Dosimetric study of five-field intensity-modulated radiotherapy compared with conventional three-dimensional conformal radiotherapy for rectal cancer

Objective： The aim of the study was to compare the difference of dose distribution in clinical target volume and organ at risk （OAR） between five-field intensity-modulated radiotherapy （IMRT） and conventional three-dimensional conformal radiotherapy （3DCRT） in the radiotherapy of rectal cancer. Methods： Fifteen patients with rectal cancer treated with radio- therapy （RT） were retrospectively analyzed. Among the patients, seven received RT preoperatively and 8 postoperatively. The target volume and the OARs such as the small bowel, bladder and femoral heads were contoured for each patient. 3DCRT-plan and IMRT-plan were performed for each patient respectively, with the prescribed dose covering at least 95% of the planning target volume （PTV）. The conformity index （CI） and homogeneity index （HI） were used for evaluation of the dose distribution in the target volume, and the Dx% （the lowest dose to the x% volume of the OARs that received the highest dose of irradiation） and the mean dose were used for evaluation of the dose to OARs. Paired-T test was used for companson of the difference between the two plans. Results： In the IMRT-plan and 3DCRT-plan, the CI were 0.94 and 0.87 （P = 0.000） and the HI were 1.13 and 1.17, respectively （P = 0.001）. For small bowel, the D30%, D50% and the mean dose were 19.67 Gy, 15.13 Gy and 18.81 Gy in the IMRT-plan and 25.20 Gy, 22.20 Gy and 22.89 Gy in the 3DCRT-plan, respectively （P 〈 0.001 for all pairs of parameters）. For bladder, the D30%, D50%, and the mean dose were 24.80 Gy, 34.20 Gy and 28.70 Gy in the IMRT- plan, and 35.07 Gy, 44.67 Gy and 35.68 Gy in the 3DCRT-plan, respectively （P 〈 0.001 for all pairs of parameters）. For femoral heads, the D5% in the IMRT-plan and 3DCRT-plan were 40.6 Gy and 40.47 Gy, respectively （P = 0.936）, and the mean dose were 30.14 Gy and 25.57 Gy, respectively （P = 0.001）. Conclusion： Five-field IMRT-plan is better than 3DCRT-plan in the conformity and the dose homogeneity within target volume and also better in sparing the small bowel and bladder.

Evaluation of whole-course three-dimensional conformal radiotherapy combined with late-course accelerated hyperfractionated radiotherapy for esophageal carcinoma patients

Objective： The aim of the study was to evaluate the therapeutic effect and safety of whole-course three-dimensional conformal radiotherapy （3DCRT） combined with late-course accelerated hyperfractionated radiotherapy （LCAFR） on patients with esophageal carcinoma. Methods： one hundred and one patients with esophageal carcinoma were divided into two groups. Observing group （49 cases） were treated by whole-course 3DCRT. Patients in control group （52 cases） were treated by conventional radiotherapy. Clinical efficiencies and radiation toxicities were compared between two groups. Results： The side effects including radiation esophagitis （63.2%） and tracheitis （49.0%） decreased in observing group, but there was no significant difference between two groups （69.2% and 55.7% in controls）. The 1-, 2-and 3-year tumor local control rates and overall survival rates in the observing group were significantly improved compared with the control group, being respectively 87.8%, 75.5%, 63.3% vs 71.2%, 55.8%, 42.3% and 85.7%, 71.4%, 46.7% vs 69.2%, 51.9%, 26.9% （all P 0.05）. Conclusion： The therapeutic effect of whole-course 3DCRT combined with LCAFR for esophageal carcinomas is superior to conventional radiotherapy.

