Abstract
For accurate and easily shielding irregular shaped organ, its minimized penumbra region and a low melting point alloy 'Lead Y' and synchronizing instrument have been developed. The 'Lead Y' is the quaternary eutectic alloy and it is composed of Lead 30.0% Tin 11.5% Bismuth 48 5% Cadmium 10.0% The density of its at $22^{\circ}C$ is $9.8g/cm^3$ and the melting temperature has $40^{\circ}C\;to\;68^{\circ}C$. The thickness of 'Lead Y' for perfect shielding of Co-60 gamma ray and LINAC 10MeV x-ray is 6cm and 7cm respectively. The 'Lead Y' shielding block is casted directly on the styrofoam from which is cut with hot wire of synchronizer device. The special features and advantages of the Lead Y shielding block could be summarized as follows; 1. The shielding block for radiotherapy is rapidly processed only with boiling water and styrofoam. 2. It is not injure one's health and not danger of a fire, because of not generating of any metals vapor and evil smelling. 3. It is very effective to minimize secondary penumbra for the protection of healthy tissue from unnecessary ionizing radiation regardless of the magnification source to skin distance. 4. The HVL of the Lead Y is 1.2cm for Co-60 gamma ray and it's shielding effect is almost same as the pure lead block. 5. The hardness of Lead Y is 1.5 times higher than lead block. 6. It's reavailability is higher than lead block and then one block of Lead Y is reavailable about 30 to 40 times. 7. It is usefull for shielding of x-ray, gamma ray, beta-ray, electron and neutron radiation. 8. The materials for Lead Y are easy to acquire with reasonable price and tractable.
고(高)에너지 방사선(放射線) 치료(治療)에 있어서 정상조직(正常組織)의 완전차폐(完全遮蔽)를 위하여 $5{\sim}8cm$ 납두께의 부정형(不定形) 차폐(遮蔽)벽돌을 제작(製作)해야하는 난점(難點)이 있었다. 저자(著者)들은 납 30.0%, 주석 11.5% 비스므스 48.5%, 카드미늄 10.0%를 사중(四重) 공정결합(共晶結合)시켜 밀도(密度)가 $9.8g/cm^3$ 용융온도(熔融溫度)가 $68^{\circ}C$인 저용융(低熔融) 차폐물질(遮蔽物質)을 개발(開發)하여 이를 Lead Y라고 명명(名命)하였다. 제작(製作)된 Lead Y Block을 $68^{\circ}C$에서 용융(熔融)시켜 보호(保護)해야할 중요(重要)한 장기(臟器)의 형태(形態)대로 제작(製作)된 styrofoam 음형(陰形)에 부어서 차폐효과(遮蔽效果)가 큰 차폐(遮蔽)벽돌을 쉽고 안전(安全)하게 제작(製作)할 수 있었고 납보다 더 단단하고 재현성(再現性)이 크며 저렴(低廉)한 가격(價格)으로 구입(購入)이 가능(可能)하므로 방사선(放射線) 치료효과(治療效果)에 큰 도움을 줄 수 있었다.