In 2011, the threshold dose for cataract was lowered from 8 Gy to 0.5 Gy, and the recommended occupational equivalent dose limit for the lens of the eye was also lowered from 150 mSv/year to 20 mSv/year. Even before amendment of the relevant domestic laws and regulations, it is better for us interventional radiologists to adapt ourselves to this change and to resolve the shortage of lead aprons/eyewears/shields as soon as possible. Second personal dosimeter outside the lead apron is necessary to avoid underestimation of the lens dose.
Diagnostic reference level (DRL) is a useful tool in interventional radiology as well for management of patient dose with regard to avoiding unnecessary radiation risks, though the complexity of the procedure must be taken into account. Dose survey of interventional procedures for the next revision of Japanese DRL is planned to be conducted in the near future.

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Recent technological innovations in interventional radiology (IVR) might produce better image quality with lower radiation doses; however, the widespread use of increasingly complex IVR procedures may still result in significant radiation exposure to both the patient and operator. In this article, we present recommended guidelines, measurement of patients’ radiation dose and previous reports regarding patients’ radiation dose in recent IVR procedures including our dose reduction trial during DEB-TACE for HCC to obtain and refresh the information needed to understand the importance of dose reduction trial and the risks of recent IVR procedures.

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The number of medical examinations which use interventional radiology (IVR) has increased recently. Because of more advanced and complex procedures in IVR, a longer treatment time is frequently required. Therefore, it is important to determine an effective radiation dose to lessen exposure. This review describes radiation exposure of medical personnel, and ways to reduce radioactivity exposure doses are suggested.
Computed tomographic (CT) fluoroscopy is gaining a wider role in non-vascular IVR, and the over-couch X-ray tube system is being used for biliary IVR. These procedures are associated with higher exposure. Therefore, to reduce radiation exposure to the operator, it is essential to avoid direct exposure by the primary beam to the hands during the procedures. In vascular IVR, most of the exposure to the operators is caused by scatter radiation from the patient. Almost every benefit coming from a reduction in the patient dose will secondarily reduce scatter radiation to the device operator as well. Using appropriate shields help in reducing scatter radiation to the operator.
To reduce radiation exposure of medical personnel from IVR, it is imperative to observe the three vital principles of radiation exposure protection, namely, time, shield, and distance. Furthermore, any reduction in healthcare workers’ radiation exposure always leads to a reduction of exposure to the patient as well.

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X-ray exposure management in medicine is not controlled strictly because of justification of medical procedures. However, appropriate management of X-ray exposure is desirable to prevent future radiation injury. FDA (Food and Drugs Administration) and ICRP (International Commission of Radiation Protection) published several recommendations regarding avoidance of radiation injury during IVR (Interventional Radiology) procedures. In this report, we will introduce the development of a scintillator-based dosimeter coupled with an optical fiber (SOF dosimeter) dedicated for skin exposure dose and trial use in the clinical setting.
The SOF dosimeter has good properties of dose linearity, dose rate dependency, angular dependency and energy dependency. Especially, energy dependency for X-ray tube voltage from 50 to 150 kVp is less than 3%. Since the SOF probe consists of plastic, the probe is not visualized in a fluoroscopic image. This contributes to real-time dosimetry without interfering with the IVR procedure. Skin cumulative dose measurement was performed for 54 hepatocellular cancer (HCC) patients undergoing transarterial chemoembolization (TACE), Kerma air product (KAP) and fluoroscopic time are not simply proportional to skin dose measured with the SOF dosimeter.
The SOF dosimeter will contribute not only to patient skin dosimetry but also the operator’s exposure dose management. As future work, we will establish a comprehensive dosimetry system during IVR procedures using the SOF dosimeter.

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Background & aim:
DC Bead, drug-eluting beads, was launched in Japan in February, 2014 for the treatment of HCC. Post-marketing surveillance has been conducted to examine the utilization, safety and efficacy of DC Bead under daily medical practice conditions. In this presentation, analysis results are reported focusing on the utilization and safety and efficacy of DC Bead.
Materials & Method:
This was a post-marketing, observational study conducted in 26 centers to evaluate the safety and effectiveness of DC Bead in Japanese patients with HCC. Patients were observed for 30 days following enrollment.
Results:
300 patients were enrolled from 26 centers in Japan. The number of patients included in the safety analysis was 282. Regarding adverse drug reactions, 232 events occurred in 119 patients (42.2%). The results of the evaluation of embolization performance, based on digital subtraction angiography findings, showed that “complete embolization” was observed in 137 patients, “intensive embolization” in 101 patients, “moderate embolization” in 35 patients, “mild embolization” in 4 patients, and “not evaluable” in 2 patients; the embolization success rate was 85.3% (238/279 patients).
Conclusion:
This study well demonstrated DC Bead to be an embolic agent providing effective and safe treatment of HCC under daily medical practice conditions in Japan.

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