there has been a trend in the past few years towards the use of high dose rate (HDR) energy emitting sources in brachytherapy applications in which much higher activity sources are inserted or implanted within a patient&#39;s body for much shorter periods of treatment time.  
      These HDR sources are sometimes inserted in a single fraction or more often with a few separate insertions.  
      Together with the increased interest for this treatment modality more sophisticated applicators have been developed and the classical plastic or metal applicators are replaced step by step with combined applicator-balloon or balloon-based devices. These devices are surrounded by an inflatable balloon system, which balloon system is introduced with the applicator into a natural body cavity or where a cancer tumour has been excised by means of surgery.  
      Following surgical removal of a tumour, the inflatable balloon system is introduced into the cavity caused by the removal of the tumour. After inflating the balloon system one or more energy emitting sources are introduced at one or more locations within the body cavity in order to treat the tissue surrounding said surgically excised tumour with radiation in order to kill any cancer cells that may be present in the margins surrounding the excised tumour.  
      An inflatable balloon system allows an immobilization of the region within the cavity the patient&#39;s body to be treated by radiation, or a centering of the treatment region, or it provides a displacement of organs at risk away from the treatment region to be irradiated.  
      From the above it will be clear that a correct positioning of the applicator and the reproducibility of the position of the applicator is important and will have a direct influence on the clinical outcome. The dose rate emitted by the energy emitting source inserted within the body cavity and present at a certain point will be determined from the distance of the source to the tissue and this distance is dependent from the inflation or deflation status of the balloon system applicator.  
      As the balloon system applicator is inserted inside a body cavity a visual control of the inflation status is impossible. The use of additional imaging techniques, like ultrasound or X-ray imaging, constitutes an extra discomforting burden for the patient and cannot be maintained during the radiation treatment when radiation is being delivered to the treatment region.  
      As result, with the inflatable balloon system devices presently known the risk of any misadministration of a radiation dose to the patient is very high and can not be controlled or corrected.  
      It is therefor an object of the invention to provide a device for radiation treatment of proliferative tissue surrounding a cavity in an animal patient body according to the above preamble capable in monitoring the real, actual functional status of the inflated balloon system present inside said body cavity, especially when said device is utilized with an after loading apparatus.  
      The device is according to the invention characterized in that said device comprises monitoring means for monitoring the inflation status of the inflatable balloon system. Hence with the device according to the invention the actual inflation status of the inflated balloon system can be determined, providing accurate information about the operational conditions of the device during radiation treatments being performed in an animal body. Any malfunction can be easily detected thereby obviating the risk of any misadministration of a radiation dose to the patient.  
      More in particular said monitoring means are according to the invention arranged in comparing the actual inflation status being monitored with a pre-determined desired inflation status of the inflatable balloon system and in operating the device based on control signals generated as a result of said inflation status comparison. Hence these features allow any correction of any unfavourable operational conditions, which may adversely affect the radiation treatment being performed in the cavity of said animal body.  
      Especially in one preferred embodiment said radiation delivering means are arranged in retracting said at least one energy emitting source from said cavity based on control signals generated by said monitoring means as a result of said inflation status comparison. This safe measure prevents an uncontrolled radiation dose being administered to the animal body (patient) during a malfunction of the balloon system.  
      In another preferred embodiment said at least one energy emitting source is an activatable energy emitting source and wherein said radiation delivering means are arranged in de-activating said at least one energy emitting source in said cavity based on control signals generated by said monitoring means as a result of said inflation status comparison. Therefor the device according to the invention is not only suitable for energy emitting sources who emit radioactive radiation according to the principle of natural radioactive decay, but also for energy emitting sources who are to be activated in order to emit radiation, like an X-ray emitter, or laser source, etc.  
      In another preferred embodiment said inflation means are arranged in inflating and/or deflating the balloon system based on control signals generated by said monitoring means as a result of said inflation status comparison. This feature allows the inflation status of the balloon system to be corrected within a safety pressure bandwidth.  
      In this latter embodiment said monitoring means may comprise at least one pressure sensor for generating pressure data corresponding to the actual pressure of said pressurized medium in said inflated balloon system, said pressure data being used for said inflation status comparison.  
      More in particular the monitoring means are arranged in comparing said pressure data with a pre-determined pressure bandwidth and in operating the device based on control signals generated as a result of said pressure comparison.  
      In preferred embodiments said at least one pressure sensor can be positioned inside or outside the balloon system,  
      In another advantageous embodiment of the device according to the invention said monitoring means comprise an imaging device for generating image data corresponding to the actual balloon wall contour of the inflated balloon system, said image data being used for said inflation status comparison.  
