The link between micro- and macro-parameters for radiation interactions that take place in living biological systems is described in this paper. Meanwhile recent progress and development in microdosimetry and nanodosimetry are introduced, including the methods to measure and calculate these micro- or nano-parameters. The relationship between radiobiology and physical quantities in microdosimetry and nanodosimetry was presented. Both the current problems on their applications in radiation protection and radiotherapy and the future development direction are proposed.
Humans ; Physics ; Radiation Protection ; Radiobiology ; Radiometry

Dose calculation algorithms based on the Monte Carlo (MC) method are widely regarded as the most accurate tool available in radiotherapy. The MC simulation in radiotherapy has been split into two parts, the radiation source simulation and patient simulation. In this research, a virtual source for simulating the linear accelerator head was constructed with measurement-driven models. The dependence between the calculation accuracy and the specification of various parameters was studied by comparison between the measurement data and calculation results. It has been shown that the dose profile obtained by MC simulation can be consistent with measurement data, suggesting that the compound effect of primary photons and secondary photons are considered with appropriate parameter specification. The requirement of modeling for MC simulation can be met in clinical conditions.
Computer Simulation ; Humans ; Models, Biological ; Monte Carlo Method ; Phantoms, Imaging ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Conformal ; methods

Craniospinal radiation is one of essential components in the treatment flow for a number of central nervous system malignancies. Meticulous attention to technique and dosimetry is required to produce optimum tumor control. In this paper, an optimized treatment regimen was proposed based on multiple techniques. The CT images for a 17-year-old male patient in need of craniospinal radiation were acquired for 3D conformal treatment planning. The split-beam technique, the extended penumbra fields matching technique, and the multiple leaf collimator segments and extended SSD technique were synthesized in the treatment regimen so as to work out an optimized treatment plan. The added few segments improved the dose homogeneity in spinal cord. The maximal point dose was decreased from 124% to 108% of the prescribed dose in it. Comparative study on the anthropomorphic phantom showed that the data collected by thermoluminescent detectors and the data obtained by calculation were basically coincident. These results suggest that the proposed technique be clinically acceptable.
Adolescent ; Brain Neoplasms ; diagnostic imaging ; radiotherapy ; Humans ; Magnetic Resonance Imaging ; Male ; Neoplasms, Germ Cell and Embryonal ; radiotherapy ; Radiometry ; methods ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Conformal ; methods ; Spinal Cord Neoplasms ; diagnostic imaging ; radiotherapy ; Tomography, X-Ray Computed

Objectives To investigate the occipital cortex metabolite alterations in repetitive and severe neonatal hypoglycemia rats treated with sodium pyruvate and to reveal the protective role of sodium pyruvate using high resolution 1H nuclear magnetic resonance spectroscopy.Methods Thirty-six 2-dayold Sprague-Dawley rats were randomly divided into hypoglycemia group and pyruvate group with 18 rats in each group.Rats in both groups received intraperitoneal injections of insulin (40 U/kg body weight) at 2,4 and 6 days of age to induce severe hypoglycemia (blood glucose value ≤ 1.4 mmol/L).In the hypoglycemia group,2.5 hours after insulin injection,intraperitoneal injection of 50％ glucose (2 ml/kg) was administered to terminate hypoglycemia,while in the pyruvate group,50％ glucose (2 ml/kg) and sodium pyruvate solution 2.5 ml/kg (500 mg/kg) were injected.Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay was used to observe the status of injured neurons in six neonatal rats,and metabolite changes in occipital cortex of the other 12 rats were detected by 1H nuclear magnetic resonance spectroscopy.The difference between the two groups was compared by independent-samples t test.Results Neonatal rats of both groups reached severe hypoglycemia level 2.5 hours after insulin injection.Compared with hypoglycemia group,pyruvate group had fewer injured neurons (45±5 vs 113 ± 12,t=0.782,P=0.013) and lower injured index in the occipital cortex (0.15 ± 0.03 vs 0.36 ± 0.06,t=l.143,P=0.020).Pyruvate group showed significant decreases in the concentration of taurine [(13.31 ± 2.06) vs (18.44 ± 3.86) mol/kg,t=8.231],glutamine[(1.50 ± 0.24) vs (2.02 ± 0.40) mol/kg,t=3.137],glutamate[(7.04 ± 0.95) vs (9.40 ± 1.73) mol/kg,t=6.449],aspartate[(1.51 ± 0.28) vs (2.15 ± 0.58) mol/kg,t=2.561] and creatine [(6.37±0.99) vs (8.46± 1.77) mol/kg,t =4.226] in the occipital cortex (all P'＜0.017).Conclusions Simultaneous use of glucose and sodium pyruvate to terminate hypoglycemia in repetitive and severe neonatal hypoglycemia rats can effectively alleviate severe hypoglycemia-induced occipital lobe damage via regulating excitatory amino acid neurotransmitters,energy metabolism and other metabolic pathways.

