EFECTO BREMSSTRAHLUNG PDF

EFECTO BREMSSTRAHLUNG PDF

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Producción de Bremsstrahlung o radiación de frenadoDel alemán bremsen ” frenar” También llamado Efecto Comptom Cundo se incrementa la energía de un. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy; Bremsstrahlung thermique comme sonde. After injection of Y resin microsphere, the only method to visualize the distribution of Y is the scintigraphic imaging of bremsstrahlung.

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Y resin microsphere radioembolization is used to treat inoperable hepatic tumors. After injection of Y resin microsphere, the only method to visualize the distribution of Y is the scintigraphic imaging of bremsstrahlung radiation. The purpose of this study was to evaluate the characteristics and usefulness of bremsstrahlung imaging in Y resin microsphere treatment. Twenty patients 22 administrations underwent intra-arterial Y resin microsphere treatment.

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Bremsstrahlung – Wikipedia

For pre-treatment planning, images of Tcm albumin macroaggregate MAA arterial injection and hepatic contrast angiography were obtained. Post-treatment bremssttrahlung images were taken and compared with efscto images.

The extrahepatic activity was evaluated on bremsstrahlung images. To correlate the size and vascularity of the tumors with tumor visualization on bremsstrahlung images, the individual tumors were grouped according to visualization on each image and compared with one another by size and tumor-to-normal ratio.

All post-therapeutic bremsstrahlung images showed similar contours of the liver with pre-treatment angiography.

No extrahepatic activity was seen in all cases. The visualized tumors on bremsstrahlung images were significantly larger than the non-visualized tumors. Tumor-to-normal ratios of the visualized tumors efeecto bremsstrahlung images were significantly higher than those of the non-visualized tumors. Bremsstrahlung images after intra-arterial Y resin microsphere treatment are useful in evaluating the intrahepatic distribution of radioisotope and detecting possible extrahepatic activity.

Surgical resection or liver transplantation is the ideal curative therapies of the malignant hepatic tumors [ 12 ]. Many hepatic malignant tumors cannot be surgically resected because they are locally advanced or involving both hepatic lobes at the time of diagnosis.

A variety of therapeutic methods have been introduced for unresectable hepatic tumors, such as systemic chemotherapy, external radiation therapy, trans-arterial chemoembolization, percutaneous ethanol injection, and percutaneous efectto ablation [ 3 — 6 ]. Trans-arterial radioembolization using Y labeled microspheres was introduced in the s [ 7 ].

This method includes infusion of beta ray-emitting Y labeled microspheres into the hepatic arteries so that the microspheres are delivered to the hepatic tumors [ 7 — 9 ]. Until now, two kinds of microspheres are clinically available: Y labeled microsphere radioembolization can provide a safe and effective therapeutic method for both hepatocellular carcinoma and metastatic hepatic tumor [ 612 — 16 ]. In the randomized trial bremsstrahlungg Hazel et al. In addition to baseline angiography for evaluation of vascular anatomy, it is necessary to outline the possible distribution of microspheres for a successful treatment result with Y microspheres.

For this purpose, a Tcm albumin macroaggregate MAA hepatic angiography scan is done to determine the tumor vascularity, which is represented by the tumor-to-normal ratio, and to calculate the degree of shunting to the lung, and to detect any possible extrahepatic localization.

Using Tcm MAA pre-treatment imaging, the liver to lung shunt and extrahepatic regurgitation e. The required therapeutic activity of Y microspheres can be calculated using a partition model, in which calculation of the tumor-to-normal ratio of radioactive microsphere distribution is needed [ 19 ].

It is necessary to know the actual distribution of Y microspheres after administration into the hepatic artery, because intrahepatic distribution of radioactivity can predict the therapeutic effect, and unexpected adverse effects can be caused by extrahepatic regurgitation of microsphere distribution.

Interaction of beta particles with the tissue can produce bremsstrahlung radiation and this can be imaged with a gamma camera. This bremsstrahlung imaging is the only method to visualize the distribution of Y in exsitence.

But the usefulness of bremsstrahlung imaging has not been evaluated enough. The purpose of this study is threefold: From December to June20 consecutive patients with primary or metastatic hepatic tumors that were not indicated for resection were enrolled this study. Patients who had distant metastasis, impaired hepatic function of Child-Pugh classification C, direct bilirubin more than 2. This study was approved by the institutional review board of Korea University Hospital and informed consents were obtained from all patients who participated in the study.

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Hepatic contrast angiography for pre-treatment planning was performed in all patients. On anterior and posterior images of Tcm MAA, regions of interest ROIs were placed in the visually distinguishable intrahepatic tumors, the whole liver and the lung. The counts and pixel number for each ROI were recorded. The liver to lung shunt was defined as the percentage of total counts of the whole lungs to total counts of the liver and the lung.

The average count rate per pixel of the each tumor over the average count rate per pixel of the normal non-tumorous liver from each view was defined as the tumor-to-normal ratio. Possible extrahepatic radioactivity to the stomach, the duodenum and the gallbladder was evaluated. Y microsphere activity for administration was calculated using a partition model that uses the tumor-to-normal ratio on Tcm MAA images, the volume of the targeted liver segments, and the volume of the tumor, according to the following equations [ 19 ].

From published decay data in MIRD format [ 20 ] the average energy released in the beta decay of Y is 0. When A GBq of Y microspheres is evenly distributed in M grams of tissue, the absorbed radiation dose to the tissue is. On the day of the treatment, an intervention radiologist performed superselection of the hepatic artery, referring to pre-treatment hepatic angiography and Tcm MAA images, and then Y resin microspheres were delivered through the catheter placed at the intended location of treatment.