      The monitoring means are thereby arranged in comparing said image data with a pre-determined balloon wall contour and in operating the device based on control signals generated as a result of said contour comparison.  
      Hence with the use of image data instead of pressure data the actual inflation contour of the balloon system inside the cavity in the patient&#39;s body is monitored and used for correcting the device in the event that any malfunction or deviation from the optimal operational conditions are detected.  
      In order to obtain more accurate information concerning the actual operational conditions of the device and the balloon system in a specific embodiment the monitoring means are arranged in converting said image data obtained with said imaging device into a three-dimensional image of the actual balloon wall contour of the inflated balloon system.  
      Said imaging device may be constructed as ultrasound imaging probe or as a video camera, which imaging devices are in a preferred embodiment insertable inside the balloon system in order to obtain more actual local information allowing a more accurate and prompt correction of the operational status of the device in case of a malfunction or deviation.  
      In yet another advantageous embodiment said monitoring means comprises at least one radiation dose sensor for generating radiation data corresponding to measured radiation emitted by said at least one energy emitting source being placed within said cavity and corresponding to the actual distance between said at least one radiation dose sensor and said at least one energy emitting source within said cavity, said radiation data being used for said inflation status comparison.  
      More in particular the monitoring means are arranged in comparing said radiation data with a pre-determined desired distance between said at least one radiation dose sensor and said at least one energy emitting source within said cavity and in operating the device based on control signals generated as a result of said radiation comparison.  
      The radiation data being generated by the radiation sensor is a measure of the actual distance between the sensor connected to the balloon system and the energy emitting source placed within the cavity and which source emits the radiation that is detected with the radiation sensor. The radiation intensity of emitted radiation decreases with the distance according to pre-determined rules. By comparing the actual distance as obtained from the measured radiation with a pre-determined desired distance accurate information can be obtained about the actual inflation status of the balloon system.  
      In the event the balloon system becomes deflated due to a malfunction the radiation being detected by the sensor will reveal a shorter or decreased distance between the sensor and the source emitting said radiation. Also in the event of an over-inflating of the balloon system the radiation being detected by the sensor will reveal a longer or increased distance. In both situations the device is controlled in order to correct for these malfunctions or deviations from the optimal operational conditions.  
      Preferably said at least one radiation sensor is connected to the inner or outer wall of the balloon system.  
      Furthermore the inflation means may comprise a piston-cylinder combination having a cylinder and a piston movable accommodated in said cylinder. More in particular said inflation means comprise piston drive means for displacing said piston within said cylinder based on control signals generated by said monitoring means.  
      Furthermore a medium conduct is present interconnecting the cylinder with the inflatable balloon, whereby an additional feature consists of a supply vessel for said medium being present in said medium conduct.  
      More in particular a first valve is accommodated in said medium conduct between said supply vessel and said piston-cylinder combination, whereas a second valve is accommodated in said medium conduct between said piston-cylinder combination and said inflatable balloon system. As in a specific embodiment both said first and said second valve can be actuated by said monitoring means the inflation status of the balloon system can be accurately controlled and any malfunction can be detected and direct specific measures can be performed avoiding the misadministration of a radiation dose to the patient.  
      In another specific embodiment said radiation delivering means are constructed as an after loading apparatus.  
      Likewise the method according to the invention is characterized by the step of monitoring the inflation status of the inflatable balloon system before and during the performance of said radiation treatment. With the method according to the invention accurate information about the operational conditions of the radiation treatment being performed in an animal body can be obtained. Any malfunction can be easily detected thereby obviating the risk of any misadministration of a radiation dose to the patient.  
      In an further aspect the method according to the invention further characterized by the steps of comparing the actual inflation status being monitored with a pre-determined desired inflation status of the inflatable balloon system and of controlling the condition of the performance of the radiation treatment based on control signals generated as a result of said inflation status comparison.  
      Further implementations of the method according to invention comprises the steps of retracting said at least one energy emitting source from said cavity based on control signals generated as a result of said inflation status comparison or of inflating and/or deflating the balloon system based on control signals generated as a result of said inflation status comparison.  
      Other aspects of the method according to the invention are described in the claims. 
    
    
      The invention will now be described with reference to a drawing, which shows in:  
       FIG. 1 a  first embodiment of a device according to the invention;  
       FIG. 2 a  second embodiment of a device according to the invention;  
       FIG. 3 a  third embodiment of a device according to the invention;  
       FIGS. 4   a - 4   b  a fourth embodiment of a device according to the invention. 
    
    
      For the sake of clarity corresponding parts of the embodiments shown in the enclosed drawings are depicted with identical reference numerals.  
