IMAGING CAPSULE

RELATED APPLICATIONS

The present application claims priority from US Provisional application number 63/151,724 filed on February 21, 2021, US Provisional application number 63/195,717 filed on June 2, 2021 and US Provisional application number 63/286,163 filed on December 6, 2021 the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the production of a radioactive substance for an intra-lumen imaging capsule.

BACKGROUND OF THE INVENTION

One method for examining the gastrointestinal tract for the existence of polyps and other clinically relevant features that may provide an indication regarding the potential of cancer is performed by swallowing an imaging capsule that will travel through the tract and view the user's situation internally. In a typical case the trip can take between 24-48 hours after, which the imaging capsule exits in the user's feces. Generally the capsule is surrounded by non transparent liquids therefore a radioactive material is used to image the user and not a visible light source.

Typically the user swallows a contrast agent to enhance the imaging ability of the imaging capsule. Then the user swallows the imaging capsule to examine the gastrointestinal tract while flowing through the contrast agent. The imaging capsule typically includes a radiation source, for example including a radioisotope that emits X-rays or Gamma rays. The radiation is typically collimated to allow it to be controllably directed in a specific direction during the imaging process. The imaging capsule typically includes a detector to detect particles from X-ray fluorescence and/or Compton back-scattering that are reflected responsive to the radiation emitted from the radiation source.

In a typical implementation a radio-opaque contrast agent is used so that a position with a polyp will have less contrast agent and will measure a larger back-scattering count to enhance accuracy of the measurements.

The imaging capsule records the measurements and transmits measurements (e.g. a count rate) to an external analysis device, for example a computer or other dedicated instruments for analysis and reconstruction of an image of the wall of the colon and/or small bowel.

US Patent application No. 7,787,926 to Kimchy the disclosure of which is incorporated herein by reference, describes details related to the manufacture and use of such an imaging capsule.

Generally, a selected amount of radioactive material is placed in a radiation chamber in the imaging capsule. Using high specific density radioactive material, it is possible to use a very small amount of material to have the desired activity. With a material having a lower specific activity, it is desired to have the radioactive material, which is usually dense and hence blocks radiation, mixed with a low-density x-ray transparent material to have the most effective release of a radiation flux from the radiation source, by having the dense radioactive material spread out so that it will not block the emission of radiation.

Typically the radioactive substance used to produce the radiation needs to have a long enough half life time so that it will be effective when used after being stored and shipped to the vicinity of the user. Additionally, the radioactive material needs to emit particles with sufficient energy to produce X-ray fluorescence and/or Compton back-scattering, which are detectable by the detectors in the imaging capsule. SUMMARY OF THE INVENTION

An aspect of an embodiment of the invention, relates to preparation of a radiation substance for use as a radiation source in an intra-lumen imaging capsule. An initial substance of mercury or gold of specific isotopes is taken to produce the radiation source. The initial substance is bombarded with electrons, neutrons, Protons, Deuterium or Alpha particles to produce a small amount of radioactive isotopes of mercury or gold with a half-life that enables it to serve as a radiation source for examining the gastrointestinal tract of a user, for example more than 48 hours or 72 hours to at least be active while examining a user’s colon. The bombarding process creates also other substances, therefore a chemical process is applied to separate the products and extract the desired radioactive isotope to be used in an imaging capsule. The extracted radioactive substance is introduced into a small canister that can fit inside an imaging capsule and be swallowed by a user.

There is thus provided according to an embodiment of the disclosure, a method of preparing a radiation substance for releasing radiation from an intra lumen imaging capsule, comprising:

Bombarding an initial substance with a neutron flux, proton nuclei, deuterium nuclei or electrons, producing products comprising one or more isotopes and/or isomers of which some are radioactive with a half-life of more than 48 hours;

Collecting at least one of the products of the bombarding to serve as a radiation source of an imaging capsule;

Introducing the radiation source into a canister configured to fit into an imaging capsule that can be swallowed by a user.

