Mitsuru Izumisawa

Novel embossed radiography system utilizing energy subtraction

Digital subtraction is useful for carrying out embossed radiography by shifting an x-ray source, and energy subtraction is an important technique for imaging target region by deleting unnecessary region in vivo. X-ray generator had a 100-μm-focus tube, energy subtraction was performed at tube voltages of 40 and 60 kV, and a 3.0-mm-thick aluminum filter was used to absorb low-photon-energy bremsstrahlung x-rays. Embossed radiography was achieved with cohesion imaging using a flat panel detector (FPD) with pixel sizes of 48×48 μm, and the shifting distance of the x-ray source in horizontal direction and the distance between the x-ray source and the FPD face were 5.0 mm and 1.0 m, respectively. At a tube voltage of 60 kV and a tube current of 0.50 mA, x-ray intensities without filtering and with filtering were 307 and 28.4 μGy/s, respectively, at 1.0 m from the source. In embossed radiography of non-living animals, the spatial resolution measured using a lead test chart was approximately 70 μm, and we observed embossed images of fine bones, soft tissues, and coronary arteries of approximately 100 μm.

X-ray fluorescence computed tomography system for biomedical imaging

An x-ray fluorescence (XRF) computed tomography (CT) system utilizing a cadmium telluride (CdTe) detector is described. The CT system is of the first generation type and consists of a cerium x-ray generator, a turn table, a translation stage, a two-stage controller, a CdTe spectrometer, a multichannel analyzer (MCA), a counter board (CB), and a personal computer (PC). When an object is exposed by the x-ray generator, iodine K-series fluorescences are produced and are detected from vertical direction to x-ray axis using the spectrometer. Fluorescent photons are selected out using the MCA and are counted by the PC via CB, and XRF CT is performed by repeating translation and rotation of an object.

Tunable narrow-photon-energy x-ray source using a silicon single crystal

A preliminary experiment for producing narrow-photon-energy cone-beam x-rays using a silicon single crystal is described. In order to produce low-photon-energy x-rays, a 100-µm-focus x-ray generator in conjunction with a (111) plane silicon crystal is employed. The x-ray beams from the source are confined by an x-y diaphragm, and monochromatic cone beams are formed by the crystal and three lead plates. The x-ray generator consists of a main controller and a unit with a high-voltage circuit and a 100-µm-focus x-ray tube. In this experiment, the maximum tube voltage and current were 35 kV and 0.50 mA, respectively, and the x-ray intensity of the microfocus generator was 343 μGy/s at 1.0 m from the source with a tube voltage of 30 kV and a current of 0.50 mA. The effective photon energy is determined by Braggs angle, and the photon-energy width is regulated by the angle delta. Using this generator in conjunction with a computed radiography system, quasi-monochromatic radiography was performed using a cone beam with an effective energy of approximately 15.5 keV.

The relationship between histopathological findings in oral squamous cell carcinoma and FDG uptake on PET

ObjectivesIt is known that, in fluorine-18 fluorodeoxyglucose Positron Emission Tomography (FDG PET) for the diagnosis of oral cancer, FDG uptake may vary even among different cases of the same squamous cell carcinoma. However, the details of this phenomenon have not yet been elucidated. In this study, we analyzed the relationship between histopathological findings in oral squamous cell cancer and PET findings on FDG uptake.MethodsWe examined 45 patients with oral squamous cell carcinoma who had undergone FDG PET before treatment. FDG uptake was assessed by a standardized uptake value (SUV) calculated according to the PET-measured tissue concentration of FDG, the administered dose of radionuclide, and the body weight of the patient. The relationship between the mean SUV and each of the following parameters was examined: histological grade of malignancy, degree of cell differentiation, size and/or local extent of the primary lesion, and cell density of the tumor.ResultsThe mean SUV of FDG uptake did not depend on the histological grade of malignancy or on the degree of cell differentiation, but tended to be greater the larger the primary lesion. SUV also depended on cell density, increasing with the percentage of tumor parenchyma.ConclusionsIt is concluded that cancer cell density greatly influences the SUV of FDG, in that a tumor with fewer cellular elements in cancer tissue tends to become a false negative.

A huge osteoma of the mandible detected with head and neck computed tomography

Abstract We encountered a patient with a huge osteoma extending over half of the mandible, which was incidentally discovered on a head-and-neck computed tomography (CT) by an otolaryngological examination for vertigo. A tumorous lesion of the right mandible was noted, and the patient was referred to our department. The tumor extended from the median mandible over the right anterior margin of the ramus of the mandible. To improve the abnormal intraoral morphology, tumor resection and orthopedic surgery were performed. The histopathological diagnosis was a cancellous osteoma. Dentures were attached after surgery, and the postoperative course has been favorable with no tumor re-enlargement.