       FIG. 1  discloses a lateral view of an embodiment of a device for radiation treatment of proliferative tissue surrounding a cavity in an animal body according to the invention. In this drawing a part of the animal body is depicted with reference numeral  1 , for example the head of a patient, or a breast of a woman. A cancer tumour has been removed from said part  1  of said animal body during a surgical procedure a cavity  2 . As any cancer cell may still be present in the margins surrounding the surgically excised tumour in said cavity  2  a radiation treatment of said cancer cell is desirable with the use of radioactive emissions from energy emitting sources positioned inside said cavity  2 .  
      To this end an applicator  10  is introduced into the cavity  2 , which device  10  comprises a supportive probe  11  having an inflatable balloon system  12  connected to a distal end  11   a  of said supportive probe  11 . Once the deflated balloon system  12  has been introduced inside the cavity  2 , the balloon system  12  is inflated by suitable inflation means by injecting a pressurized medium  25  (for example a fluid) via a passageway  14  in the supportive probe  11  towards the distensible reservoir formed by the balloon system  12 .  
      Said pressurized medium  25  could be a fluid or a gaseous medium or a liquid containing radioactive particles. Also other type of pressurized media, radioactive or not, can be utilized.  
      In addition, the supportive probe  11  is provided with a guidance channel through which a flexible catheter tube  13  is guidable until it extends with its distal end  13   b  within the cavity  2 . The catheter tube  13  is connected with its proximal end  13   a  with radiation delivery means  20 , here a remote afterloader apparatus  20  for performing radiation therapy treatments of the cancer tissue surrounding the cavity  2 . The afterloader apparatus  20  contains a radiation shielded compartment  20   a,  in which compartment an energy emitting source  22  is accommodated.  
      The energy emitting source  22  is attached to a distal end  21   b  of a source wire  21 , which source wire can be advanced through the hollow catheter tube  13  by means of wire drive means  20   b.  The energy emitting source  22  can be advanced from said radiation shielded compartment  20   a  through the hollow catheter tube  13  towards a desired location within the cavity  2 .  
      The positioning of the energy emitting source  22  at different locations within its hollow catheter tube  13  and in the cavity  2  gives more possibilities for performing a radiation therapy treatment session. The total dose distribution of the tissue to be treated will be conformal with the volume of the tumour tissue surrounding the cavity  2  by optimizing the dwell times for the different positions within the cavity  2  of the energy emitting source  22 . Moreover the guidance of the energy emitting source  22  through the hollow catheter tube  13  within the cavity  2  allows a temporarily insertion of the source  22  in the reproducible manner at different locations.  
      With the use of an afterloader device  20  it is possible to use the device  10  according to the invention to perform radiation therapy treatment sessions with so called High Dose Rate (HDR) or Pulse Dose Rate (PDR) in emitting sources, which requires special and save handling prior to each treatment session. These HDR or PDR sources are characterised by a high radiation intensity profile and are thus for safety reasons accommodated in a radiation shielded compartment  20   a  within the afterloader  12 . A radiation therapy treatment session with such high intensity energy emitting sources requires specific proceedings concerning handling a storage of these sources.  
      To this end in a proper operation of the inflatable balloon system  12  is necessary in order to avoid any misadministration of a radiation dose to the patient. The device  10  according to the invention comprises monitory means for monitoring the inflation status of the inflatable balloon system  12 . More particular said monitoring means  16  uses at least one pressure sensor  17  which is accommodated in a medium conduct  15 . The pressure sensor  17  senses the actual pressure of the pressurized medium  25  inside the inflate balloon system  12 . Said sensor  17  generates a pressure signal  17   a  conformal with the pressure being sensed and said pressure signal  17   a  is fed to the monitoring means  16 .  
      According to the invention said monitoring means  16  are arranged in comparing said pressure being sensed by the pressure sensor  17  with a predetermined pressure bandwidth. Said predetermined pressure bandwidth describes a range of pressures of said pressurized medium  25  under which pressure circumstances the device  10  according to the invention can be operated under normal conditions.  
      In the event a significant deviation of the pressure being sensed by said pressure sensor  17  and the predetermined pressure bandwidth is detected the monitoring means  12  are arranged in controlling the device  10  based on control signals generated as a result of said pressure comparison.  
      In other words, in the event the pressure being sensed by the pressure sensor  17  lies outside the predetermined pressure bandwidth the monitoring means  16  will generate suitable control signals based on which the device  10  will be controlled. In a first control step a control signal  23   a  will be generated by the monitoring means  16  and fed to the afterloader apparatus  20  in order to actuate the wire drive means  20   b.  For example in the event that the pressure of the pressurized medium  25  inside the balloon system  12  becomes significantly low (for example due to a leakage) the control signal  23   a  generated by the monitoring means  16  will result in an immediate retraction of the source wire  21  and the emitting source  22  by the wire drive means  20   b.    