In an embodiment of the disclosure, the initial substance includes mercury (Hg 196) that is bombarded with a neutron flux to produce Hg 197 and Au 198; or includes gold (Au 197) that is bombarded with protons or deuterium nuclei to produce Hg 197m and Hg 197g; or includes gold (Au 197) that is bombarded with protons or deuterium nuclei to produce Hg 197m and Hg 195 that decays into Au 195. Optionally, the method further comprises separating the products of said bombarding with a chemical process to enable said collecting. In an embodiment of the disclosure, the method further comprises placing the canister into a swallowable imaging capsule. In an embodiment of the disclosure, the initial substance is a powder. Alternatively, the initial substance is a liquid. In an embodiment of the disclosure, the initial substance is bombarded in a high thermal neutron flux nuclear reactor. Alternatively, the initial substance is bombarded using a high energy linear accelerator or a cyclotron. Further alternatively, the initial substance is bombarded using electrons from an electron accelerator. In an embodiment of the disclosure, a superabsorbent polymer (SAP) is filled into the canister before introducing the radiation source. Optionally, the SAP is cured with UV light. In an embodiment of the disclosure, the canister is sealed with an adhesive. Optionally, the adhesive is cured with UV light.

In an embodiment of the disclosure, the chemical process dissolves the products of the bombarding. Alternatively or additionally, the chemical process etches an activated area of the initial substance to collect the products serving as the radiation source. Optionally, the canister is prefilled with a liquid absorbent. In an embodiment of the disclosure, the canister is put aside for a waiting period before it is ready to be placed in an imaging capsule to be swallowed by a user. Optionally, in the chemical process the radiation source is dissolved and mercury is extracted to be used as the radiation source leaving gold behind. In an embodiment of the disclosure, dense atoms of the radiation source are mixed with a chemical compound in the canister to spread out the radiation source and prevent radiation blockage. Optionally, the radiation source is introduced into the canister in liquid form. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and better appreciated from the following detailed description taken in conjunction with the drawings. Identical structures, elements or parts, which appear in more than one figure, are generally labeled with the same or similar number in all the figures in which they appear, wherein:

Fig. 1A is a schematic illustration of a first process of producing a radioactive substance, according to an embodiment of the disclosure;

Fig. IB is a flow diagram of a first process of producing a radioactive substance, according to an embodiment of the disclosure;

Fig. 2A is a schematic illustration of a second process of producing a radioactive substance, according to an embodiment of the disclosure;

Fig. 2B is a flow diagram of a second process of producing a radioactive substance, according to an embodiment of the disclosure;

Fig. 3A is a schematic illustration of a third process of producing a radioactive substance, according to an embodiment of the disclosure; and

Fig. 3B is a flow diagram of a third process of producing a radioactive substance, according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Fig. 1A is a schematic illustration of a first process 100 of producing a radioactive substance 110 and Fig. IB is a flow diagram 150 of the first process 100 of producing a radioactive substance 110, according to an embodiment of the disclosure. In an embodiment of the disclosure, an initial substrate 105 including a mercury isotope (Hg 196) is provided (155) to produce the radioactive substance 110, including Hg 197, by bombarding the initial substance 105 with a neutron flux 120. Optionally, the initial substance 105 (Hg 196) may be provided as mercury Hg 196 that is oxidized to form an HgO powder, reacted with Sulfur to form an HgS powder, reacted with chlorine to form Hg 2CI2 or reacted with chlorine and in addition with Oxygen to form Hg ₂ C10. Alternatively or additionally, the mercury Hg 196 may be reacted with chlorine, bromine and oxygen to form Hg4 (Br, 0)2 O2 or other compounds of mercury (Hgl96).

In an embodiment of the disclosure, a small quantity of the initial substance 105 in the form of a mercury based powder (e.g. between about 5-10 mg) is placed in a quartz tube 115 (or other appropriate container) and placed in a high thermal neutron flux nuclear reactor 101 to be activated (160). Typically the flux may be of the order of 1.6E14 n/cm ² /sec to 2E14 n/cm ² /sec and activated (160) by thermal neutrons for 100-200 hours, e.g., about 100, 150 or 200 hours.

In an embodiment of the disclosure, at the end of the activation (160) with thermal neutrons an enriched powder (radioactive substance 110) of Hg 197 is formed. Optionally, the activity of the Hgl97 that was formed in the reactor 101 is typically 18,000 mCi (millicuries) to 22,000 mCi per mg. Thus, a small quartz tube 115 with 5-10 mg of isotopically enriched Hgl96, with about 55% will typically provide 90,000 mCi to 220,000 mCi (for example in the case of 10 mg HgO (or other mercury compound)) in the quartz tube 115.

