• Journal of radiological science and technology
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• v.44 no.6
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• pp.629-633
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• 2021

This article is designed to look into the radiation exposure dose to each body part and the shielding effect for workers using an additional shielding to reduce their radiation exposured by scattering radiation which is generated in a space between the operating table and lead curtain during interventional radiology(IR) procedures. After placing a human phantom on the table of SIEMENS' angiography machine, the following measurements were taken, depending on the presence of an additional shield of lead equivalent of 0.25 mmPb, manufactured for this purpose: dose to gonad, dose to an area where the personal dosimeter is placed, and dose to an area of eye lens is located. An ion chamber(chamber volume 1,800 cc) was utilized to measure scattering radiation. The two imaging tests were carried out as follows: fluoroscopy of the abdomen (66 kV, 100 mA, 60 seconds) and of the head (70 kV, 65 mA, 60 seconds); and digital subtraction angiography(DSA) of the abdomen (67 kV, 264 mA, 20 seconds) and of the head (79 kV, 300 mA, 20 seconds). In all the experiments, the shielding efficiency of the gonad position was the largest at 59.8%. In case an additional shielding was used as protection against scattering radiation that came through the operating table and the lead curtain during an IR, the radiation shielding efficiency was estimated to be up to 59.8%, leading to a conclusion that its presence may effectively reduce the radiation exposure dose of medical staffs.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.97-102
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• 2018

The purpose of this study is to provide the basic data for reducing unnecessary radiation dose to the abdomen and fetus of pregnant women by presenting proper height of shielding protector for efficient abdominal shielding in chest PA examination of Korean pregnant women. The subjects of this study were 288 persons who were eligible for this study among 798 pregnant women who had chest PA examination from January 1, 2015 to December 31, 2016 Retrospective study was performed. Measurements was performed from the apex of the right and left lungs to costophrenic angle of the right and left lungs and to the lowest costophrenic angle among the right and left lungs at the top of the image(this line called Joo's line in this study). The mean of the right and left lung height of pregnant women were 259.09 mm and 263.57 mm, respectively. Also, the average height of the Joo's line designed by the researcher for proper abdominal radiation protection was 322.15 mm. For proper and efficient abdominal radiation protection for pregnant women, it is necessary to adjust the shielding according to the height of the pregnant woman. It is appropriate that the height of the shielding protector should be adjusted so that the upper part of the shield is located at 342.30 mm below from upper part of the detector.

• Journal of Radiation Protection and Research
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• v.27 no.1
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• pp.1-10
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• 2002

