Medknow Publications Acta Medica Okayama 0971-6203 50 1 2025 Investigating the Effects of Reconstruction Conditions on Image Quality and Radiomic Analysis in Photon-counting Computed Tomography 100 107 EN Miyu Ohata Department of Radiological Technology, Graduate School of Health Sciences, Okayama University Ryohei Fukui Department of Radiological Technology, Faculty of Health Sciences, Okayama University Yusuke Morimitsu Division of Radiological Technology, Okayama University Hospital Daichi Kobayashi Division of Radiological Technology, Okayama University Hospital Takatsugu Yamauchi Division of Radiological Technology, Okayama University Hospital Noriaki Akagi Division of Radiological Technology, Okayama University Hospital Mitsugi Honda Division of Radiological Technology, Okayama University Hospital Aiko Hayashi Department of Radiology, Hiroshima University Hospital Koshi Hasegawa Department of Radiological Technology, Graduate School of Health Sciences, Okayama University Katsuhiro Kida Department of Radiological Technology, Faculty of Health Sciences, Okayama University Sachiko Goto Department of Radiological Technology, Faculty of Health Sciences, Okayama University Takao Hiraki Department of Radiology, Faculty of Medicine, Dentistry and Pharmaceutical, Okayama University Introduction:Photon-counting computed tomography (CT) is equipped with an adaptive iterative reconstruction method called quantum iterative reconstruction (QIR), which allows the intensity to be changed during image reconstruction. It is known that the reconstruction conditions of CT images affect the analysis results when performing radiomic analysis. The aim of this study is to investigate the effect of QIR intensity on image quality and radiomic analysis of renal cell carcinoma (RCC). Materials and Methods:The QIR intensities were selected as off, 2 and 4. The image quality evaluation items considered were task-based transfer function (TTF), noise power spectrum (NPS), and low-contrast object specific contrast-to-noise ratio (CNRLO). The influence on radiomic analysis was assessed using the discrimination accuracy of clear cell RCC. Results:For image quality evaluation, TTF and NPS values were lower and CNRLO values were higher with increasing QIR intensity; for radiomic analysis, sensitivity, specificity, and accuracy were higher with increasing QIR intensity. Principal component analysis and receiver operating characteristics analysis also showed higher values with increasing QIR intensity. Conclusion:It was confirmed that the intensity of the QIR intensity affects both the image quality and the radiomic analysis. No potential conflict of interest relevant to this article was reported.

Medknow Publications Acta Medica Okayama 0971-6203 49 4 2024 Backside Irradiation of Ultraviolet-A for Correcting Nonuniformity Error of Gafchromic XR-QA2 Films 563 567 EN Nobuyoshi Tanki Department of Radiological Technology, Graduate School of Health Sciences, Okayama University Sachiko Goto Department of Radiological Technology, Faculty of Health Sciences, Okayama University Toshizo Katsuda Department of Medical Radiation Technology, Shizuoka College of Medicalcare Science Rumi Gotanda Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare Tatsuhiro Gotanda Department of Radiological Technology, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare Tadao Kuwano Department of Radiology, Osaka Center for Cancer and Cardiovascular Diseases Prevention Purpose: Radiochromic film is used for quality assurance and quality control of X-ray equipment in the diagnostic radiology. In addition, three-dimensional dose distribution of computed tomography (CT) is measured. To correct the nonuniformity and uncertainty of radiochromic films for dose measurement of CT, the films are preirradiated ultraviolet (UV)-A rays. There is a difference in the UV protection strength of radiochromic films. A concern exists about the effects of the UV-A irradiation intensity. We thus irradiated with UV-A rays from the backsides of the films to assess if backside irradiation was possible. Materials and Methods: Gafchromic XR-QA2 and RTQA2 were used in this study. The UV-A rays were simultaneously irradiated on the front and backsides of each film for 12 h. The yellow layer of each film was scanned and imaged. The average pixel values ± standard deviations (SDs) were compared. In the statistical analysis, a paired t-test was performed. To compare, the active-layer densities engendered by the UV-A rays. Calibration curve was created with 48 h of preirradiation of UV-A. Results: The mean pixel values ± SD for Gafchromic XR-QA2 on the front and backsides were 130.776 ± 0.812 and 81.015 ± 1.128, respectively. On the other hand, the mean pixel values ± SD for Gafchromic RTQA2 on the front and backsides were 62.299 ± 1.077 and 133.761 ± 1.365, respectively. The statistical results of the paired t-test were significantly different (P < 0.01) between both films. Fitting equation of the calibration curve is shown below. y = -390.47 ± 200 + (443.45 ± 10x80).5068 ± 0.0434. Conclusion: Based on the relationship between the sensitivity of the active layer to UV-A rays and the strength of UV protection on the surface, we concluded that backside irradiation is recommended for Gafchromic XR-QA2, and frontside irradiation is recommended for Gafchromic RTQA2. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 78 3 2024 Assessment of a New Elbow Joint Positioning Method Using Area Detector Computed Tomography 215 225 EN Takuya Akagawa Department of Radiological Technology, Tokushima Red Cross Hospital Ryohei Fukui Department of Radiological Technology, Faculty of Health Sciences, Okayama University Katsuhiro Kida Department of Radiological Technology, Faculty of Health Sciences, Okayama University Ryutaro Matsuura Department of Radiological Technology, Faculty of Health Sciences, Okayama University Makoto Shimada Department of Radiology, Osaka International Cancer Institute Mitsuhiro Kinoshita Department of Radiology, Tokushima Red Cross Hospital Yoko Akagawa Department of Radiology, Tokushima Red Cross Hospital Sachiko Goto Department of Radiological Technology, Faculty of Health Sciences, Okayama University Original Article 10.18926/AMO/67196 We propose a sitting position that achieves both high image quality and a reduced radiation dose in elbow joint imaging by area detector computed tomography (ADCT), and we compared it with the ‘superman’ and supine positions. The volumetric CT dose index (CTDIvol) for the sitting, superman, and supine positions were 2.7, 8.0, and 20.0 mGy and the dose length products (DLPs) were 43.4, 204.7, and 584.8 mGy • cm, respectively. In the task-based transfer function (TTF), the highest value was obtained for the sitting position in both bone and soft tissue images. The noise power spectrum (NPS) of bone images showed that the superman position had the lowest value up to approx. 1.1 cycles/mm or lower, whereas the sitting position had the lowest value when the NPS was greater than approx. 1.1 cycles/mm. The overall image quality in an observer study resulted in the following median Likert scores for Readers 1 and 2: 5.0 and 5.0 for the sitting position, 4.0 and 3.5 for the superman position, and 4.0 and 2.0 for the supine position. These results indicate that our proposed sitting position with ADCT of the elbow joint can provide superior image quality and allow lower radiation doses compared to the superman and supine positions. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 77 1 2023 Image Quality Assessment of Deep Learning Image Reconstruction in Torso Computed Tomography Using Tube Current Modulation 45 55 EN Kazuhiro Takeuchi Department of Radiology, Kagawa University Hospital Yasuhiro Ide Department of Radiology, Kagawa University Hospital Yuichiro Mori Department of Radiology, Kagawa University Hospital Yusuke Uehara Department of Radiology, Kagawa University Hospital Hiroshi Sukeishi Department of Radiology, Kagawa University Hospital Sachiko Goto Department of Radiological Technology, Graduate School of Health Sciences, Okayama University Original Article 10.18926/AMO/64361 Novel deep learning image reconstruction (DLIR) reportedly changes the image quality characteristics based on object contrast and image noise. In clinical practice, computed tomography image noise is usually controlled by tube current modulation (TCM) to accommodate changes in object size. This study aimed to evaluate the image quality characteristics of DLIR for different object sizes when the in-plane noise was controlled by TCM. Images acquisition was performed on a GE Revolution CT system to investigate the impact of the DLIR algorithm compared to the standard reconstructions of filtered-back projection (FBP) and hybrid iterative reconstruction (hybrid-IR). The image quality assessment was performed using phantom images, and an observer study was conducted using clinical cases. The image quality assessment confirmed the excellent noise- reduction performance of DLIR, despite variations due to phantom size. Similarly, in the observer study, DLIR received high evaluations regardless of the body parts imaged. We evaluated a novel DLIR algorithm by replicating clinical behaviors. Consequently, DLIR exhibited higher image quality than those of FBP and hybrid-IR in both phantom and observer studies, albeit the value depended on the reconstruction strength, and proved itself capable of providing stable image quality in clinical use. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 1 2002 Detection of defects at BGA solder joints by using X-ray imaging 191 196 EN Tetsuhiro Sumimoto Toshinori Maruyama Yoshiharu Azuma Sachiko Goto Munehiro Mondou Noboru Furukawa Saburo Okada In the surface mount technology, a ball grid array (BGA) has been used in the production of PC boards. This paper deals with the detection of defects at BGA solder joints in PC boards by using X-ray imaging. Types of defects at BGA solder joints are solder bridge, missing connection, solder voids, open connection and misregistration of parts. The problems of image analysis for the detection of defects at BGA solder joints are the detection accuracy and image processing time according to the speed of the production line. To get the design data for the development of the inspection system used in the surface mount process, it is important to develop image analysis techniques based on X-ray image data. At the first step of our study, we attempt to detect the characteristics of the solder bridges based on the image analysis technique. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 2 2003 Development of image analysis for detection of defects of BGA by using X-ray images 1131 1136 EN Tetsuhiro Sumimoto Toshinori Maruyama Yoshiharu Azuma Sachiko Goto Munehiro Mondou Noboru Furukawa Saburo Okada In the surface mount technology, Ball Grid Array (BGA) has been used in a production of PC boards, because of their excellent characters such as high density of the lead pin pitch, better lead rigidity and self-alignment during re-flow processing. This paper deals with the development of image analysis for the detection of defects at BGA solder joints in PC boards by using X-ray images. In the conventional IC boards, it is possible to detect defects of solder joints by visual inspection, because the lead of IC package is set on its outside. However, we can't detect visually defects at BGA solder joints, because they are hidden under the IC package. In a production line, the inspection of BGA in PC boards depends on the function test of electric circuits in the final process. To improve a cost performance and the reliability of PC boards, an inspection of BGA is required in the surface mount process. Types of defects at BGA solder joints are solder bridge, missing connection, solder voids, open connection and miss-registration of parts. As we can find mostly solder bridge in these defects, we pick up this to detect solder bridge in a production line. The problems of image analysis for the detection of defects at BGA solder joints are the detection accuracy and image processing time according to a line speed of production. To get design data for the development of the inspection system, which can be used easily in the surface mount process, it is important to develop image analysis techniques based on X-ray image data. At the first step of our study, we attempt to detect the characteristic of the solder bridges based on an image analysis. No potential conflict of interest relevant to this article was reported.

岡山大学環境管理センター Acta Medica Okayama 0917-1533 17 1995 診療用X線検査における撮影条件と被曝線量の関係について―特に腹部検査を対象して― 63 70 EN Yoshitada Nakagiri Yoshiharu Azuma Koichi Sibuya Sachiko Goto Toshinori Maruyama Katsuhiko Sugita Masayo Sonoyama Yasuki Morioka Keiji Inamura Seiji Tahara Hirofumi Uno Shigefumi Kadohisa Tatsuya Inoue Yoshio Hiraki Patient dose is important consideration in the radiological examination and our environment regarding radiation. Many studies have been published about patient dose, but those data were classified by each organ or tissue. Actuarially, patient dose should be checked by each examined part of patient and each exposure equipment. In this paper, we measured absorbed dose at the depth of 0-200mm with the Mix-DP phantom. The phantom is made by tissue equivalent meterial and is designed to similitude abdominal part. Percentage Depth Dose (PDD) was calculated from these doses. Three single-phase generators and three three-phases generators were used in this measurement. These measurements were analyzed by each equipment, and consequently the clear difference of PDD between the exposure equipments was not found. As the result, we can estimate patient dose at a random depth by using PDD. Furthermore, we can easily know patient dose from the tube-voltage and current time product by the calculation including PDD.These data are very useful to manager patient dose on radiological diagnosis. No potential conflict of interest relevant to this article was reported.