Hot spots and cold spots always appear in the matched region of electron-photon fields. The degree of this kind of dose heterogeneity depends on the physical characteristic of a treatment unit and the energy of electrons. In this paper, a set of dosimetric parameters have been measured on electron rays and x rays for the Elekta Precise treatment unit and the Elekta Synergy treatment unit, respectively. The hot spots and cold spots in the region of perpendicular electron-photon matching fields have been analysed quantitatively. The method to extend penumbra for photon beam profiles was proposed for improving the dose uniformity in the matched regions. And the dose profiles in the matched regions for different treatment units were compared. The results showed that there were stronger hot spots and cold spots for treatment unit with smaller penumbra for photon beams either under the condition of unmodified photon beam profile or the condition of modified photon beam profile.
Computer Simulation ; Electrons ; Head and Neck Neoplasms ; radiotherapy ; Humans ; Models, Theoretical ; Photons ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, High-Energy

Objective:To synthesize 177Lu-prostate-specific membrane antigen (PSMA)-617 with domestic 177Lu (made in China), and explore its optimal labeling condition, biodistribution, stability, and safety. Methods:177Lu-PSMA-617 was prepared with domestic 177Lu by a manual method. The optimal labeling condition, radiochemical purity, stability ( in vivo and in vitro), lipid-water partition coefficient, and plasma protein binding rate were determined. The uptake rate of 177Lu-PSMA-617 was evaluated by using 22RV1 cells. Biodistribution and SPECT/CT imaging were performed on normal mice with imported 177Lu-PSMA-617 as control group. The blood routine test was performed to evaluate the safety. Results:The best labeling result of domestic 177Lu-PSMA-617 can be obtained under the following conditions: pH=4.5, 100 ℃ for 30 min. And the radiochemical purity was ≥99%. The product was stable in vivo and in vitro, with the radiochemical purity >95% in 72 h. The plasma protein binding rate was (35.3±5.3)%, the lipid-water partition coefficient was -2.27±0.06, and the specific uptake rate of domestic 177Lu-PSMA-617 by 22RV1 cells reached the highest in 1 h ((7.58±0.84)%), which was slightly lower than the imported 177Lu-PSMA-617 ((7.86±0.96)%), but there was no significant difference between them ( t=-0.439, P>0.05). The distribution and SPECT/CT imaging of normal mice showed that domestic and imported 177Lu-PSMA-617 in blood were cleared quite fast, and both of them were excreted mainly through the kidneys. No obvious adverse reactions were found in the toxicity test of domestic and imported 177Lu-PSMA-617. There was no obvious abnormality in blood routine and liver and kidney metabolism. Conclusion:The domestic 177Lu-PSMA-617 has many advantages, such as qualified quality control, good biological properties and safety, which support its potential application value in diagnosis of prostatic neoplasms.

Objective To explore the value of conventional and functional MRI image parameter in preoperative grade of pancreatic neuroendocrine tumours (pNET).Methods Data of 35 cases of pNET were retrospectively analyzed,including tumor size,intensity of T1WI's and T2WI's signal,enhancement feature,and apparent diffusion coefficients (ADC)value.All kinds of tumors were classified into G1 to G3 according to WHO's classification in 2010.Results There were 40 pNETs (mean size(4.2±2.9)cm) among the 35 patients (20 male,and 15 female).By WHO's tumor grading,the number of patients from G1 to G3 was 18(45％),12(30％),and 10(25 ％),respectively.A higher grade was associated with larger tumor size (P＜0.05).Intensity of T1WI and T2WI signal has no significance for predicting tumor grade.Enhancement feature had statistical significance on tumor's grade (P＜0.05).ADC value decreased with the increase of tumor's grade,(2.23±0.80) × 10-3,(1.80±0.73) × 10-3,(0.92±0.24) ×10-3 mm2/s respectively for tumors from grade G1 to G3.Conclusion Enhancement features of MRI image and ADC value are conducive to preoperative grading of pNET.

The development of medical image segmentation technology has been briefly reviewed. The applications of auto-segmentation of organs at risk and target volumes based on Atlas and deep learning in the field of radiotherapy have been introduced in detail, respectively. Then the development direction and product model for general automatic sketching tools or systems based on solid clinical data are discussed.
Image Processing, Computer-Assisted ; Radiotherapy/trends* ; Radiotherapy Planning, Computer-Assisted ; Technology ; Tomography, X-Ray Computed

Objective:To explore the reasons why patients with severe mental disorders and their family members refuse to participate in the community management and treatment service network.Methods:Totally 12 patients with severe mental disorders hospitalized and 7 family members in a ClassⅢ Grade A psychiatric hospital in Chengdu between January and May 2018 received semi-structural interviews using descriptive qualitative research methods. The content analysis and Nvivo 10.0 were used to organize and analyze the interview materials.Results:The five themes that affected refusal of patients with severe mental disorders and their family members to participate in the community management and treatment network were: poor perception of the patients, which covered the sub-themes of insufficient awareness of severe mental disorders and incorrect understanding of the community management and treatment service network; negative emotions of the patients and their family members, including the sub-themes of severe feelings of stigma and lack of trust; the patients and their family members actual needs were not met; the introverted personality traits of the patients; the decision-making game between the patients and the main caregiver of the family.Conclusions:Strengthening publicity, fully protecting the privacy of the patients, eliminating doubts, building a professional psychiatric prevention team, providing a diverse community management and treatment service network, and grasping the relevant drivers for the patient's refusal to participate in the community management and treatment service network can help enhance the enthusiasm of patients with severe mental disorders and their family members to participate in the community management and treatment service network.

The development of an expert consensus based on specific domestic situations will provide practical guidance to the efforts aiming at improving cleft care in China. The team approach of twenty-one cleft centers were pooled together, covering pre-surgical orthopedics, primary surgical repair, orthodontic treatment, alveolar bone graft, secondary deformity correction, palatal fistulae repair, the diagnosis and treatment of velopharyngeal incompetence, speech therapy, otitis media management, and skeletal deformity correction. Agreement was achieved among the authors concerning the application of critical surgical and non-surgical techniques. The ambition of this consensus is to introduce more clinicians to the revolution of sequential treatment of clefts, and form the basis for a more comprehensive cleft care manual in the future.
Alveolar Bone Grafting ; Cleft Lip ; Humans ; Velopharyngeal Insufficiency