Japanese Journal of Radiological Technology
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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Volume 70, Issue 9
Displaying 1-8 of 8 articles from this issue
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Opening Article
Originals
  • Fabrication of Improved Multi-slit Equipment to Obtain the Input-output Characteristics of Computed Radiography Systems: Correction of the Heel Effect, and Application to High Tube-voltage Experiments
    Itsumi Maehata, Hiroaki Hayashi, Kazuki Takegami, Syohei Ujita, Natsum ...
    2014 Volume 70 Issue 9 Pages 867-876
    Published: 2014
    Released on J-STAGE: September 22, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.9.867
    JOURNAL FREE ACCESS
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    Multi-slit equipment is a new experimental apparatus that can measure the input-output characteristics of a CR (computed radiography) system with limited influence of the fading effect. Kimoto et al. recently proposed a new type of multi-slit apparatus in which the multi-slit setup, the insertion region of the phosphor plate, and plate shielding are integrated to create a single handy-type item (an all-in-one type multi-slit apparatus). However, some problems remained unsolved. The aims of this study were to devise a setup for application to high tube voltage conditions, and to improve the all-in-one type multi-slit equipment so as to correct the heel effect. We examined the capabilities of our improved multi-slit equipment using diagnostic X-ray apparatus and found that it can obtain input-output characteristics with 5% accuracy for tube voltages of 40–140 kV and SID (source to image receptor distances) of 50–200 cm.
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  • Uncertainty of Cross Calibration-applied Beam Quality Conversion Factor for the Japan Society of Medical Physics 12
    Naoki Kinoshita, Akinobu Kita, Akihiro Takemura, Yasuhiro Nishimoto, T ...
    2014 Volume 70 Issue 9 Pages 877-882
    Published: 2014
    Released on J-STAGE: September 22, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.9.877
    JOURNAL FREE ACCESS
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    The uncertainty of the beam quality conversion factor (kQ,Q0) of standard dosimetry of absorbed dose to water in external beam radiotherapy 12 (JSMP12) is determined by combining the uncertainty of each beam quality conversion factor calculated for each type of ionization chamber. However, there is no guarantee that ionization chambers of the same type have the same structure and thickness, so there may be individual variations. We evaluated the uncertainty of kQ,Q0 for JSMP12 using an ionization chamber dosimeter and linear accelerator without a specific device or technique in consideration of the individual variation of ionization chambers and in clinical radiation field. The cross calibration formula was modified and the beam quality conversion factor for the experimental values [(kQ,Q0)field] determined using the modified formula. It’s uncertainty was calculated to be 1.9%. The differences between (kQ,Q0)field of experimental values and kQ,Q0 for Japan Society of Medical Physics 12 (JSMP12) were 0.73% and 0.88% for 6- and 10-MV photon beams, respectively, remaining within ± 1.9%. This showed kQ,Q0 for JSMP12 to be consistent with (kQ,Q0)field of experimental values within the estimated uncertainty range. Although inter-individual differences may be generated, even when the same type of ionized chamber is used, kQ,Q0 for JSMP12 appears to be consistent within the estimated uncertainty range of (kQ,Q0)field.
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Clinical Technology
  • Verification of the Protective Effect of a Testicular Shield in Postoperative Radiotherapy for Seminoma
    Yoshitsugu Matsumoto, Yoshiyuki Umezu, Toshioh Fujibuchi, Yoshitaka No ...
    2014 Volume 70 Issue 9 Pages 883-887
    Published: 2014
    Released on J-STAGE: September 22, 2014
    DOIhttps://doi.org/10.6009/jjrt.2014_JSRT_70.9.883
    JOURNAL FREE ACCESS
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    In postoperative radiotherapy for seminoma, control of the testicular absorbed dose is important, since exposure of the testis can lead to temporary or permanent infertility. In this case, instead of using a dog-leg-shaped field, treatment using a field focused near the aorta was provided in several disease stages of seminoma. However, the precise need for testicular shielding during treatment and dose of testis exposure was not clear. We examined these questions by measuring the testicular absorbed dose with and without a testicular shield using two clinical treatment plans and a phantom. The distance from the testis phantom and the lower end of the irradiation field was varied. Where the total dose for the tumor was 20 Gy, the testicular absorbed dose was below 0.1 Gy, the threshold dose for temporary infertility. At this dosage, the distance between the testis phantom and the edge of the irradiation field was 14.6 cm without the shield and 9.99 cm with the shield. Using a testes shield, it was thus possible to reduce the dose by 58.5%.
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Program of the 42nd Autumn Scientific Congress
The 70th Annual Scientific Congress Educational Lecture
Basic Lecture—Disease of the Brain: From Diagnosis to Treatment
JIRA Topics
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