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Objective:By comparing the positioning errors caused by 3D printed personalized breast bracket and common headrest in intensity-modulated radiation therapy (IMRT), the fixation effect of 3D printed personalized breast bracket in IMRT was analyzed.Methods:Thirty-two breast cancer patients from January to July 2021 were randomly divided into a the 3D printed breast bracket group and common headrest group. All patients in two groups were kept in supine position, head tilted to the healthy side, the affected hand held the grip bar on the same side of the horizontal bar, the healthy hand held the opposite side of the vertical bar, and the chest and mandible were fixed with thermoplastic film. CBCT scan was performed weekly, and gray level registration was carried out according to the three registration regions of interest: breast or chest wall field, supraclavicular and inferior field, and axillary field. The positioning errors in the left and right, head and foot, abdomen and back directions were analyzed between two groups.Results:In the 3D printed breast bracket group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, head and foot, abdomen and back directions were (1.75±1.26), (1.77±1.11) and (1.70±1.08) mm, (1.75±1.25), (1.72±1.09) and (1.70±1.05) mm,(1.86±1.34), (2.14±2.13) and (1.66±1.19) mm, respectively.In the common headrest group, the positioning errors of breast or chest wall field, supraclavicular and inferior field and axillary field in the left and right, the head and feet, the abdomen and back directions were (2.54±1.84), (2.73±3.62) and (2.18±2.45) mm, (3.25±2.02), (3.52±2.26) and (2.62±2.83) mm, (3.25±2.05), (4.44±2.90) and (3.10±3.18) mm, respectively.The positioning errors significantly differed between two groups (all P<0.05). Conclusions:The positioning error of 3D printed personalized breast bracket fixation is less than that of common headrest fixation. The positioning consistency of 3D printed personalized breast bracket in the three target areas of breast or chest wall field, supraclavicular and inferior field and axillary field is better than that of common headrest.
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Objective To evaluate the accuracy of image registration based on bony structure (RBS) and grey-scale (RGS) in positioning correction of radiation treatment,and their reliability in clinical application.Methods Setup errors of anthropomorphic phantom (chest& abdomen,head& neck) were simulated with x-,y-,z-directions.CBCT images were acquired for each simulation and registered with planning CT.using bony structure and grey-scale registration separately.Geometry accuracy of all registration were then obtained and analyzed.Results The errors of RBS and RGS in x-,y-,z-directions were (-0.65 ±0.22) mm and (-0.70±0.17) mm (P=0.00),(1.02 ±0.27) mm and (0.90±0.20) mm (P =0.00),(1.46 ± 0.53) mm and (1.47 ± 0.47) mm (P =0.54) for head& neck positioning; with (0.82±0.33) mm and (0.79±0.18) mm (P=0.03),(2.45±1.17) mm and (1.61 ±0.84) mm (P =0.00),(1.44 ± 3.25) mm and (0.19 ± 1.11) mm (P =0.00) for chest& abdomen positioning.Conclusions RGS is more accurate and stable than RBS.The accuracy of image registration is a little better for head& neck than that for chest& abdomen.The algorithms of image registration used in clinical application needs to be tested independently and the systematic error needs to be corrected before applying in different treatment techniques according to their accuracy requirement.
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Objective: Metrological verification for the medical emergency vehicle terminal 3G system, in order to facilitate the accurate positioning, route correctly, timely treatment, high success rate, and increase the credibility and effectiveness of treatment process records provided in the verification process or perform the burden of adducing evidences for emergency first-aid course. Methods:Metrological verification the positioning error, azimuth error and velocity error of emergency medical 3G system terminal. Results:The vehicle terminal measurement device and measurement method, which can satisfy the requirements of verification terminal technology and provide a valid certificate. Conclusion:Metrological verification has the very good function to emergency medical vehicles to successfully treat patients and subsequent verification and perform the burden of adducing evidences.
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Objective To investigate the development and application of thoracic-abdominal tumor precise positioning puncture devices.Methods Based on the principle of locating and pendulum,as well as the isocenter multi-angle non-coplanar light principle on the chest and abdomen precise radiation therapy,the thoracic-abdominal tumor precise positioning puncture devices was developed with the use of tumor center spatial location method and radiotherapy positioning coordination system transfer method of radiation oncology treatment planning system (TPS).Results The device was applied to puncture chest tumor,reaching 100％ accuracy rate of one time biopsy.The average error in the space between tumor center (pre-puncture points) and actual puncture point (the actual arrival at the needle tip) was 2.59 mm,and the average displacement in the space distance of skin marker was 0.56 mm.Conclusion Using the newly developed thoracic-abdominal tumor precise positioning puncture devices can reduce the dependence on doctor's experience and the technique,as well can significantly improve the accuracy rate of puncture.As a result,it is a promising device which can be put in application.
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Objective To design leaf patterns for Multileaf Collimator(MLC)routine quality assurance(OA)with a 2D diode array.Methods According to the detector distribution characteristic of the 2D diode array and basillg on the"picket fence"pattern,design the"stepwise"pattern.For each diode involving MLC QA,a calibration curve of relative output versus leaf positioning error was measured through delivering a set of patterns with different intentionally introduced positioning errors.When this proposed technique was delivered,the referenced patterns were exposed,and the calibration curves were used as a mean to quantitative determination of the leaf possible positioning errors through the detector readings.Results Compared with the"picket fence"pattern,the"stepwise"pattern not only had a high detecting efficiency,but also increased the dosimetric sensidvity to leaf positioning error.A 1 mm Ieaf positioni.error corresponds to a dose variation of 25% for the"stepwise"pattern,while for the"picket fence"pattern the same positioning error just causes a 17% dose vailation.Conclusions The new"stepwise"pattern is more efficient to be carried out,and more sensitive to sub-millimeter changes of leaf positioning.
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The purpose of this study was to evaluate the positioning errors according to the method of bonding lingual brackets. Dental models of twenty orthodontic patients with malocclusion were selected for this study. The positioning errors were measured on each model that brackets were bonded to. Three different bonding methods were used. For the first method, the bracket was bonded intimately to the lingual surface of the model. For the second method, the bracket was bonded intimately to the lingual surface after setting up using articulator. The passive bracketing, bonding the bracket ligated first to ideal archwire, was used after setting up as the last method. The results were as follows: 1. The brackets bonded without setting up showed greater angulation errors in the upper 1st premolar and the lower canine than those in other bonding methods. The brackets bonded without passive bracketing showed greater positioning errors in upper central incisor, lower 1st and 2nd premolars. 2. The brackets bonded without setting up showed greater torque error in lower 2nd premolar than those in other bonding methods. The brackets bonded without passive bracketing showed greater torque errors in all upper teeth, lower 1st and 2nd premolars. 3. The brackets bonded without passive bracketing showed greater rotation errors between upper central incisors, lower central incisors, lower lateral and central incisor, lower canine and lateral incisor. 4. The brackets bonded without setting up showed greater in-out errors between upper canine and lateral incisor than those in other bonding methods. The brackets bonded without passive bracketing showed greater in-out errors between upper central incisors, upper central and lateral incisors, upper 1st and 2nd premolars, lower lateral and central incisors, lower canine and lateral incisor. These results suggest that there is a large amount of positioning error in lingual brackets even by an indirect bonding technique, and it may be reduced by passive bracketing.