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We quantified the level of backscatter radiation generated from physicians’ heads using a phantom. We also evaluated the shielding rate of the protective eyewear and optimal placement of the eye-dedicated dosimeter (skin surface or behind the Pb-eyewear). We performed diagnostic X-rays of two head phantoms: Styrofoam (negligible backscatter radiation) and anthropomorphic (included backscatter radiation). Radiophotoluminescence glass dosimeters were used to measure the eye-lens dose, with or without 0.07-mm Pb-equivalent protective eyewear. We used tube voltages of 50, 65 and 80 kV because the scattered radiation has a lower mean energy than the primary X-ray beam. The backscatter radiation accounted for 17.3–22.3% of the eye-lens dose, with the percentage increasing with increasing tube voltage. Furthermore, the shielding rate of the protective eyewear was overestimated, and the eye-lens dose was underestimated when the eye-dedicated dosimeter was placed behind the protective eyewear. We quantified the backscatter radiation generated from physicians’ heads. To account for the effect of backscatter radiation, an anthropomorphic, rather than Styrofoam, phantom should be used. Close contact of the dosimeter with the skin surface is essential for accurate evaluation of backscatter radiation from physician’s own heads. To assess the eye-lens dose accurately, the dosimeter should be placed near the eye. If the dosimeter is placed behind the lens of the protective eyewear, we recommend using a backscatter radiation calibration factor of 1.2–1.3.

The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaruor snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two species. For γ-radiation, there was excellent agreement in the self-absorption rate with the approximate curve of the Japanese macaque, with an average deviation of 2%. The maximum deviation of 12% was for the kidney, which has two organs, so the error with the approximate curve is slightly larger due to the energy loss created between organs.

In 2011, the International Commission on Radiological Protection recommended reducing the threshold dose and occupational equivalent dose limit for the lens of the eye. However, this recommendation was based on limited epidemiological evidence and a few assumptions. Additional epidemiological and biological studies are thus required to understand radiation cataracts and optimize radiation protection practices. Glutathione is present in large amounts in the lens and inhibits the onset and progression of cataracts. A few studies have reported changes in glutathione levels in laboratory animal lenses after irradiation, but evidence about dose rate and time dependence remains lacking. In this study, we analyzed dose rate- and time-dependent changes in whole-eye reduced glutathione (GSH) and oxidized glutathione (GSSG) levels after γ-irradiation. We found that both decreases in eye GSH levels and delays in eye GSH recovery depended on dose rate. Our results support the concept that changes in GSH levels influenced on radiation cataractogenesis, consistent with previous biological research. This study will contribute to the mechanistic understanding of radiation cataractogenesis.

Ionizing radiation exposure affects the redox state in vivo. Recently, whole-blood antioxidant capacity (WBAC) has been reported to decrease in a dose-dependent manner after acute total body irradiation (TBI). However, changes in WBAC after localized and chronic irradiations have not been reported. This study analyzed changes to WBAC in mice after either localized irradiation (irradiation of the left hind leg only) or chronic TBI using the i-STrap method. Leg-localized irradiation exerted limited effects on WBAC, while WBAC decreased in a dose rate-dependent manner after TBI. Further, the WBAC reached the minimum value in a shorter period at a smaller dose rate. Our results suggest that changes in WBAC do not directly reflect absorbed dose, but may reflect radiation-induced biological damage at the systemic level. This study will contribute to the understanding of radiation-induced injuries and diseases, and will facilitate the establishment of biomarkers for radiation exposure.