      In another embodiment (not depicted) the energy emitting source  22  is an activatable source, like an X-ray emitting source or laser device and in the event of a malfunction the device according to the invention (and in particular the afterloader  20 ) is arranged in de-activating the energy emitting source within the cavity  2 .  
      These safe measures prevent an uncontrolled radiation dose being administered to the cancer tumour surrounding the cavity  2  inside the animal body  1  during a malfunction (leakage) of the balloon system  2 .  
      In an other control step a control signal  23   b  generated by the monitoring means  16  will be fed to the inflation means  30  in order to actuate the inflation means such that the balloon system  12  is inflated or deflated until the medium pressure of the medium  25  present in the balloon system  12  will fall within the predetermined pressure bandwidth corresponding with the optimal operation conditions.  
      A specific embodiment of the inflation means is here described by way of example. However it should be note that also other types of inflation means are suitable and can be implemented in the device according to the invention. The inflation means  30  in this example comprise a piston-cylinder combination  30  having a cylinder  31  and a piston  32  which is movable accommodated in said cylinder  31 . The piston-cylinder combination  30  is provided with piston drive means  35  for displacing said piston  32  within the cylinder  31 . To this end the piston  32  is mounted on a piston rod  33 . The displacement of the piston  32  inside the cylinder  31  by the piston drive means  35  takes place based on control signals generated by the monitoring means  16 .  
      The piston-cylinder combination  30  is provided with an cylinder chamber  34  in which the amount of medium  25  for inflating the balloon system  12  of the device  10  according to the invention is accommodated. The piston-cylinder combination  30  is connected with the passage way  14  and the inflatable balloon system  12  by means of a medium conduct  15 . In said medium conduct  15  a supply vessel  19  is accommodated which is suited for storing a certain amount of medium  25 . The storage vessel  19  is closed by means of a first valve  18   a  which is accommodated in the medium conduct  15  between the piston-cylinder combination  30  and the storage vessel  19 . Between the piston-cylinder combination  30  and the passage way  14 /the balloon system  12  a second valve  18   b  is accommodated in the medium conduct  15 .  
      Both valves  18   a  and  18   b  can be actuated by the monitoring means  16  with the use of suitable control signals. For example in the event that the balloon system  12  needs to be inflated (for example as a result of a possible decrease in the operational pressure inside the balloon system  12 ) the monitoring means  16  generate suitable control signals based on the comparison between the actual sensed low pressure inside the balloon system  12  and the predetermined optimal pressure bandwidth. These control signals will effect a closure of the first valve  18   a  and an opening of the second valve  18   b.  A likewise actuation of the piston drive means  35  will be effected, such that medium  25  present in the cylinder chamber  34  is pushed through the conduct  15  through the open second valve  18   b  and the passage way  14  towards the balloon system  12 , thereby inflating the balloon system  12 .  
      Likewise, in the event that a too high pressure inside the balloon system is sensed suitable control signals generated by the monitoring means  16  will actuate the piston drive means  35  such that the piston  32  is retracted inside the cylinder  31  thereby redrawing or deflating medium  25  out of the balloon system  12  and the passage way  14  towards the cylinder chamber  34 . With this control step the actual pressure inside the balloon system  12  will decrease.  
      In  FIG. 2 a  further embodiment of a device according to the invention is disclosed wherein a pressure sensor  17 ′ is accommodated inside the balloon system  12  for detecting the actual pressure of the pressurized medium  25  within the balloon system  12 . The pressure sensor  17 ′ generates pressure data which are fed via a signal line  17   a  to the monitoring means  16 . The monitoring means  16  operate in the similar way as described in relation to the embodiment of  FIG. 1 .  
      In  FIG. 3  another embodiment of a device according to the invention is described, wherein an imaging device  17 ″ is used for generating image data, which correspond to the actual contour or shape of the balloon wall of the inflated balloon system  12 . The image data generated by the imaging device  17 ″ is fed via a signal line  42  and  17   a  towards the monitoring means  16 , which operate in a similar way as described in relation to the embodiments of  FIGS. 1 and 2 .  
      The imaging device  17 ″ in the embodiment as disclosed in  FIG. 3  is placed inside the balloon system  12  via an insertion catheter  40 , which is guided through an appropriate insertion channel (not depicted) present in the supportive probe  11  until within the balloon system  12 . The imaging device  17 ″ is connected to a signal cable  42 , which is inserted and retracted through the insertion catheter  40  until within the balloon system  12  using suitable drive means  41 .  