Clinical Research on Three-Dimensional Conformal Radiotherapy of Non-Small Cell Lung Cancer

OBJECTIVE To investigate the clinical efficacy and toxic effect of the 3-dimensional conformal radiation therapy （3DCRT） for non- small cell lung cancer （NSCLC）. METHODS Fifty-two patients with the Stage-I and IV NSCLC were treated with 3DCRT. Cross analysis of the clinical data was conducted in the comparison between the 52 cases with 3DCRT and the other 50 cases with the conventional radiation therapy （CRT）. In the 3DCRT group, only the primary tumor and positive lymph-node draining area were included in the clinical target area, setting 4 to 6 coplanar or non-coplanar irradiation fields, with 2 Gy or 3 Gy/fraction, 1 fraction a day and 5 fractions per week. The total dose ranged from a test dose （DT） of 66 Gy to 72 Gy. In the CRT group, the field area contained the primary tumor plus the homolateral hilum of the lung, the mediastinum superior or hol-mediastinum, and opposed anteroposterior irradiation. When the dosage reached DT 36-40 Gy, an oblique portal administered radiation was conducted in order to avoid injuring the spinal cord. The DT was 1.8-2.0 Gy/fraction, 1 fraction a day, 5 fractions per week, with a total dose of 60 Gy to 70 Gy. RESULTS The therapeutic effect （CR ＋ PR） was 90.4% in the 3DCRT group, and was 72% in the CRT group. There was statistically significant difference between the two groups, P 〈 0.01. There was a clinical symptom improvement attained by 96.5% and 86.4% respectively in the two groups, and there was a statistically significant difference between the groups, P 〈 0.01. The 6-month, 1 and 2-year overall survival rates were 92.3%, 75.0% and 42.3% in the 3DCRT group, and 76%, 60% and 30% in the CRT group, respectively. There was a significant difference in the 6-month overall survival rate between the groups, P 〈 0.05. There was no obvious significant difference in the 1 and 2-year overall survival rates between the two groups, P 〉 0.05. The toxic reaction was 12.5% and 23.7% respectively in the 3DCRT and CRT groups. Acute radioactive esophagitis and leucopenia were markedly lower in the 3DCRT group than in the CRT group. There was a statistically significant difference between the groups, P 〈 0.05. No toxic reaction of Stage-III and over was found in the 3DCRT group during radiation therapy. CONCLUSION The 3DCRT method has a satisfactory shortterm efficacy and improvement of clinical symptoms in treating NSCLC, with a mild toxic reaction and good tolerance in patients. It can be used for enhancing the tumor-control rate and bettering the quality of life.

Effects of three-dimensional conformal radiotherapy on the esophageal carcinoma

Objective： Radiation therapy is an important component of the multidisciplinary management of esophageal carcinoma. Three-dimensional conformal radiation therapy requires the precise definition of the target volume. We aimed to compare the treatment results and radiation toxicities between three-dimensional conformal radiotherapy （3D-CRT） and conventional radiotherapy （CR） for patients with cervical and thoracic esophageal carcinoma. Methods： From June 2004 to December 2006, a random study was performed on 106 patients treated with 3D-CRT or CR, 53 patients in each group. The patients in CR group received conventional radiotherapy in 2.0 Gy/f, 5 f/week and total dose was 66-70 Gy in 6.5 or 7 weeks. The patients in 3D-CRT group were treated by 3D-CRT in 2.0 Gy/f, 5 f/week and total dose was 64-70 Gy in 6 weeks. The local control rates, survival rates and radiation toxicities for the two groups were investigated. Results： The 1-year and 3-year local control rates were 83.0% and 60.4% in 3D-CRT group and 64.2% （x^2 = 4.853, P = 0.028） and 32.1% （x^2 = 9.812, P = 0.002） in CR group. The 1-year and 3-year survival rates were 73.6% and 50.9% in 3D-CRT group and 54.7% （x^2 = 4.102, P = 0.043） and 32.1% （x^2 = 3.886, P = 0.049） in CR group. Between the two groups, there was no significant difference in radiation toxicities. Conclusien： The 1-year and 3-year local control rates and survival rates of patients with esophageal carcinoma treated by 3D-CRT is superior to CR. However, longer-term results and radiation toxicity need further study which involves more patients and prolonged follow-up.

