[Report based on fiscal 2005 diagnostic X-ray equipment questionnaire survey-conditions of radiography-].

In this report, we summarize the survey of diagnostic X-ray equipment conducted in 2005, focusing on exposure conditions. What we would like to point out in this report is how prevalent digital image receptor systems have become, including flat panel detectors (FPD), which did not exist in our last survey five years ago. FPD have become popular very quickly among the digital receptor systems used in general radiography. Twenty-three percent of all chest standing-position X-ray equipment now have FPD. Since FPD has become prevalent, exposure conditions are becoming somewhat different from screen/film systems (s/f) and computed radiography (CR). While the image receptor system is expected to shift to FPD, we would like to continue our survey to determine what exposure conditions will be like in the near future.

[Report based on fiscal 2005 diagnostic X-ray equipment questionnaire survey-A photography system-].

In accordance with a questionnaire survey of diagnostic X-ray equipment enforced in 2005, this report was focused mainly on a photography device. The paper questionnaire was mailed to 667 institutions, and the collection rate was 20.4%. Introductions of digital photographic devices are progressing and flat panel detectors (FPD) are spreading in addition to computed radiography (CR). Examination revealed that the spread rate of FPD was 14.4%. The inverter-type device occupied 73.4% in group of high-voltage-generation devices. We reason that the spread rate indicates changeover to an inverter-type device. Changes in photography equipment and photography devices will bring change in photographic technology. Such investigation will be necessary in the future.

[Characteristics of specifications of transportable inverter-type X-ray equipment].

Our X-ray systems study group measured and examined the characteristics of four transportable inverter-type X-ray equipments. X-ray tube voltage and X-ray tube current were measured with the X-ray tube voltage and the X-ray tube current measurement terminals provided with the equipment. X-ray tube voltage, irradiation time, and dose were measured with a non-invasive X-ray tube voltage-measuring device, and X-ray output was measured by fluorescence meter. The items investigated were the reproducibility and linearity of X-ray output, error of pre-set X-ray tube voltage and X-ray tube current, and X-ray tube voltage ripple percentage. The waveforms of X-ray tube voltage, the X-ray tube current, and fluorescence intensity draw were analyzed using the oscilloscope gram and a personal computer. All of the equipment had a preset error of X-ray tube voltage and X-ray tube current that met JIS standards. The X-ray tube voltage ripple percentage of each equipment conformed to the tendency to decrease when X-ray tube voltage increased. Although the X-ray output reproducibility of system A exceeded the JIS standard, the other systems were within the JIS standard. Equipment A required 40 ms for X-ray tube current to reach the target value, and there was some X-ray output loss because of a trough in X-ray tube current. Owing to the influence of the ripple in X-ray tube current, the strength of the fluorescence waveform rippled in equipments B and C. Waveform analysis could not be done by aliasing of the recording device in equipment D. The maximum X-ray tube current of transportable inverter-type X-ray equipment is as low as 10-20 mA, and the irradiation time of chest X-ray photography exceeds 0.1 sec. However, improvement of the radiophotographic technique is required for patients who cannot move their bodies or halt respiration. It is necessary to make the irradiation time of the equipments shorter for remote medical treatment.

[Characteristics of a new non-invasive x-ray output analyzer].

The X-ray systems study group used the Victoreen NERO mAx model 8000, a new non-invasive X-ray output analyzer, to measure the tube voltage, tube voltage waveform, tube current, and irradiation time for conditions corresponding to general radiography and mammography. The measurement results were then compared with those obtained using a conventional invasive measuring instrument. The peak values of the tube voltage measured by the NERO mAx and the invasive measuring instrument were compared. The NERO mAx had a good measurement error range of -1.2 to +0.9 kV. For tube current measurement by the NERO mAx, the maximum error for general radiography conditions was +11 mA and that for mammography conditions was +6 mA. For irradiation time measurement, the value for general radiography conditions was slightly greater and the value for mammography conditions was slightly less than the corresponding values obtained by the invasive measuring instrument. If radiation quality is changed during measurement of the characteristics, measurement values change. Since the NERO mAx incorporates two types of X-ray detectors, it shows good measurement reproducibility. The NERO mAx has been shown to have suitable characteristics for use as a measuring instrument for constancy tests. In the future, constancy tests should be used to quantitatively control the factors determining clinical image quality.