岡山大学環境管理センター Acta Medica Okayama 0917-1533 20 1998 腹部単純X線撮影時の被曝線量―岡山県下の病院の現況― 17 21 EN Yoshitada Nakagiri Yoshiharu Azuma Toshinori Maruyama Koichi Sibuya Sachiko Goto Katsuhiko Sugita Yasuki Morioka Sigefumi Kadohisa Tatsuya Inoue Yoshio Hiraki In 1995, we have published a paper about the basic data on the relation between X-ray exposure equipment and patient dose in Vol. 17 of the Journal "Environment Research and Control". In this time, we questioned hospitals in Okayama Prefecture about exposure equipments of abdomen. And we compared each hospital's exposure equipments with the basic data, calculated each patient dose, then we studied that differences. Various imaging system, for example; screen/film or imaging plate has been used at each hospitals, so that exposure are various and patient doses are very different. The exposure equipment decide that the X-ray photograph is good or bad, so we cannot treat it easily. But we think that we have to try to take X-ray photographs which are suit the purpose of diagnosis which as a small patient dose as possible. No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 7 2 1997 混合粒子型硫酸バリウム｢バリトゲンHD｣の評価 105 112 EN Eitarou Nobuhara Yoshihiro Takeda Kohichi Shibuya Nobuhiro Oguri Tadashi Arioka Sachiko Goto Yasuki Morioka Harutaka Niiya Yoshitada Nakagiri Ikuo Joja Katsuhiko Sugita Yoshio Hiraki 10.18926/15290 混合粒子型硫酸バリウムバリトゲンHD200w/v%懸濁液について,バリトゲン160w/v%懸濁液と比較検討を行った｡懸濁液安定性は両者共良かった｡臨床評価においては,付着性,胃小区描出能は同程度であり,辺縁の描出能は良かったが凝集･ムラ付き,気泡は多くみられ懸濁液濃度について検討を加える必要があると考える｡飲み易さは,バリトゲンHD200w/v%懸濁液のほうが濃度が高いのにもかかわらず飲み易く好評であった｡ No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 8 1 1997 電子線治療における骨の線量分布に対する影響に関する検討 37 42 EN Yoshitada Nakagiri Keiji Inamura Seiji Tahara Hirofumi Uno Yoshiharu Azuma Koichi Sibuya Sachiko Goto Toshinori Maruyama Yasuki Morioka Katsuyosi Sakae Mitsuhiro Takemoto Katsuhiko Sugita Yoshio Hiraki 10.18926/15282 電子線治療は,体表面またはその近傍に発生する悪性腫瘍の治療にしばしば用いられる治療法である｡電子線はエネルギーに対応した飛程を持っており,飛程を越えると急激に線量は減少する。この性質は腫瘍に一定の線量を照射し,腫瘍後方に存在する決定臓器を保護することができるので,病巣を選択的に治療するのに好都合である｡しかし,照射野内に人体軌部組織より密度の違う物質が存在する場合,散乱,吸収の影響が大きく,電子線線量分布は乱れたものとなる｡今回,人体内にある骨を想定してVolumeの違う骨Phantomを使用して影響を調べたところ,骨幅によって骨後方および断端に線量の乱れが生じることがわかった｡すなわち,骨の中央ではある程度後方に距離が離れると,線量は大きく減少する現象が見られた。また,横方向の線量分布は骨断端近くで一旦線量の減少が見られ,断端を離れると急激に増加する｡したがって,実際の臨床において,Target Volume近くに骨が存在する場合は総線量の決定に際して注意が必要である｡ No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 8 2 1998 The Influence of Film Processing Temperature and Time on Mammographic film Characteristics 121 129 EN Toshinori Maruyama Sachiko Goto Yoshiharu Azuma Yoshitada Nakagiri Koichi Shibuya Katsuhiko Sugita Tomoyuki Takeuchi Mitsugi Honda Akira Yoshida 10.18926/15261 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. No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 8 2 1998 自作ファントムによる硫酸バリウム製剤の濃度及び混合比の検討 113 119 EN Koichi Shibuya Tomonori Miyahara Kazuyuki Sumi Yasuhiko Okura Koichi Miyake Kazuhiro Okuda Nobuyoshi Tandani Yoshiharu Azuma Sachiko Goto Toshinori Maruyama Yoshitada Nakagiri Katsuhiko Sugita Yoshio Hiraki 10.18926/15260 胃Ⅹ線検査に造影剤として用いられる硫酸バリウム懸濁液の濃度を,簡便に,客観的に決定する目的で,歯科用アルギン酸塩印象材を用いて,コインの図柄を写しとったファントムを制作した｡これを使って二種類の硫酸バリウム製剤の適正濃度(PD)を調べた結果,BARITOP PとBARICON MEALを単体,若くは混合した場合には,おおよそ,PD(W/V%)=0.75C+165(ただし,CはBARICON MEALの混合比(%))となった｡また,BARICON MEALはコントラストが高く,精密検査に有利だと考えられ,BARITOP PとBARICON MEALを混合すると濃度の許容範囲が広がるため,通常の検査に都合がよいと考えられた｡更に,このファントムは簡便に作成することができ,しかも,硫酸バリウム懸濁液との親和性も良いことから,硫酸バリウム製剤やⅩ線TV装置の評価,増感紙･フィルム系の評価等にも応用できると考えられた｡ No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 9 2 1999 Improvement of image quality on mammographic screen-film system by extended-cycle process 83 90 EN Sachiko Goto Toshinori Maruyama Yoshiharu Azuma Yoshitada Nakagiri Yoshihiro Takeda Katsuhiko Sugita Fumie Kimura Shigefumi Kadohisa 10.18926/15252 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. No potential conflict of interest relevant to this article was reported.

