ABSTRACT
Objective To apply metal artifact reduction algorithm to reduce metal artifacts based on 12 bit and 16 bit CT images,and aimed to analyze the effects on CT value and dose distribution.Methods The metal implant was inserted into the phantom,and the original 12 bit CT image and original 16 bit CT image were derived from CT scanning.The images were processed using NMAR algorithm,so the corrected 12 bit image and corrected 16 bit image were obtained.A patient's CT was chosen with artificial femur,and used the NMAR algorithm to reduce metal artifacts.Furthermore,the CT values of original images and corrected images were compared and analyzed.In the planning system,dose distribution was calculated based on each image by same radiation treatment plan.The dose distribution difference of each image was compared and analyzed.Results For the 12 bit image,the CT value of metal was 3 071 HU,which was much smaller than the metal's actual CT value ll 080 HU.The metal's CT value for the 16bit image was 11 098 HU,which was very close to the actual value.The original CT images contained a lot of artifacts around the metal,resulting in a large deviation of CT values from the reference image.After NMAR correction,metal artifacts were reduced significantly,and the CT values were close to the reference images.The dose distribution of the corrected 16 bit image was closest to that of the reference image.The maximum dose deviation on the central axis was 1.8％.The difference between the 12 bit image and the reference image downstream the metal was notable,and the maximum dose deviation on the central axis was 81.6％.The X-rays passed through the artifact region in original image,the dose distribution was obviously different from the reference image,and the maximum dose deviation was 21.6％.Conclusions For the patient with metal implant,using the NAMR algorithm on the 16 bit image result in accurate CT value of CT image,so that the accurate dose distribution will be obtained.
ABSTRACT
Objective To reconstruct 16?bit images of metal implants using the extended function of computed tomography ( CT) imaging, and to analyze the effect of the metal CT value on calculation of dose distribution by evaluation of metal CT values in different scanning conditions. Methods A stainless steel rod and a titanium rod were inserted in a phantom. The 12?and 16?bit images and CT value distribution of metal implants were obtained by scanning the phantom using 120 kV tube voltage and 230 mA tube current. The 16?bit images and CT value distribution of metal implants were obtained by scanning the phantom using fixed tube current ( 230 mA) with varied tube voltage ( 100, 120, and 140 kV) or fixed tube voltage ( 120 kV) with varied tube current ( 180, 230, and 280 mA) . In the Varian treatment planning system, a single?field plan and a parallel?opposed field plan were designed based on the CT images. The dose distribution was calculated and compared by the paired t test. Results The CT values of the stainless steel rod and the titanium rod were both 3 071 HU in 12?bit CT images. In 16?bit CT images;however, the CT value of the stainless steel rod was significantly larger than that of the titanium rod. There were no significant differences in CT value of 16?bit image and dose distribution in radiotherapy plan between three scanning conditions with different tube currents. Under three scanning conditions with different tube voltages, the maximum CT values were 13 568, 13 127, and 12 295 HU for the stainless steel rod and 8 420, 7 140, and 6 310 HU for the titanium rod, respectively. Conclusions High?density metal implants cannot be distinguished by 12?bit images, while the distribution of metal CT value can be obtained by 16?bit images. The dose distribution of metal implants based on 12?bit images is different from that based on 16?bit images. Changes in tube voltage cause substantial changes in the CT value for metal implants, leading to changes in dose distribution in radiotherapy. Variation of tube current within a certain range causes slight changes in metal CT value and dose distribution.
ABSTRACT
La Dermatitis de Contacto secundaria a metales tiene una alta prevalencia en Chile y el mundo, sin embargo estas reacciones han sido poco estudiadas, pese a que podrían verse hasta en un21 por ciento de personas previamente sensibilizadas. Níquel, Cobalto y Cromo son los metales mayormente implicados. La mayoría corresponde a reacciones eccematosas. Test de parche es el gold standard para el estudio de alergia a metales, no obstante, rara vez se utiliza debido principalmente al bajo índice de sospecha de estas reacciones y a la dificultad para disponer de la aleación exacta del metal utilizado. El tratamiento muchas veces consiste en retirar el implante, puesto que el cuadro se torna inmanejable. Se presenta un caso clínico altamente sospechoso de alergia a implantes metálicos, al que se le realizó el estudio completo de alergia a metales, si bien esta no se demostró. Se realiza una revisión de la literatura existente.
Contact dermatitis secondary to metals has a high prevalence in Chile and around the world. Nevertheless, these reactions have been slightly studied, even though they might be found inpreviously sensitized people, with a percentage of 21 percent. Nickel, cobalt and chromium are the most involved metals. The majority of them correspond to eczematous reactions. Patch test is the gold standard for the study of metal allergies; however, specific tests to the implant material are rarely performed, mainly because of the low index of suspicion for these reactions and the difficulty to have the exact alloy of the metal used. Treatment often consists on removing the implant, since the situation becomes unmanageable. A highly suspicious clinical case of allergy to metallic implants is presented, a complete study of allergy to metals was made, although it couldnt be demonstrated. A review of the existing literature was conducted.
Subject(s)
Humans , Male , Middle Aged , Dermatitis, Allergic Contact/diagnosis , Dermatitis, Allergic Contact/etiology , Metals/adverse effects , Prostheses and Implants/adverse effects , Patch Tests/methods , Orthotic Devices/adverse effects , Dermatitis, Allergic Contact/therapyABSTRACT
The X-ray examination of corpse is most useful in medico-legal autopsies, in various ways, especially related to establishment of identity. The identification of decomposed body poses difficulty as compared to fresh body as ordinary means of identification like fingerprints & photographs have little value in such cases. Old healed fractures, bony deformities, metallic implants and foreign bodies in bones are extremely helpful for identification of a body where previous history is available. In the present case, a metallic rod in right femur visible on X-ray examination led to positive identification in decomposed body.
