Comparison of sensitivity characteristics between GAFCHROMIC LD-V1 and GAFCHROMIC XR-QA2 in mammographic dosimetry.

In recent years, radiochromic films have begun to be used for dosimetry in mammography; however, the most sensitive GAFCHROMIC XR-QA2 (XR-QA2) film is no longer available owing to its discontinuation. In this study, we evaluated the sensitivity characteristics of GAFCHROMIC LD-V1 (LD-V1) as an alternative to XR-QA2 in the field of mammography, at a low dose and low energy. Our results show that the average ratio of the concentration change of LD-V1 divided by the concentration change of XR-QA2 at each absorbed dose was 53.7%, indicating the sensitivity of LD-V1 to be approximately half of XR-QA2. In addition, the linearity of the concentration change is sufficient even within a dose range of 0.59-14.52 mGy, which is lower than the manufacturer's recommended dose range. Therefore, the LD-V1 is capable of accurate dose assessment even with a low dose and the low level of energy used in mammography.

Dosimetry using a radiochromic film and a mammography phantom.

Mammography is one of the most effective diagnostic methods for the early detection of breast cancer; however, it poses the risk of radiation exposure. To date, mammography dosimetry has been performed according to the mean glandular dose; however, the actual exposure in the breast has not been assessed. Here, we have measured dose distributions and depth doses using both radiochromic films and mammographic phantoms, and a three-dimensional intra-mammary dose assessment was conducted. The absorbed dose distribution at the surface was markedly higher on the chest wall side but lower on the nipple side. The absorbed doses in the depth direction exponentially decreased. The glandular tissue near the surface may be irradiated with an absorbed dose of 7.0 mGy or higher. Since LD-V1 could be placed inside the phantom, the absorbed dose inside the breast could also be evaluated in three dimensions.

Evaluation of factors associated with the effectiveness of radiation protection glasses.

The effects of lead equivalent and lens area of radiation-protective eyewear on lens exposure control were examined. The simulated patient underwent 10-min X-ray fluoroscopy, and the lens dose of the simulated surgeon wearing radiation protection glasses was measured using lens dosemeters attached to the corner of the eye and eyeball. In total, 10 types of radiation protection glasses were selected for measurement. Correlation analysis of the equivalent dose in the lens of the eye with lead equivalence and lens area was performed. The equivalent dose in the lens of the eye of the corner of the eye was negatively correlated with the area of the lens. The equivalent dose in the lens of the eye and the eyeball showed a strong negative correlation with lead equivalence. Lens dosemeters worn at the corner of the eye may overestimate the equivalent dose in the lens of the eye. Moreover, the reduction in exposure of the lens was significantly influenced by the lead equivalent.

THREE-DIMENSIONAL DOSIMETRY OF MAMMOGRAPHY USING A BLOCK CUBE BREAST PHANTOM AND RADIOCHROMIC FILM.

This study developed a phantom with a shape similar to that of the breast and use GAFCHROMIC films that can be placed inside the phantom to measure the detailed breast dose distribution in mammography. GAFCHROMIC EBT3 was placed on the block cube breast phantom and irradiated with a mammography device to measure the absorbed dose distribution inside the phantom in the horizontal and depth directions. The dose distribution in the horizontal plane was the highest in the centre on the chest wall side, and it decreased in a fan shape. Along the depth of the phantom, the doses absorbed across the entire cross-section were 16.15 mGy at the surface and 7.51, 3.25 and 1.68 mGy at depths of 10, 20 and 30 mm, respectively. Compared with the mean glandular dose, the proposed method can measure breast dose distributions in greater detail and is applicable to various breast shapes.

Accuracy assessment methods of tissue marker clip placement after 11-gauge vacuum-assisted stereotactic breast biopsy: comparison of measurements using direct and conventional methods.

BACKGROUND: The objective of the study was to compare direct measurement with a conventional method for evaluation of clip placement in stereotactic vacuum-assisted breast biopsy (ST-VAB) and to evaluate the accuracy of clip placement using the direct method. METHODS: Accuracy of clip placement was assessed by measuring the distance from a residual calcification of a targeted calcification clustered to a clip on a mammogram after ST-VAB. Distances in the craniocaudal (CC) and mediolateral oblique (MLO) views were measured in 28 subjects with mammograms recorded twice or more after ST-VAB. The difference in the distance between the first and second measurements was defined as the reproducibility and was compared with that from a conventional method using a mask system with overlap of transparent film on the mammogram. The 3D clip-to-calcification distance was measured using the direct method in 71 subjects. RESULTS: The reproducibility of the direct method was higher than that of the conventional method in CC and MLO views (P = 0.002, P < 0.001). The median 3D clip-to-calcification distance was 2.8 mm, with an interquartile range of 2.0-4.8 mm and a range of 1.1-36.3 mm. CONCLUSION: The direct method used in this study was more accurate than the conventional method, and gave a median 3D distance of 2.8 mm between the calcification and clip.

