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.

Background: The use of high-density barium sulfate was recommended by the Japan Society of Gastroenterological Cancer Screening (JSGCS) in 2004. We evaluated the diagnostic validity of gastric cancer screening that used high-density barium sulfate.Methods: The study subjects were 171 833 residents of Osaka, Japan who underwent gastric cancer screening tests at the Osaka Cancer Prevention and Detection Center during the period from 1 January 2000 through 31 December 2001. Screening was conducted using either high-density barium sulfate (n = 48 336) or moderate-density barium sulfate (n = 123 497). The subjects were followed up and their medical records were linked to those of the Osaka Cancer Registry through 31 December 2002. The results of follow-up during 1 year were defined as the gold standard, and test performance values were calculated.Results: The sensitivity and specificity of the screening test using moderate-density barium sulfate were 92.3% and 91.0%, respectively, while the sensitivity and specificity of the high-density barium test were 91.8% and 91.4%, respectively. The results of area under receiver-operating-characteristic (ROC) curve analysis revealed no significant difference between the 2 screening tests.Conclusions: Screening tests using high- and moderate-density barium sulfate had similar validity, as determined by sensitivity, specificity, and ROC curve analysis.

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.

Nowadays mass screening for gastric cancer is popularized in Japan. In the screening, gastric radiography is carried out using contrast medium, usually barium sulfate. Recently, high concentration barium sulfate has been developed and used in several medical facilities. However, high concentration barium sulfate flows out from the stomach faster than moderate concentration one used in the past, which happens to interfere with diagnosis. The flow rate is considered to depend on the viscosity of barium sulfate which changes based on gastric pH and temperature. In this study, viscosity changes of barium sulfate with pH and temperature changes are examined on two types of high concentration one, 185B barium and 200C barium, and one type of moderate concentration one, 145A barium. The radiographs of gastric phantom applied with three types of barium sulfate are also tested in several conditions of pH and temperature. The results indicate that 185B barium is the best among three types for gastric radiography. The study on characteristics of barium sulfate may improve radiography technology in mass screening for gastric cancer.

It is important to reduce x-ray exposure in subjects who undergo mass screening for gastric cancer. We constructed three types of lead acrylic filters and evaluated their ability to reduce exposure. X-ray tube load increase, dose area reduction, density of gastric phantom images and lead acrylic filter shadows were evaluated. Three different thicknesses of lead acrylic filters were examined, one was a regular thickness, another was half the thickness, and the other was twofold the thickness. Objectivization, reduction rate of exposure, x-ray tube load increase, and the density of each gastric phantom image was taken with or without the three types of lead acrylic filters. The filter shadow in the image of the gastric phantoms using the three types of lead acrylic filters were evaluated with 4 levels. Dose area reductions using the three types of filters were 6.03%, 10.92%, and 13.64%, for the half thickness, regular thickness, and twofold thickness, respectively (p<0.05). The x-ray tube load increases using the three types of filters were 2.67%, 5.61%, and 4.99%, respectively (p>0.05). There was no significant difference between the density of gastric phantom images with or without the filters (p>0.05). The lead acrylic filter shadows were significantly difference among the three types filters (p<0.05). We conclude that the use of lead acrylic filters is effective for the reduction of exposure in screening for gastric cancer. A lead acrylic filter of twofold thickness is most effective for the reduction of exposure.

This research aims to support chest computed tomography (CT) medical checkups to decrease the death rate by lung cancer. We have developed a remote cooperative reading system for lung cancer screening over the Internet, a secure transmission function, and a cooperative reading environment. It is called the Network-based Reading System. A telemedicine system involves many issues, such as network costs and data security if we use it over the Internet, which is an open network. In Japan, broadband access is widespread and its cost is the lowest in the world. We developed our system considering human machine interface and security. It consists of data entry terminals, a database server, a computer aided diagnosis (CAD) system, and some reading terminals. It uses a secure Digital Imaging and Communication in Medicine (DICOM) encrypting method and Public Key Infrastructure (PKI) based secure DICOM image data distribution.We carried out an experimental trial over the Japan Gigabit Network (JGN), which is the testbed for the Japanese next-generation network, and conducted verification experiments of secure screening image distribution, some kinds of data addition, and remote cooperative reading. We found that network bandwidth of about 1.5 Mbps enabled distribution of screening images and cooperative reading and that the encryption and image distribution methods we proposed were applicable to the encryption and distribution of general DICOM images via the Internet.