The new recommendation of the International Commission on Radiological Protection for occupational eye dose is an equivalent dose limit to the eye of 20 mSv year–1, averaged over a 5-year period. This recommendation is a drastic reduction from the previous limit of 150 mSv year–1. Hence, it is important to protect physicians’ eyes from X-ray radiation. Particularly in interventional radiology (IVR) procedures, many physicians use protective lead (Pb) glasses to reduce their occupational exposure. This study assessed the shielding effects of novel 0.07 mm Pb glasses.The novel glasses (XR-700) have Pb–acrylic lens molded in three dimensions. We studied the novel type of 0.07 mm Pb glasses over a period of seven consecutive months. The eye dose occupational radiation exposure of seven IVR physicians was evaluated during various procedures. All IVR physicians wore eye dosimeters (DOSIRIS™) close to the left side of the left eye. To calculate the shielding effects of the glasses, this same type of eye dosimeter was worn both inside and outside of the Pb lenses.The average shielding effect of the novel glasses across the seven physicians was 61.4%. Our results suggest an improved shielding effect for IVR physicians that use these glasses. No physician complained that the new glasses were uncomfortable; therefore comfort is not a problem.The lightweight glasses were acceptable to IVR physicians, who often must perform long procedures. Thus, the novel glasses are comfortable and reasonably protective. Based on the results of this study, we recommend that IVR physicians use these novel 0.07 mm Pb glasses to reduce their exposure.

An electronic cigarette (e-cigarette) is a product used to smoke aerosol by heating a solution of “e-liquid” that consists of propylene glycol (PG) and glycerol (GLY) containing nicotine and flavors. In this study, thermal decomposition products generated from three brands of e-cigarettes were determined at various electric power levels. When using neat PG or GLY instead of e-liquid, propylene oxide was detected only in the gas phase from PG and not detected from GLY. In contrast, glycidol was detected only from GLY and not from PG. Almost all of the glyoxal and acrolein was detected from GLY, but formaldehyde and methyl glyoxal were detected from both PG and GLY. Using commercially available e-liquids, the same results were obtained. Nearly all chemical compounds generated from e-cigarettes have a carbon number of 3 or less except for nicotine and flavors. We measured chemical compounds generated from e-cigarettes at various electric power levels (1–85 W). At an electric power of 10 W, the generation of chemical compounds was very low; however, when the electric power exceeded 40 W, it increased exponentially. As thermal decomposition products of e-liquid, acetaldehyde, acrolein, and propylene oxide mainly occur as gaseous matter, while glyoxal, methylglyoxal, and glycidol mainly occur as particulate matter. Formaldehyde exits in both gaseous and particulate matter forms. Thermal decomposition products can be divided into three groups: thermal decomposition products originating from PG and GLY, those originating from other sources, and those directly generated. Concentrations of these thermal decomposition products were mostly higher than those in traditional cigarettes. In particular, thermal decomposition products generated from one of the studied e-cigarettes were very high; e.g., formaldehyde reached 4400 μg/15 puffs at 50 W. E-cigarette users must know that hazardous substances are generated even within the recommended electric power limits.

As a new form of cigarettes, heated tobacco products (HTPs) have been rapidly distributed worldwide. In this study, an improved method for analyzing gaseous and particulate compounds generated from HTPs is described. Smoke is collected using a GF-CX572 sorbent cartridge with 300 mg of carbon molecular sieves, that is, Carboxen 572 (CX572), and a 9 mm glass-fiber filter (GF). After collection, the CX572 particles from the cartridge are transferred along with the GF and deposited into a vial containing two phases of carbon disulfide and methanol. The CX572 particles settle into the lower carbon disulfide phase, while nonpolar compounds are desorbed. After the sample is allowed to stand, the solution is slowly stirred. The two-phase mixture of carbon disulfide and methanol is combined into a homogeneous solution. Polar compounds are then desorbed, while the desorbed nonpolar compounds remain in solution. For the analysis of carbonyl compounds, an enriched 2,4-dinitrophenylhydrazine solution is added to a portion of the combined solution for derivatization and subsequent high-performance liquid chromatography analysis. For the analysis of volatile organic compounds and water, a portion of the combined solution is analyzed by gas chromatography–mass spectrometry or equipped with a thermal conductivity detector. By applying the proposed GF-CX572 one-cartridge method to the analysis of the mainstream smoke generated from HTPs and traditional cigarettes, several chemical compounds are detected, and the chemical composition of smoke is revealed. The GF-CX572 one-cartridge method can analyze gaseous and particulate chemical compounds from the HTP smoke by utilizing not only the entire puff volume but also one puff volume because the GF-CX-572 cartridge can be replaced with a new cartridge within 3 s. An overview of the chemicals generated from HTPs is obtained in detail by one-puff volume sampling. In addition, the generated chemical compounds strongly depend on the temperature of tobacco leaves in HTPs.

