JaLCDOI 10.18926/11755
Title Alternative New Stepwedge for Bootstrap Sensitometry in Medical Radiography
FullText URL 001_019_027.pdf
Author Yoshida, Akira| Kobashi, Toshimi| Ohkawa, Yoshihiro| Mikami, Yasutaka| Hiraki, Yoshio| Azuma, Yoshiharu| Yamada, Toshiharu| Sugita, Katsuhiko|
Abstract A new stepwedge has been developed for bootstrap sensitometry, which is used for determining the characteristic curve of radiographic screen/film systems. Since each step of the stepwedge is separated by the lead septum, flare generated under one step will not penetrate the region of another step. The metal of the stepwedge can be changed with various materials. Characteristic curves obtained with new stepwedge bootstrap (NSB) and conventional stepwedge bootstrap (CSB) techniques were compared with those obtained for screen/film systems with inverse sqare sensitometry. The inverse square method was used as the reference standard for accuracy. The NSB method provided characteristic curves that agreed well with those obtained using the inverse square method. The slope of the curve in the CSB method was lower than that in the inverse square or NBS method, because of scatter radiation. The shape of the characteristic curve from the NSB method did not vary with the materials of step metals (aluminum and copper). The cumulative error involved when using the bootstrap method is also discussed.
Keywords Stepwedge Bootstrap Characteristic curves Sensitometry Radiographic screen/film systems
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1991-03-25
Volume volume1
Start Page 19
End Page 27
ISSN 0917-4494
language 日本語
File Version publisher
NAID 120002313394
JaLCDOI 10.18926/11766
Title Alternative Basic properies of beam flatness analyzer (THEBES 7000)
FullText URL 007_1_023_027.pdf
Author Nakagiri, Yoshitada| Oguri, Nobuhiro| Maruyama, Toshinori| Okawa, Yoshihiro| Wakasa, Hiroyuki| Nagaya, Isao| Azuma, Yoshiharu| Shibuya, Koichi| Goto, Sachiko| Mikami, Yasutaka| Inamura, Keiji| Morioka, Yasuki| Sugita, Katsuhiko| Hiraki, Yoshio|
Abstract 癌の有力な治療法の1つである放射線治療はシステム全体の許容誤差が±5%と、正確な治療が要求されている。正確な線量を正確な場所に照射されなければならない。そのためには日頃から照射装置のQuality Control が重要である。Beam平坦度の測定はその中でも、重要な項目で1/6月の測定頻度が勧告されている。今回、市販のBeam Flatness Analyzer (7000型 THEBES) を使用する機会を得たので、その基礎的性能であるChamber 相互の感度のちがい、測定値の再現性、識別可能な最小線量について実験を行った。各項目とも誤差が非常に少なく、日常の使用に際してそのデータは十分信頼できるものであることがわかった。
Abstract Alternative Lrradiation, which is one of the effective therapies to Cancer, is required to be accurate within ±5% of the tolerable error of the total system. An accurate dose has to be irradiated accurately at a target volume. For that Quality Control of the irradiation equipment is cotinually important. As the measurement of Beam Flatness is an important item, it is obligated to be measured once a week. In this paper as we have an opportunity to use a Beam Flatness Analyzer sold on a corporation of medical instrument, we experiment about the difference of sensitivity of mutual Chamber which is its basic property, the reproducibility of the measured score, and the minimum value of measuralbe dose. We find that the difference in every item is so small that its data is very reliable in a daily use.
Keywords 放射線治療 (radiation therapy) ビーム平坦度 (beam flatness) 性能評価 (valuation of property) 電子加速器 (electron accelerator)
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1996-09-30
Volume volume7
Issue issue1
Start Page 23
End Page 27
ISSN 0917-4494
language 日本語
File Version publisher
NAID 120002313499
JaLCDOI 10.18926/11878
Title Alternative Dosimetry in Radiography
FullText URL 004_069_073.pdf
Author Nakagiri, Yoshitada| Goto, Sachiko| Mikami, Yasutaka| Azuma, Yoshiharu| Sibuya, Koichi| Inamura, Keiji| Tahara, Seiji| Uno, Hirohumi| Takata, Yoshiaki| Tandani, Nobuyoshi| Yamada, Toshiharu| Sugita, Katsuhiko| Hiraki, Yoshio|
Abstract Utilization of radiation in medical treatment is increasing more and more ; consequently, It becomes more important to estimate exposure dose correctly. Altough there are many reports about exposue dose for patients, most of them merely describe the results of the measurements by parts of the body. Exposure dose differs with equipment, instruments, screen-firm system, contition of radiography, and so on. This paper describes the relation between skin dose and contitions of radiography, and also shows the result of measurement of "TPR" which needs to know the absorbed dose of each organ.
