Radiation medicine最新文献

Purpose: The aim of this study was to evaluate the clinical capability of three-dimensional (3D) perfusion imaging of hepatocellular carcinoma (HCC) by performing dynamic scanning using a 256-slice multidetector-row CT (MDCT) scanner.

Materials and methods: Two patients with HCC were examined in this study. They were scheduled to undergo transcatheter arterial infusion therapy using an arterial infusion reservoir system. The CT system used was a newly developed prototype scanner of 256-slice MDCT. Dynamic CT scanning was performed with intraarterial injection via the reservoir route, and perfusion analysis was done based on the 3D data.

Results: The blood flow volume per unit volume in the tumors was significantly increased compared with that in normal hepatic parenchyma. Using a 3D workstation, 3D perfusion images could be displayed by fusing CT images with perfusion images about blood flow volume.

Conclusion: Three-dimensional perfusion images, which enable 3D evaluation of perfusion in HCCs, can be generated using 256-slice MDCT.

Rice body formation is generally a rare disorder related to rheumatoid arthritis. It can also be observed in cases of systemic lupus erythematosus, seronegative arthritis, infectious arthritis (tuberculosis, atypical mycobacterial infection), nonspecific arthritis, and osteoarthritis. It is generally located within joints or bursae. Multiple rice bodies of tendon sheaths are rarely encountered. Rice body formation may also be encountered without underlying systemic disorders. We present a case of multiple rice body formation that accompanied chronic nonspecific tenosynovitis of the flexor tendons of the wrist.

A 31-year-old man came to the hospital complaining of gross hematuria. Pelvic computed tomography (CT) showed mild thickening of the anterior wall of the urinary bladder. After injection of contrast material, the inner part of the anterior wall of the urinary bladder was mildly enhanced. Magnetic resonance imaging (MRI) showed that the anterior wall of the urinary bladder had localized thickening. There was a discrete area of hyper-intensity in the lesion on T2-weighted images. Differentiation of the lesion from malignancy was difficult based on the CT and MRI findings. The urologists decided to perform transurethral resection of this lesion. The pathological findings showed inflammatory granulation tissues in the peculiar muscle plate and Schistosoma haematobium eggs. His travel history showed that he had traveled to about 30 nations and had been swimming in a lake in Africa several years ago. He began therapy with praziquantel. MRI has better contrast resolution than CT and so detects findings of inflammatory change better than CT. Although it is difficult to distinguish a tumor from the inflammatory change, MRI nevertheless plays an important role in the diagnosis of patients with continuous hematuria, especially those with a history of travel to Africa and/or the Middle East.

Purpose: This study was undertaken to evaluate the changes in the radiopacity and mechanics of polymethylmethacrylate (PMMA) bone cement with the addition of barium.

Materials and methods: Barium sulfate powder was added to a PMMA bone cement with an initial 10% barium concentration. The changes in radiopacity and strength were evaluated by testing cement blocks containing four barium concentrations (10%, 20%, 30%, 40%). Radiopacity was evaluated by measuring the computed tomography (CT) values of the bone cement, and strength was evaluated by compressive, three-point bending, and impact load tests.

Results: CT values increased in proportion to the barium concentration. The compressive load test showed that cement with a 40% barium concentration was significantly more fragile than cement with lower barium concentrations. The three-point bending load test showed that the cement became more fragile in proportion to the barium concentration. The impact load test showed that cement with 30% and 40% barium concentrations was significantly more fragile than cement with 10% and 20% barium concentrations.

Conclusion: Radiopacity is increased and strength is reduced by adding increasing concentrations of barium powder to bone cement. The results of the present study suggest that adding barium permits the radiopacity and strength of bone cement to be adjusted in clinical practice.

Purpose: The aim of this study was to evaluate the technical success, complications, and effectiveness of re-radiofrequency (re-RF) ablation for recurrent lung tumors previously treated with RF ablation.

Materials and methods: Reenlargement at the site of ablation seen on follow-up computed tomography (CT) is defined as local progression. CT-guided re-RF ablation was performed during 11 treatment sessions (mean tumor size 2.6 cm diameter) in 10 patients. The treated lesions consisted of five recurrences of primary lung cancer and six metastatic lung tumors from the esophagus (n = 2), bladder (n = 2), kidney (n = 1), and colon (n = 1).

Results: At 3 of the 11 treatment sessions there were no relapses; at 8 of the 11 sessions local progression was seen at a median of 7 months (range 3-17 months). The local progression rate was significantly higher for tumors > 2.5 cm (P < 0.05). Minor complications included pneumothorax not requiring drainage (n = 3), subcutaneous emphysema (n = 1), and self-limited hemoptysis (n = 2).

Conclusion: Re-RF ablation for lung tumors was feasible without any major complications. Although our study comprised only a few cases with a short follow-up period, patients with re-RF ablation were at higher risk of local progression.

Purpose: We compared the radioresponse of cervical carcinoma that was closely related to local disease control by the tumor regression rate (RR) during intracavitary radiotherapy (ICRT) and external beam radiotherapy (EBRT) on the presumption that ICRT has a stronger treatment impact than EBRT because of its specific dose distribution.

Materials and methods: A total of 37 patients were treated by EBRT at 45.0 Gy over 5 weeks, followed by high-dose-rate ICRT at 6.0 Gy per weekly insertion at point A three to five times and by boost EBRT. RR was defined as the slope (day(-1)) of the tumor-volume shrinkage curve fit to an exponential regression equation. Assuming that the tumors were ellipsoid, the tumor volume was estimated using magnetic resonance (MR) images obtained before treatment, after 45.0 Gy of EBRT, and after the third ICRT insertion. RRs were compared based on the radiotherapy method.

Results: RR ranged between -0.008 to 0.093 day(-1) (median 0.021 day(-1)) during EBRT and -0.001 to 0.097 day(-1) (median 0.018 day(-1)) during ICRT, showing no significant difference or correlation between treatments.

Conclusion: Contrary to expectations, RR did not directly relate to the impact of physical treatment. RR could be related to biological factors, such as the amount of tumor clearance and changes in tumor consistency during treatment.

Purpose: The dose changes in the buildup region and beam attenuation by a carbon fiber tabletop were investigated for 6-and 18-MV photon beams.

Materials and methods: Measurements were performed for 2 x 2 cm to 40 x 40 cm field sizes. The surface dose and percentage depth doses (PDD) were measured by a Markus parallel plate chamber. Attenuation measurements were made at the cylindrical phantom for 180 degrees rotation of the beam.

Results: A carbon fiber tabletop increases the surface dose from 7.5% to 63.0% and from 4% to 43% for small fields at 6 and 18 MV, respectively. The increase was nearly fivefold for the 10 x 10 cm field and nearly twofold for the 40 x 40 cm field. Beam attenuation of the tabletop varies from 3.0% to 5.6% for 180 degrees and 120 degrees gantry angles for 6 MV.

Conclusion: The carbon fiber tabletop significantly decreases the skin-sparing effect. The dosimetric effect of the tabletop may be higher, especially for the intensity-modulated radiation therapy depending on the beam orientation. Attenuation should be considered and corrected such as any material under the patient at the treatment planning stage.