OBJECTIVE: To compare the application among intensity-modulated radiotherapy (IMRT), three-dimensional conformal radiotherapy(3D-CRT) and conventional radiotherapy (CRT) for locally advanced middle-low rectal cancer. METHODS: From January 2015 to December 2016, 93 locally advanced middle-low rectal cancer patients with clinical stage cT3N+M0 or cT4N0/+M0 who underwent preoperative concurrent chemoradiotherapy at Department of Colorectal Surgery, the Third Affiliated Hospital of Kunming Medical University and had complete data were enrolled in this retrospective cohort study. Patients were divided into IMRT group (17 cases), 3D-CRT group (28 cases) and CRT group (48 cases) according to different radiotherapy methods. The frequency and dose of CRT were 1 time/day, 5 times/week, for a total of 5 weeks, with a single dose of 2.0 Gy, the total dose was 50 Gy. Frequency and dose of 3D-CRT and IMRT were 1 time/day, 5 times/week, for a total of 23 to 28 times, with a single dose of 1.8 to 2.0 Gy, and a total dose of 45.0 to 50.4 Gy. The chemotherapy regimen was performed with capecitabine tablets at a dose of 825 mg/m twice a day for 5 days every week, at the same time during radiotherapy. The efficacy, chemotherapy adverse reactions and immune function of the three groups were compared. RESULTS: There was no significant difference in the baseline data among the three groups (all P>0.05). The proportion of patients receiving permanent ostomy in the IMRT group and the 3D-CRT group was 29.4%(5/17) and 32.1%(9/28) respectively, which was lower than 58.3%(28/48) in CRT group, and the difference was statistically significant (χ²=7.982, P=0.030), while this proportion was not significantly different between IMRT and 3D-CRT group(χ²=0.037, P=0.848). The pathologic complete response(pCR) rate was 23.7%(22/93) in the whole study, and the pCR rate was 39.3%(11/28) in the 3D-CRT group, which was higher than that of CRT group and IMRT group [12.5%(6/48) and 29.4%(5/17)], and the difference was statistically significant (χ²=7.407, P=0.025), while there was no significant difference in pCR rate between CRT group and IMRT group (χ²=2.554, P=0.110). There was no adverse reaction of grade 3 or above in all three groups. No significant difference in the incidence of bone marrow suppression, abnormal liver and kidney function markers, digestive tract reaction or radiation dermatitis was found(all P>0.05). After receiving concurrent chemoradiotherapy, the proportion of CD3/CD4 cells in the IMRT group and the CRT group decreased compared with that before treatment(23.1±9.3 vs. 31.1±10.9, 27.4±10.7 vs. 33.6±7.2, respectively); the proportion of CD3/CD8 cells was up-regulated (36.1±15.2 vs. 24.8±10.9, 30.9±14.4 vs. 24.0±8.3,respectively), and the differences were statistically significant (both P<0.05), while the above indexes before and after treatment were not significantly different in the 3D-CRT group(all P>0.05). After treatment, the proportion of CD4/CD8 cells in IMRT group decreased (0.8±0.6 vs. 1.6±1.0, t=3.838, P=0.003), while this proportion was not significantly different in CRT group and 3D-CRT group(all P>0.05). CONCLUSIONS IMRT and 3D-CRT can reduce the rate of permanent stoma. 3D-CRT can increase pCR rate. No obvious advantage is shown in IMRT as compared with 3D-CRT in the short-term efficacy. On the contrary, an immunosuppressive status may occur. Therefore, 3D-CRT is recommended as the best preoperative treatment strategy for patients with locally advanced middle-low rectal cancer, especially for those with immunosuppression status.
Humans ; Radiotherapy ; methods ; standards ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Conformal ; standards ; Radiotherapy, Intensity-Modulated ; standards ; Rectal Neoplasms ; radiotherapy ; Retrospective Studies

As a powerful global optimization approach, genetic algorithms (GA) can solve a variety of optimization problems in which the objective function is discontinuous, non-differentiable, or highly non-linear, to produce high convergence speed and vast search space. In this thesis, GA is used to optimize the beam weights of intensity modulated radiation therapy (IMRT) inverse planning, and 2D and 3D isodose contour as well as dose volume histogram (DVH) are used to evaluate the treatment plan. Also presented in this thesis are the results of calculation with discussions.
Algorithms ; Humans ; Models, Theoretical ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Conformal ; methods ; standards

UNLABELLEDTo study the method for dose calculation and beam weight optimization of intensity-modulated radiation therapy (IMRT).

