OBJECTIVETo evaluate the feasibility and accuracy of using Megavoltage CT(MVCT) for head and neck dose calculation.

METHODSThe cheese Phantom was imaged using MVCT scanner, and the MVCT value density calibration curve was established. Conventional CT and MVCT image of nasopharyngeal carcinoma was acquired respectively, and IMRT plan was designed on conventional CT image of NPC patient. The conventional CT plan was copied to MVCT image. The dose distribution was calculated for tumor and normal tissue using the MVCT value density calibration curve, and compared with that of conventional CT. Ten NPC patients were collected for dose verification of IMRT plan on MVCT images.

RESULTSThe MVCT numbers depended linearly on the electron density of the sample, and the stability of the MVCT numbers to electron density was good.The error between the measured dose and calculated dose in measured point was less than 3%.The isodose distribution was well agreement with that calculated by planning system.

CONCLUSIONSPerforming dose recalculation using MVCT of Tomotherapy in head and neck region was feasible.and the dose distributions on kVCT and MVCT were in excellent agreement.

Algorithms ; Head and Neck Neoplasms ; radiotherapy ; Humans ; Phantoms, Imaging ; Radiosurgery ; instrumentation ; methods ; Radiotherapy Dosage ; Tomography, Spiral Computed ; instrumentation

The upper slicing system is the main components of the optical system in MSCT. This paper focuses on the design of upper slicing system and its accuracy analysis to improve the accuracy of imaging. The error of slice thickness and ray center by bearings, screw and control system were analyzed and tested. In fact, the accumulated error measured is less than 1 microm, absolute error measured is less than 10 microm. Improving the accuracy of the upper slicing system contributes to the appropriate treatment methods and success rate of treatment.
Computer Simulation ; Equipment Design ; Tomography, Spiral Computed ; instrumentation ; methods

The QUASAR Penta-guide Phantom with fiducial markers was scanned, and the CT images were transferred to Pinnacle workstation. Skin and target volumes were contoured and transferred to TomoPlan treatment planning system. The phantom was scanned with Megavoltage CT (MVCT). MVCT images were matched to the planning CT. Automatic adjustment of treatment couch was completed. It was found that the green laser coincided with the etched center crosshairs in lateral and longitudinal directions with an error less than 2 mm. However 2 mm vertical tabletop lag was found, but could be eventually corrected. Verifications for specific patients with head and pelvic tumors were also completed, the residual setup error were analyzed. The automatic movement of tabletop after image match is satisfactory.
Humans ; Radiotherapy Planning, Computer-Assisted ; instrumentation ; methods ; Radiotherapy, Intensity-Modulated ; instrumentation ; methods ; Tomography, Spiral Computed ; instrumentation ; methods

The present paper introduces the components and operating principle of Sensation 16 CT date measuring system (DMS), analyzes the fixed position of modules and channels in array detector modules (ADM), the Checkup table, Tuneup table and IRS table in ICS Syngo Service. The author also puts forward a solution of manual handling of defective channels.
Artifacts ; Radiographic Image Interpretation, Computer-Assisted ; methods ; Software ; Tomography, Spiral Computed ; instrumentation

The paper introduces a helical tomotherapy (HT) adaptive system in assessment of parotid gland dose variation in head and neck cancer. The system, which helical therapy unit is equipped with, is based on megavoltage computed tomography (MVCT) images to calculate the actual volume and dose of region of interest (ROI). Whether to change plan is judged on the fact for the realization of adaptive radiotherapy. One case of nasopharyngeal carcinoma was as a sample to evaluate parotid gland dose variation during the treatment. On every week and last time, patient was scanned by MVCT before treatment, a total of eight MVCT images. As the treatment progressed, the parotid gland volume was shrinking and the dose was increasing. The parotids volume variation was negatively related with D50 and V1 (both P < 0.05).
Adult ; Head and Neck Neoplasms ; diagnostic imaging ; Humans ; Male ; Parotid Gland ; diagnostic imaging ; Radiotherapy Dosage ; Radiotherapy Planning, Computer-Assisted ; instrumentation ; methods ; Software ; Tomography, Spiral Computed ; instrumentation ; methods

PURPOSEDiscuss the new method of individual internal fixation with steel plate customization.