Subject(s)
Adult , Autopsy , Forensic Anthropology/instrumentation , Forensic Anthropology/methods , Humans , India , Male , Metals , Postmortem Changes/diagnostic imaging , RadiographyABSTRACT
Subject(s)
Cadmium , Cell Line , Cell Line, Transformed , Cell Survival , Chromium , Heat-Shock Proteins , HSP27 Heat-Shock Proteins , Ions , Molecular Chaperones , Osteoblasts , Osteogenesis , TitaniumABSTRACT
Este estudo cefalométrico prospectivo foi desenvolvido com o propósito de descrever, comparativamente, os resultados de duas estratégias de correção da sobremordida. Foram selecionados 27 pacientes, com faixa etária entre 11 e 15 anos, apresentando maloclusões de Classe II, Divisão 1, com sobremordida de no mínimo 4 milímetros. Desses, 9 indivíduos serviram como grupo controle, 9 foram tratados com aparelhos fixos e arco contínuo de liga níquel-titânio com curva reversa de Spee, de espessura de 0,016 e os outros 9 pacientes foram tratados com a mecânica de intrusão da técnica do arco segmentado. Foram colocados implantes metálicos de referência intra-mandibulares, para sobreposições de traçados, em todos os componentes da amostra. Telerradiografias cefalométricas, em norma lateral, para a avaliação do comportamento dos incisivos inferiores, e a 45 graus, para a avaliação dos primeiros premolares e primeiros molares inferiores, foram tomadas no início do tratamento e após o nivelamento da curva de Spee do arco inferior, e após aproximadamente 6 meses no grupo de controle. Os resultados na região de incisivos inferiores indicaram que: não houve diferença estatística entre os dois métodos de tratamento; houve intrusão real, avaliada pelos deslocamentos dos centros de resistência dos incisivos tratados com a mecânica de intrusão da técnica do arco segmentado; as bordas incisais, dos grupos experimentais, sofreram deslocamentos intrusivos; as raízes dos incisivos nos grupos tratados mostraram um deslocamento para lingual. As posições dos primeiros premolares não foram influenciadas pelos tratamentos realizados. Na região dos molares, as posições das coroas não foram influenciadas pelos tratamentos realizados. Na região dos molares, as posições das coroas não foram influenciadas pelos tratamentos; no entanto, os tratamentos promoveram significante restrição da irrupção quando considerados os pontos radiculares
A prospective study was carried out with the purpose of comparing the results of two treatment strategies for deep overbite correction. The sample comprised 27 Class II, Division 1, with deep overbite cases (age 11 to 15 years). One group was treated with a continuous arch wire technique (0.016 nickel-titanium wire with reverse curve of Spee); in other group, the semented arch technique (Burstone) was used for correction of vertical malocclusion; a control group of nine cases was used. Metallic implants were used for superimpositions. Lateral cephalometric radiographs were used for evaluation of lower first bicuspids and first molars. The radiographs were taken before and immediately after leveling of lower arch. Statistical analysis was performed on the collected data. The results showed that both techniques produced highly significant incisor intrusion (incisal edge). There was no difference between both treatment strategies on lower incisors. A real intrusion was observed on the center of resistance of the lower incisors treated by the segmented arch technique. A lingual movement of the root apex was observed on both techniques. There was no significant difference between the three groups on lower first bicuspids. Lower first molars crowns were not influenced by these two treatments. However, the molar root points were restricted in their normal eruption
Subject(s)
Child , Adolescent , Dental Implants , Cephalometry , Overbite , Incisor , Malocclusion, Angle Class II , Orthodontics, Corrective , Mathematical Computing , Statistics, NonparametricABSTRACT
Since the first attemt of internal fixation not much more than a century ago, implants have come to play an important role in orthopaedic surgery. Yet little has been reported about complications which may result from implant surgery. During the period of May 1980 to April 1984, 32 cases of fixation failures were treated in the Department of Orthopaedic Surgery, Hallym College, Kang Nam Sacred Heart Hospital and results were obtained as follows: 1. The most common area involved femoral shaft, but the highest rate was distal femur. 2. The most common period of failure was between 2 to 4 months postoperatively. 3. The leading cause of failure was remaining defects at fracture site. 4. The authors recommend accurate reduction of fracture and bone graft, if necessary, adequate immobilization postoperatively and co-coperation of patient to avoid failure of implant.
Subject(s)
Humans , Femur , Heart , Immobilization , TransplantsABSTRACT
The ten cases of metallic failure after I-M nailing & plate fixation who were treated at depart tment of orthopaedic surgery, Soon Chun Hyang University during nine years from June, 1974 to May, 1983 were clinically analysed. The survey as summerized as follows: l. Of the ten cases, six cases were seen the breakage of plate, two cases were the loosening of screw, one case was the brakage of nail & one case was the angulation of nail. Of the six cases of plates, two cases were DCP, three cases were ordinary plate & one case was Thornton plate. 2. Of the six cases who metallic failure occurred as plate failure, five cases were the femur fractures, one case was the tibia fracture. All case who metallic failure occurred as nail failure were ferumr fractures. Of the two cases of screw loosening, one case was the fermur fracture. One case was the tibia fracture. 3. The average interval between operation and metallic failure. 1) The plate breakage was 6.3 months. 2) The screw loosening was 7 months. 3) The nail breakage was 6 months. 4) The nail angulation was 8 months. 4. The causes of failure after internal fixation. 1) The causes of plate breakage.