Late course three-dimensional conformal radiotherapy for esophageal carcinoma

Objective： The aim of our study was to evaluate the clinical results and acute side effects of late course three-dimensional conformal radiotherapy （3DCRT） for esophageal carcinoma. Methods： From January 2004 to October 2006, 70 patients with esophageal carcinoma received late course 3DCRT. Their clinical data were analyzed retrospectively. The short-term clinical results, acute side effects, local control rates and survival rates were evaluated. Results： The complete response rate was 62.9%, partial response rate was 35.7%, and the overall response rate was 98.6%. The 1-, 2-and 3-year local control rates were 77.1%, 51.4% and 45.7%, respectively. The 1-, 2-and 3-year overall survival rates were 75.7%, 54.3% and 38.6%, respectively. The median survival time was 26 months. Conclusion： The technique of late course 3DCRT is an effective treatment for esophageal carcinoma and tend to improve the overall survival rate.

Radiotherapy Intensified by Increase of Fraction Size Using Three-Dimensional Conformal Radiotherapy in Bladder Preservation Therapy

Purpose: The impact of radiotherapy on bladder cancers heightened by increase of fraction size using three-dimensional conformal radiotherapy (3DCRT) was verified with biologically effective dose (BED, Gy10). Method: Twenty-five patients who were considered unsuitable for total cystectomy underwent 3DCRT between 2009 and 2014. When a gross tumor volume (GTV) did not neighbor guts and the patient was cooperative to radiotherapy (radical), the GTV was treated with a fraction size of ≥3.0 Gy, while a clinical target volume (CTV) of a whole bladder and lymph nodes at small pelvis were treated with a conventional fraction size of 2.0 Gy. When a GTV neighbored guts (palliative), only a CTV was treated with an increased fraction size of 2.5 Gy. Results: Compared to conventional two-dimensional radiotherapy, BED increased to 62.3 - 77.0 Gy10 (radical) or to 56.1 - 68.0 Gy10 (palliative) but the treatment period shortened to 4 - 5 weeks. Acute adverse events (≤3 months), determined by common terminology criteria for adverse events, were Grade 2 at most, but late adverse events were not observed. Only one patient (6%) lost the bladder. Conclusions: Patients who receive bladder preservation therapy appear good candidates to intensify impact of radiotherapy with 3DCRT.

Clinical observation of gemcitabine and concomitant three-dimensional conformal radiotherapy in the treatment of locally advanced non-small cell lung cancer

Objective： To evaluate the clinical effect of gemcitabine and concurrent three-dimensional conformal radiation therapy （3D-CRT） for locally advanced non-small cell lung cancer （NSCLC）. Methods： From April 2002 to June 2005, 38 patients with inoperable stage Ⅲ NSCLC were treated with gemcitabine and 3D-CRT simultaneously. Chemotherapy consisted of intravenously gemcitabine 350 mg/m^2 on days 1, 8, 15, 22, 29, 36.3D-CRT was delivered up to a total dose of 60-64 Gy with a 2.0 Gy dose fraction per day, 5 days per week. Results： The overall response rates of primary tumor and mediastinum metastatic node were 86.8% （33/38） and 90.6% （29/32） respectively, and 91.7% （22/24） and 78.6% （11/14） for squamous cell carcinoma and adenocarcinoma respectively. The acute side effects of patients were mostly myelosuppression, nausea, vomiting, radiation-induced esophagitis and pneumonitis （RTOG 1/11）, however, all of them were cured. Conclusion： Concurrent application of gemcitabine and 3D-CRT can improve the overall response rate for locally advanced NSCLC without aggravating the side effects.

