Kunihiko Sawada

Influence of lead apron shielding on absorbed doses from panoramic radiography

OBJECTIVES This study investigated the absorbed doses in a full anthropomorphic body phantom from two different panoramic radiography devices, performing protocols with and without applying a lead apron. METHODS A RANDO(®) full body phantom (Alderson Research Laboratories Inc., Stamford, CT) was equipped with 110 thermoluminescent dosemeters at 55 different sites and set up in two different panoramic radiography devices [SCANORA(®) three-dimensional (3D) (SOREDEX, Tuusula, Finland) and ProMax(®) 3D (Planmeca, Helsinki, Finland)] and exposed. Two different protocols were performed in the two devices. The first protocol was performed without any lead shielding, whereas the phantom was equipped with a standard adult lead apron for the second protocol. RESULTS A two-tailed paired samples t-test for the SCANORA 3D revealed that there is no difference between the protocol using lead apron shielding (m = 87.99, s = 102.98) and the protocol without shielding (m = 87.34, s = 107.49), t(54) = -0.313, p > 0.05. The same test for the ProMax 3D showed that there is also no difference between the protocol using shielding (m = 106.48, s = 117.38) and the protocol without shielding (m = 107.75, s = 114,36), t(54) = 0.938, p > 0.05. CONCLUSIONS In conclusion, the results of this study showed no statistically significant differences between a panoramic radiography with or without the use of lead apron shielding.

Evaluation of effective dose from a RANDO phantom in videofluorography diagnostic procedures for diagnosing dysphagia

OBJECTIVES Videofluorography (VF) is useful for diagnosing dysphagia; however, few reports have investigated appropriate effective doses for VF. The present study aimed to estimate the effective radiation dose in VF for diagnosis of dysphagia. METHODS Radiation doses to tissues and organs were measured using the anthropomorphic RANDO woman phantom as an equivalent to the human body. Effective doses were estimated according to the recommendations of the International Commission on Radiological Protection (ICRP) 60 in 1990 and IRCP 103 in 2007. The tissues measured were those recommended by ICRP 60 and ICRP 103 including gonads (ovaries and testes), red bone marrow and tissues in which excessive radiation commonly causes malignant tumours including lung, thyroid gland, stomach, large intestine, liver, oesophagus, bladder, breast, bone marrow, skin, brain and salivary gland. Skin dose was also measured using thermoluminescent dosimeters. RESULTS Using ICRP 103, the effective dose was estimated as 118.1 μSv at a tube voltage of 50 kV and 82.4 μSv at 45 kV. However, using ICRP 60 the effective dose for 1 min of VF was estimated at 62.4 μSv and 47.2 μSv under the same exposure conditions. CONCLUSIONS Using ICRP 103, the effective dose for VF per examination at a total estimation time of 1 min was estimated as approximately 2.5-8.3 times that observed for digital panoramic radiography and 1/12 to 3 times depending on the measurement device for cone beam CT (CBCT). This value can be decreased in the future using a smaller irradiation field and decreased time for examination in VF in the future.

Cone-beam computed tomography for the diagnosis of mandibular condylar fractures: 11 case reports

The temporomandibular joint has many complex anatomical and functional features compared with other joints. Therefore, caution should be exercised in the diagnosis of temporomandibular joint fractures. Although panoramic tomography is widely used for the screening of orofacial trauma as well as other diseases, this modality often overlooks evidence of a condylar fracture. Cone-beam computed tomography is also used for diagnosing orofacial diseases. The purposes of this report are to show the usefulness of cone-beam computed tomography in diagnosing condylar fractures and to describe the imaging features of condylar fractures.

Reduction of moving artifacts caused by breathing in rats for in vivo micro-computed tomography

AbstractObjectives This study developed software for the reduction of moving artifacts caused by breathing in rats by means of teeth tracking when CT images were taken using in vivo micro-computed tomography (micro-CT).MethodsRaw projection data from the CT of teeth in rats were chosen retrospectively, and then correlated with moving artifacts caused by breathing. An m-mode image was reconstructed from the projection data and used to calculate motion as a function of position. The projection data were corrected and the CT images were reconstructed using the corrected projection data.ResultsThe reconstructed CT images were sharper than the original CT images. There was fog in the periodontal ligament space in the original images because of motion artifacts. The images were clearer after processing.ConclusionsThe artifacts caused by breathing in in vivo micro-CT images of rat teeth were reduced using this software.

Osteochondroma of the coronoid process of the mandible.

We describe a rare case of osteochondroma of the coronoid process of mandible accompanied by severe trismus in a 14-year-old Japanese boy. The patient had initially been diagnosed as having internal derangement of the temporomandibular joint (TMJ), and conservative treatment had failed to improve the symptoms. Despite extremely limited TMJ movement, panoramic radiography revealed no abnormality, but magnetic resonance imaging suggested internal derangement of the left TMJ. Five months later, the trismus worsened and computed tomography revealed a bone-like mass confluent with the coronoid process, which was finally diagnosed as osteochondroma. The patient then underwent intra-oral coronoidectomy.

Radiographic appearance of fibrous dysplasia associated with the maxillary sinus

Fibrous dysplasia is a relatively rare tumorous lesion in the maxillofacial region. The radiographic appearance of this lesion varies widely in the jaw. Generally, the occurrence rate is higher in the maxilla than in the mandible.The purpose of this study was to report six cases of fibrous dysplasia associated with the maxillary sinus. In this study, we examined radiographic patterns which demonstrated the lesions affect on the sinus radiographically.Mixed radiopacity and radiolucency (the so-called ground glass appearance) was also seen in each of these cases. In four cases in which CT images were obtained, the lesion showed buccal expansion and infiltration into the maxillary sinus.

