| 摘要 |
A brachytherapy source for use in radiation treatment of the body includes radioactive material, and a housing. The housing is used to contain the radioactive materials, and is formed by at least one tube having two ends. The two ends of the at least one tube are sealed by welding such that a radiation distribution of the brachytherapy source approximates a point source that is free of cold zones to minimize underexposure or overexposure of the body to radiation and to simplify the placement of the brachytherapy source in the body. Preferably, the ends of the at least one tube are sealed by laser welding, and a laser performs the laser welding while the brachytherapy source is rotated relative to the laser, which is activated in short pulses. For example, the laser is activated in a first series of pulses to initially collapse one end of the at least one tube and to at least partially close off the one end, then the laser is activated for a second series of pulses to seal off the one end of the at least one tube and remove excess material, next the laser is activated in a third series of pulses to initially collapse the other end of the at least one tube and to at least partially close off the other end, and finally, the laser is activated for a fourth series of pulses to seal off the other end of the at least one tube and remove excess material. |