The effects of three-dimensional conformal radiotherapy combined with whole brain irradiation on brain metastases

Objective： To observe the recently therapeutic effects and toxicity of three-dimensional conformal radiotherapy combined with whole brain irradiation for patients with brain metastasis. Methods： 33 cases were treated by whole brain irradiation at first, the dose of which was 36-40 Gy （18-20 f）. Then three-dimensional conformal radiotherapy was added to the focus with a total dose of 20-25 Gy, whose fractionated dose was 2-5 Gy/time, 5 times/week or 3 times/week. Results： Within 1 month after radiotherapy, according to imaging of the brain, the CR of all patients was 45.5%, PR 36.4%, NC 15.1%, and PD 3%. For the 32 cases with neural symptoms before radiation, the CR of the symptoms was 40.6% and PR 59.4%. All patients gained different increases in KPS grade. By the end of the follow-up period, there were 22 deaths with the mean survival time up to 9.3 months. Conclusion： Three-dimensional conformal radiotherapy combined with whole brain irradiation can not only effectively control brain metastases and improve life quality, but also tends to prolong survival time.

Clinical observation in three-dimensional conformal radiotherapy (3D-CRT) with concurrent chemotherapy in treatment of postoperative cerebral gliomas

Objective:The aim of the study was to investigate the efficacy of three-dimensional conformal radiotherapy (3D-CRT) combined with Temozolomide (TMZ) concurrent chemotherapy in treatment of postoperative cerebral gliomas by prospective randomized controlled trials. Methods: Sixty-two patients with cerebral glioma who had residual tumor were divided into 3D-CRT group (radiotherapy group, n=31) and 3D-CRT with concurrent chemotherapy group (chemoradiotherapy group, n=31) prospectively. All patients received a dose of 50-60 Gy/25-30 F/5-6 weeks by 6 MV-X ray, three-dimensional conformal radiotherapy, 1 f/d, 5 times a week. Chemotherapy regimen was Temozolomide:75 mg/m2/d, concomitantly with radiotherapy, followed by 150-200 mg/m2/d, 5 days, 28 days per cycle, totally 3-6 cycles. Results: The total response rate was 35.3% (11/31) in radiotherapy group. The response rate was 61.3% (19/31) in chemoradiotherapy group. There was significant difference in curative effect (P=0.042). There was no significant difference in survival comparison of two groups (P=0.263). Stratified analysis showed the patients with grade Ⅲ gliomas of chemoradiotherapy group had better prognosis than ones of radiotherapy group (P=0.043). Conclusion: The 3D-CRT with concurrent chemotherapy can improve the survival of cerebral gliomas with pathological grade Ⅲ.

Three-Tesla Magnetic Resonance and Computed Tomography Imaging in Three-Dimensional Conformal Radiotherapy for Localized Prostate Cancer

Aims and background: we evaluate CT-3Tesla MRI fusion in conformal radiotherapy for localized prostate cancer.Methods: 18 consecutive patients underwent a 3T MRI scan under radiotherapy planning conditions, after the CT scan. Bowel and bladder preparation were prescribed. CT and MR images were automatically fused;prostate and seminal vesicles were contoured on CT and on MRI, organs at risk were defined on CT-MRI fusion. Late rectal and sexual toxicity, differences in target volume between MRI and CT and differences in rectal and penile bulb dose distribution based on CT only or on CT-MRI fusion were evaluated.Results: one patient experienced a late rectal toxicity;no patient had sexual toxicity. The difference between the mean MRI and CT target volumes was statistically significant (p = 0.0001 paired Student's t-test). The dose-volume histogram (DVH) analysis shows a significant reduction of the dose received by the rectum and the penile bulb in MRI-plans compared to CT-plans.Conclusions: 3 Tesla MRI scan under radiotherapy planning conditions along with bowel preparation significantly improves the definition of the target volume sparing normal tissue irradiation.

Management of Hepatocellular Carcinoma Patients with Portal Vein Thrombosis Using Three-Dimensional Conformal Radiotherapy

Objective: To determine the possible therapeutic gain of using three-dimensional conformal radiotherapy (3D-CRT) as a treatment option for portal vein tumor thrombus (PVTT) in patients with hepatocellular carcinoma (HCC) and to evaluate the tolerance and toxicity of using such treatment. Materials and methods: Sixty two patients were enrolled in this prospective study between June 2013 and August 2015. The clinical target volume (CTV) was the PVTT and the prescribed dose was 50 Gy/25 fractions. The median follow-up time was 7.4 months. Results: The thrombus crude response rate was 40.4% and the only significant prognostic factor for response was the thrombus size. Responders had significant better survival compared to non-responders with a median survival of 12.5 and 8 months respectively (P Conclusions: The results of this study suggest that radiotherapy should be considered as a safe treatment option for HCC patients with PVTT. It is effective not only for PVTT local control but also for survival, although prospective randomized trials are needed to confirm these results.

