Europäisches Patentamt *EP001084733A1* (19) European Patent Office Office européen des brevets (11) EP 1 084 733 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.7: A61N 5/10, G21G 4/08, 21.03.2001 Bulletin 2001/12 A61K 51/12 (21) Application number: 99118544.8 (22) Date of filing: 20.09.1999 (84) Designated Contracting States: • Menuhr, Helmut, AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU c/o AEA Technology QSA GmbH MC NL PT SE 38110 Braunschweig (DE) Designated Extension States: • Hunt, Dave, Dr., c/o AEA Technology plc AL LT LV MK RO SI Oxfordshire OX11 ORA (GB) (71) Applicant: AEA Technology QSA GmbH (74) Representative: Teipel, Susanne, Dr. 38110 Braunschweig (DE) Schwabe, Sandmair, Marx Patentanwälte (72) Inventors: Stuntzstrasse 16 • Fritz, Eberhard, Dr., 81677 München (DE) c/o AEA Technology QSA GmbH 38110 Braunschweig (DE) (54) Radiation source for endovascular radiation treatment in form of a wire (57) The present invention relates to a radioactive or then activated activatable material is a β-emitter, a γ- radiation source in form of a wire comprising a matrix of emitter or x-ray emitter. The source may further com- a ductile and/or plastic bindermaterial and a radioactive prise a means for containment. and/or activatable material. Preferably the elastic bind- The radioactive radiation source of the invention is ermaterial is a metal, a metal alloy or a radiation resist- preferably used in intravascular radiation treatment e.g. ant plastic material or mixture thereof. The radioactive to treat cancer, tumours, non-malign cell growth, or scar tissue or to prevent restenosis. EP 1 084 733 A1 Printed by Jouve, 75001 PARIS (FR) 1 EP 1 084 733 A1 2 Description general has been applied advantageously, the devices available for delivery of radiation sources and the radi- [0001] The present invention relates to a radiation ation sources themselves have certain drawbacks source for use in endovascular radiation treatment with which limit their usefulness. Typically, the devices in- fission product radioactivity and/or irradiation activated 5 clude a catheter, which is directed by way of a guide wire radioactivity, which radiation source is provided in the inserted therein to the site of treatment. The catheter is form of a wire and is suitable for being delivered in a then used to internally direct the radiation source to the catheter to the selected site to be treated within the vas- site of treatment. cular system of a patient. The invention further relates [0007] One typical problem encountered with the to use of said radiation source as well as a method of 10 catheter and/or the radiation source is related to stiff- treatment. ness of the source which is essentially proportional to its length. Thus shorter radiation sources are typically BACKGROUND OF THE INVENTION used to allow them to follow the tortuous anatomy of the heart. To irradiate the entire site of the vessel to be treat- [0002] Endovascular radiation treatment is the 15 ed a so-called "stepping-treatment" is then employed, present method of choice to prevent formation of scar wherein the radiation source is moved back and forth in tissue in a blood vessel which has been injured in vari- the vessel. Since, however, exact positioning is not pos- ous ways, for example, as trauma from surgical or diag- sible in a constantly moving vessel, irradiation is not pre- nostic procedures or for treatment of cancer and tu- cisely controllable in this "stepping-treatment". Thus, mours. One area of the vascular system of particular 20 long sources are desirable which allow for one-step concern with respect to such injury relates to coronary treatment of the site in its entire length. arteries that are subjected to procedures for removing [0008] For example, US-A-5,833,593 discloses a flex- or reducing blockages due to plaque within the arteries. ible source wire which is modified at its treatment end Partial and even complete blockage of the coronary ar- to receive a radioactive element. A plug seals the un- teries by the formation of an arteriosclerotic plaque is 25 modified section of the source from the lumen of the well known and a serious medical problem. Such block- modified segment or container which contains the radi- ages may be treated using arterectomy devices which oactive element. Both ends of the source wire are mechanically remove the plaque, hot or cold lasers sealed to prevent leakage of radioactivity. which vaporise the plaque, stents which hold the artery [0009] US-A-5,683,345 discloses an apparatus and a open and other devices and procedures well known in 30 method for brachytherapy. The radiation source used the art. The most common of them is the percutaneous according this document consists of individual treating transluminal coronary angioplasty (PTCA), more com- elements which may be joined together to form a train monly referred to as balloon angioplasty. of treating elements by use of several lengths of high [0003] Long term success of balloon angioplasty pro- tempered spring wire to