High energy photon beams from medical linear accelerators produce large scattered radiation by various components of the treatment head, collimator and walls or objects in the treatment room including the patient. These scattered radiation do not provide therapeutic dose and are considered a hazard from the radiation safety perspective. Scattered dose of therapeutic high energy radiation beams are contributed significant unwanted dose to the patient. ICRP take the position that a dose of 500mGy may cause abortion at any stage of pregnancy and that radiation detriment to the fetus includes risk of mental retardation with a possible threshold in the dose response relationship around 100 mGy for the gestational period. The ICRP principle of as low as reasonably achievable (ALARA) was recommended for protection of occupation upon the linear no-threshold dose response hypothesis for cancer induction. We suggest this ALARA principle be applied to the fetus and testicle in therapeutic treatment. Radiation dose outside a photon treatment filed is mostly due to scattered photons. This scattered dose is a function of the distance from the beam edge, treatment geometry, primary photon energy, and depth in the patient. The need for effective shielding of the fetus and testicle is reinforced when young patients ate treated with external beam radiation therapy and then shielding designed to reduce the scattered photon dose to normal organs have to considered. Irradiation was performed in phantom using high energy photon beams produced by a Varian 2100C/D medical linear accelerator (Varian Oncology Systems, Palo Alto, CA) located at the Yonsei Cancer Center. The composite phantom used was comprised of a commercially available anthropomorphic Rando phantom (Phantom Laboratory Inc., Salem, YN) and a rectangular solid polystyrene phantom of dimensions $30cm{\times}30cm{\times}20cm$. the anthropomorphic Rando phantom represents an average man made from tissue equivalent materials that is transected into transverse 36 slices of 2.5cm thickness. Photon dose was measured using a Capintec PR-06C ionization chamber with Capintec 192 electrometer (Capintec Inc., Ramsey, NJ), TLD( VICTOREEN 5000. LiF) and film dosimetry V-Omat, Kodak). In case of fetus, the dosimeter was placed at a depth of loom in this phantom at 100cm source to axis distance and located centrally 15cm from the inferior edge of the $30cm{\times}30cm^2$ x-ray beam irradiating the Rando phantom chest wall. A acryl bridge of size $40cm{\times}40cm^2$ and a clear space of about 20 cm was fabricated and placed on top of the rectangular polystyrene phantom representing the abdomen of the patient. The leaf pot for testicle shielding was made as various shape, sizes, thickness and supporting stand. The scattered photon with and without shielding were measured at the representative position of the fetus and testicle. Measurement of radiation scattered dose outside fields and critical organs, like fetus position and testicle region, from chest or pelvic irradiation by large fie]d of high energy radiation beam was performed using an ionization chamber and film dosimetry. The scattered doses outside field were measured 5 - 10% of maximum doses in fields and exponentially decrease from field margins. The scattered photon dose received the fetus and testicle from thorax field irradiation was measured about 1 mGy/Gy of photon treatment dose. Shielding construction to reduce this scattered dose was investigated using lead sheet and blocks. Lead pot shield for testicle reduced the scatter dose under 10 mGy when photon beam of 60 Gy was irradiated in abdomen region. The scattered photon dose is reduced when the lead shield was used while the no significant reduction of scattered photon dose was observed and 2-3 mm lead sheets refuted the skin dose under 80% and almost electron contamination. The results indicate that it was possible to improve shielding to reduce scattered photon for fetus and testicle when a young patients were treated with a high energy photon beam.

• Journal of radiological science and technology
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• v.30 no.3
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• pp.213-219
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• 2007

The purpose of this study is to evaluate shielding effect of radiation protector for interventional radiologists in procedures by measuring inside and outside of radiation protector. In this study, we measured the radiation dose of 4 interventional radiologists during TACE and PTBD procedure for 4 month(2005.05-2005.09). Absorbed dose were measured by TLD placed underneath and over radiation protector such as Goggle, Thyroid protector, Apron and placed on the 4th finger of Hand. In addition, we measured background radiation dose in the control room using TLD. During TACE procedure, using 0.07 mmPb Goggle decreased average 53.8% of radiation dose rate in continuous fluoroscopic mode and decreased average 77.6% of radiation dose rate in pulse fluoroscopic mode. Using 0.5 mmPb Thyroid protector decreased average 88.9% of radiation dose rate in continuous fluoroscopic mode and decreased average 92.8% in pulse fluoroscopic mode. During PTBD procedure, using 0.07 mmPb Goggle decreased radiation dose rate average 62.7%, 87.9% by 0.5 mmPb Thyroid protector, 90.5% by 0.5 mmPb Apron. The average fluoroscopic time of PTBD was 6.14 min. shorter than TACE procedure, but radiation exposure dose rate of PTBD was 3 times higher in total body dose, and 40 times higher in hand dose rate than TACE. Interventional radiologists must wear thicker protector recommended over 0.5 mmPb. Also, they must use lead Goggle during interventional procedure. Abdomen dose decreased average 38.4% by drawing a lead curtain under the patient's table, therefore, they must draw a lead curtain to shield scattering ray. Radiation exposure dose decreased average 59.0% by using pulse fluoroscopic mode. So radiologists would better use pulse fluoroscopic mode than continuous fluoroscopic mode to decrease exposure dose.