The clinical observation of three-dimensional conformal radiotherapy combined with FOLFOX chemotherapy for rectal cancer of postoperative local recurrence

Objective The aim of this study was to explore the three-dimensional conformal radiotherapy combined with FOLFOX scheme chemotherapy in the treatment of postoperative recurrence of rectal cancer.

Clinical observation of platinum-based combined with concurrent three-dimensional conformal radiotherapy in patients with locally advanced non-small cell lung cancer

Objective： The aim of our study was to explore the shortterm efficacy of platinumbased combined with concur rent chemoradiotherapy for locally advanced nonsmallcell lung cancer （NSCLC）. Methods： Between 2006 to 2010, 78 cases of locally advanced NSCLC were enrolled into this trial. All patients were given platinumbased chemotherapy combined with concurrent threedimensional conformal radiotherapy （3DCRT）. Chest CT scans were obtained during endexpiratory and endinspiratory pauses when performing positioning. Image fusion was done after the image data was transferred to treat ment plan system （TPS）. The target volume was delineated on the fusion images. The chemotherapy was given on the first day of radiotherapy. Comprehensive examinations were conducted 46 weeks after concurrent chemoradiotherapy to assess shortterm efficacy. Results： Complete remission （CR） was achieved in 8 cases and partial remission （PR） in 54 cases. The efficiency rate reached 79.5%. Grade IllIV radiation esophagitis occurred in 11.5%. No exit and death cases during treat ment. Conclusion： Concurrent chemoradiotherapy could significantly improve the shortterm efficacy and prolong survival of stage III NSCLC, meanwhile the adverse reactions could be tolerated.

Clinical observation of three-dimensional conformal radiotherapy(3D-CRT) with concurrent chemotherapy in treatment of recurrent cervical cancers

Objective： The aim of the study was to explore the efficacy of three-dimensional conformal radiotherapy （3D- CRT） combined with TP concurrent chemotherapy in treatment of recurrent cervical cancers. Methods： From May 2005 to May 2009, 36 patients with recurrent cervical cancer were treated by 3D-CRT of 60-66 Gy and TP （docetaxel 70 mg/m^2, d1; cisplatin 20 mg/m^2, dl-d3; 21 days per cycle, totally 2 cycles） concurrent chemotherapy. Results： All of the patients had finished the 3D-CRT, the total response rate, complete response rate and partial response rate were 80.0% （28/35）, 45.7% （16/35）, and 34.3% （12/35）, respectively. The pain-alleviation rate was 91.4% （32/35）. The hemorrhage control rate was 94.3% （33/35）. The median overall survival was 21.2 months. The 1-, 2- and 3-year survival rates were 54.3%, 37.1% and 22.8%, respectively. The life qualities of the patients were improved, without any treatment related death. Conclusion： Radiotherapy is effective and well-tolerated for recurrent cervical cancers, and it can promote regional control of the disease and prolong survival time.

Analysis of the efficacy and safety of conventional radiotherapy of chest wall and clavicular field and three-dimensional conformal radiotherapy in patients after modified radical mastectomy

