Objective: To understand the occupational external exposure dose among radiation workers in a first-class hospital at Grade 3 of Suzhou, and to provide reference for radiological protection. Methods: The individual dose of 1156 radiation workers in the hospital from 2010 to 2017 were detected, the annual collective effective dose and per capita annual effective dose were analyzed for different years, different occupations (diagnostic radiology, radiotherapy, nuclear medicine, interventional radiology) , gender, and age. Results: From 2010 to 2017, the total annual collective effective dose was 351.40 person·mSv, the per capita annual dose was 0.30 mSv/a, and radiation workers whose annual effective dose was less than 1 mSv accounted for 94.98%. There were 5 interventional radiology workers and 1 nuclear medicine worker with annual effective dose between 2 and 4 mSv. There was no worker with annual effective dose over 4 mSv. The per capita annual effective dose of nuclear medicine workers was the highest (0.40 mSv/a) . The per capita annual effective dose was not significantly different between radiation workers with different genders and ages (P>0.05) . Conclusion Most of radiation workers have low individual dose level in the hospital. It is important to focus on nuclear medicine workers and interventional radiology workers.

Objective To evaluate the application value of quantitative immune fecal occult blood test (FOBT) in colonoscopy for the screening of colorectal cancer in health check-up participants. Methods The subjects were selected from July 2017 to June 2018 in the Health Management Center of the Second Affiliated Hospital of Suzhou University. The subjects were the healthy individuals who chose quantitative immune FOBT or chemical method plus immunogold double-method FOBT (referred to as"double-method FOBT"), excluding those who had interfering factors. Individuals with a positive result in primary screening were selected and conducted with colorectal cancer by colonoscopy. If the polyploidy lesions were observed during colonoscopy, the biopsy or excision was performed, and the pathological diagnosis was performed. The positive rate of primary screening, compliance rate of colonoscopy and pathological results of colonoscopy were compared between the two methods. Quantitative immunoassay FOBT was analyzed in different gender, age group, physical examination nature, positive rate of primary screening, compliance rate of colonoscopy and pathological results of colonoscopy. Results 18 728 people chose quantitative immunoassay FOBT and 6 212 people chose double-method FOBT at the same time. There was no significant difference in gender and age between the two groups (all P>0.05), which was comparable. The detection rate of quantitative immune FOBT was higher than double-method FOBT (74.62% vs 32.23%, P<0.001). The positive rate of quantitative immune FOBT in primary screening was lower than double-method FOBT (4.11% vs 5.34%, P=0.003). The colonoscopy screening rate in positive population by quantitative immune FOBT was higher than double-method FOBT (27.83% vs 13.08%, P=0.001). These differences were statistically significant. The detection rate of total lesions by colonoscopy was 71.88% in positive population by quantitative immune FOBT. It was 42.86% in double-method FOBT. There was no statistical difference between the two methods (P=0.05). The detection rates of quantitative immune FOBT were significantly different among different genders, ages and physical properties (all P<0.001). The detection rate was higher in males than in females (79.14% vs 68.75%). The detection rate was highest in the group between 40 and 59 years old (79.96%). The individual detection rate was higher than the group (90.08% vs 66.07%). The positive rates in primary screening were significantly different among different ages (P=0.001).It was highest in the group aged 60 or above (5.59%). The colonoscopy screening rate in positive population by quantitative immune FOBT was highest in the group aged 50 or above (36.96%). The detection rate of inflammatory lesions were significantly different among different ages (P<0.001). The detection rate of colorectal cancer in males was higher than in females (11.11% vs 0.00%, P=0.009). In addition, with the increasing of fecal occult blood value, the detection rate of cancer was increased (P=0.041). Conclusion The quantitative immune FOBT is an ideal non-invasive examination for early screening of colorectal cancer. It has important application values.

