Study Of The Dosage Distribution Character In Iridium-192 Single Lume Radiotherapy Shielding

OBJECT:To investigate the character and rule of peripheral dosage distribution,which 3 different lead shields produced inside Iridium-192 single-cavity after-loading.It would provide theoretical basis for different angle shielding and for after-loading in-cavity radiotherapy for rectal carcinoma.MATERIAL AND METHOD:3 different angle lead shields were made,then the dosage around the cavity was measured and dosage distribution curve discribed after lead shielding using Iridium-192 alter-loading machine,slow sensitive film and density instrument.The character and rule of dosage distribution was studied.RESULT:The effective shielding scale was 83.8±3.7,144.5±2.9 and 190.3±2.7 respectively when lead shields were 120°,180°and 240°.CONCLUSION:It will be useful for protecting normal tissues while selecting suitable lead shields.That is when the cancer tissue was irradiated by radical cure radiation dosage the normal tissue was irradiated by lower and tolerable dosage.It would decrease the incidence of complication and adverse effects.