放射線エネルギーの違いによる喉頭癌における吸収線量の影響

We investigated the usefulness of Gafchromic MD-55 film (Nuclear Associates, Inc.) for measuring the radiation doses on the radiotherapy of laryngeal cancers. Since larynx has thin wedge-shaped structure in anterior neck adjacent to airway, the radiation doses to the lesion may be diminished because of build-up and build-down. So, the dose has been measured with conventional measuring systems such as thermoluminescent dosimetry (TLD). However, it was not possible to evaluate the dose distribution correctly using TLD, because it is impossible to float a TLD chip in an air cavity. In this study, we employed Gafchromic MD-55 film as a dosimeter, for it can be set on the area of interest and with a measurability of dose range of 3 to 100 Gy, though it has no energy dependency. And this radiometer is composition near the soft tissue of the human body. The dose distributions to larynx were investigated with this film using neck phantom under each radiation beam energy of 4, 6 and 10 MV x-rays. Our neck phantom is made from acrylic resin and simulates a normal larynx on the basis of image information of computed tomography (CT). Moreover we observed secondary build-up and build-down curves in tissue in the vicinity of air cavities, especially at 10 MV x-rays. These findings suggest that patients with TI-T2 glottic cancers with anterior commissure invasion may receive more effective treatment with 4 MV x-rays rather than with 6 MV and 10 MV x-rays.Tl声門癌に対して放射線治療を単独で行うのは確立している方法である｡しかし,頚部は解剖学的に複雑であり,前方に薄いⅤ字形で,喉頭が気道に隣接している構造を持つので,病巣への線量はbuild-upとbuild-downの影響による線量低下が生じることが考えられる｡すなわち,放射線エネルギーの選択が喉頭癌の局所的制御に影響を及ぼすと言える｡この影響は,より高い放射線エネルギーでは,それに伴いより強く起きるということが基礎実験にて報告されている｡また,それらの線量測定は,熱ルミネセンス線量計(TLD)のような従来の測定システムで測定されていた｡しかし,空気空洞へTLD を単体 で浮かせ線量を正確に測定し評価を行うのは困難である｡本研究において,我々は Gafchromic MD-55 film (Nuclear Associates, Inc.)を使用し測定した｡ Gafchromic MD-55 film は,フィルムタイプ線量計でありエネルギー依存性がなく,3～100 Gyを測定可能であり,アクリル製頸部ファントムの空気組織境界面及び,空洞部に線量計を容易に精度良く配置することが可能である｡また,この線量計は人体の軟部組織に近い組成である｡そこで, 4, 6および10MVの各エネルギーでこの線量計を用いてエネルギーの違いによる,頸部ファントムを用いて喉頭の線量評価を行った｡その結果,我々は,特に放射線エネルギー10MVで頸部ファントムにおける,前部組織-組織空洞境界面-空洞部の一連したbuild-upおよびbuild-downを線量計で評価することができた｡これらの研究の結果､前交連浸潤を有するT1-T2に相当する声門癌患者は,放射線エネルギー6MVおよび10MVではなく,4MVを用いることによって,より効果的な放射線治療を行えると推測できる

Changes in Plasma Concentrations of Vitronectin in Patients with Diabetic Nephropathy

To investigate the role of vitronectin in the progression of diabetic nephropathy, plasma concentrations of vitronectin were measured by enzyme-linked immunosorbent assay in patients with diabetes mellitus and compared with normal control subjects. In diabetic patients with normoalbuminuria and microalbuminuria, plasma concentrations of vitronectin were significantly higher than those of control subjects. Plasma concentrations of vitronectin in diabetic patients with chronic renal failure were significantly lower than those with normal renal function. There was a significant positive correlation between plasma concentration of vitronectin and blood platelet counts. In the early stage of diabetic nephropathy, vitronectin may be increased caused by synthesis from activated platelets. With progression of diabetic nephropathy, plasma vitronectin may be decreased because of accumulation in sclerotic glomeruli and arteriosclerotic lesions. In conclusion, the plasma concentration of vitronectin appears to be an important marker for the progression of diabetic nephropathy.</p

Suitability on the densitometry systematize in Laser Densitometer Model 1710 for Gafchromic MD-55-2 film

