[Purpose]To analyze the results of upper gastrointestinal cancer screening in rural areas of Lhasa from 2015 to 2019.[Methods]Upper gastrointestinal cancer screening program was conducted among residents aged 40～69 years old from 3 rural project sites in Lhasa selected by cluster sampling method from 2015 to 2019.The detected malignant tumors and precancerous le-sions were treated and confirmed by pathological examination.The detection rate of esophagus and stomach cancer were calculated by region,sex and age and compared by x2 test.[Results]A total of 1 399 people underwent gastroscopy,among whom 1 288 completed pathological biopsy(92.07％).Three cases of esophageal cancer were detected with a detection rate of 0.21％(3/1 399),all of which were advanced squamous cell carcinoma.Eight cases of gastric cancer were detected with a detection rate of 0.57％(8/1 399),and 2 cases were early gastric cancer.The detection rate of low-grade and high-grade epithelial neoplasia of gastric mucosa was 0.64％(9/1 399)and 0.21％(3/1 399),respectively.There was no significant difference in the detection rate among different regions,sexes and age groups(all P＞0.05).[Conclusion]The detection rate of upper gastrointesti-nal cancer in screening population in Lhasa is lower than the national average level.Men and the elderly are important target populations for upper gastrointestinal cancer screening,and increasing participation rates is necessary for more effective screening outcomes.

Objective:To optimize the scan parameters for ultra-low dose computed tomography (ULDCT) of the chest using spectral purification technology, and assess the feasibility of maintaining image quality while reducing radiation dosage.Methods:An anthropomorphic chest phantom embedded with simulated pulmonary nodules was utilized for low-dose computed tomography(LDCT) and ULDCT scans. LDCT was conducted using a reference tube current of 25 mAs and a pitch of 1.0. ULDCT incorporating spectral purification technology was conducted using four reference tube currents, i. e., 50, 100, 150, and 200 mAs (labeled ULDCT1-4), and a pitch of 1.5. Other parameters were consistent. The volume CT dose index and the dose-length product were extracted from the dose reports, and then the effective doses were calculated. The objective image quality was assessed using metrics including image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The subjective image quality of ULDCT images was assessed on a four-point scale with LDCT images as reference.Results:The ULDCT4 at a reference tube current of 200 mAs showed a lower effective dose compared to LDCT ( t = -17.30, P < 0.001). The objective image quality assessments indicated that noise levels in four ULDCT groups were higher than those in LDCT ( t = 21.96, 10.56, 3.15, 3.14, P < 0.05). Notably, the SNR and CNR for the aortic arch were higher in ULDCT4 compared to LDCT ( t = 3.55, 71.96, P < 0.05). The SNR of pulmonary nodules in ULDCT4 was comparable to that in LDCT ( P > 0.05), but the CNR was higher ( t = 0.79, P < 0.001). Subjective image quality assessments reveal that the image quality of ULDCT4 was higher than that of LDCT, with scores of 3.80±0.46 for noise, 3.70±0.46 for contrast and sharpness, and 3.37±0.66 for pulmonary nodules. Conclusions:ULDCT (200 mAs) using spectral purification technology can yield higher image quality than LDCT while substantially reducing the radiation dose, thus demonstrating substantial clinical potential and the promise of replacing LDCT in early lung cancer screening.