Background and purpose Movement artifact during lung CT can degrade image quality and, particularly in the case of computer aided diagnosis, make diagnosis inaccurate. In this study, diaphragmatic movement during full arrested inspiration in lung CT was evaluated to identify the optimum time after commencement of breath holding for image acquisition. Methods For analysis two lung areas were used in this study. These areas, on two images from different time periods after breath holding on the same slice, were evaluated in 47 patients. Results In approximately 74% of the patients 1 s after commencement of breath holding diaphragm motion was noted to be in the cranial direction. A comparison of the lung areas after 30 s and those after 1 s and 4 s showed significant differences. Those after 7 s showed no significant difference. Conclusions The results show that the lung base should be scanned at 7 s from the commencement of breath holding. Also, the lungs should also be scanned from the base to apex.

This study examined the usefulness of a pulse oximeter in hepatic digital subtraction angiography (DSA) with oxygen administration for breath holding. Oxygen saturation and dissociation times were measured using a pulse oximeter. Twenty-eight patients inhaled oxygen at a rate of 3 liters/min through a nasal tube. Saturation times ranged from 0 to 140 seconds to achieve arterial oxygen-hemoglobin saturation of almost 100%. Dissociation times ranged from 0 to 600 seconds after oxygen termination.

HRCT上すりガラス濃度 (ground-glass opacity: GGO) を呈する限局性肺病変は, 組織学的に腫瘍が肺胞上皮 置換性に進展する小型肺腺癌の可能性が高く, 早期診断に有用である.1990年3月から1999年12月に当センターにて1カ月以上の経過観察後に縮小傾向がないために外科切除された2cm以下の限局性肺病変232病変中, 術前のHRCT (スキャン厚: 2mm) で視覚評価により病変の大部分 (80%以上) がGGOを呈する49病変を組織学的に検討した. 47病変 (96%) が小型肺腺癌であり, Noguchi分類type Aが22病変, type Bが20病変, type Cが5病変で, 他の組織型の肺癌は認めなかった. 残り2病変 (4%) が良性病変で, pulmonary lymphoproliferative disorderとsarcoidosisであった. HRCTにてGGOを呈する2cm以下の限局性肺病変のほとんどは予後がきわめて良好とされるNoguchi分類type A-Bの小型肺腺癌であり, type Cの肺腺癌や稀ではあるが良性病変も認められる.

We perform lung cancer screening computed tomography (LSCT) with helical CT using 30 cm for males and 26 cm for females as the standard conditions of the scan range. We discuss the differences in tissue dose, organ dose, and effective dose according to these scan ranges. We discuss the differences in tissue dose, organ dose, and effective dose according to these scan ranges. We compared tissue dose, organ dose, and effective dose among LSCT and conventional lung cancer screening using chest radiography and chest fluorography. Scanning parameters were 120 kV, 25 mA, 10 mm slice thickness, and 20 mm/2 sec/rotation. The effective doses were 1.40 mSv for males and 1.15 mSv for females for LSCT, 0.02 mSv for chest radiography, and 0.07 mSv for chest fluorography. When the scan range was expanded from 26 cm to 30 cm on LSCT, the absorbed doses of the abdomen and bone marrow, and the effective doses increased because the scan range covered organs of the abdomen including liver, stomach, lumbar vertebrae, lower ribs, and thoracic vertebrae. Therefore, we propose that it is necessary to interrupt the x-rays at precisely the time that the scan reaches the bottom of the lung in order to reduce the effective dose.

肺腺癌の病理組織像で肺胞上皮置換性に進展する領域が高分解能CT (high-resolution CT: HRCT) において, すりガラス濃度 (ground-glass opacity: GGO) として描出され, その病変に占める面積は予後と良好に相関する. この有用な画像所見であるGGOの占める面積比 (%) に基づいて限局性肺病変を分類し, 病理組織診断と対比検討した. 1990年から1999年までに外科切除され, 病理組織診断がなされた最大径2cm以下の232病変に対し, HRCT上で腫瘤が最大面積を呈する画像における腫瘤影内のGGOの占める面積比を視覚的に定量し, 10%未満 (軟部組織濃度型), 10%以上50%未満 (軟部組織濃度優位型), 50%以上90%未満 (すりガラス濃度優位型), 90%以上 (すりガラス濃度型) に分類した. すりガラス濃度型の88%, すりガラス濃度優位型の60%は小型肺腺癌の野口分類のtype Aおよびtype Bの腺癌であった. 軟部組織濃度優位型の51%はtype Cの腺癌, 22%がtype A, Bの腺癌であった.軟部組織濃度型の35%は良性病変であり, 28%がtype D, E, Fの腺癌, 15%がその他の原発性肺癌であった. 限局性肺病変をHRCT上でGGOの占める面積比で分類すると, 肺腺癌の亜型分類を踏まえた良悪性病変の推測が可能であり, 治療方針の参考となる.

