Radiation protection is one of the most essential efforts for radiologists. The newest update of medical radiation protection in Japan focused on the field of interventional radiology. In this situation, it is required to choose for interventional radiologists to participate in it reluctantly or proactively. To enhance the value of interventional radiology in society, our effort of commitment to learning, collaborating, and assuming our awesome responsibility is requested. We will contribute to the safety of medical facilities and society.

In response to the recommendation by the International Commission on Radiological Protection to lower the equivalent eye dose limit, the Japanese Government in April 2021 lowered the equivalent dose limit for the eye lens for occupational exposure. A considerable number of interventional radiology operators are exposed to levels above the new limit. For this reason, a need exists to more accurately evaluate eye lens dose in interventional radiology operators by using a novel direct eye dosimeter, the DOSIRIS™ (IRSN, France), which is capable of measuring a 3-mm dose equivalent under protective glasses. The DOSIRIS is a thermoluminescent dosimeter that exhibits good energy dependence and better directional properties than other dosimeters. Dosimetry using DOSIRIS might be accurate and compatible with the latest regulations.

The medical staff involved in fluoroscopy-guided procedures are at potential risks of radiation-induced cataract. Therefore, proper monitoring of the lens doses is critical, and radiation protection should be provided to the maximum extent that is reasonably achievable. The collar dosimeter is necessary to avoid underestimation of the lens dose, and the third dosimeter behind the protective eyewear would be helpful for those who are likely to exceed the dose limit. The reduction of the patient doses will correspondingly reduce the staff doses. Proper placement of the ceiling-mounted shields and minimization of the face-to-glass gap are the keys to effective shielding. The optimization of procedures and devices that help maintain a distance from the irradiated area and to prevent the looking-up posture will substantially reduce the lens dose.

Computed tomography (CT) fluoroscopy-guided procedures, such as those used for percutaneous biopsy, drainage, and radiofrequency ablation, are highly safe and quite often very successful due to the precision offered by the real-time, high-resolution tomographic images. Even so, international guidelines raised concerns regarding operator exposure to high doses of radiation during these procedures. In light of these concerns, operators conducting CT fluoroscopy-guided procedures not only need to be cognizant of the exposure risk but also exhibit sufficient knowledge of radiation protection. This paper reviews the current literature on experimental and clinical studies of radiation exposure doses to operators during CT fluoroscopy-guided procedures. In addition to the literature review, this paper also introduces different approaches that can be implemented to ensure appropriate radiation protection.

As per the International Commission on Radiological Protection 2010 recommendation, it was stated that "interventional radiologists performing difficult procedures with high workloads may be exposed to high doses" and that education and training of medical staffs in radiation exposure is "an urgent priority." There are many reports on the textbook aspects of radiation protection, but reports on the practical aspects of radiation protection have remained to be scarce. Various methods of reducing radiation exposure are described as "useful" or "can be reduced," but the priority of these methods and the "extent" to which they contribute to reducing radiation exposure are not clear. Thus, in this article, we will look into the protection of interventional radiologist from radiation exposure in a practical way, giving priority to clarity rather than academic accuracy.

An 81-year-old man with previously diagnosed cancer of the pancreatic body presented with melena and anemia. Upper gastrointestinal endoscopy showed gastric varices with bleeding in the entire stomach. Contrast-enhanced computed tomography identified a splenic vein occlusion resulting from invasion by the pancreatic body cancer and dilated collateral pathways from the splenic hilum to the gastric fundus. The patient was diagnosed with gastric varices associated with left-sided portal hypertension caused by obstruction of the splenic vein and underwent percutaneous transsplenic embolization with n-butyl-2-cyanoacrylate mixed with lipiodol. Splenic subcapsular hematoma occurred and was treated conservatively. The patient died of advanced cancer 5 months after the procedure, without experiencing rebleeding. Percutaneous transsplenic embolization was effective in treating gastric variceal bleeding caused by left-sided portal hypertension.

We report two cases of chronic portal vein occlusion with jejunal varices successfully treated using percutaneous intervention with a combined transhepatic and transsplenic approach. Case 1 was a 60-year-old man with uncontrolled jejunal variceal bleeding, and case 2 was a 79-year-old man with anastomotic jejunal variceal bleeding and cholangitis. Single access via the transhepatic or transsplenic route failed to allow catheter advancement through the occlusion. After introducing pull-through access via the transhepatic and transsplenic routes, a metallic stent was could be used to dilate the occluded portal vein. Anastomotic jejunal varices functioning as hepatopetal collaterals were embolized after the establishment of antegrade portal flow. No symptom relapse was observed during the follow-up period (31 months for case 1 and 34 months for case 2).

We present a case of subcapsular hepatic hemorrhage with a concomitant diffuse arterioportal shunt successfully treated with transcatheter arterial embolization. An 85-year-old man with duodenal carcinoma developed hemorrhagic shock three days after pancreaticoduodenectomy. Contrast-enhanced computed tomography revealed an extensive subcapsular hepatic hematoma with extravasation. At the same time, diagnostic angiography showed innumerable foci of petechial extravasation from disrupted isolated arteries and the right inferior phrenic artery. In addition, a comorbid diffuse arterioportal shunt in the hematoma area was detected. We performed transcatheter arterial embolization on the peripheral side of the hepatic artery while preserving the proximal portion. Subsequently, the transcatheter arterial embolization for the right inferior phrenic artery was also performed. Complete hemostasis and occlusion of the arterioportal shunt were successful without fulminant liver failure.

We present two cases of external iliac artery perforation occurring after endovascular interventions successfully treated with direct closure using super-selective transcatheter coil embolization. Two patients, one 78-year-old man and one 78-year-old woman, underwent cardiac catheterization via the right femoral approach for coronary artery disease and atrial fibrillation. Following the procedures, both patients suffered severe acute hypotension, and contrast-enhanced computed tomography revealed a massive retroperitoneal hematoma due to perforation of the right external iliac artery. We attempted direct perforation site closure with super-selective transcatheter embolization using microcoils and achieved complete hemostasis in both cases. Our technique could be an alternative treatment option for external iliac artery perforations associated with the endovascular intervention.

We treated a 64-year-old man who had an inferior mesenteric arteriovenous malformation with multiple shunts. As multiple varicosities in the draining vein became enlarged, two dilated shunts on the superior rectal and sigmoid colon arteries were coil embolized. Two days after embolization, a varicosity near the shunt (65 mm diameter) ruptured, causing intra-abdominal hemorrhage and surgical hemostasis. There were thrombi in the ruptured varicosity and its draining vein. The likely cause was a pressure increase in the incompletely thrombosed varicosity due to shunt blood flow from the remaining shunts after embolization.