Biomedical subjects

K Nagaiwa

Publications and source records attributed to K Nagaiwa.

5 recordsLinked to original sources

PubMed1982

Clinical evaluation of single photon emission computed tomography of the brain.

Single photon emission computed tomography (ECT) was performed on 67 patients. ECT images were taken with a Shimadzu scintillation camera, LFOV-E, before a delayed scan. Eighteen of 67 patients showed abnormal findings on the ECT images. Fourteen of the 18 had a transmission X-ray CT (TCT) study as well. There were eleven cases with brain metastasis, and a surgical wound. Eleven of forty-nine ECT-negative patients had a TCT study as well, and intracranial lesions were found in five. The smallest lesion found by ECT was 0.5 cm in diameter on the TCT image and the largest lesion missed by ECT was a tumor in the corpus callosum, measuring 4.2 X 2.7 cm. As far as the patients who also received TCT study are concerned, both the ECT and the ordinary scan were thought to be equal in sixteen patients and ECT to be superior in seven whereas the ordinary scintigram was superior in two. At present, ECT is considered to be useful when it is used in addition to the ordinary scans. In the field of clinical nuclear medicine, the development of new radiopharmaceuticals which are labeled with single photon emitters and which can show the metabolic activity of the brain is eagerly awaited.

Adult↗

PubMed1982

A combined method of scintigram and echogram as a trial of integrated image diagnosis.

We developed a method which combines a scintigram and echogram(s) on the basis of precise positional correlation. In our method, an ordinary scintillation camera (Ohio Nuclear sigma 410S) and an ultrasound diagnosis equipment (Aloka Echo Camera) are used, both of which are connected through the interface made by us. This method presents a scintigram with dotted lines through which echograms have been taken, giving us more detailed inside information which we can not obtain from scintigram only. Also obtained are positional correlations between the organ of interest and its neighbouring organs. This method is easily applicable to ordinary scintillation cameras and is useful for our daily practice.

Aged↗

PubMed1981

[Basic studies on radionuclide computed tomography using a rotating chair (author's transl)].

Radionuclide Computed Tomography (RCT) was studied from the technical standpoint of view. In this study, a gamma camera (Ohio Nuclear sigma 410S) and a rotating chair designed by one of us were used. The computer used was Scintipac 1200 (32 kW memories and 2.4 MB X 2 disk memories). A cylindrical phantom having a diameter of 20 cm was also designed by us into which various-sized tubes could be inserted for resolution study. The phantom was set on the chair, the center of which was 20 cm off from the surface of the detector. The chair was rotated manually 10 degrees, and finally 36 digital images in the form of 64 X 64 elements were obtained, covering an entire circumference. RCT images were displayed in the form of 128 X 128 elements on a X-ray film through a Microdot Imager. At first, the phantom was filled with 99mTc solution and the uniformity of the RCT image on it was checked using several formulae for count rate correction to find out which one of the formulae was best fitted. For the reconstruction of the RCT image, "filtered back projection" was used. Then, we found that, as far as out phantom study was concerned, simple geometrical mean on the data from the two opposing directions was found the best for the count rate corrections, which was exclusively used thereafter. The fluctuation on the uniform source was found to be approximately 15%. For the resolution study, hot tubes having diameters of 1.0, 2.0, 3.0, and 4.0 cm and cold tubes of 1.5, 2.4, 3.5, and 4.7 cm were inserted into the phantom. As for the hot tubes, all the tubes were depicted on the RCT image whereas 2.4 cm was the smallest depicted for the cold tubes. FWHM was checked with a fine line source in the phantom and was found to be 2.0 cm regardless to its depth. The Alderson liver phantom was also used to detect defects in the air and it was found both balls having diameters of 2.7 and 3.7 cm could be depicted on the RCT image. Now we are evaluating clinical usefulness of this technique on the liver. The results will be published in the near future.

Evaluation Studies as Topic↗

PubMed1980

[Gamma dose estimation to the gastric wall after administration of a capsule containing a large dose of 131I (author's transl)].

Gamma dose to the gastric wall from a capsule containing 1.85 GBq (50 mCi) of 131I was estimated in 6 patients who had received total thyroidectomy for thyroid carcinoma some years before. The tests were done with a 37 MBq (1 mCi) capsule each in 5 patiens and with a 185 MBq (5 mCi) capsule in one patient. All the patients were requested to fast in the morning. The capsule was given with a glass of water (200 ml). Then, the patient kept supine position under the scintillation camera for a period of one hour except one patient on whom the test was suspended at 30 minutes because of early clearance of the radioactivity from the stomach. In one of 5 patients who were tested for a period of one hour, serial scinticamera images showed almost no movement and minimum dissolution of the capsule. The remaining 4 patients showed slight to moderate movements of the capsules with a variety of dissolution speeds. Data processings were done by Scintipac-1200. The estimated doses at the distance of 0.5 cm from the source were 3.820, 2.074, 1.445, 1.154 and 1.462 grays (382.0, 207.4, 144.5, 115.4 and 146.2 rads) per initial one hour and 375 mGy (37.5 rad) per initial 30 minutes, respectively. From these data, it is thought to be wise to advise the patient to rotate or shake the body on bed occasionally after swallowing the capsules containing a large dose of 131I for the treatment of thyroid cancer. It is also desirable to recommend the patient to walk around even though the controlled patient's room is small. Additional water may be also meaningful to avoid unnecessary irradiation to the gastric wall.

Adult↗

PubMed1980

Subtraction scintigraphy with 67Ga-citrate and 99mTc-colloid in the diagnosis of intrahepatic masses.

Subtraction scintigraphy of the liver with 67Ga-citrate and 99mTc-colloid (99mTc-phytate) was performed by subtracting the image of the latter from the image of the former in 34 patients who were suspected of having intrahepatic masses, especially hepatoma. The computer used was Scintipac 1200 (32 KW memories and 2.4MBX2 disk memories). Both images were taken in a digital form (128 X 128 elements). After normalizing both images, 4 different factors (0.6, 0.8, 1.0, and 1.2) were applied to the 99mTc image before the subtraction from the 67Ga image. We found that this technique was very useful for the detection of abnormal 67Ga accumulation in the liver.

Adult↗