This study endeavored to clarify the usefulness of single-exposure dual-energy subtraction computed radiography (CR) of the chest and the ability of soft-copy images to detect low-contrast simulated pulmonary nodules. Conventional and bone-subtracted CR images of 25 chest phantom image sets with a lowcontrast nylon nodule and 25 without a nodule were interpreted by 12 observers (6 radiologists, 6 chest physicians) who rated each on a continuous confidence scale and marked the position of the nodule if one was present. Hard-copy images were 7 × 7-inch laser-printed CR films, and soft-copy images were displayed on a 21-inch noninterlaced color CRT monitor with an optimized dynamic range. Soft-copy images were adjusted to the same size as hard-copy images and were viewed under darkened illumination in the reading room. No significant differences were found between hard- and soft-copy images. In conclusion, the soft-copy images were found to be useful in detecting low-contrast simulated pulmonary nodules.

1988年から1996年まで当センターで外科的切除された原発性肺癌731症例について, N因子診断の正診率は66. 3%であった. このうち, 術前CTにおいて縦隔リンパ節に短径10mm以上の腫大を認め, 転移陽性と判断した原発性肺癌症例のうち, 術後診断で転移を認めなかった, いわゆるcN2pNO67症例中, 当センターで術前CTを施行した48症例について検討を行った. false positiveのリンパ節の組織学的所見はリンパ濾胞の発達したものが殆どであったが, サルコイド様反応を呈した症例も認めた. 組織型や腫大リンパ節の部位, 原発巣の部位などでの有意な傾向は認めなかったが, 48例中29例に何らかの他病変が指摘可能であった. 正しいN因子の診断は, 適切な治療や正確な予後判定に不可欠であり, 特に手術適応症例においてはMRIや超音波気管支内視鏡, 縦隔鏡を用いた生検などを含めた正確な診断が必要と考えられた.

術前CTにおいて縦隔リンパ節に短径10mm以上の腫大を認め, 転移性と判断した原発性肺癌症例のうち, 術後診断で転移を認めず, サルコイド様反応を認めた肺癌5例の術前CT像の検討を行った. 症例は65歳から75歳で, 男性4例, 女性1例である. 病理組織は扁平上皮癌2例, 腺癌3例であった. 短径10mm以上の腫大を認め, 病理学的にサルコイド様反応を認めたリンパ節の部位は1番リンパ節が5例中3例, 3番リンパ節が5例中3例であった. サイズは短径長径ともに10mmの円形リンパ節が7個と最も多かった. しかし, 術前の画像上での特徴での診断は困難であり, さらに多くの症例での検討と, 手術適応症例においては縦隔鏡による組織診断を含めた正確な診断が必要と考えられた.

The number of deaths due to lung cancer has been increasing in Japan. The ability to detect lung cancer in its early stage using conventional chest radiographs unfortunately is limited. However, helical computed tomography(CT), which is able to scan the entire lung in a single breath-hold, offers excellent image contrast resolution. We therefore introduced a mobile helical CT unit with a dieselized electric generator into our lung cancer screening programs. Helical CT images were obtained under the following scanning conditions: 120 kV, 140 mA, 10 mm slice-thickness, and 20 mm/2 sec/rotation, with a 10 mm reconstruction increment. Scanninng the entire lung in a single breath-hold, the average breath-hold time required for males was 30 seconds and that for females 26 seconds. In our vehicle, the CT unit is set up in an examination room that is directly adjacent to the room where the generator is located. When vibration and noise levels were measured in the examination room(using vibrator and sound detectors), the bed vibration and noise level caused by the generator were determined to be 22.5 gal and 70.8 dB, respectively. Using the commercial external electric power supply(3 phase, 200 V) to the CT unit, the vibration and noise level on the bed were 2.94 gal and 68.8 dB, respectively. The vibration level caused by the generator was 7.7 times greater than that caused by the external power supply. When used under actual conditions, however, the resolution and contrast of the images provided power supply. When used under actual conditions, however, the resolution and contrast of the images provided by the generator showed no difference compared with those provided by the external power supply.