prevent the treating elements cedures is largely limited due to restenosis or re-closing 35 from becoming too spaced apart while moving through of the intraluminal passageway through the artery by for- the catheter. mation of scar tissue. Restenosis is experienced in ap- [0010] Other typical drawbacks encountered with pri- proximately 30 to 50 % of the patients within six months or art radiation sources and devices for delivering the after balloon angioplasty. Apparently, restenosis is to a same to the site to be treated are related to the duration significant extent a natural healing response to the ves- 40 of exposure, controllability of the radiation exposure sel injury caused by inflation of the angioplasty balloon. (dosage, homogeneity of treatment), the necessity to [0004] Prior attempts to inhibit restenosis have includ- conduct a "stepping-treatment", or difficulties in com- ed the use of various light therapies, chemo-therapeu- pletely and controllably retracting the radiation source tical agents, stents, arterectomy devices, hot and cold from the catheter and therefore the risk of undesirable lasers and so on. The most promising approach to inhibit 45 exposure of both the patient and any medical personal restenosis after PTCA is the use of endovascular radi- "handling" the treatment device. ation therapy, i.e. the exposure of the potential or actual [0011] To solve this problem the European patent ap- restenotic site to ionising or radioactive radiation (brach- plication No. 99 111 100.6 discloses a radiation source ytherapy). comprising a deflectable container comprising at least [0005] Another important field for radiation treatment 50 two seeds or radiation emitting elements. The deflecta- is the localised, internal radiation treatment of cancer, ble container joins the relatively short and stiff seeds to tumours and/or non-malignant cell growth. The advan- form a flexible radiation source. Similarly EP 99 111 tage of a localised radiation treatment is that the healthy 099.0 teaches to form a flexible radiation source by di- tissue surrounding said tumour is exposed to the possi- rectly linking the individual seeds together while still al- bly hazardous radiation to only a very minor extent, 55 lowing relative movement. Still both radiation sources since the radiation can be directed specifically to the tar- have the problem that they are limited with respect to get region of the tumour. miniaturisation in that they either require the container [0006] Although endovascular radiation therapy in or require providing the linkage between the seeds. The 2 3 EP 1 084 733 A1 4 latter radiation source further implies the risk that the vention is used in brachytherapy, preferably endovas- linkage between the seeds is interrupted during the cular brachytherapy, to treat restenosis, cancer, tu- treatment. In this case it may be difficult to retract the mours and non-malignant cell growth or scar tissues. entire radiation source out of the body to be treated. [0022] The present invention makes possible the ob- [0012] Further, in manufacture of the seeds or source 5 jects of (1) providing a radiation source having in- there is the constant demand for miniaturisation, since creased mechanical stability at sufficient flexibility of the only miniaturisation will provide sufficiently small sourc- source to follow the bends of a small vessel, of (2) pro- es to treat smaller vessels of the patient and thus to suc- viding improved security in view of leakage of radioac- cessfully allow for cancer or tumour therapy in other an- tive material in case the source is damaged or otherwise atomical sites. 10 manipulated during manufacture thereof e.g. by cutting [0013] It is the object of the invention to overcome or forming the same, of (3) providing a considerable sim- these and other drawbacks of prior art radiation sources. plification in manufacture of producing the radiation source, especially when activatable materials are used, and of (4) allowing for miniaturisation of the source in SUMMARY OF THE INVENTION 15 the sub-millimeter region. [0014] This object is solved by the radiation source of DETAILED DESCRIPTION OF THE INVENTION the invention as disclosed in the appending claims. [0015] According to the present invention there is pro- [0023] The present invention provides a radioactive vided a radioactive radiation source in form of a wire 20 radiation source in form of a wire comprising a matrix of comprising a matrix of a ductile and/or plastic binderma- a ductile and/or plastic bindermaterial and a radioactive terial and a radioactive and/or activatable material. and/or activatable material. Said activatable material [0016] Preferably, the plastic bindermaterial has a low can be transformed into an activated material, usually capture cross-section for the method of activation of the in the form of an isotropically enriched stable isotope, to activatable material and/or a low attenuation factor for 25 obtain the activated radiation source to be used in ther- the emitted radiation.