Basic and cIinicaI studies demonstrate that depression is associated with abnormaI neuraI pIasticity in some brain regions,incIuding the prefrontaI cortex and hippocampus. Brain-derived neurotro-phic factor(BDNF)and its signaIing pathways pIay a cruciaI roIe in reguIating neuraI pIasticity and deveI-opment of depression. Ketamine or scopoIamine can produce a quick and sustained antidepressant effect,and both can quictIy activate BDNF-signaIing pathways reIated to neuraI pIasticity. In order to pro-vide the theoreticaI basis for future researches on new antidepressants,the neuraI pIasticity mechanisms of faster-onset antidepressants are reviewed in this paper.

Objective To find a new algorithm for PET/CT image fusion.Methods A variational model was used based on the wavelet transform.Firstly,PET and CT images were decomposed using wavelet transform.Then,images in approximate channel and detail channel were fused according to the two proposed assumption.Finally,decomposed images were synthesized to form fused image.Results Compared with the results form MATLAB wavelet fusion toolbox,the experimental results showed that the new variational image fusion model could provide more accurate result for target location in radiotherapy planning.Conclusion According to experiments,the new algorithm can reach good results and meet requirement of clinical demands.

Selection of CR and DR is very important for digital radiology departments in modern hospitals. This paper discusses the components of CR and DR as well as their technical requirements.

Objective To find a method for calculating the scatter dose of irregular fields. Methods The original Day function was improved to vary with radiation depth, and the improved Day function was used for irregular fields to calculate scatter dose. Results The accuracy was greatly improved by making Day function depend on radiation depth, and the error was within 1.5%. Conclusion This method can be used to calculate the scatter dose of irregular fields as well as rectangular fields.

This paper mainly discusses the development status in quo of field stretcher and its attachment with the history of field stretcher reviewed.The development trends of field stretcher in the future are also presented.

Objective To help the hospitals at all levels in China to realize IMRT by adding the accurate location equipments and TPS based on the existing general radiation therapy from research of the new method for static Intensity-modulated radiation therapy. Method Based on the controlled technique of CRT, a new split method for fabricating the three-dimensional physics compensator to achieve the IMRT was developed. Results The Experiment manifested that the compensator fabricated by the way could make the high dosage shape of target in accordance with the form of tumor and could adjust the distribution of the dosage according to remedy requirement. Conclusion The method is simple and feasible, and has brilliant clinical prospective and popularized significance.

Objective To develop a laser treatment machine for the benign prostatic hyperplasia(BPH),which can both avoid the transurethral resection symptoms(TURS) and rapidly remove the big BPH.Methods The machine adopted a long plus laser with 80W average power and 1000W peak value power in order to rapidly vaporize the neoplasm.Because of its high power,short operation time and small thermal penetraction depth,it could avoid the post-operation edema of the organ is resulted from the concretion of traditional continuous-wavelength YAG laser.The control system based on AT89C51 dominated the laser power,and meanwhile,it monitored the process to protect the machine.It was connected with the Hospital Information System(HIS) via RS232.Results The chicken breast tissues were irradiated with the sample machine under water,and the groove irradiated by laser was 4mm in width and 2.5mm in depth with the irradiation speed of 5mm/s.The arbonation of tissue surface was slight and the thermal damage to the adjacent tissues was the minimal.Conclusion This machine can rapidly vaporize the neoplasm with the minimal thermal damage to the adjacent non-irradiated tissues.It is desirable for the treatment of big BPH.

Objective To study the application of the genetic algorithm with two populations in optimization of both IMRT beam weight and orientation.Methods The genetic algorithm with two populations was used to optimize IMRT beam weight and orientations with three dimensional pencil beam dose calculation model. The algorithm was implemented in Visual c#. Net. And the results were analyzed. Results The modest change of the beam orientation resulted in more conformal dose distribution in target volume, and large high dose area was included. Further more, genetic algorithm with two populations gave such a clinically acceptable computation time. Conclusion Little change had distinct influence on dose distribution when there were few beam orientations. The genetic algorithm with two populations was an effective and global optimization method because of its parallel, robust and global. It provided satisfying results when used to optimize IMRT beam weight and orientations

Objective To study a novel method for the high-dose-rate brachytherapy (HDR) CT image to the intensity modulated radiation therapy (IMRT) CT image deformable image registration and dose accumulation.Methods The applicator in the HDR CT image is first segmented and removed,then a deflation step is performed on the applicator-free HDR CT image by solving the Navier-Stokes equation.Demons algorithm is utilized to register the deflated HDR CT image to the IMRT CT image,along with the HDR dose.The deformed HDR dose is then added on the IMRT dose and yield the final accumulated dose.Results The HDR CT image and IMRT CT image,as well as the corresponding dose distribution,from five cervical cancer patients are used for evaluation of the proposed algorithm,the results show that the proposed method can effectively get rid of the influence of the applicator and produce an accurate accumulated dose.Conclusions Dose accumulation and supervision is an important step in adaptive radiotherapy for accurate dose delivery and treatment plan re-optimization.The proposed method in this study can effectively accumulate the HDR dose to the IMRT dose domain,and the accuracy is proved to be sufficient for clinical needs.

Objective To investigate the influence of respiratory motion on target dose distribution in three-dimensional conformal radiation therapy(3DCRT) and intensity modulated radiation therapy(IM-RT). Methods A 2D air vented ionization chamber array MatriXX system,a platform which can mimic the clip motion of lung tumor, and a home-made solid water(RW3) phantom were used to measure the 2D dose distribution of static and moving targets irradiated by 3DCRT and IMRT beams using multiple gantry an-gles. The period of the moving platform was set to 3.5 s and the amplitude was ± 1 cm. Then the differences of dose distribution between the static phantom and moving phantom were compared and analyzed with the MatriXX system software. Results Compared with the static phantom in 3DCRT, the penumbra of dose distribution of the periodic moving phantom along the moving directions was increased by 6-9 mm, the high dose area was shrinked by about 5 ram,and the low dose area was extended by 5 mm,but the area of 50% i-sodose and the dose center area changed very little. When a single segment beam of IMRT was delivered and measured and the maximum dose of measuring plane was normalized to 100% ,the average difference of dose distribution between the static and dynamic phantoms was ±27% (from -56.4% to 56.1%) ;When all of the segment beams of IMRT were dehvered and the integrated dose distribution was measured ,the dose differ-ences were less than ±3% ,and the maximum difference of dose distribution was about ±15% which mainly appeared at the field margin and were similar to 3DCRT. Conclusions The dose distribution of most cen-ter areas of the periodic moving target using multi-fraction 3DCRT/IMRT beams is similar to that of the static target, while the high dose area of the former is shrinked and the low dose area is extended.