本文介绍三种电离室的结构和性能。体积为0.5cm

3

，以纯石墨为壁体的电离室，在X射线管电压为60~220kV、半价层为0.07mmCu和2.5mmCu时，其能量响应的最大误差不超过1.5%，而对

137

Cs和

60

Co γ射线的校正因子（附加3.75mm有机玻璃平衡帽）也处在上述范围内；体积为2cm

3

，分别以酚醛塑料、纯石墨、聚四氟乙烯为壁体的电离室，在上述能量范围内，其能量响应最大误差为3~5%；体积为200cm

3

，以酚醛塑料为壁体的电离室，其最大校正因子为5%。上述电离室可作次级标准伦琴计和防护剂量测量用。

Three kinds of ionization chamber for X-ray and

γ

-ray dosimetry are here described: a) Ionization chamber of 0.5cm

3

with pure graphite wall and alumunium collecting electrode. In case of radiation having a HVL between 0.07mm Cu to 2.5mm Cu corresponding to a X-ray tube voltage of about 60 to 220kV

the maximun error of the energy response was below 1.5%. The calibration factor of

137

Cs and

60

Со

γ

radiation also fell in with above range when an additional 3.75mm thick lucite build-up cap was fitted. b) Ionization chamber of 2cm

3

with bakelite

pure graphite or teflon wall the maximun error of energy respose was lied between 3~5%; c) Ionization chamber of 200 cm

3

with bakelite plastic wall

the maximun error of energy response was below 5%. All of them can be used as secondary standard Röntgen meter and in protection dose measurement.