Dose verification, as part of the radiotherapy QA chain, is a significant method to ensure the patients' safety and efficacy of treatment. The increasing application of precision radiotherapy techniques in clinic has advanced the need of three-dimensional ( 3D) dose verification. Gel dosimeters, prevailing for its intrinsic 3D high-resolution measurement and good tissue equivalence, can serve as effective supplement to the clinical radiotherapy dosimetric system. This paper reviews the method ology, dose response mechanism, characterizations of the state-of-the-art gel dosimeters. Gel dosimeters, outstanding for 3D dose measurement, have a great potential to explore both for clinical application and academic research.

Objective:To explore the feasibility and optimization effect of modifying the Henry Ford Hospital (HFHS) RapidPlan model for stereotactic body radiation therapy planning based on local requirements.Methods:The following changes were made based on Henry Ford Health System(HFHS) Rapid Plan Lung SBRT model, taking the latest clinical guideline evidence and local clinical practice into account: Internal gross target volume(IGTV) and organ at risk(OAR) structure, lung, were added and set corresponding parameters.The upper value of planning target volume (PTV) was adjusted from 109% to 125%. The original training library was replaced with 73 local historical simultaneous integrated boosting plans, and statistical verification and outlier cleaning of the initial trained model were performed using Model Analytics software. Totally 10 cases not included in the model library were selected for independent verification, and automatic optimization result of the models before and after modifying were compared under the same beam condition. The following dosimetric parameters were compared after target dose normalization: conformal index (CI) of target volume, the mean doses, maximum doses and dose-volume parameters of OARs.Results:The " tail" of the PTV′s DVH and the " shoulder" and " tail" of the IGTV′s DVH of model M (local) validation plan (M (local)_P) performs higher than the original model HFHS (HFHS_P). The PTV_CI (1.07±0.13) of M local_P were significantly smaller than HFHS_P (1.25±0.24) ( Z=-2.497, P<0.05). Except for Heart_ D15 cm 3 and Heart_ Dmax, most of the M local_P dosimetric parameters of OARs were lower than HFHS_P, and the standard deviation was smaller. However, the difference of between two plans was no more than 3.06%. 10 HFHS_P plans don′t satisfy dose parameters requirement, two of which PTV_CI values are 1.52 and 1.74, far beyond the clinically acceptable range. Conclusions:Commercial model HFHS could be localized by replacing training library and adjusting parameters. Moreover, plans optimized by the modified model are local clinical acceptable in the aspects of target volume conformity and hotspots, and have a better performance in terms of OAR sparing and plan consistency.

Objective:To characterize the key dose response properties of the novel presage sheet dosimeters for radiotherapy dose verification, including absorption spectra, linearity, dose range and stability.Methods:The same batch of presage sheet dosimeters were irradiated by a radiotherapy linac. The absorption spectra within 400-700 nm were read out with a spectrophotometer, and the R-G-B3 absorption changes read out with a film flatbed scanner was compared before and after irradiation.Results:An absorption peak was clearly identified at 628 nm, where absorptions change in high linearity with delivered doses ( R2=0.9999). A flat valley region is identified around 490 nm, where dose induced absorption changes were negligible. The readout sensitivity of the R-channel of the flatbed scanner was higher than both in green and blue channels. In the dose range below 10 Gy, the R-channel absorptions are in significant linearity with doses ( R2=0.9999), with absorptions change in an obvious quadratic trend in the range beyond 10 Gy ( R2=0.9999). The dose range of presage sheets was more than 94.6 Gy. The absorptions were well preserved within 1 h post-irradation, and then are shown to increase gradually, where the increase speeds are dose-related. The post-irradiation integrity of dose falloff gradients are shown with negligible gradient blurring. Conclusions:The novel presage sheets shown to have reasonable dose response linearity, large dose range, desirable post-irradiation dose gradient integrity and negligible fractionation effect, which indicates its great potentials in integral dose verification of high-dose and multiple target radiotherapy deliveries.