医療の高度化に伴い,放射線治療分野においても急速な技術革新が行われている｡QOL(Quality of Life)を考慮に入れた治療が求められる多くの場合,放射線治療が大きな選択肢の一つであることは言うまでもない｡このような状況下の中で,正常組織に影響を与えず病巣に限局した放射線を照射する技術が開発され,外照射においては,欧米に習い我が国でも研究段階から臨床へ移り変わろうとしている｡その際に,投与線量評価を欠かすことができないが,従来から使用されているいずれの線量計も新しい治療法に対応しきれていない｡そこで,フィルムタイプ線量計, Gafchromic MD-55-2 film の開発により,いくつかの問題が解決されてきている｡しかし,この線量計を精度良く測定する濃度測定器が必要になるが,現段階において規格化されたガイドラインが存在しないのが現状である｡そこで本研究では,当施設で保有しているⅩ線フィルム線量測定用 Laser Densitometer Model 1710 を用いて Gafchromic MD-55-2 fllm による線量測定を行い,問題点の抽出を行うとともに線量測定精度の考察を行った｡For the medical advancement, the speedy technical innovation is performed also in the radiotherapy. When patients can search for QOL (Quality of Life), the radiation therapy is one of the choices. The radiation therapy system for limited irradiation to lesion without affecting normal tissue has been developed over several years. On the technology of external irradiation in our country, the level is improving to clinical stage from study grade. In such things, a new requirement will come out also as for the measuring method of the medication dose. However, conventional various radiometers have many problems to the dosimetry of the new radiotherapy method. Gafchromic MD-55-2 film, which has new form of radiochromic film based on poly-diacetylene and has been introduced for medical applications recently, is expected to solve some problems. Now, in clinical usage of this film, there is no comprehensive guideline for densitometry system and it's calibration yet. So, in this paper, the densitometry of Gafchromic MD-55-2 film was performed with Laser Densitometer Model 1710 for general-purpose film dosimetry system. And then, problems in the densitometry were extracted and the accuracy of dosimetry was investigated

Incidence of endophthalmitis after intravitreal injection of an anti-VEGF agent with or without topical antibiotics

Intravitreal injection (IVI) of anti-vascular endothelial growth factor (VEGF) is the standard treatment modality in various types of retinal diseases. However, endophthalmitis remains the most serious complication. Despite the lack of evidence that antibiotics prevent endophthalmitis, topical antibiotics are still used routinely in Japan. We conducted a retrospective multicenter study by analyzing records from patients who underwent IVI of anti-VEGF agents with or without antibiotic treatment. In the analysis of a total of 147,440 eyes, the incidence of endophthalmitis was 0.007%: 0.005% with no use of antibiotics, 0.009% with antibiotic pretreatment, 0.012% with posttreatment, and 0.005% with pre- and posttreatment. There was no statistically significant difference among the four groups (chi-square test, p = 0.57). Most facilities used masks, sterilized gloves, and drapes. Nine of the 10 eyes that developed endophthalmitis received topical antibiotics, and all infected eyes underwent IVI with aflibercept, not the prefilled syringe delivery system. In four patients who received multiple IVI, the detection of causative bacteria revealed resistance to used antibiotics. Data from this large population, treated with or without antibiotics, suggests that antibiotic prophylaxis does not reduce the rate of endophthalmitis after IVI

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

The Effect of Medical Cooperation in the CKD Patients: 10-Year Multicenter Cohort Study

Introduction: While chronic kidney disease (CKD) is one of the most important contributors to mortality from non-communicable diseases, the number of nephrologists is limited worldwide. Medical cooperation is a system of cooperation between primary care physicians and nephrological institutions, consisting of nephrologists and multidisciplinary care teams. Although it has been reported that multidisciplinary care teams contribute to the prevention of worsening renal functions and cardiovascular events, there are few studies on the effect of a medical cooperation system. Methods: We aimed to evaluate the effect of medical cooperation on all-cause mortality and renal prognosis in patients with CKD. One hundred and sixty-eight patients who visited the one hundred and sixty-three clinics and seven general hospitals of Okayama city were recruited between December 2009 and September 2016, and one hundred twenty-three patients were classified into a medical cooperation group. The outcome was defined as the incidence of all-cause mortality, or renal composite outcome (end-stage renal disease or 50% eGFR decline). We evaluated the effects on renal composite outcome and pre-ESRD mortality while incorporating the competing risk for the alternate outcome into a Fine-Gray subdistribution hazard model. Results: The medical cooperation group had more patients with glomerulonephritis (35.0% vs. 2.2%) and less nephrosclerosis (35.0% vs. 64.5%) than the primary care group. Throughout the follow-up period of 5.59 +/- 2.78 years, 23 participants (13.7%) died, 41 participants (24.4%) reached 50% decline in eGFR, and 37 participants (22.0%) developed end-stage renal disease (ESRD). All-cause mortality was significantly reduced by medical cooperation (sHR 0.297, 95% CI 0.105-0.835, p = 0.021). However, there was a significant association between medical cooperation and CKD progression (sHR 3.069, 95% CI 1.225-7.687, p = 0.017). Conclusion: We evaluated mortality and ESRD using a CKD cohort with a long-term observation period and concluded that medical cooperation might be expected to influence the quality of medical care in the patients with CKD