In an embodiment of the disclosure, imaging capsule 140 is designed to be swallowed providing 40-50 mCi so that at the end of the procedure after an average of 60 hours or so, the activity of the radiation source would be in the range of 15-25 mCi. Optionally, the radiation source is put aside for a waiting period of about 100 to 200 hours before using the radioactive substance llOin an imaging capsule 140. The waiting period enables the radiation source to reach a desired state in which it releases radiation with energies that are optimal for scanning the user and not hazardous (high energies that are harmful and not informative for the imaging capsule 140). Likewise it is assumed that transport time and logistics require about 100-200 hours for packaging (e.g., encapsulation in the imaging capsule 140, sealing and testing) and transporting the imaging capsule 140 to the user. The radioactive substance 110 of an imaging capsule at the outset, coming out of the reactor should provide radiation in the range of 200-400 mCi.

In an embodiment of the disclosure, the result (165) of the activation process includes radioactive Hg 197 and some radioactive Au 198. Optionally, a chemical process is applied to separate (170) the mercury (Hg 197) from the gold (Au 198). In a Hot Cell, the activated quartz tube 115 is opened and about 0.5 to 1 ml of concentrated HCL 122 is poured into the quartz tube 115 to dissolve the Mercury compound. The solution in the quartz tube 115 is stirred to make sure all the Mercury compound is dissolved. The solution 122 in the quartz tube 115 with the dissolved mercury compounds may form HgCL if HC1 is used to dissolve the powdered radioactive substance 110. The solution 122 is then poured into a rotation tube 117 designed to be inserted into a high speed centrifuge separator such as Eppendorf Microcentrifuge Model 5430 or 5430R (Eppendorf North America) the rotation tube 117 is then rotated at high speed, typically 15,000 - 20,000 RPM for a few minutes in order to separate the HgCL from the Gold micro particles that were formed in the nuclear reactor due to Hg 197 atoms decaying into Au 197. The Gold atoms were activated to become Au 198 due to the neutron flux 120 in the nuclear reactor 101. Using the centrifuge, the Gold particles are separated from the HgCL solution and sink to the bottom of the rotation tube 117 under the centrifugal force. Following the centrifuge separation, the solution 122 is collected from the top carefully not stirring the liquid in order not to collect the fine Gold powder at the bottom of the rotation tube 117.

The resulting product of this process (165) is a solution comprising Hg 197 typically with 200-400 mCi per uL that is then used as the radiation source for the X-Ray imaging capsule 140. Typically, this solution will be poured (175) into an aluminum or plastic canister 119, of about 1-2 uL per canister 119 and sealed (185), for example with an adhesive such as UV cured glue. The canister 119 may then be placed (190) inside the imaging capsule 140 to serve as the radiation source.

In some embodiments of the disclosure, a small amount of superabsorbent polymer (SAP) 125 is filled (180) into the canister 119 before introducing the liquid solution 122 of HgCh to cause the dense radioactive substance 110 to be surrounded by radiation transparent material (e.g., sponge like) to enhance the release of radiation from the radiation source. The superabsorbent polymer 125 may be produced by SAP solutions, such as an acrylic acid blended with sodium hydroxide in the presence of an initiator to form a poly-acrylic acid sodium salt (sometimes referred to as sodium polyacrylate). Alternatively, other materials may be used to produce the superabsorbent polymer (SAP) 125, such as polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, and starch grafted copolymer of polyacrylonitrile to name a few of the SAP 125 that may be dispensed into the canister 119.

In an embodiment of the disclosure, the SAP 125 is made of a mixture of acrylic acid, water, cross-linking agents, and UV initiator chemicals that are blended. The liquid HgO, HgS or other Mercury compound solution 122 is dispensed into a canister 119 filled with the SAP 125. Optionally, UV cured glue is used to seal the top of the canister 119. The canister 119 is then subjected to high intensity UV which both polymerizes the SAP inside the transparent canister 119 and at the same time polymerizes the UV cured glue sealing the canister 119 for use as a radioactive source for the x-ray imaging capsule.

In an alternative embodiment of the disclosure, the activation process (160) of the initial mercury based powder substance 105 is performed for a short period of time, for example for 6 hours in a reactor with 4E13 n/cm ² /sec thermal flux for which lmg of 55% Hg 196 isotopically enriched HgO ends up with 353 mCi/mg activity. Due to the short activation time, only a small amount of Aul98 is formed, therefore the Aul98 can be ignored and the separation process is not performed to separate the gold from the powdered radioactive substance 110 (e.g., HgO). The HgO, HgS or other Mercury compound is then mixed with a low radiation absorbing polymeric paste (e.g., the denture silicone impression material elite HD+ manufactured by Zhermack from Italy) and then dispensing the mixed paste into an aluminum canister or plastic canister for use in the x-ray imaging capsule 140.