METHODSThe IMRT dose calculation model based on two-dimensional convolution was constructed, the program of dose calculation and beam weight optimization with genetic algorithm was written with Visual c#.Net, and the optimization results were analyzed.

RESULTSGenetic algorithm optimization of beam weights can produce highly conformal dose distributions within a clinically acceptable computation time.

CONCLUSIONGenetic algorithm is valid and efficient in IMRT beam weight optimization, which may facilitate IMRT treatment planning.

Algorithms ; Humans ; Models, Statistical ; Models, Theoretical ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Conformal ; methods ; standards

OBJECTIVE: To compare the accuracy of different methods for image registration in image-guided adaptive brachytherapy (IGABT) for cervical cancer. METHODS: The last treatment planning CT images (CT1) and the first treatment planning CT images (CT2) were acquired from 15 patients with cervical cancer and registered with different match image qualities (retained/removed catheter source in images) and different match regions [target only (S Group)/ interested organ structure (M Group)/body (L Group)] in Velocity3.2 software. The dice similarity coefficient (DSC) between the clinical target volumes (CTV) of the CT1 and CT2 images (CTVCT1 and CTVCT2, respectively) and between the organs-at-risk (OAR) of the two imaging datasets (OARCT1 and OARCT2, respectively) were used to evaluate the image registration accuracy. RESULTS: The auto-segmentation volume of the catheter source using Velocity software based on the CT threshold was the closest to the actual volume within the CT value range of 1700-1800 HU. In the retained group, the DSC for the OARs of was better than or equal to that of the removed group, and the DSC value of the rectum was significantly improved ( < 0.05). For comparison of different match regions, the high-risk target volume (HRCTV) and the low-risk target volume (IRCTV) had the best precision for registration of the target area, which was significantly greater than that of M group and L group ( < 0.05). The M group had better registration accuracy of the target area and the best accuracy for the OARs. The DSC values of the bladder and rectum were significantly better than those of the other two groups ( < 0.05). CONCLUSIONS The CT value range of 1700-1800 HU is optimal for automatic image segmentation using Velocity software. Automatic segmentation and shielding the volume of the catheter source can improve the image quality. We recommend the use of interested organ structures regions for image registration in image-guided adaptive brachytherapy for cervical cancer.
Brachytherapy ; methods ; standards ; Female ; Humans ; Organs at Risk ; diagnostic imaging ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; methods ; standards ; Radiotherapy, Image-Guided ; methods ; standards ; Software ; Tomography, X-Ray Computed ; methods ; standards ; Uterine Cervical Neoplasms ; diagnostic imaging ; radiotherapy

OBJECTIVETo propose a new computer software-based medical image processing technique with high resolution digital scanner for radiotherapy verification.

METHODSUnder the platform of Windows 2000, the software, programmed with Visual C++.NET, was developed according to modular design. All data of the films and the treatment planning system could be processed as images or dose curves for a robust result.

RESULTSMany functions such as data acquisition, automatic analysis and computation and image processing were integrated in the system. Both geometric and dosimetric errors could be calculated at the same time to verify the radiotherapy accuracy.

CONCLUSIONThis system has good accuracy and stability for cost-effective radiotherapy verification.

Film Dosimetry ; instrumentation ; Humans ; Image Processing, Computer-Assisted ; Radiotherapy Dosage ; standards ; Radiotherapy Planning, Computer-Assisted ; methods ; Reproducibility of Results ; Software

After the rapid development of medical equipment including CT or PET-CT, radiation doses from medical exposure are now the largest source of man-made radiation exposure. General principles of radiation protection from the hazard of ionizing radiation are summarized as three key words; justification, optimization, and dose limit. Because medical exposure of radiation has unique considerations, diagnostic reference level is generally used as a reference value, instead of dose limits. In Korea, medical radiation exposure has increased rapidly. For medical radiation exposure control, Korea has two separate control systems. Regulation is essential to control medical radiation exposure. Physicians and radiologists must be aware of the radiation risks and benefits associated with medical exposure, and understand and implement the principles of radiation protection for patients. The education of the referring physicians and radiologists is also important.
Guidelines as Topic ; Humans ; International Agencies ; *Occupational Exposure ; Positron-Emission Tomography ; Radiation Injuries/etiology/prevention & control ; *Radiation Protection ; Radiation, Ionizing ; Radiotherapy Dosage/standards ; Reference Values ; Tomography, X-Ray Computed