Fluorescent x-ray tomography system for atomic imaging

A fluorescent x-ray tomography system is useful in performing fluorescent x-ray analysis for target atoms in biomedical objects utilizing a drug deliverly system. This tomography system is employed in order to measure iodine distribution in objects, and the system consists of a cerium x-ray generator, a 58-μm-thick stannum filter, a tungsten collimator, and a computed radiography system. Because K-series characteristic x-rays from the cerium target are absorbed effectively by iodine-based contrast media, iodine fluorescent x-rays from iodine atoms in the objects are produced. In the tomography system, when the objects are exposed by fan beams, the stannum filter easily transmits iodine Kα rays from a slice plane, and tomograms are obtained using the CR system and the collimator.

Demonstration of enhanced K-edge angiography utilizing a samarium x-ray generator

The samarium-target x-ray tube is useful in order to perform cone-beam K-edge angiography because K-series characteristic x-rays from the samarium target are absorbed effectively by iodine-based contrast media. This generator consists of the following components: a constant high-voltage power supply, a filament power supply, a turbomolecular pump, and an x-ray tube. The x-ray tube is a demountable diode which is connected to the turbomolecular pump and consists of the following major devices: a samarium target, a tungsten hairpin cathode (filament), a focusing (Wehnelt) electrode, a polyethylene terephthalate x-ray window 0.25 mm in thickness, and a stainless-steel tube body. In the x-ray tube, the positive high voltage is applied to the anode (target) electrode, and the cathode is connected to the tube body (ground potential). In this experiment, the tube voltage applied was from 50 to 70 kV, and the tube current was regulated to within 0.10 mA by the filament temperature. The exposure time is controlled in order to obtain optimum x-ray intensity. The electron beams from the cathode are converged to the target by the focusing electrode, and bremsstrahlung x-rays were absorbed using a 50-µm-thick tungsten filter. The x-ray intensity was 1.04 μGy/s at 1.0 m from the x-ray source with a tube voltage of 60 kV and a tube current of 0.10 mA, and angiography was performed using a computed radiography system and iodine-based microspheres 15 µm in diameter. In angiography of non-living animals, we observed fine blood vessels of approximately 100 µm with high contrasts.

Same-Day Preventive Embolization and Surgical Excision of Carotid Body Tumor

To the Editor, Since carotid body tumors (CBTs) are situated at the bifurcation of the common carotid artery (CCA), they can easily infiltrate neighboring blood vessels and nerves, leading to Horner’s syndrome or lower cranial nerve symptoms such as pain; hoarseness associated with pressure; and dysphagia. Complete surgical removal is the treatment of choice whenever technically achievable. However, surgery is associated with increased risks because of the location of CBTs; difficulties encountered during their removal; and their highly vascular nature (Fig. 1A). Preoperative embolization of CBTs has been advocated because it reduces operative time and intraoperative blood loss [1]. No literature exists on preoperative embolization and surgery performed on the same day, although the most widely recommended time delay between preoperative embolization and surgery is 1–2 days to avoid recanalization of the vessels by collateral circulation and adhesion of the tumor due to inflammation [1]. We performed preoperative embolization and surgery on the same day in order to maximize their benefits. Between March 2013 and September 2016, 10 consecutive patients (3 men, 7 women; median age 49 years, range 23–62 years) with a CBT underwent preoperative embolization at a single institution. We performed preoperative CBT embolization as follows: intravenous (i.v.) heparin (5000 IU) was administered intraprocedurally (500–1000 IU added every hour) to prevent thromboembolic complications related to the catheter procedure. A 5-Fr-long sheath was introduced after puncturing the right femoral artery. Selective angiography of the external carotid or common carotid artery was performed via a 5-Fr headhunter-type catheter (Glidecath, Terumo, Tokyo, Japan). Superselective catheterization of the arteries feeding the CBT was performed using a 2.2-Fr microcatheter (Progreat-b, Terumo, Tokyo, Japan) and a 0.014-inch

Case report of a mental nerve neurilemmoma

We present a case of a mental neurilemmoma with characteristic findings on cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI). A 62-year-old man was referred to our hospital for a painless swelling in the right cheek. CBCT imaging demonstrated dilatation of the mental foramen. On MRI, a layered pattern on T2-weighted images and enhancement with gadolinium were observed within a low-signal pseudo-capsule. On the basis of these findings, a neurilemmoma was considered likely, and this diagnosis was confirmed histologically.

Second harmonic x-ray irradiation from weakly ionized linear ferrum plasma

In the plasma flash x-ray generator, a 200 nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the formation of weakly ionized linear plasma, consisting of ferrum ions and electrons, around the fine target, and intense K-series characteristic x-rays are produced from the plasma axial direction. At a charging voltage of 50 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 15 kA. In the spectral measurement, Kβ rays were intense, and higher harmonic x-rays were observed. The pulse widths were 0.5 μs, and the maximum x-ray intensity was approximately 300 μGy.