Keywords 線量測定 低エネルギー 被曝
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1994-01-31
Volume volume4
Start Page 69
End Page 73
ISSN 0917-4494
language 日本語
File Version publisher
NAID 120002313669
JaLCDOI 10.18926/15261
Title Alternative 現像温度および時間のマンモフイルム特性に与える影響
FullText URL 008_2_121_129.pdf
Author Maruyama, Toshinori| Goto, Sachiko| Azuma, Yoshiharu| Nakagiri, Yoshitada| Shibuya, Koichi| Sugita, Katsuhiko| Takeuchi, Tomoyuki| Honda, Mitsugi| Yoshida, Akira|
Abstract The influence for developing temperature and processing time within film processing conditions was investigated using four mammographic films, Konica New CM, Fuji UM-MA HC, Kodak Min-R M and Kodak EB/RA (for rapid system). And Fuji UR-2, a double-emulsion film, was used as a control. Those sensitometric strips exposed by a sensitometer were processed in the different combinations of developing temperatures ranging from 28 to 36℃, processing times from 45 to 210 sec. Average gradient, relative speed and base plus fog obtained from the measured film characteristic curves were evaluated for the different developing temperatures and times. Fuji UR-2 was scarcely affected and mammographic films were greatly affected in the different combinations without an increase in base plus fog except EB/RA. In New CM, UM-MA HC and Min-R M, the average gradients and the relative speeds increased as the developing temperature was higher and the developing time was longer, but the increases were limit on the combination of 36℃ and 210 sec in New CM and UM-MA HC. In EB/RA, the average gradients were almost constant and the relative speeds increased slightly like the double-emulsion film. These results suggested that it would be possible to contribute to dose reduction and advancement of contrast in New CM, UM-MA HC and Min-R M by changing these processing parameters.
Abstract Alternative フィルム処理条件において,現像温度と処理時間に対する影響を4種類のマンモグラフィ用フィルムKonica New CM, Fuji UM-MA HC,Kodak Min-R M,迅速処理用Kodak EB/RAについて調べた。そして,比較基準用として両面乳剤フィルムFuji UR-2を用いた。感光計で露光したフィルムを現像温度28~36℃,処理時間45~210秒で処理した。特性曲線から得られたフィルム特性(平均階調度,相対感度,カブリ濃度)を異なる現像温度,現像時間に対して評価した。UR-2はほとんど影響を受けず,マンモグラフィ用フィルムは,カブリ濃度が上昇することなく,現像条件の影響を大きく受けた。New CM, UM-MA HC,Min-R Mは現像温度の上昇,処理時間の延長に伴い,平均階調度と相対感度は増加した。しかし,New CM, UM-MA HCの36℃,210秒で増加は限度に達した。EB/RAの平均階調度は一定で,相対感度は両面乳剤フイルムと同 様にわずかな増加であった。これらの結果は,New CM, UM-MA HC, Min-R Mにおいて,処理条件を変化させることにより,被曝低減,コントラスト向上に貢献できる可能性を示唆していた。
Keywords マンモグラフィ (Mammography) 現像処理パラメータ (Processing Parameter) 特性曲線 (Characteristic Curve) 平均階調度 (Average Gradient) 相対感度 (Relative Speed)
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1998-01-31
Volume volume8
Issue issue2
Start Page 121
End Page 129
ISSN 0917-4494
language 英語
File Version publisher
NAID 120002307943
JaLCDOI 10.18926/15252
Title Alternative Extended-cycle processによる乳房撮影用増感紙/フィルムシステムの画質改善
FullText URL 009_2_083_090.pdf
Author Goto, Sachiko| Maruyama, Toshinori| Azuma, Yoshiharu| Nakagiri, Yoshitada| Takeda, Yoshihiro| Sugita, Katsuhiko| Kimura, Fumie| Kadohisa, Shigefumi|
Abstract Extended-cycle process is the term used for a processor in which the processing time has been prolonged usually to approximate 210 seconds. It has been known that the extended-cycle process of some single-emulsion films as used for mammography may enhance film contrast and increase film speed. So the speed was increased in lower speed and higher resolution system than conventional systems by means of using the extended-cycle process in this paper. We investigated how much the resolution of the system was kept. A single screen-single emulsion combination, Konica