METHODCustomize individual internal fixation with steel plate according to 3D reconstruction of CT images and Ugnx. Pro/E machining method.

RESULTSuccess in customization about the first individual internal fixation with clavicular hook plate for the treatment of multisegmental fracture of clavicle.

CONCLUSIONThe new method of individual internal fixation with steel plate customization according to 3D reconstruction of CT images and Ugnx, Pro/E machining technique is a good news for patients of orthopaedic trauma. We are fully confident of the future development of the method of individual internal fixation with steel plate customization.

Bone Plates ; Equipment Design ; Fracture Fixation, Internal ; instrumentation ; Fractures, Bone ; diagnostic imaging ; Humans ; Image Processing, Computer-Assisted ; methods ; Imaging, Three-Dimensional ; Internal Fixators ; Steel ; Tomography, Spiral Computed ; methods

Computed tomography angiography (CTA) is a useful approach for diagnosing vascular diseases. In this paper, we proposed a reconstruction algorithm for dual-source spiral CT with variable pitch. The projection data are collected by the double-source double-multislice spiral CT (DSDMS-CT). However, the pitch of the DSDMS-CT is variable other than being constant. We have developed a new formula performing interpolation along Z-axis for dual-source spiral CT with variable pitch. The dual-source spiral CT with variable pitch can chase contrast bolus more flexibly and more effectively. The simulation results show the correctness and efficiency of the proposed algorithm.
Algorithms ; Coronary Angiography ; methods ; Humans ; Tomography, Spiral Computed ; instrumentation ; methods

OBJECTIVETo improve the safety and accuracy of trans-pedicle internal fixation for cervical vertebra by the parameter data measuring by CT reconstruction.

METHODSThirty volunteers were enrolled and be subjected to high-speed spiral CT for getting the data of C3-C7. The data included pedicle point-midline distance, pedicle sponge width, pedicle angle. The cervical vertebra pedicle morphology were reconstructed.

RESULTSReconstructed CT image data displayed that pedicle sponge width become larger and larger from C3 to C7; the pedicle depth didn't change significantly even from C3 to C7; pedicle angle become small from C3 to C7 and the range is from 33.76 degrees to 47.20 degrees; pedicle point-midline distance were almost similar even from C3 to C7. There were not statistical differences between the right side and the left side, but there were statistical differences between man and woman.

CONCLUSIONReconstructed CT image can provide useful data for clinical cervical vertebra trans-pedicle internal fixation.

Adult ; Bone Screws ; Cervical Vertebrae ; anatomy & histology ; diagnostic imaging ; Female ; Fracture Fixation, Internal ; instrumentation ; methods ; Humans ; Image Processing, Computer-Assisted ; Male ; Middle Aged ; Tomography, Spiral Computed ; methods

According to the structural characteristics of spiral CT systems and our experiences, some relevant solutions to common malfunctions in daily maintenance are suggested.
Computers ; Equipment Design ; Equipment Failure ; Equipment Failure Analysis ; methods ; Humans ; Maintenance ; Tomography, Spiral Computed ; instrumentation

OBJECTIVETo study regular patterns of cone artifact resulted from interpolation algorithm of spiral CT.

METHODSBased on the principle of interpolation algorithm and back-projection reconstruction, a mathematical model of the reconstructed image was established to clarify the relation of the scanning parameters and the characteristics of the scanned object with the cone artifact. Experiments were carried out by a set of acrylic phantoms on siemens plus 4 CT scanners.

RESULTSThe artifact in the image was directly proportional to the table increment per gantry rotation of the scanner, and was positively correlated to the tangent of half cone-angle and inversely to the radii in the reconstruction plane of the phantom. The theoretical analysis was validated by experimental results.

CONCLUSIONThe cone artifact is related to the scanning parameters and the characteristics of the scanned object.

Algorithms ; Artifacts ; Computer Simulation ; Image Processing, Computer-Assisted ; methods ; standards ; Models, Theoretical ; Phantoms, Imaging ; Tomography, Spiral Computed ; instrumentation ; methods