In a further alternative embodiment of the disclosure, HgO, HgS or other Mercury compounds (radioactive substance 110) that have been activated for a short time in a reactor as described above are dissolved in high concentration HC1 or other acid to form HgCh solution or other Hg based compound solution. The solution is dried and then dissolved with a small amount of Alcohol, typically 2-3 uL/mg of the Hg compound, and then the process follows a similar route as described above mixing the solution with a SAP.

In a further alternative embodiment of the disclosure, a Chromatography technique is used to separate between the Hg compound in the solution and the Gold atoms suspended in the solution. For this process, a solvent is allowed to climb through packed columns where the rate of ascent is different for different solutes, including the Hg and the Gold particles. Flash Chromatography may also be used where the solute is pressured through the column. Other types of Chromatography such as Planar or Thin-Fayer Chromatography may be used for this separation. Fig. 2A is a schematic illustration of a second process 200 of producing a radioactive substance 210 and Fig. 2B is a flow diagram 250 of the second process 200 of producing the radioactive substance 210, according to an embodiment of the disclosure.

In an embodiment of the disclosure, gold (Au 197) is used as an initial substance 205 for producing a radioactive mercury Hg 197 substance 210. The initial substance 205 is bombarded for example, using a high energy linear accelerator or a cyclotron 201 with protons 220, deuterium nuclei or alpha particles to irradiate gold atoms and transform them into mercury isotopes/isomers. This nuclear reaction, which is with an optimal cross section of about 82 mB (millibam) at around 10 MeV produces (265) Hgl97g (with a half- life of 64 Hours) and some Hgl97m (cross section 32 mB with a half-life of 23 Hours) that decays to Hgl97g emitting 137 and 279 Kev gamma photons. The aim is to minimize the user’s exposure to harmful radiation from the Hgl97m, which emits particles with energies that could penetrate the imaging capsule shield and particles with energies that may be harmful to the user.

In an embodiment of the disclosure, this problem is avoided by waiting long enough for the Hgl97m to substantially decay, leaving mostly Hgl97g with only a relatively small amount of Hg 197m; hence the proton energy is chosen for max Hgl97g and min Hgl97m taking into account that by the time the source will be in the user, there will be much less Hgl97m due to its shorter half-life. Typically, 200 mCi (100 mCi of Hgl97g and 100 mCi of Hgl97m) will require waiting 120 hours to by which time there will be 62 mCi of Hgl97g and 2.5 mCi of Hg 197m. This source can then be used in the x-ray imaging capsule with low exposure for the patient.

For high volume production of Hgl97, a high current accelerator or cyclotron is preferable, typically with a beam current of 5-10 mA. This beam flux allows for a few tens of sources to be produced every hour.

In an embodiment of the disclosure, after Positron or Deuterium bombardment (260), the radioactive substance 210 is separated (270) in a chemical process by rinsing the radioactive substance 210 in high concentration Nitric acid solution 217 (typically 70%) to dissolve the mercury (Hgl97) while not dissolving the gold (Au). The solution 217 is then dispensed the liquid into a canister 219 containing a superabsorbent. (SAP) 225. The canister 219 is then assembled and sealed, for example by pressure or an adhesive such as UV cured glue. The source is then ready to be placed in the capsule 140.

In an embodiment of the disclosure, irradiation by bombardment (260) may be performed with 18 MeV protons on the surface of the target with a maximum beam current of up to 10 m A. A 1 mm aluminum (Al) vacuum window acts as an energy degrader from 18 to 10 MeV which is the target proton energy for selection of the ratio of Hgl97g vs. Hgl97m.