Relationship between Bone Mineral Density and Body Composition Estimated by Dual-Energy X-ray Absorptiometry: Comparison between Groups Aged 20-39 and 40-59 Years.

Bone mineral density (BMD) is affected by lean body mass and body weight to various degrees in the course of aging. The attempt of this study is to determine the optimal time to begin prevention of osteoporosis. In this study, female hospital employees aged 20-59 years were divided into 2 age groups, 20-39 years and 40-59 years based on age at peak BMD, and the relations of total BMD, subtotal BMD and lumbar spine BMD to lean body mass and body weight were examined in both groups. Subtotal BMD was calculated by subtracting head BMD from total BMD along with whole body measurement. While persistent positive correlations were found among all factors in the 20-39-year-old group, subtotal BMD and lumbar spine BMD were positively correlated to lean body mass in the 40-59-year-old group. Thus, lean body mass and body weight appeared to exert a profound influence on subtotal BMD in those aged 20-39 years, but lean body mass in those aged 40-59 years. Lean body mass appears to provide the best prediction of subsequent development of osteoporosis.

Evaluation of GAFCHROMIC EBT2 dosimetry for the low dose range using a flat-bed scanner with the reflection mode.

Recently developed radiochromic films can easily be used to measure absorbed doses because they do not need development processing and indicate a density change that depends on the absorbed dose. However, in GAFCHROMIC EBT2 dosimetry (GAF-EBT2) as a radiochromic film, the precision of the measurement was compromised, because of non-uniformity problems caused by image acquisition using a flat-bed scanner with a transmission mode. The purpose of this study was to improve the precision of the measurement using a flat-bed scanner with a reflection mode at the low absorbed dose dynamic range of GAF-EBT2. The calibration curves of the absorbed dose versus the film density for GAF-EBT2 were provided. X-rays were exposed in the range between ~0 and 120 mGy in increments of about 12 mGy. The results of the method using a flat-bed scanner with the transmission mode were compared with those of the method using the same scanner with the reflection mode. The results should that the determination coefficients (r (2) ) for the straight-line approximation of the calibration curve using the reflection mode were higher than 0.99, and the gradient using the reflection mode was about twice that of the one using the transmission mode. The non-uniformity error that is produced by a flat-bed scanner with the transmission mode setting could be almost eliminated by converting from the transmission mode to the reflection mode. In light of these findings, the method using a flat-bed scanner with the reflection mode (only using uniform white paper) improved the precision of the measurement for the low absorbed dose range.

Improved detection of gastric cancer during screening by additional radiographs as judged necessary by the radiographer.

PURPOSE: The aim of this study was to determine whether additional radiographs, as judged necessary by the radiographer, improves cancer detection during gastric cancer screening. MATERIALS AND METHODS: We analyzed 144 gastric cancer cases among 137 744 individuals who underwent X-ray screening for gastric cancer. Radiographs were obtained by 17 radiographers at a screening center in Japan from April 2004 to March 2008. Additional radiographs were taken based on the radiographer's judgment in cases of suspected cancer. During double-blind reinterpretation of the cancer case radiographs by two radiologists, we determined the number of cancer cases that were detected by standard radiographs alone. We next determined the number of cancer cases detected using both standard radiographs and additional radiographs. RESULTS: Compared to the number of cancer cases detected with standard radiographs alone (120 cases detected, 24 cases undetected), the number of cancer cases detected with both standard and additional radiographs (137 cases detected, 7 cases undetected) significantly increased (17 cases; P < 0.001, McNemar test). CONCLUSION: We found that taking additional radiographs, when judged necessary by the radiographer during radiographic gastric cancer screening, improves cancer detection.

Sonographic assessment of hyoid bone movement during swallowing: a study of normal adults with advancing age.