Objective:To optimize the scan parameters for ultra-low dose computed tomography (ULDCT) of the chest using spectral purification technology, and assess the feasibility of maintaining image quality while reducing radiation dosage.Methods:An anthropomorphic chest phantom embedded with simulated pulmonary nodules was utilized for low-dose computed tomography(LDCT) and ULDCT scans. LDCT was conducted using a reference tube current of 25 mAs and a pitch of 1.0. ULDCT incorporating spectral purification technology was conducted using four reference tube currents, i. e., 50, 100, 150, and 200 mAs (labeled ULDCT1-4), and a pitch of 1.5. Other parameters were consistent. The volume CT dose index and the dose-length product were extracted from the dose reports, and then the effective doses were calculated. The objective image quality was assessed using metrics including image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The subjective image quality of ULDCT images was assessed on a four-point scale with LDCT images as reference.Results:The ULDCT4 at a reference tube current of 200 mAs showed a lower effective dose compared to LDCT ( t = -17.30, P < 0.001). The objective image quality assessments indicated that noise levels in four ULDCT groups were higher than those in LDCT ( t = 21.96, 10.56, 3.15, 3.14, P < 0.05). Notably, the SNR and CNR for the aortic arch were higher in ULDCT4 compared to LDCT ( t = 3.55, 71.96, P < 0.05). The SNR of pulmonary nodules in ULDCT4 was comparable to that in LDCT ( P > 0.05), but the CNR was higher ( t = 0.79, P < 0.001). Subjective image quality assessments reveal that the image quality of ULDCT4 was higher than that of LDCT, with scores of 3.80±0.46 for noise, 3.70±0.46 for contrast and sharpness, and 3.37±0.66 for pulmonary nodules. Conclusions:ULDCT (200 mAs) using spectral purification technology can yield higher image quality than LDCT while substantially reducing the radiation dose, thus demonstrating substantial clinical potential and the promise of replacing LDCT in early lung cancer screening.

[Purpose]To analyze the results of upper gastrointestinal cancer screening in rural areas of Lhasa from 2015 to 2019.[Methods]Upper gastrointestinal cancer screening program was conducted among residents aged 40～69 years old from 3 rural project sites in Lhasa selected by cluster sampling method from 2015 to 2019.The detected malignant tumors and precancerous le-sions were treated and confirmed by pathological examination.The detection rate of esophagus and stomach cancer were calculated by region,sex and age and compared by x2 test.[Results]A total of 1 399 people underwent gastroscopy,among whom 1 288 completed pathological biopsy(92.07％).Three cases of esophageal cancer were detected with a detection rate of 0.21％(3/1 399),all of which were advanced squamous cell carcinoma.Eight cases of gastric cancer were detected with a detection rate of 0.57％(8/1 399),and 2 cases were early gastric cancer.The detection rate of low-grade and high-grade epithelial neoplasia of gastric mucosa was 0.64％(9/1 399)and 0.21％(3/1 399),respectively.There was no significant difference in the detection rate among different regions,sexes and age groups(all P＞0.05).[Conclusion]The detection rate of upper gastrointesti-nal cancer in screening population in Lhasa is lower than the national average level.Men and the elderly are important target populations for upper gastrointestinal cancer screening,and increasing participation rates is necessary for more effective screening outcomes.

Objective To analyze the CT features of solitary pulmonary nodules(SPN) in patients with malignant tumor with the aim of improving its diagnosis and differential diagnosis in this special background .Methods From May 2014 to De-cember 2018, the CT data of 76 pathologically confirmed SPNs in patients with malignant tumor were retrospectively analyzed . The CT features of SPNs, including density, morphology and change of peripheral lung field and adjacent structures, were mainly analyzed.The characteristics of different types of nodules and their differences were summarized .Results Among the 76 SPNs, there were 41(53.9％) primary lung cancers, 14(18.5％) metastatic tumors, and 21(27.6％) benign lesions(in-cluding 12 inflammatory nodules, 7 tuberculous nodules and 2 benign tumors).Of all nodules, there were 57(75％) solid nodules, including 23(40.4％) primary lung cancers which mainly manifested as nodules with rough margin , close to adjacent vessel and bronchus and usually had internal or edge features(19, 82.6％), 14(24.6％) metastatic tumors which mainly showed as round or oval, homogeneous density, smooth margin nodules(12, 85.7％), and 18(31.6％) inflammatory nodules which mainly showed as lesions with rough and blurred margin accompanied by peripheral patch or fibrosis (14, 77.8％). There were 19(25％) sub-solid nodules, including 18(94.7％) primary lung cancers, which mainly manifested as nodules with heterogeneous density and clear border(14, 77.8％).There was only 1(5.3％) sub-solid inflammatory nodule.Conclu-sion The pathological nature of SPNs in patients with malignant tumors is various .Understanding their CT characteristics is helpful for diagnosing and differentiating and providing useful information for further treatment .