岡山大学医学部保健学科 Acta Medica Okayama 1345-0948 14 1 2003 線量測定用GAFCHROMIC XR TYPE Tの特性 23 29 EN Mariko Kubotsu Yoshitada Nakagiri Ayako Ujifuku Yukiko Taniguchi Miho Hachiya Yoshiharu Azuma Sachiko Goto Toshinori Maruyama Hideki Aoyama Seiji Tahara Keiji Inamura Toshimitsu Watanabe Katsuhiko Sugita 10.18926/15204 医療の高度化に伴い,近年では長時間のⅩ線透視を行うInterventional Radiology(IVR)手技が頻繁に行われ,副作用としての難治性放射線皮膚障害例の報告が増加している｡確定的影響である放射線皮膚障害はしきい値を超えると発症し,線量に依存して障害の程度が重篤となるため,患者被曝線量の測定が重要である｡しかし,IVRでは照射部位が多彩で,焦点-皮膚間距離が不安定なため,その測定方法は確立されていない｡本研究では,近年IVR等低エネルギー線量測定用フイルムとして開発されたCAFCHROMIC XR TYPE T について性能評価を行い,患者皮膚入射面の被曝線量測定への応用の可能性について検討した｡その結果,線量特性,線質特性,ネット値の安定性に良好な特性を示し,臨床に使用可能であったので報告する｡ No potential conflict of interest relevant to this article was reported.

岡山大学医学部保健学科 Acta Medica Okayama 1345-0948 14 1 2003 放射線治療時の治療患部外散乱被曝線量に関する研究 15 22 EN Atsushi Kawabe Yoshitada Nakagiri Kazuki Kobashi Naoki Yasumura Takahiro Yamashita Sachiko Goto Toshinori Maruyama Kouichi Shibuya Katsuhiko Sugita 10.18926/15203 現代の医療のなかで癌治療において不可欠な存在となった放射線治療｡一方,放射線被曝はたとえわずかであってもリスクが伴い,厳しく規制されている｡ただし医療被曝はこの限りになく,過去においては癌患者に放射線治療をおこなう際の患部以外の被曝についてはあまり問題視されなかった｡これには癌の治療という前提に加え,長期生存の可能性が低く,存命中に晩発障害が発生することが低いと考えられていたからである｡しかし,集学的治療が確立した今後の放射線治療においては完治する放射線治療患者が多くなり,治癒後の余命が長くなることが予測される｡放射線被曝による確率的影響は閾値がなく,影響は当然現れるであろう｡そこで,放射線治療をおこなう際の患者の散乱線被曝線量,治療室内散乱線量,さらに高エネルギー放射線発生装置を取り扱うときに問題となっている中性子を測定した｡その結果,測定線量は治療患部外被曝,室内散乱線量ともに無視できない量であることがわかった｡中性子については,人体に影響がある線量は検出されなかったが,中性子の存在は室内物品の放射化の可能性を示唆するもので定期的な測定管理が必要である｡また,Ⅹ線撮影室用の防護衣による散乱線被曝の低減効果は放射線治療室では無意味であった｡ No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 5 1995 清涼飲料入り胃X線検査用造影剤 111 114 EN Koichi Shibuya Yoshitada Nakagiri Yoshiharu Azuma Sachiko Goto Katsuhiko Sugita Yasuhiko Okura Nobuyoshi Tandani Eitaro Nobuhara Yasutaka Mikami 10.18926/11936 胃検診の受診者を増やし、検査を円滑に行う上で、造影剤である硫酸バリウム懸濁液の飲みにくさが障害の一つとなっている。これを改善する試みとして、懸濁液に市販の粉末清涼飲料を混入し検討したところ72.1％の人から通常のものよりも飲みやすいという回答を得た。今後、臨床的な検討を加えながら、さらに創意工夫していく必要がある。 No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 5 1995 リニアック（東芝LMR-15A）の故障の統計と分析 99 103 EN Yoshitada Nakagiri Yasutaka Mikami Yoshiharu Azuma Koichi Sibuya Sachiko Goto Keiji Inamura Seiji Tahara Hirofumi Uno Katsuhiko Sugita Yoshio Hiraki 10.18926/11931 放射線治療の成否は厳密に設定されたTarget Volumeに如何に正確な線量を照射するかによって決まる。治療術式の過程において、最も大きな誤差を生む要因は照射機器である。誤差の少ない治療を目指す第一歩は機器を正確に作動させることであり、日常からの保守点検および整備が必要である。今回、岡山大学附属病院で1976年から1991年までに使用されたリニアックについて、その故障状況を集計し、部位別故障件数、管球の寿命、稼動率などを分析検討した。