M-100/CM-H was employed as a low speed and high resolution system. This film after exposure was processed in the different combinations of developing temperatures, 30, 32 and 34℃, and processing time of 210 seconds. On the other hand, Konica M-200/CM-H was employed as a high speed system. This film was processed in the standard-cycle processing (34℃, 90 seconds). Those systems were compared on contrast, speed, screen-film blur and noise by a characteristic curve, MTF (modulation transfer function) and WS (wiener spectrum). Furthermore, the RMI 165 phantom was used to evaluate visibility of mammographic details of these systems. As a result, in the extended-cycle process at the developing temperatures of 32 or 34°C and processing time of 210 seconds for M-100/CM-H, it was possible to increase the speed as much as the higher speed system, M-200/CM-H. Then the contrast, the MTF and the visibility were also improved as compared to the higher speed system. Furthermore patient dose could be reduced at the developing temperature of 34℃ and processing time of 210 seconds in M-100/CM-H.
Abstract Alternative 通常,extended-cycle processは処理時間が約210秒に延ばされた現像機のために使われる用語である。乳房撮影に使われるような片面乳剤フィルムにおけるextended-cycle processは,フィルムコントラストを増し,感度をあげることが良く知られている。そこで,本論文ではextended-cycle processにより低感度,高解像度システムの感度を上げ,どの程度解像度が維持されるかを調べた。片面増感紙/片面フィルムの組合わせであるKonica M-100/CM-Hを低感度,高解像度システムとして用いた。露光後のフィルムは現像温度30,32, 34度,処理時間210秒の異なる組合わせで現像処理した。一方,高感度システムとしてKonica M-200/CM-Hを用い,このフィルムは標準現像(34℃,90秒)された。感度,増感紙/フイルムのぼけ,雑音に関して,特性曲線,MTF(modulation transfer function), WS(wiener spectrum)によってこれらのシステムを比較した。さらにこれらのシステムにおける乳房写真の細部視覚評価のためにRM165ファントムを使用した。その結果,M-100/CM-Hに対するextended-cycle process現像温度32, 34℃,処理時間210秒のextended-cycle processにおいて,高感度システムM-200/CM-Hと同等の感度を上げることが可能であった。そのとき,コントラスト,MTF,視覚的検出能も高感度システムより向上した。さらに,現像温度34℃,処理時間210秒では,被曝線量の低減が可能であった。
Keywords image quality mammography single screen-single emulsion film system high-resolution screen extended-cycle process
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1999-02-26
Volume volume9
Issue issue2
Start Page 83
End Page 90
ISSN 0917-4494
language 英語
File Version publisher
NAID 120002307881
Author Sumimoto, Tetsuhiro| Maruyama, Toshinori| Azuma, Yoshiharu| Goto, Sachiko| Mondou, Munehiro| Furukawa, Noboru| Okada, Saburo|
Published Date 2003-5
Publication Title Instrumentation and Measurement Technology Conference
Volume volume2
Content Type Journal Article
Author Sumimoto, Tetsuhiro| Maruyama, Toshinori| Azuma, Yoshiharu| Goto, Sachiko| Mondou, Munehiro| Furukawa, Noboru| Okada, Saburo|
Published Date 2002-12
Publication Title Industrial Technology
Volume volume1
Content Type Journal Article
JaLCDOI 10.18926/11808
Title Alternative RESOLUTION PROPERTIES OF CRT MONITORS
FullText URL 002_081_088.pdf
Author Takeuchi, Tomoyuki| Yoshida, Akira| Azuma, Yoshiharu| Sugita, Katsuhiko| Nakamura, Nobue| Kishi, Kanji| Hiraki, Yoshio|
Abstract We have developed a new technique for measuring the modulation transfer function (MTF) of a cathode ray tube (CRT) monitor. The "nominal" MTF was measured by displaying a line image of a width of one pixel on the CRT monitor using the pattern generator. We also measured the effective pixel width. In order to obtain the "actual" MTF, the nominal MTF was divided by the sinc function which is the Fourier transform of the effective pixel width. The results indicate that the corrected MTF converges to the constant value as the effective pixel width is narrower. Thus, the actual MTFs were determined and compared in the horizontal direction for two CRT monitors.