Two low-temperature-inducible Chlorella genes for delta12 and omega-3 fatty acid desaturase (FAD): isolation of delta12 and omega-3 fad cDNA clones, expression of delta12 fad in Saccharomyces cerevisiae, and expression of omega-3 fad in Nicotiana tabacum.

In an attempt to clarify the involvement of fatty acid desaturases (FADs) in the freezing tolerance of Chlorella vulgaris IAM C-27, developed by hardening, we have isolated cDNA clones for two types of FADs from the Chlorella strain, based on the sequence information of genes for delta12 and omega-3 FADs, respectively desaturating oleic acid (18:1) to linoleic acid (18:2) and linoleic acid (18:2) to linolenic acid (18:3). The deduced amino acid sequence of the first clone, designated CvFad2, showed about 66% similarity to the microsomal delta12 FADs from several higher plants and this gene had delta12 FAD activity when expressed in Saccharomyces cerevisiae. The predicted protein encoded by a second gene, designated CvFad3, showed about 60% similarity to the microsomal and plastidial omega-3 FADs from several higher plants. The features of the amino acid sequences of the C- and N-terminal regions of CvFAD3 and fatty acid analysis of polar lipids in transgenic tobacco plant expressing the CvFad3 gene suggested that this gene encodes the microsomal omega-3 FAD. Southern blot analysis showed that both genes were single-copy genes in the genome of the Chlorella strain. Different transcriptional patterns were observed with the two genes during hardening in Northern blot analysis.

[Report based on Fiscal 2000 Diagnostic X-ray Equipment Questionnaire Survey (conditions of X-ray units and similar equipment)].

The X-ray Systems Study Group, in an attempt to determine the current status and changes in the state of X-ray equipment, reception systems, and equipment control, conducted investigational research by distributing a questionnaire survey to 400 facilities. The rate of recovery was 33%. The capacity of transformers has been increasing in spite of the three-phase 415 V decrease in the power supply of X-ray equipment. Among high-voltage generators, inverter-type X-ray equipment accounted for 81.3% of units. The ratio of the X-ray tube of a conventional rotational system to that of a high-speed rotational system was 1:3, and 54.9% had target angles of 12 . Many X-ray tubes had a heat capacity of less than 200-300 kHU. The body parts that had the shortest times on radiography were adult chest and pediatric chest. In many cases, the shortest time used was 10 msec. Facilities in which the shortest time was less than 10 msec accounted for almost half of the total number. Facilities where the radiation dose of radiography had decreased showed 1/4 of the digitalization whole. Measurement was carried out when the equipment was bought in 94.9% of facilities, and measurement when the service contract was finished was done in 77.1% of the responding facilities.

[Report based on fiscal 2000 diagnostic x-ray equipment questionnaire survey(conditions of radiography)].

X-ray equipment has seen advances in inverters and the digitalization of reception systems. The X-ray Systems Study Group, in order to examine changes in the conditions of radiography, including pediatric radiography, variations in shortest irradiation time, and standardization of the conditions of radiography, carried out investigative research using a questionnaire survey that was sent to 400 facilities. The recovery rate was 33%. In terms of the reception system, half of the general radiography systems were using computed radiography (CR). Seventy percent of respondents used an intensifying screen and film(S EF)in stomach double-contrast radiography. About 80% used digital radiography (DR) and digital subtraction angiography (DSA) in aorta abdominalis angiography. At least 70% of high-voltage generators were of the inverter type. The conditions of radiography were not greatly influenced by changes in reception systems and X-ray equipment. Many pediatric radiographies were carried out by radiological technologists. We consider it useful to conduct such survey investigations.