Radiochemical separation

In an embodiment of the disclosure, the source substance 205 is provided in the form of a disk or foil. Optionally, for the partial dissolution of the irradiated product side a pneumatic device with a PTFE mask sealed by an O-ring exposing only the irradiated side of the radioactive substance 210 to the acid is applied to the radioactive substance 210 in the form of a disk or foil. Thus, it has no contact to areas of the radioactive substance 210, which have been exposed to metal parts or cooling water of the cyclotron while the acid dissolves the target material. The etching of the irradiated part of the gold disk or foil is carried out with 0.7 mL of aqua-regia (30% HCl+65% HNO3) at room temperature for 90 min. The resulting solution 217 is then decanted in a 5 mL round flask for evaporation to dryness using a rotary evaporator. To avoid loss of activity the bath temperature is limited to 40 °C and the pressure is carefully reduced stepwise from 100 mbar to 1 mbar. The drying process is finished after complete crystallization of the yellow residue. The resulting solid was redissolved in 500 ml 2 Mole HC1 and the remaining Au material is extracted with four 500 ml MIBK. The main part of mercury radionuclide (60-80%) remains in the 2 Mole HC1 which is evaporated to dryness again. The residue is dissolved in 0.5 ml 0.2 Mole HC1 and is then ready to be dispensed into canisters with 2 pL per canister. Exemplary processes

In another embodiment of the disclosure, the radioactive substance 210 (HgO + AuO) after neutron activation in a reactor or other suitable thermal neutron source is dissolved in high concentration acid and tested to validate that the right radioactivity concentration can be achieved for a source suitable in size and in activity for the X-Ray imaging capsule.

Dissolution in Nitric Acid:

In an embodiment of the disclosure, nitric acid may be used. With nitric acid complete dissolution after about 0.5 hours of magnetic mixing of 0.541 gr HgO in 0.7054g HNO3 was observed. A clear colorless solution was obtained. The solution is stable due to an excess of nitric acid.

HgO +2 HNO3 = Hg (N0 ) ₂ + H2O

Separation of Mercury (Hu) from Gold in the solution

In an embodiment of the disclosure, mercury nitrate is used since it is a salt with sufficient solubility to meet the concentration requirements. The mercury nitrate is formed by the dissolution of mercury II oxide in nitric acid, however under these conditions any gold oxide present will also react to give a soluble gold nitrate salt.

Mercury and gold nitrates may be separated by the action of hydrogen peroxide which selectively reduce the gold nitrate to solid gold metal, leaving the mercury II nitrate in solution. The gold precipitate can then be removed by microfiltration. Mercury nitrate solutions are unaffected by hydrogen peroxide.

Absorption of Aqueous Mercury Nitrate:

Optionally, the volume available in a canister is 4pL into which lpL of mercury nitrate solution needs to be inserted on a solid substrate, i.e. 1 part solution on 3 parts absorbent. Several solid absorbents may be used such as SAP polymers and inorganic sorbents such as zeolites, silica gel, alumina, activated carbon etc.

Fig. 3A is a schematic illustration of a third process 300 of producing a radioactive substance 310, and Fig. 3B is a flow diagram 350 of the third process 300 of producing the radioactive substance 310, according to an embodiment of the disclosure.

In an embodiment of the disclosure, the initial substance 305 provided (355) is gold (Au 197) for producing a radioactive gold Au 195 substance 310 with a half-life of 186.1 days. The initial substance 305 is bombarded (360) for example, using a high energy linear accelerator or a cyclotron 301 with protons 320 or deuterium nuclei to irradiate gold atoms and transform them into mercury and gold isotopes.

This nuclear reaction which is with optimal cross section of about 780 mB at around 30 MeV. Produces (365) Hg 195m (proton, 3 neutron reaction) (half-life 40 Hours) and some Hg 195 (half-life 9.9 hours), which decays into Au 195 emitting gamma photons, x-ray photons and beta electrons of various energies. The aim is to minimize user exposure to radioactive substances that produce hazardous energies; hence, after producing Hg 195m and some Hg 195, using optimal timing to maximize production before saturation due to the half- life. Optionally, the Hgl95m and Hgl95, which decays to gold (Aul95), are separated chemically (370) from the radioactive substance 310 by processing the radiation substance 310 using the method for separation of Mercury from Gold as described above. In an embodiment of the disclosure, the radioactive substance 310 is placed in a container 317 with a solvent 322. Alternatively the mercury and gold may be separated using an ion exchange process. The dissolved Hgl95 is dispensed (375) into small canisters 319, which are then filled (380) or pre-filled with a liquid absorbent 325 such as cellulose, cotton wool, or using a chemical reaction to lock the Hg atoms in a cement like matrix, for example, using CaO and dissolving HgO in Nitric Acid, then mixing them to form a matrix that holds the Mercury (Hg) spread out inside the cement.

