Indices for the evaluation of glandular dose heterogeneity in full-field digital mammography.

This study aims to evaluate the indices of glandular dose heterogeneity in full-field digital mammography. The distributions of GD in a breast phantom with a skin layer of 4 mm were determined using the Monte Carlo method with simulated x-ray fluence spectra. First, the GD to air kerma (GD/Kair) volume histogram was obtained from the GD distributions, which were indicated by the glandular volume (%) as a function of GD/Kair. The GD indices, namely, the maximum glandular dose (GD2%) and glandular volume percentage (%) receiving at least the mean glandular dose (MGD) (VMGD) were calculated from the GD/Kairvolume histogram. Next, the scatter plots of GD2%/MGD andVMGDwere drawn as functions of the normalised mean glandular dose (DgN). Finally, (GD2%)iand (VMGD)iwere obtained from the relationship between the GD indices and DgN for 596 clinical irradiation cases based on individual irradiation conditions. The values of GD2%/MGD were more affected by breast thickness than glandularity and tube voltage, and they decreased according to the power law of DgN for all the target/filter combinations. The values ofVMGDwere proportional to DgN and decreased with increase in the compressed breast thickness. The values of (MGD)iand (GD2%)ifor 596 clinical irradiation cases were estimated to range from 0.6-3.0 mGy to 1.1-7.0 mGy, respectively, and (VMGD)iwas in the range 32%-48%. (GD2%)iand (VMGD)iare mainly affected by breast thickness. These indices are useful for the evaluation of glandular dose heterogeneity in mammography.

[Construction and Analysis of a Digital Mammography Database: Analysis of Breast Compression Pressures at Four Facilities].

We analyzed the compression pressures in 2772 mammography images of 807 patients acquired by digital mammography equipment at four facilities. The analysis included the average compression pressure at all facilities, difference in compression pressure at each facility, differences between the pressures used by radiological technologists in the same facility, and difference attributed to the breast structure. We also analyzed the effects of the compression pressure on the breast thickness and mean glandular dose (MGD) at each facility. The median values of the compression pressure and breast thickness for the 2772 images at all facilities were 86.5 N and 43 mm, respectively. The compression pressures differed among the institutions. The maximum difference in the median pressures among the four facilities was 38.6 N, while the difference in the breast thickness was 6 mm. The radiological technologists working at the same facility used almost the same compression pressure. However, differences between the compression pressures used by different radiological technologists were observed. The compression pressure in a dense breast was smaller than that in a non-dense breast. The difference in the compression pressure affected the breast thickness and MGD. The results of this analysis could be utilized for an optimal imaging in future digital mammography.

Angioleiomyoma of the cheek: a case report.

Angioleiomyoma is a form of subcutaneous vascular leiomyoma that usually occurs in the extremities. Leiomyoma of the oral cavity represents only 0.4% of soft tissue neoplasms and 0.06% of leiomyomas. Isolated cases of angioleiomyoma have been reported in the knee and lower thigh, gastrointestinal tract, genital and renal tract, and brain. Histopathologic examination by biopsy is necessary to establish a diagnosis, and immunohistochemical staining, along with conventional hematoxylin-eosin staining, is important. The differential diagnosis includes hemangioma and angiosarcoma. At present, surgical resection is the standard therapy for leiomyoma, and recurrence is extremely rare. We report a rare case of angioleiomyoma of the cheek in a 45-year-old man. The postoperative course was uneventful, without complications.