Our aim in this study was to evaluate hyoid bone movement trajectories and the age-related changes during swallowing in healthy subjects by ultrasonography. Data were obtained from 30 healthy volunteers (15 men, 15 women) in three age groups (20-39, 40-59, 60-79 years). The subjects were examined while sitting in an upright position, with the back against a wall to control movement. The transducer was placed in a longitudinal scan above the larynx. The subjects were then given 5 mL of mineral water. The water bolus was held in their mouth until they were forced to do a rapid swallow. The imaging was repeated five times for averaging. The movement was divided into 4 phases: slowly ascending phase (A-B, Elevation); rapidly ascending phase (B-C, Anterior); temporary pause phase (position of maximum rise, Remain); and rapidly and slowly descending shifts toward the resting position phase (C-D, Return). We easily visualized the hyoid bone trajectory by using ultrasonography. In all cases, ultrasonographic analysis of the hyoid bone was confirmed to have a similar trajectory, as determined with videofluoroscopy. The average swallowing duration measurements increased with age. The measurement of the maximally elevated point of the hyoid bone decreased with age. The movement of the hyoid bone during swallowing can be visualized by US. The trajectory of the hyoid bone in sagittal section indicated the capability of swallowing, and may detect some anomalies in swallowing.

Film-reading ability of radiographers in detecting gastric cancer during screening using X-ray examination.

PURPOSE: The aim of this study was to evaluate the film-reading ability of radiographers in detecting gastric cancer during screening X-ray examinations. MATERIALS AND METHODS: A test set of 100 patients (50 negative and 50 positive; mean age 62 years, range 33-78 years) given a stomach X-ray examination were selected from those who underwent gastric cancer screening in Osaka, Japan, between 2000 and 2003. Eleven radiographers and four radiologists scored the test set on a five-point scale. A receiver operating characteristic (ROC) analysis was performed, and the area under the ROC curve (AUC) was defined as a measure of film-reading ability to detect cancer. RESULTS: No significant difference (two-tailed P = 0.962, Welch's t-test) was observed between averaged AUC values from radiographers (0.76, range 0.85-0.62) and radiologists (0.75, range 0.86-0.62). CONCLUSION: Film-reading ability of radiographers in detecting gastric cancer during screening X-ray examinations was not significantly different from that of radiologists. Our results suggest that radiographers can assist radiologists to detect gastric cancer during screening.

Sonographic visualization of the normal stomach: left lateral decubitus position.

The aim of this study was to evaluate the usefulness of an imaging technique that takes into account the effect of posture change on the stomach in transabdominal ultrasonography (US). A total of 240 adult patients (healthy subjects) underwent gastric US. In all subjects, the lesser curvature of the stomach (LCS) and left liver were measured in two different positions [left lateral decubitus (LLD) and supine]. The maximal length of the LCS was defined as the measured range between the cardial orifice and the left liver tip. The anteroposterior length (L1) and maximal longitudinal length (L2) of the left liver were determined on epigastric longitudinal scans. The mean LCS in the supine and LLD positions was 90.2 +/- 34.7 and 124.4 +/- 44.4 mm, respectively. The mean L1 in the supine and LLD positions was 54.0 +/- 12.7 and 65.6 +/- 14.4 mm, respectively. The mean L2 in the supine and LLD positions was 84.3 +/- 18.5 and 107.0 +/- 25.8 mm, respectively. The results for the measured LCS, L1, and L2 differed significantly between the supine and LLD positions (P < 0.05). This study demonstrated that the LCS could be clearly visualized on longitudinal scanning in the LLD position. Therefore, this position may potentially be more useful for gastric US, even in view of the limitations of this approach.

Sonographic examination of the appendix in acute infectious enteritis and acute appendicitis.

PURPOSE: To use transabdominal sonography to determine the frequency of visualization of the adult normal appendix in patients with suspected acute infectious enteritis (AIE) compared with patients with acute appendicitis (AA) and a control group. METHODS: A total of 296 patients divided into 3 different groups underwent sonographic examination, including 120 randomly selected asymptomatic patients, 91 consecutive patients with AIE, and 85 consecutive patients with AA. In the 3 groups, visualization rate, outer appendiceal diameter, presence or absence of inflamed periappendiceal fat, and location of the appendix were recorded. RESULTS: The visualization rates of the appendix were 49.2%, 70.3%, and 96.5% for the control, AIE, and AA groups, respectively (P < 0.05). The mean +/- SD outer appendiceal diameters for the 3 groups were 4.5 +/- 1.2 mm, 4.5 +/- 1.4 mm, and 7.9 +/- 2.0 mm, respectively. The difference between outer appendiceal diameter in the control and AIE groups was not statistically significant. Periappendiceal inflamed fat was detected in all AA cases, but in none of the AIE cases. CONCLUSION: The appendix was visualized more often in patients with AIE than in the control group, although the outer appendiceal diameter of the AIE group was not significantly different from that of the normal appendix seen in the control group.