| abstract |
Particles or "seeds" (10) are manufactured for implantation into tumours within a human body for emitting X-rays to destroy or reduce the tumours. The seeds contain palladium (14) which is substantially enriched in a palladium-102 and which is activated by exposure to neutron flux so as to contain a minor, but significant, fraction of X-ray emitting palladium-103. The palladium is distributed in or throughout a base material so as to reduce self-shielding by the palladium. The seeds include an X-ray-opaque marker (18) to facilitate external visualization of the seeds after their implantation, the marker preferably being formed of a material, such as lead or rhodium, which does not activate to contain undesirable isotopes under the radiation conditions in which palladium-102 is activated to palladium-103. The base material-distributed palladium and the marker are encased in an elongated shell (22) which is formed by welding a pair of end caps (27) to a tubular member (24), the construction of the shell reducing the mass of material at the end of the seed, thereby providing a more isotropic angular distribution of X-rays. |