Abstract: Objective: To study the value of individualized contrast medium injection scheme in improving the biosafety of pulmonary artery CTA. Materials and methods: 50 patients clinically suspected of pulmonary embolism from January 2018 to June 2020 were randomly assigned into groups A and B. Group A was the routinely group, the injection scheme was 20mL of normal saline, 50 mL of contrast agent and 30 mL of saline, with the injection rate of 4.5 mL/s. Group B was the individualized group, and the injection scheme was 20 mL of normal saline, (contrast medium dosage=weight×0.6 mL) and 30 mL of normal saline, the injection rate of contrast medium=dosage of contrast agent/10 s while the injection rate of physiological saline was 4.5 mL/s. We adopted t-test of independent samples to compare the data of age, height, weight, dosage and rate of contrast agent injection, CT value of main pulmonary artery and left and right pulmonary arteries and subjective evaluation of image quality between the two groups. Kappa test was used to evaluate the consistency of subjective evaluation of the image quality between the two doctors. Results: There was no statistical significance in the difference of age, height and weight between the two groups; the difference between the two groups in the dosage and rate of contrast mediumt injection was statistically significant; there was no statistical significance in CT value of main pulmonary artery and left and right pulmonary arteries and subjective evaluation of image quality between the two groups; Kappa test indicated that the two doctors held high consistency in subjective evaluation of image quality, with Kappa=0.80. Conclusion: On the premise of ensuring the quality of CTA images of pulmonary artery, personalized injection scheme can effectively reduce the dosage of contrast medium and slow down the injection rate for patients with weight less than 75 kg, thus reduces the potential risk of biological safety for patients.