冲洗和扫描条件对胶片剂量响应的影响

目的 分析冲洗和扫描条件对胶片剂量与吸光度(A)值的影响,建立基于卤化银胶片剂量仪的临床质量保证程序。方法 选择不同洗片温度、不同批次胶片、不同批次药水及同批次药水和胶片分析剂量与A值的响应。测试扫描仪不均匀性、稳定工作时间和噪声对胶片剂量响应的影响。结果 同一剂量水平A值随温度升高而增大;不同批次胶片剂量与A值响应差异较大;不同批次药水、胶片剂量与A值响应差异明显;同一批次胶片剂量与A值响应与药水时间呈现一定规律。扫描仪扫描的不均匀性最大达0.03,相同剂量A值在预热10 min后稳定,噪声影响随剂量和分辨率增加而加大。结论 最佳洗片温度为 29~31℃;不同批次胶片不能混用,更换胶片、药水时需重新获取刻度片。扫描仪需进行不均匀性校准,最佳扫描设置为72 dpi、16 bit,且要预热 5~10 min。

Analysis the effects of film dosimetry during processing and scanning

Objective To explore the effects of different flushing and scanning processing on optical density (A) responding and set up the clinic quality assurance protocol based on silver halide emulsions radiographic films. Methods Setting different flushing temperature and choosing different batch′s film and developer and fixer or fixer in the same batch with different analyzing dose were performed to analyze the effect on A value;The effect of light uniform, the stabilize work time and the noise of different scanning resolution were discussed. Results The A value at the same dose level would enhance as the temperature increased;the responding curve of dose and A value with different batches of films varied a lot;the responding curve of dose and A value with different batches of films and developer and fixer solution had marked variations;the responding of dose and A with the same batches would show some low. The heterogeneity of the scanner would achieve 0.03;the A value of the same dose would gradually steady while the time of scanning was more than 10 minutes;the affect of noise would increase as the dose and resolution ratio increased. Conclusions The best processing temperature is 29－31℃. Different batches of film couldn′t be confounded. A new calibration must be obtained when the film dosimetry to evaluate dose distribution is used. A 5－10 min warm up for stabilize work and the best setting resolution/depth lever are 72 dpi/16 bit for scanning films are determined.