Objective:To explore the efficacy and safety of conventional radiotherapy of chest wall and clavicular field and three-dimensional conformal radiotherapy in patients after modified radical mastectomy.Methods: A total of 84 patients who were admitted in our hospital after modified radical mastectomy were included in the study and divided into the conventional radiotherapy group (n=42) and the three-dimensional conformal radiotherapy group (n=42) according to different radiotherapy methods. The patients in the conventional radiotherapy group were given conventional radiotherapy of chest wall and clavicular field, while the patients in the three-dimensional conformal radiotherapy group were given three-dimensional conformal radiotherapy. The serum tumor markers and peripheral blood T lymphocyte subsets 6-8 weeks after treatment in the two groups were detected. The clinical efficacy, and toxic and side effects in the two groups were evaluated.Results: The serum CA15-3, CA125, CEA, and CK19 levels after treatment in the two groups were significantly reduced when compared with before treatment, CD3+,CD4+, and CD4+/CD8+ were significantly elevated, while CD8+ was significantly reduced when compared with before treatment, but the comparison of the above indicators between the two groups was not statistically significant. The occurrence rate of radioactive skin damage and pneumonia after treatment in the conventional radiotherapy group was significantly higher than that in the three-dimensional conformal radiotherapy group. Conclusions:The two kinds of radiotherapy schemes have an equal efficacy, but the toxic and side effects of three-dimensional conformal radiotherapy are significantly lower than those by the conventional radiotherapy, with a certain advantage.

Three-Dimensional Conformal and Intensity Modulated Dynamic Radiotherapy in Juvenile Nasopharyngeal Angiofibroma

Objective: Juvenile Nasopharyngeal Angiofibroma (JNA) is a benign neoplasm with a high vascularity component, greater craniofacial involvement in adolescent patients, and aggressive local behaviour. In unresectable patients, radiotherapy is a therapeutic option for local control. Our aim in this study was to analyze the clinical benefit and local control provided by two modalities of radiotherapy: the Three-Dimensional Conformal (3DC) technique and volumetric modulated arc therapy (VMAT), applied to pediatric patients with JNA considered unresectable and non-recurrent. Methods: In retrospective study, the information was recorded from pediatric patients with a diagnosis of non-recurrent and unresectable JNA treated with radiotherapy at the Oncology Hospital of the National Medical Center SXXI of Mexico City, from March 2010 to March 2021. Radiotherapy management and its association with clinical outcomes of tumour control, and symptoms were assessed. In addition, an evaluation of acute and chronic toxicity was performed. Results: It was found that the median age was 14 years. 9 patients (37.5%) underwent 3DC and 15 (62.5%) VMAT. In terms of local control, and progression-free survival, we did not find significant difference between radiotherapy modalities (p ≤ 0.57). Acute toxicity for both modalities presented statistical differences for radio epithelitis (p = 0.03). Only Grade I and II radiation-induced acute toxicity was observed. Regarding chronic toxicity, statistical significance was observed for craniofacial hypoplasia, in relation to its absence in the VMAT group (p = 0.001). Conclusion: The VMAT presents improvements in dosimetry parameters that improve patient toxicity. In both techniques adequate tumour control was observed, however, the rarity of the disease is a limitation to establish the most appropriate therapeutic technique.

Influences of Motion Artifacts on Three-Dimensional Reconstruction Volume and Conformal Radiotherapy Planning

Objective ：To investigate the influences of motion artifacts on three-dimensional （3D） reconstruction volume and conformal radiotherapy planning. Methods： A phantom which can mimic the clip motion of lung tumor along the cranial-caudal direction is constructed by step motor, small ball of polyethylene and potato. Ten different scan protocols were set and CT data of the phantom were acquired by using a commercial GE LightSpeedl6 CT scanner. The 3D reconstruction of the CT data was implemented by adopting volume-rendering technology of GE AdvantageSim 6.0 system. The reconstructed volumes of each target in different scan protocols were measured through 3D measuring tools. Thus, relative deviations of the reconstruction volumes between moving targets and static ones were determined. The three-dimensional conformal radiation therapy （3D- CRT） plans and conformal fields were created and compared for a static/moving target with the WiMRT treatment planning system （TPS）. Results：For a static target, there was no obvious difference among the 3D reconstruction volumes when the CT data were acquired with different pitches and slices. The appearance of 3D reconstruction volume and 3D conformal field of a moving target was quite different from that of static one. The maximum relative deviation is nearly 90% for a moving target scanned with different scan protocols. The relative deviations are variable among the different targets, about from -39.8% to 89.5% for a smaller target and from - 18.4% to 20.5% for a larger one. Conclusion ：The motion artifacts have great effects on 3 D-CRT planning and reconstruction volume, which will greatly induce distorted conformal radiation fields and false DVHs for a moving target.