We developed an analytical method for analyzing electronic cigarette (E-cigarette) smoke, and measured the carbonyl compounds and volatile organic compounds generated by 10 brands of second-generation E-cigarettes. A glass filter (Cambridge filter pad) for particulate matter and a solid sorbent tube packed with Carboxen-572 for gaseous compounds were used to collect E-cigarette smoke. These were then analyzed using a two-step elution method with carbon disulfide and methanol, followed by high-performance liquid chromatography (HPLC) and gas chromatography mass spectrometry (GC/MS). Formaldehyde (FA), acetaldehyde (AA), acetone (AC), acrolein (ACR), propanal (PA), acetol (AT), glyoxal (GO), and methyl glyoxal (MGO) were detected by HPLC in some E-cigarettes. Propylene glycol (PG), glycerol (GLY), and some esters were detected by GC/MS. GO and MGO exist mainly as particulate matter. AA, AC, ACR, PA, and AT exist mainly as gaseous compounds. FA exists as both particulate matter and gaseous compounds. These carbonyl compounds have carbon numbers C1–C3. The main components of E-liquid are PG (C3) and GLY (C3). Therefore, the oxidation of liquids, such as PG and GLY in E-cigarettes upon incidental contact with the heating element in E-cigarette, is suggested as being a possible cause for carbonyl generation. When the puff number exceeds a critical point, carbonyl generation rapidly increases and then remains constant. The results of this study are now being used to determine the following E-cigarette smoking protocol: puff volume, 55 mL; puff duration, 2 s; and puff number, 30. E-cigarette analysis revealed very large variation in carbonyl concentration among not only different brands, but also different samples of the same product. Typical distributions of carbonyl concentration were not observed in any of the E-cigarettes tested, and the mean values greatly differed from median values.

ObjectiveAlthough many patients benefi t greatly from fluoroscopically guided intervention (IVR) procedures such as percutaneous coronary intervention (PCI), one of the major disadvantages associated with these procedures, such as cardiac IVR, is the increased patient radiation dose. This study compared the entrance surface doses of x-ray equipment for cardiac IVR at the same seven cardiac catheterization laboratories between today and the past to determine the radiation doses of current cardiac IVR x-ray systems.Methods and resultsThis study was conducted in 2001, 2007, and 2014 at the same seven cardiac catheterization laboratories in and around Sendai City, Japan. The entrance surface doses with cineangiography and fl uoroscopy were compared in 2001 (11 x-ray systems), 2007, and 2014 (12 x-ray systems) using a 20-cm-thick acrylic plate and skin dose monitor. The x-ray conditions used in the measurements, including the image receptor fi eld magnifi cation mode and the recording speed for cineangiography and fl uoroscopy, were those normally used in the facilities performing PCI. Although presently, the entrance doses of x-ray equipment used for cardiac IVR tend to be lower than previously (fl uoroscopy dose in 2001, 19.3 ± 6.3 mGy/min; in 2014, 13.2 ± 6.5 mGy/min), some equipment has a high radiation dose. In addition, the dose diff erences of the x-ray systems in 2014 were greater than those in the past (fl uoroscopy dose in 2001, 3.4-fold; in 2014, 10.5-fold).ConclusionsIn IVR procedures, managing the radiation dose of cardiac IVR x-ray systems is a very important issue. Periodical measurement of the radiation dose of the x-ray equipment used for both cineangiography and fl uoroscopy for cardiac IVR is necessary.

Carbonyl compounds in E-cigarette smoke mist were measured using coupled silica cartridges impregnated with hydroquinone and 2,4-dinitrophenylhydrazine, followed by high-performance liquid chromatography. A total of 363 E-cigarettes (13 brands) were examined. Four of the 13 E-cigarette brands did not generate any carbonyl compounds, while the other nine E-cigarette brands generated various carbonyl compounds. However, the carbonyl concentrations of the E-cigarette products did not show typical distributions, and the mean values were largely different from the median values. It was elucidated that E-cigarettes incidentally generate high concentrations of carbonyl compounds.