      In a first specific embodiment of the device as disclosed in  FIG. 3  the imaging device  17 ″ is inserted with the use of the signal cable  42  and the drive means  41  towards a specific position inside the balloon system  12  for example a centre position in the middle of the balloon system (not depicted). Subsequently the imaging device  17 ″ generates image data in one measurement “sweep” covering the whole actual balloon wall contour of the balloon system  12 .  
      In other functional embodiment the imaging device  17 ″ is advanced using the signal cable  42  by the drive means  41  in a step wise manner through the insertion catheter  40  through the balloon system  12  thereby generating image data in sequential measurements or “sweeps” of the actual balloon wall contour of the balloon system  12 .  
      The image data representing the actual balloon wall contour of the balloon system  12  is fed via the signal cable  42  and  17   a  towards the monitoring means  16 , wherein said image data is converted into a three dimensional balloon wall contour indicated with reference numeral  12 ′.  
      According to the method of the invention the monitoring means  16  are arranged in comparing said three dimensional balloon wall contour  12 ′ with a pre-determined balloon wall contour as depicted as a dashed circle and reference numeral  12 ″. Based on this contour comparison using the image data obtained with the imaging device  17 ″ any deviations or malfunctions of the balloon wall  12  are quickly detected and appropriate control can be performed in order to correct for the malfunctions being detected.  
      Likewise the imaging device  17 ″ can be positioned outside the cavity  2  and the patient&#39;s body  1  in order to generate an image of the cavity  2  using suitable imaging techniques.  
      The imaging device  17 ″ (placed inside or outside the cavity  2  in the patient&#39;s body  1 ) can be an ultrasound imaging probe or a video camera. Especially an ultrasound imaging probe or a video camera can be constructed in small dimensions in order to allow an insertion through the insertion catheter  40  until within the inflated balloon system  12 .  
      In  FIGS. 4   a - 4   b  another embodiment of a device according to the invention is described, wherein a radiation sensor  40  is used for generating radiation data based on detected radiation  22   a  as emitted by the energy emitting source  22 . Based on the general principle that the radiation intensity being emitted decreases with the distance, the radiation  22   a  being detected corresponds to the actual distance between the sensor  40  and the energy emitting source  22 .  
      As the radiation sensor is connected to the inner or outer wall of the balloon system  12  the distance between the sensor  40  and the energy emitting source  22  being placed within the cavity  2  is dependent from the inflation status of the balloon system.  
      In  FIG. 4   a  the ideal operational condition of the device according to the invention is depicted, where the balloon system  12  is inflated such that it is conformal with the inner dimensions of the cavity  2 . The distance between the radiation sensor  40  and the source  22  is optimal for performing radiation treatments and the radiation being emitted by the source  22  and detected by the sensor  40  corresponds to the pre-determined optimal distance, when the balloon system is inflated as in  FIG. 4   a.    
      The radiation data generated by the sensor  40  is fed via the signal line  17   a  towards the monitoring means  16 , which operate in a similar way as described in relation to the embodiments of  FIGS. 1, 2  and  3 . In the situation of  FIG. 4   a  a comparison by the monitoring means  16  between the actual distance being detected and a pre-determined distance will reveal no malfunction concerning the inflation status of the device.  
      However,  FIG. 4   b  discloses a malfunction wherein the balloon system becomes deflated. The radiation  22   a  being detected by the sensor  40  will reveal a shorter or decreased distance between the radiation sensor  40  and the source  22  emitting said radiation  22   a.  Said distance deviation will be detected during the “real time” radiation comparison as performed by the monitoring means  16  and suitable control signals  23   a  or  23   b  (see  FIGS. 1 and 2 ) will be generated and fed to the source wire drive means  20   a  of the afterloader  20  or to the inflation means  30  in order to correct for this malfunction.  
      Also in the event of an over-inflating of the balloon system  12  the radiation  22   a  being detected by the sensor  40  will reveal a longer or increased distance and also a suitable control of the device is performed by the monitoring means  16  in order to correct for this malfunction.  
      It will be appreciated that with the device according to the invention a more safe operation of a device according to the invention with the use of an afterloader apparatus is obtained wherein possible hazardous operational conditions are avoided as with a continuous monitoring of the actual pressure inside the balloon system  12  possible changes in the operational pressure will be sensed immediately and a suitable control of the device  10  according to the invention is performed by the monitoring means  16  in order to correct for the change in the operational status of the device (balloon system  12 ).