Patient Dose on the Radiological Diagnosis of Abdomen - The Situation of Patient nose at Hospitals in Okayama Prefecture -

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

Statistics and analysis on the troubles of linear accelarator.

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。The Accuracy of radiation dose exposed the rigidly selected target volume is one of significant factors that have an influence upon the efficiency of treatment in the radiotherapy techniques. Therefore, it is necessary to daily maintain and check irradiation equipment for the radiotherapy. For the radiotherapy, the electron linear accelerator, Toshiba LMR-15A, had worked from 1976 to 1991 in Okayama University Hospital. On this study, all records regarding the operating condition were analyzed concerning parts of trouble, life of a tube and operating efficiency for these sixteen years. In a high frequency of trouble, an accelerating structure ranked first, followed by a collimator and a high voltage generator. The operating efficiency was 95% or greater. This report should be helpful to maintain and check a same model in other hosptals

Dosimetry in Radiography

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

Relationship between X-ray Exposure and Patient Dose on the Radiological Diagnosis

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

Influence of the Bone for Electron-beam Therapy

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｡The Electron-beam therapy is often used for the treatment to malignant tumors on the surface or its neighborhood of the body. An electron-beam has the range depended on its energy, and its dose is rapidly decreased at the points beyond the range. This property is available to irradiating a tumor with leaving the critical organs unexposed. However, we should take notice that the dose-distributions are disordered if materials of various densities are in the irradiation field. In this paper, we examined how the dose-distribution are disordered by using the phantom made from human bones of various volumes. As a result, the peculiar disorders of the dose-distribution due to the difference of the bone width were found at the back and edge of a bone. Moreover, the dose at the edge of a bone was decreased, but the dose at the side of a bone was rapidly increased in the distance position from the bone. It is necessary to take account of that the above peculiar phenomenon affect the total dose for the treatment when bones exist near the target volume in the irradiation field

Relationship between X-ray Exposure and Patient Dose on the Radiological Diagnosis

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