その結果、故障件数では設置され稼動を始めた1976年、装置の老朽化が進んだ1990、1991年に多かった。部位別集計では加速部に圧倒的に多く、次いで照射口、高圧部の順であった。稼動率は設置年および1987年を除いてはいずれも96％以上とよい結果であった。この結果は全国に稼動している同型の装置の保守点検に役立つものと考える。 No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 4 1994 画像処理による顎関節の解析 ―下顎頭位の判別― 75 82 EN Yoshiharu Azuma Sachiko Gotou Yoshitada Nakagiri Nobue Nakamura Kouichi Shibuya Toshiharu Yamada Katsuhiko Sugita Yasutaka Mikami Yoshio Hiraki 10.18926/11886 Tomography is clinically useful in the diagnosis of the temporomandibular joint (TMJ) syndrome. The TMJ is formed by the condyle and the glenoid fossa, and there exists TMJ space between them. Image processing was employed in the present study, and the reference points of the condyle and the glenoid fossa were determined from the tomogram. Subsequently, the TMJ space was measured automatically in the image analysis. The TMJs of 98 patients were examined practically and the characteristics of each result were studied. There is a possibility of discriminating an abnormal condylar position from a normal one by making use of the TMJ space and the distance between two reference points. No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 4 1994 X線撮影領域における線量測定　―撮影条件と臓器の被曝― 69 73 EN Yoshitada Nakagiri Sachiko Goto Yasutaka Mikami Yoshiharu Azuma Koichi Sibuya Keiji Inamura Seiji Tahara Hirohumi Uno Yoshiaki Takata Nobuyoshi Tandani Toshiharu Yamada Katsuhiko Sugita Yoshio Hiraki 10.18926/11878 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. No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 7 1 1996 ビームフラットネスアナライザ（7000型 THEBES）の基礎的性能の検討 23 27 EN Yoshitada Nakagiri Nobuhiro Oguri Toshinori Maruyama Yoshihiro Okawa Hiroyuki Wakasa Isao Nagaya Yoshiharu Azuma Koichi Shibuya Sachiko Goto Yasutaka Mikami Keiji Inamura Yasuki Morioka Katsuhiko Sugita Yoshio Hiraki 10.18926/11766 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。 No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 6 1996 清涼飲料入り胃X線検査用造影剤の臨床応用 15 21 EN Koichi Shibuya Yoshitada Nakagiri Yoshiharu Azuma Sachiko Goto Toshinori Maruyama Katsuhiko Sugita Yasuhiko Okura Koichi Natsukawa Nobuyoshi Tandani Eitaro Nobuhara Yasuki Morioka Yoshihiro Takeda Yoshio Hiraki 10.18926/11735 胃X線検査の被験者を増やし、検査を円滑に行う上で造影剤である硫酸バリウム懸濁液の飲みにくさが障害の一つとなっている。これを改善する目的で、懸濁液に市販の粉末清涼飲料を混入したところ、64.2％の人が通常のものよりも飲みやすいと答えた。臨床上も造影剤の付着が悪くなったり、胃の蠕動を促進する等の問題は生じず、有用であると考えられた。 No potential conflict of interest relevant to this article was reported.

