To ensure the image quality and to minimize the radiation dose received by the surface side of patients as well. Objective: Human organs sensitive to radiation damage are mostly glands such as breast, thyroid and prostate, which are located in the surface side of human body. Therefore, if we can reduce the radiation dose received by the surface side of patients during CT scan as much as possible, the radiation damage to them will be reduced accordingly. This experiment studies the use of Xcare technology during CT scan for the protection of patients sensitive organs. Methods: This study was divided into three phases. Phase one: to study the doses to the phantom in vitro and in vivo. A water phantom was made to simulate human body. One detection point was placed which was approximate to glands inside of the phantom, and the other was put at the same place outside of the phantom. Conventional chest CT scan, conventional low-dose chest CT scan and X-care technology chest CT scan were adopted. The radiation doses and image quality of detection points under different CT scans were recorded and analyzed statistically. Phase two: X-care technology was employed to study the doses to the different places of the phantom. The phantom of dual-source CT was fixed on the scanning table. Then we used laser light to select the water layer to locate a point as 0°, and selected one detection point every 60°clockwise facing CT scanner. In this way, six detection points were selected.X-care CTscan was employed. Before scanning, all the detection devices were cleared. The radiation dose detected after scanning minus background radiation could be seen as the radiation dose received by the surface side of the patient. The detecting results were divided into two groups according to the surface side and the back side. Then we compared the radiation doses of these two groups as well as the differences and reduction rate of the surface side and back side of a single person. And the results were tested by the nonparametric sum of two independent non-normal samples. A P value < 0.05 indicated a statistically significant difference. Phase three: the study on human body. Two hundred subjects were enrolled. Inclusion criteria: patients with pulmonary nodules to be screened or needing pulmonary examination because of tumors in other parts of the body in our hospital. They underwent CT plain scan and were randomly divided into two groups—group with conventional CT scan and with X-care technology, respectively. Both of the groups received another low-dose chest CT scan(40mAs)besides regulated dose scan. Surface test was used to measure the radiation dose. With informed consent from the patients, we selected three detection points in the surface side (one in the middle of the body and the other two in the outside of the breasts) and three detection points in the dorsal side (one in the spine and the other two in the lower margin of scapulas) of each patient. The scanning mode and statistical method were the same as those adopted in the second stage. Statistical comparisons: 1. radiation doses of the three scanning modes. 2. The detection rate of the pulmonary nodules by the three scanning modes; subjective scoring of the image quality of the pulmonary nodules. 3. The influence of three scanning modes on the image quality of mediastina and soft tissues of the chest. The test results were divided into two groups according to the surface side and dorsal side. We compared the radiation doses to the two groups as well as the differences and reduction rate of radiation doses to the surface side and dorsal side of each patient. Then, SPSS 13 statistical analysis software was used, and the difference (p<0.05) is statistically significant. Results: Radiation doses to human body were compared after the research carried out on doses in vitro and in vivo and on phantom. The total radiation dose to the surface side and the dorsal side was 1535.63mSv and 2435.50mSv, respectively. The radiation dose to the surface side was obviously less than that to the dorsal side and the reduction rate reached 35.99%. The differences between the two groups were statistically significant(Z=-7.472,P=0.000). Conclusion: By the use of X-care scanning technology of dual-energy CT, the radiation dose to the surface side of the subjects can be significantly reduced and the sensitive organs of subjects will be protected to some extent.