Stereotactic body radiotherapy in pancreatic adenocarcinoma

Background:Stereotactic body radiotherapy(SBRT)in pancreatic cancer allows high delivery of radiation doses on tumors without affecting surrounding tissue.This review aimed at the SBRT application in the treatment of pancreatic cancer.Data sources:We retrieved articles published in MEDLINE/PubMed from January 2017 to December 2022.Keywords used in the search included:“pancreatic adenocarcinoma”OR“pancreatic cancer”AND“stereotactic ablative radiotherapy(SABR)”OR“stereotactic body radiotherapy(SBRT)”OR“chemoradiotherapy(CRT)”.English language articles with information on technical characteristics,doses and fractionation,indications,recurrence patterns,local control and toxicities of SBRT in pancreatic tumors were included.All articles were assessed for validity and relevant content.Results:Optimal doses and fractionation have not yet been defined.However,SBRT could be the standard treatment in patients with pancreatic adenocarcinoma in addition to CRT.Furthermore,the combination of SBRT with chemotherapy may have additive or synergic effect on pancreatic adenocarcinoma.Conclusions:SBRT is an effective modality for patients with pancreatic cancer,supported by clinical practice guidelines as it has demonstrated good tolerance and good disease control.SBRT opens a possibility of improving outcomes for these patients,both in neoadjuvant treatment and with radical intent.

Computed tomography three-dimensional reconstruction in the diagnosis of bleeding small intestinal polyps:A case report

BACKGROUND Computed tomography(CT)small bowel three-dimensional(3D)reconstruction is a powerful tool for the diagnosis of small bowel disease and can clearly show the intestinal lumen and wall as well as the outside structure of the wall.The horizontal axis position can show the best adjacent intestinal tube and the lesion between the intestinal tubes,while the coronal position can show the overall view of the small bowel.The ileal end of the localization of the display of excellent,and easy to quantitative measurement of the affected intestinal segments,the sagittal position for the rectum and the pre-sacral lesions show the best,for the discovery of fistulae is also helpful.Sagittal view can show rectal and presacral lesions and is useful for fistula detection.It is suitable for the assessment of inflammatory bowel disease,such as assessment of disease severity and diagnosis and differential diagnosis of the small bowel and mesenteric space-occupying lesions as well as the judgment of small bowel obstruction points.CASE SUMMARY Bleeding caused by small intestinal polyps is often difficult to diagnose in clinical practice.This study reports a 29-year-old male patient who was admitted to the hospital with black stool and abdominal pain for 3 months.Using the combination of CT-3D reconstruction and capsule endoscopy,the condition was diagnosed correctly,and the polyps were removed using single-balloon enteroscopyendoscopic retrograde cholangiopancreatography without postoperative complications.CONCLUSION The role of CT-3D in gastrointestinal diseases was confirmed.CT-3D can assist in the diagnosis and treatment of gastrointestinal diseases in combination with capsule endoscopy and small intestinal microscopy.

Research on Three-Dimensional Simulation of the Internal Arc Gear Skiving

Aiming at the problems that the simulation accuracy which is reduced due to the simplification of the model,a three-dimensional simulation method based on solid modeling is being proposed.By analyzing the motion relationship and positional relationship between the caries knife and the workpiece,the coordinate system of the caries machining was established.With the MATLAB software,the cutting edge model and the blade sweeping surface model of the boring cutter are sequentially established.Boolean operation is performed on the blade swept surface formed by the tooth cutter teeth with time t and the workpiece tooth geometry as well as the undeformed three-dimensional chip geometry model and the instantaneous cogging geometry model are obtained at different times.Through the compare between gear end face simulation tooth profile and the theoretical inner arc tooth profile,we verified the accuracy and rationality of the proposed method.