岡山大学医療技術短期大学部 Acta Medica Okayama 0917-4494 6 1996 増感紙フィルム系の物理特性 ―胸部用新システム― 7 13 EN Sachiko Goto Akira Yoshida Nobue Nakamura Toshinori Maruyama Yoshiharu Azuma Koichi Shibuya Yoshitada Nakagiri Katsuhiko Sugita Mitsugi Honda 10.18926/11733 胸部専用の新しい増感紙／フィルムシステムについて物理的画質特性を測定し、従来のシステムと比較を行った。測定した新システムは、日本コダックのインサイトシステムからHC/IT-1、富士メディカルシステムのADシステムからHG-M/UR-1、コニカのEXシステムからXG-S/ES-C である。従来のシステムとして富士メディカルシステムのHR-4/Super HR-S を使用した。その結果、新システムは22～73％感度は高く、特性曲線においては低濃度部を持ち上げ、最大コントラストは高濃度側にシフトしていた。空間周波数2cycles/mmで相対鮮鋭度を比較すると、新システムが10～30％程度の低下となっていた。ノイズは、濃度1.0で新システムが35～46％の減少となった。以上より、新システムは、縦隔部の濃度を上げ、粒状性の改善を重視した設計となっていることが分かった。 No potential conflict of interest relevant to this article was reported.

岡山大学医学部保健学科 Acta Medica Okayama 1345-0948 10 2 2000 マンモグラフィ用増感紙／フィルムシステムの特性曲線における空気減弱の影響 91 98 EN Toshinori Maruyama Sachiko Goto Yoshiharu Azuma Yoshitada Nakagiri Koichi Shibuya Katsuhiko Sugita 10.18926/11721 マンモグラフィ専用装置を使用して，距離法で低エネルギー領域のX線におけるマンモグラフィ用増感紙／フィルムシステムの特性曲線を得るためには，空気滅弱の影響を考慮する必要がある。その影響について，実効エネルギーから空気減弱分を補正，照射線量測定による補正，Bednarek法を応用した新距離法の3種類の方法を使って検討した。さらに，一般撮影装置でも，マンモ用システムに対して距離法で特性曲線を作成し，エネルギーの変化による影響についても検討した。その結果，3方法の特性曲線およびグラディエント曲線は，新距離法が高濃度域でわずかにずれるもののほぼ一致した。新距離法に対する平均階調度，最大階調度の最大誤差は，2.7％，0.2％であり，一般撮影用装置の距離法と3方法との間では，一般撮影用装置の距離法に対して最大誤差は2.7％，1.5％であった。以上のことから，エネルギーの変化による特性曲線への影響はほとんどなく，低エネルギー領域での特性曲線は空気特配の補正を行うことのみで得られると考えられる。 No potential conflict of interest relevant to this article was reported.

岡山大学医学部保健学科 Acta Medica Okayama 1345-0948 10 2 2000 Breast dosimetry system in screen/film mammography 99 106 EN Sachiko Goto Yoshiharu Azuma Toshinori Maruyama Yoshitada Nakagiri Yoshihiro Takeda Katsuhiko Sugita Shigefumi Kadohisa 10.18926/11714 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. No potential conflict of interest relevant to this article was reported.

岡山大学医学部保健学科 Acta Medica Okayama 1345-0948 11 2 2001 股関節X線撮影時の女性生殖腺防護についての検討 59 64 EN Yoshitada Nakagiri Toshinori Maruyama Sachiko Goto Yoshiharu Azuma Koichi Shibuya Eri Tamura Eriko Tanimoto Fumiko Torii Yoshihiro Takeda Katsuhiko Sugita 10.18926/11690 幼小児を含めた若年者の股関節X線撮影検査においては鉛板などで生殖腺を防護して行うのが通常である。男性の場合は生殖腺は体外に露出しているので，それを鉛板で包むようにすればある程度目的は達成される。しかし，女性の場合，生殖腺は骨盤腔内に存在するため，卵巣及び子宮を防護でき診断目的領域にかからないように鉛板を成形し，腹壁上に置いて撮影する。X斬写真上ではグリッドで散乱線を除去しているため，鉛板の陰影がくっきりと撮影され，生殖腺は完全に防護されているように見える。しかし，体内では散乱線によるかなりの被曝があるものと考えられる。そこで今回，鉛板下の散乱線量を鉛板幅及び電圧を変化させ，ファントム内各深さの散乱線量を測定した。その結果，鉛板下の散乱線量が相当量認められ，その量は深さ3～4cmでピークを形成した。鉛板幅による変化は幅が狭いほど線量は大きくなり，電圧による変化は60kVと80kVを比べると80kVの方が多くなった。これを鉛板なしの場合と比較すると，ファントム内意さが増すにしたがい増大した。したがって，臨床において鉛板がずれて再撮影をすることのないよう細心の注意が必要であると考えられた。 No potential conflict of interest relevant to this article was reported.