Diagnostic reliability of 3.0-T MRI for detecting osseous abnormalities of the temporomandibular joint

We compared the diagnostic reliability of 3.0-T magnetic resonance imaging (MRI) for detection of osseous abnormalities of the temporomandibular joint (TMJ) with that of the gold standard, cone-beam computed tomography (CBCT). Fifty-six TMJs were imaged with CBCT and MRI, and images of condyles and fossae were independently assessed for the presence of osseous abnormalities. The accuracy, sensitivity, and specificity of 3.0-T MRI were 0.88, 1.0, and 0.73, respectively, in condyle evaluation and 0.91, 0.75, and 0.95 in fossa evaluation. The McNemar test showed no significant difference (P > 0.05) between MRI and CBCT in the evaluation of osseous abnormalities in condyles and fossae. The present results indicate that 3.0-T MRI is equal to CBCT in the diagnostic evaluation of osseous abnormalities of the mandibular condyle.

Comparison of manual and dose reduction modes of a MORITA R100 CBCT

OBJECTIVE: To compare effective dose differences when acquiring (1) dose reduction mode and (2) manual mode in a MORITA R100 CBCT. METHODS: 24 exposure protocols with different technique factors were performed in both the dose reduction mode and the manual mode in a Veraviewepocs 3D R100 cone beam CT device. 48 TLD were placed in a RANDO head phantom at 24 different sites. Effective doses were calculated according to the formalism published in the 103rd ICRP report. RESULTS: Effective doses for the dose reduction mode protocols ranged from 14 to 156 µSv [mean = 57 µSv, standard deviation (SD) = 37 µSv], whereas effective doses for the manual mode protocols ranged from 22 to 267 µSv (mean = 94 µSv, SD = 65 µSv). Thus, across all protocols, the dose reduction mode leads to a drop of the effective dose by 38 % (SD = 6 %). CONCLUSIONS: The estimated effective doses are significantly lower if dose reduction protocols are acquired.

364. Impact of Injection Volume on Hydrodynamic Delivery To the Liver in Mice

Hydrodynamic gene delivery is a widely prevailed method for gene delivery to the liver especially in rodents, because of its efficiency and simplicity. A transient enlargement of the liver derived from physical force, which is generated by a rapid injection of a large amount of solution through the tail vein of a mouse, plays an important role for the gene transfer.We previously demonstrated that the expansion speed of the liver is a primary determinant for gene transfer efficiency, because the liver volume at the end of the injection (final volume) was not significantly different between hydrodynamic (5 sec) and slow (60 sec) injections, as long as the same amount of volume of 9% of body weight (BW) was injected (kanefuji, et al. Mol Ther Methods Clin Deve 1;14029). However, the relationship between the injection volume and final volume has not been clarified.The present study aimed to evaluate volume-dependent physical impacts on the liver in hydrodynamic injection. Physical impacts to the liver were quantified in mice by measuring the final volume using a cone beam computed tomography (CBCT) and serum concentration of alanine aminotransferase (ALT). Hydrodynamic (9% of BW/5 sec), half-hydrodynamic (5% of BW/5 sec), and half-slow (5% of BW/60 sec) injections were performed with contrast medium including 300 mg/ml of iodine through the tail vein of mice. Just after the injections, CBCT studies were performed without any surgical intervention to collect volume data of the liver, and the final volumes were shown as the relative volume of that of control mice. Blood samples were collected for the assay of serum concentration of ALT at the time points of 1, 4, 24, 48, and 168 hours after the injections.The average final volumes were 125.8±11.5 and 119.7±4.8% in half-hydrodynamic and half-slow injections, and were not significantly different from each other, while they were significantly lower than that of 173.1±10.4% in hydrodynamic injection (p>0.99 and <0.05, respectively, Kruskal-Wallis followed by Dunns Multiple Comparison test). The average levels of ALT 4 hours after the injections were 82.6±72.4 U/L and 1582±701.5 U/L in half-hydrodynamic and hydrodynamic injections, which were significantly different from each other (p<0.01, Mann-Whitney test), and returned to the normal level within 48 hours after the injections.These results clearly indicate that the final volume evidently depends on the injection volume but not speed in both hydrodynamic and half-hydrodynamic injections. Furthermore, the reduction of the injection volume markedly suppressed the elevation of liver enzyme in serum after the injection.From a safety viewpoint, there is no doubt that an injection with less volume is advisable as far as sufficient gene delivery is guaranteed. A further study is on going to make the efficacy of half-hydrodynamic injection comparable with that of hydrodynamic injection.

Repair of a Multiple Implant-Supported Fixed Superstructure With a Metal-Ceramic Resin-Bonded Fixed Partial Denture: A Clinical Report

Even in the case of implant loss, replacement of the implant and refabrication of the superstructure are often sufficient, as long as the bone and soft tissue are in good condition. However, if implant loss accompanied by serious bone resorption occurs with a fixed implant superstructure supported by multiple implants, it is very difficult to treat. This clinical report describes the process by which multiple implant-supported fixed metal ceramic restorations were repaired with a metal ceramic resin-bonded fixed partial denture without complete refabrication after removal of one of the implants due to severe bone resorption. The 3-year follow-up indicated excellent serviceability and a well-satisfied patient.Abstract Even in the case of implant loss, re-placement of the implant and re-fabrication of the superstructure are often sufficient, as long as the bone and soft tissue are in good condition. However, if implant loss accompanied by serious bone resorption occurs with a fixed implant superstructure supported by multiple implants, it is very difficult to treat. This clinical report is to describe the process by which a multiple implant-supported fixed metal ceramic restorations were repaired with a metal ceramic resin bonded FPD (MC RBFPD) without complete re-fabrication following removal of one of the implants due to severe bone resorption. The 3-year follow-up indicated excellent serviceability and a well-satisfied patient.