Bremsstrahlung images of the abdomen were obtained using a gamma camera, 5—8 h after Y microsphere delivery. To verify the distribution of Y resin microspheres to the targeted hepatic segments and the tumor, the bremsstrahlung images were compared with hepatic angiography images taken just before Y resin microsphere delivery.

Any radioactivity detected outside the liver was identified on the bremsstrahlung images. Possible complications caused by extrahepatic leakage of Y were also evaluated. We compared the visibility of the hepatic tumors seen on Tcm MAA images and bremsstrahlung images. To identify the factors related to tumor visualization on bremsstrahlung images, patients were divided into three groups in accordance with the tumor visualization on bremsstrahlung and Tcm MAA images.

Group 1 consists of patients with same numbers of the visualized tumors on both bremsstrahlung and Tcm MAA images. Group 2 consists of patients with less visualized tumors on bremsstrahlung images than on Tcm MAA images. Group 3 consists of patients with no visualized tumors on both bremsstrahlung and Tcm MAA images.

These three groups were compared with each other for tumor volume, number of the tumors, and tumor-to-normal ratio. We selected five tumors in each case in order of size, as measured in the longest dimension using computed tomography CTfor evaluation of visibility on bremsstrahlung and Tcm MAA images.

Each tumor was categorized into two groups, based on whether it was visualized on bremsstrahlung images or not.

The longest dimensions of each tumor were compared between efectto two groups. Again, the size of the tumors was also categorized and compared in the same manner using Tcm MAA images. Each individual tumor was classified into three groups, according to agreement of visualization on two images. Group A consisted of the distinguishable tumors on both images. Group B consisted of the tumors that were visualized on Tcm MAA images, but not on bremsstrahlung images. Group C consisted of the non-visualized tumors on both images.

Additionally, the sizes were compared with each other. The tumor-to-normal ratio of each tumor wasa calculated on Tcm MAA images, and compared between visualized and non-visualized groups on bremsstrahlung images.

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In the non-visualized tumors on Tcm MAA images, tumor-to-normal ratios could not be calculated because an ROI could not be placed on those tumors. The hepatic tumors contain more Y microspheres than the adjacent normal parenchyma, so emits more bremsstrahlung radiation. The difference in Y distribution in the tumor compared with the normal liver parenchyma tumor-to-normal ratio can represent effective microsphere concentration into the tumor, and this principle is the same with Tcm MAA.

We evaluated the correlation of the tumor-to-normal ratio between Tcm MAA and bremsstrahlung images. To verify the proportional tendency between administrated Y dose and amount of bremsstrahlung radiation from the liver, the total counts of the liver was calculated, and correlation between these counts and bremsstraglung Y dose was evaluated. Statistical analysis was done with commercial statistical software, SPSS for windows The volume and number of tumors, and tumor-to-normal ratios between groups 1, 2, and 3 were compared using analysis of variance ANOVA.

Tumor-to-normal ratios measurement between bremsstrahung and Tcm MAA images were compared with t -test. The correlation between injected Y dose and liver counts on bremsstrahlung images was analyzed by simple correlation.

Bremsstrahlung

P values less than 0. A total of 20 patients were enrolled in this study. Two patients were treated twice, so a total of 22 administrations of Y microspheres were performed.

Eighteen patients were diagnosed as having primary hepatocellular carcinoma with clinical and histopathologic diagnosis, and the other two patients had the metastatic hepatic tumors, one from rectal cancer btemsstrahlung the other from pancreatic cancer.

Of 20 patients, 18 patients were male and two patients were female. All 22 bremsstrahlung images showed identical intrahepatic distribution of radioactivity with pre-treatment hepatic angiography. There were no cases showing extrahepatic activity on bremsstrahlung images.

These findings were well matched with the absence of post-treatment complications related to the extrahepatic leakage of Y Among the total 22 cases, three cases showed no distinguishable hepatic tumors on both bremsstrahlung and Tcm MAA images In the other 19 cases, at least one hepatic tumor was visualized on both bremsstrahlung and Tcm MAA images. Among 19 cases, eight showed the same number of the hepatic tumors on both bremsstrahlung and Tcm MAA images A hepatocelluar carcinoma patient treated with 0.

A hepatocellular carcinoma patient treated by 0. A patient with hepatocellular carcinoma was treated with 1. Hepatic angiography a and Tcm MAA b images showed two or three tumors in the right lobe, but the post-treatment bremsstrahlung images c showed diffuse distribution of radioisotope and no distinguishable tumor.

Comparing groups 1 and 2, the number of the visualized tumors on Tcm MAA images were 1. Characteristics of three groups: The total number of the tumors was 66 bremssrtahlung 22 case deliveries. The longest dimension of the visualized tumors on bremsstrahlung images was significantly larger than for the non-visualized tumors 4. The difference in mean diameter of the tumors between these groups on Tcm MAA images also showed a similar difference 4. According to the agreement of tumor visualization on both images, the individual tumors were classified into three bremssrrahlung.

Group A consisted of 34 tumors, group B 13 tumors, and group C 19 tumors. The mean diameters of the tumors of groups A, B, ands C were 4. Tumor-to-normal ratios of the visualized tumors on bremsstrahlung images are significantly higher than those of the non-visualized tumors 3. To evaluate the characteristics of bremsstrahlung images, tumor-to-normal ratios of bremsstrahlung and Tcm MAA images were compared.

In four cases, there was no visualized tumor and the tumor-to-normal ratio could not be calculated. So, except for these four cases, in 18 bremsstrwhlung the mean tumor-to-normal ratio was 3.