Preparation of ceramic microspheres for in situ radiotherapy of deep-seated cancer.
Radiotherapy is one of the most effective treatments for cancers. However, external irradiation provides only small doses to deep-seated cancers, and often causes damage to healthy tissues. It has been reported that 20-30 microm diameter 17Y(2)O(3)-19Al(2)O(3)-64SiO(2) (mol%) glass microspheres are useful for the in situ irradiation of cancers. Yttrium-89 (89Y) in this glass can be neutron bombarded to form the beta-emitter 90Y (half-life=64.1h). When injected in the vicinity of the cancer, such activated glass microspheres can provide a large localized dose of beta-radiation. The Y(2)O(3) content of the glass in the microspheres is limited to only 17 mol%. Chemically durable microspheres with a higher Y(2)O(3) content need to be developed. Phosphorus-31 (31P) with 100% natural abundance can also be activated by neutron bombardment to form the beta-emitter 32P (half-life=14.3d). Chemically durable microspheres containing a high phosphorus content are expected to be more effective for cancer treatment. We prepared pure Y(2)O(3) and YPO(4) microspheres using a high-frequency induction thermal plasma melting technique, and investigated the resulting structure and chemical durability. We successfully prepared smooth, highly spherical polycrystalline Y(2)O(3) and YPO(4) microspheres with diameters in the range 20-30 microm. Both the Y(2)O(3) and YPO(4) microspheres showed high chemical durability in saline solutions buffered at pH=6 and 7. These microspheres are expected to be more effective than the conventional glass microspheres for the in situ radiotherapy of cancer.
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan. kawashita@sung7.kuic.kyoto-u.ac.jp
Masakasu
M
Kawashita
Ryo
R
Shineha
Hyun Min
HM
Kim
Tadashi
T
Kokubo
Yoshiaki
Y
Inoue
Norio
N
Araki
Yasushi
Y
Nagata
Masahiro
M
Hiraoka
Yoshiki
Y
Sawada
D001918:Brachytherapy / Q000379:methods*; D002516:Ceramics / Q000138:chemical synthesis* / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage* / Q000138:chemical synthesis*; D006801:Humans; D007267:Injections; D008422:Materials Testing; D008863:Microspheres; D009369:Neoplasms / Q000532:radiotherapy*; D010316:Particle Size; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015019:Yttrium / Q000737:chemistry*; D015021:Yttrium Radioisotopes / Q000008:administration & dosage*
D020099:Coated Materials, Biocompatible; D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D015019:Yttrium; C091417:yttria