Keywords CRT Monitor Resolution Effective Pixel Width Modulation Transfer Function (MTF)
Publication Title 岡山大学医療技術短期大学部紀要
Published Date 1992-02-05
Volume volume2
Start Page 81
End Page 88
ISSN 0917-4494
language 日本語
File Version publisher
NAID 120002313719
JaLCDOI 10.18926/11714
Title Alternative スクリーン/フィルム乳房撮影法における乳房線量測定システム
FullText URL 010_2_099_106.pdf
Author Goto, Sachiko| Azuma, Yoshiharu| Maruyama, Toshinori| Nakagiri, Yoshitada| Takeda, Yoshihiro| Sugita, Katsuhiko| Kadohisa, Shigefumi|
Abstract The average glandular dose to glandular tissue m mammography is generally assumed to be a function of beam quality (HVL), x-ray tube target material, tube voltage, breast thickness, breast composition and, to a lesser extent, x-ray tube voltage waveform. The average glandular dose is generally determined from published tables with knowledge of the above function. Tables for a high frequency x-ray generator are not yet published. In our study, the lookup tables for the average glandular dose were made at 28 kV (high frequency x-ray generator), employing a breast simulating tissue (0-100% adipose tissue, 0-100% glandular tissue) phantom for an Mo target - Mo filter source assembly. We tried to estimate breast composition from x-ray mammograms by digital image processing techniques, also using the simulating tissue phantom. Then the system that automatically calculates the average glandular dose from digitized clinical x-ray mammograms was built. It is considered that this system can contribute to objective evaluation of the average glandular dose.
Abstract Alternative 乳房X線撮影法において乳腺組織に対する平均放射線吸収線量,すなわち平均乳腺線量は放射線のリスクの最も有用な測定法であり,現在,乳房に対する線量の評価に用いられている指標である。一般に,平均乳腺線量は線質(HVL),X線管球ターゲット材料,管電圧,圧迫乳房厚さ,乳房構成および(ある程度)X線管電圧波形の関数であるとされている。平均乳腺線量は,上記の関数についての情報を備えた表が公表されており,一般にその表を使って決定されている。近年,インバータ式といわれる高周波X線発生装置が普及してきた。しかし,その装置用の表は,まだ公表されていない。我々の研究では,乳房組織をシュミレートするファントム(0~100%乳腺組織,0~100%脂肪組織)を使用して,28kVでMoターゲット―Moフィルタソースアセンブリーを備えた高周波X線発生装置のために,平均乳腺線量用のルックアップテーブルを作成した。同様に,乳房組織をシュミレートするファントムを使用して,乳房X線写真から,ディジタル・イメージプロセシング技術によって,乳房構成の評価を試みた。そして,ディジタイズされた臨床乳房X線写真から,平均乳腺線量を自動的に計算するシステムを構築した。サンプル数が少ないため断定はできないが,日本女性は,基準構成(50%の脂肪および50%の乳腺組織)と比較すると,脂肪が少ない傾向を分析結果は示唆していた。また,平均乳腺吸収線量の限度は,明確に規定されていないが,American College of Radiology(ACR)は4 mGyなどを推奨している。また日本では,3 mGyが推奨されているが,我々の撮影システムはこれらを十分満足していた。このように本システムは,平均乳腺線量の客観的な評価に寄与するとともに,DR(digital radiography)などに応用すると,すなわちルックアップテーブルをDRのコンピュータに保存しておけば,撮影後すぐに乳房構成および平均乳腺線量を算出できる可能性をもつ。
Keywords Screen/Film Mammography (スクリーン/フィルム乳房撮影法) Breast composition (乳房構成) Average glandular dose (平均乳腺線量) Entrance skin exposure (皮膚入射線量) Breast-equivalent material phantom (乳房組織等価ファントム)
Publication Title 岡山大学医学部保健学科紀要
Published Date 2000-03-24
Volume volume10
Issue issue2
Start Page 99
End Page 106
ISSN 1345-0948
language 英語
File Version publisher
NAID 120002313736