Khảo sát các điều kiện ảnh hưởng lên sự ổn định màu của liều kế radiochromic dạng phim sau chiếu xạ

KHAO SA T CA C DIE U KIEN ANH HlTdNG LEN SU* ON DINH MA U

CUA LIEU KE RADIOCHROMIC DANG PHIM SAU CHIEU XA

NGUYEN NGUYET DIEU, DOAN BINH, PHAM THI THU HONG,

CAO VAN CHUNG, NGUYEN THANH DUOC

Trung tdm Nghien ciru vd Trien khai Cdng ngh? Buc xg

202A Dudng 11, P. Linh xudn. Q. Thu DOc, Tp. Ho Chi Minh

Email: [email protected]

Abstract: B3 dosimeter is a thin film with average thickness of 0.0194 mm, which is

supplied by the Gex Company from the United States. This dosimeter was influenced

by many factors: light, temperature, humidity during and after irradiation process. In

fact, B3 film dosimeters will be stable under certain conditions such as tightly sealed

packs, controlled irradiation and stored temperature after irradiated. Therefore,

investigation of the stability effect of postirradiated B3 film dosimeters on the heating

temperature, heating time and storing time is carried out before the absorbed dose is

read and followed standard reading procedures. When exposed to ionizing radiation,

the dosimeters change from colorless to colour. The absorbed doses are read on a

Genesys 20 Spectrophotometer at a wavelength of 544 nm. Absorbed dose range is

investigated from 0.55 to 80 kGy. Experimental results were indicated that colour

stability of the postirradiated dosimeters at a temperature of 65± 3°C for 30 minutes

and keeping them in desiccator for 5 minutes before read out. Under these conditions,

colour stability of B3 film dosimeter has maintained for 3 months.

Tdrklwa: chieu xg. do dn dinh, gamma, lieu ke dgng phim

I. Gl6l THIEU

Lieu ke dang phim B3 dupe san xuit boi Cong ty Gex - Hoa Ky. Cdng ty Gex cung

cap lieu ke phim B3 va h$ do lieu hoan chinh, sau khi da thuc bien nhieu cai tien chdt lugng

trong qua trinh san xuat va dong goi sdn phdm, nhihig cdi tien lien tuc nay mang lal ket qua

cao va giam sai so trong qua trinh chieu xg ciing nhu dgc lieu.

Lieu ke dupe dtuig de xac djnh lieu hap thu buc xa nguon gamma va tia dien tu dua

tren dp chuyen mau khi tiep xiic voi biic xg ion hoa. Lieu ke phim B3 c6 kich thuoc nho ggn,

\k dgng mang mong eo dg day trung binh 0,0194 mm, thanh phdn cau tao la hon 90% PVB,

con lgi la chdt mau, chat mau trong lieu ke co cdu tnic ben la hexa (hydroxyethyl) amino

triphenyl acetonitril. Lieu ke co tinh on dinh truoc va sau khi chieu xa, co dp hap thu gdn

giong voi nuoc.

Lieu ke dang phim B3 chiu tac dgng cua nhieu yeu to nhu nhiet do, dp am va thoi gian

luu sau chieu xa. Sau chieu xa, lieu ke dugc sdy va li trong dieu ki6n nhiet dp va thoi gian

thich hop nham 6n dinh do mdu cho lieu ke. Vi vay, ngi dung cua bai bao nay la: khdo sat

tuong quan giiia lieu hap thu, th6i gian sdy, nhiet dp sdy va thoi gian lim anh huong din 6n

dinh mau cua lieu ke.

II. THUC NGHIEM

1. Chuan bj lieu ke

Lilu kl phim B_3 nhay vdi dnh sdng va dp dm, do do tnr6c khi chieu xa lilu kl cdn

dugc bao bi kin. Tai moi lieu chilu tuong iing voi moi khodng nhi?t do va thoi gian sdy khdo