Following the filling of canisters 319 with the radiation substance 310 extracted from the Cyclotron/accelerator, in a liquid form, the canister 319 is sealed (385) and put aside for a waiting period, for example for 300-600 hours before it is ready for use and placed (390) in an imaging capsule 140 to be swallowed by a user. This delay time is planned to allow for the Fig 195m, Hgl95 and other small fractions of radionuclide short lived isotopes to decay so that by the end of this decay period, almost all radionuclide impurities are diminished and only Au 195 with a half-life of 186.1 Days remains. This radioisotope has low fractions of high energy components, thus exposes the user to a minimal dose while the capsule is not scanning, and the collimator shutter is closed.

For high volume production of Hg 195m and Hg 195 that decay to Au 195, a high current accelerator or cyclotron 301 is preferable, typically with a beam current of 1-10 mA. This beam flux allows for a few tens of sources to be produced every hour.

In an alternative embodiment of the disclosure, an electron accelerator is used to promote "stopping radiation" producing gamma photons with energies in the range of 10-25 MeV. Using photonuclear reactions with Gold as the target, (Aul97, >99.99%) to induce a (v,2n) reaction to produce Au 195 radioisotopes. After Irradiation, the Au 195 is dissolved and dispensed into small canisters filled with liquid absorbent such as cellulose, cotton wool, or using a chemical reaction to lock the Au atoms in a cement like matrix and maximize radiation release by having the dense atoms spread out to prevent self-absorption of radiation. The canisters 319 are then left for a long period of time, typically 60 days or more (10 half-lives of Au 196) to reduce the amount of Au 196 which is formed by a (v, n) and has a half-life of 6.183 days and needs to be reduced since this isotope emits high energy gamma photons which contribute substantially to the user exposure.

Alternatively, the Au target is grinded to a fine powder and the powder is mixed with a paste to stabilize the position of the powder and reduce self- absorption. The mixture is then filled into small (e.g., cylindrical) canisters 319, sealed and used as the radiation source for the imaging capsule 140. The canisters 319 are initially left for a long period of time, typically 60 days or more (10 half- lives of Au 196) to reduce the amount of Au 196 which was formed by the bombarding (v, n). The Au 196 has a half-life of 6.183 days and needs to be reduced since this isotope emits high energy gamma photons which contribute substantially to the user exposure to harmful radiation.

In an alternative embodiment of the disclosure, an electron accelerator is used to promote "stopping radiation" producing gamma photons with energies in the range of 10-25 MeV. Using a photonuclear reaction with Mercury (Hg) as the target, (e.g., encased in an aluminum cylinder or hallow sphere) activating the Hg 198 Isotope in the Mercury, which has 10% abundance in natural Mercury to induce a (v, n) reaction, producing Hg 197 radioisotopes. Other radioisotopes that may be produced in this process decay within minutes and some stable Isotopes of Mercury (Hg) are also produced but have no effect on the x-ray radiation emitted from the radiation source. After Irradiation, Hg is dispensed into small canisters filled with a liquid absorbent such as cellulose, cotton wool, or using a chemical reaction to lock the Hg atoms in a cement like matrix and maximize radiation release by having the dense atoms spread out to prevent self-absorption of radiation.

Alternatively, other forms of mercury (Hg) compounds such as an HgO or HgS powder are used as the initial substance. The compound may be placed in a hollow sphere or cylinder and bombarded. After being activated by bombarding, the target may be processed and placed into canisters as described above.

In another embodiment of the disclosure, Three routes to get sufficiently pure 195 Au with a half-life of about 186.1 days, are used: the 194Pt(d,n), 195Pt(p,n) or 193Ir(3He,n) reactions on highly enriched targets and appropriate limitation of incident particle energy and/or applying long cooling times to let the shorter-lived Au by-products decay. In these above reactions, the start material is enriched Platinum 194, enriched platinum 195 or enriched Iridium 193. That are bombarded in an accelerator/cyclotron with Deuterium, Protons and/or Alpha particles respectfully to produce Au 195. In all these reactions, a long wait will decay unwanted radioactive isotopes and leave Au 195 as the dominant isotope for use in the x-ray imaging capsule with only traces of other radioisotopes with a substantially shorter half-life.

It should be appreciated that the above described methods and apparatus may be varied in many ways, including omitting or adding steps, changing the order of steps and the type of devices used. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every embodiment of the invention. Further combinations of the above features are also considered to be within the scope of some embodiments of the invention.

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims, which follow.