Hiroaki Ishii

Two scheduling problems with fuzzy due-dates

Abstract Up to now, almost all of papers on scheduling problems assume that due-dates are fixed and none treats fuzzy due-dates as far as we know. But in some situations due-dates are not rigid and some violations may be accepted. Considering these cases, this paper investigates scheduling problems with fuzzy due-dates, that is, a generalized two machine open shop scheduling problem with fuzzy due-dates and an identical machine scheduling problem with fuzzy due-dates.

Lung Cancer Ablation: Complications

Although radiofrequency ablation for lung cancer is generally safe (with a mortality rate <1%), it may cause various complications. Common complications include pneumothorax, pleural effusion, and parenchymal hemorrhage. Although most complications can be treated conservatively or with minimal therapy, physicians should be aware of rare but serious complications. Potentially fatal complications include massive hemorrhage, intractable pneumothorax due to bronchopleural fistula, pulmonary artery pseudoaneurysm, systemic air embolism, and pneumonitis. Other serious complications include injury to the nearby tissues (e.g., brachial nerve plexus, phrenic nerve, diaphragm, and chest wall), needle tract seeding, lung abscess, empyema, and skin burn. Although cavitation of the ablation zone is usually insignificant clinically, such a cavity occasionally ruptures, leading to pneumothorax and bleeding. Cavities may also serve as a scaffold for fungal colonization. Precautions to minimize risk should be taken whenever possible. Nevertheless, serious complications may occur, and thus physicians should be aware of the appropriate treatments for these complications. This article reviews complications associated with lung cancer ablation.

Two machine open shop scheduling problem with bi-criteria

Abstract In this paper, we consider a bi-criteria two machine open shop scheduling problem. The two criteria to be minimized are maximum completion time and maximum lateness. We show that either there exists a unique optimal solution, or there exists a line segment of nondominated solutions.

Transosseous Route for CT Fluoroscopy–Guided Radiofrequency Ablation of Lung Tumors

PURPOSE To retrospectively evaluate radiofrequency (RF) ablation of lung tumors performed via the transosseous approach. MATERIALS AND METHODS Twelve lung tumors (mean diameter, 1.0 cm; range, 0.4-1.6 cm) in 12 patients were treated by RF ablation via a transscapular and/or transrib route with the use of a bone biopsy needle under computed tomographic fluoroscopy guidance. Therapeutic outcomes evaluated included feasibility, safety, and local efficacy. Complications were assessed based on the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. RESULTS The transosseous route was successfully employed in all patients, and the electrode was successfully advanced into all tumors with this approach. The mean distance of penetrated bone was 0.57 cm (range, 0.19-1.16 cm). Complications occurred in eight RF ablation sessions, including six grade 1 events (two cases of pneumothorax and one case each of asymptomatic rib fracture 6 mo after treatment, neuralgia, pulmonary hemorrhage, and hemothorax), two grade 2 events (pneumonia and high fever), and one grade 3 event (pneumothorax requiring pleurodesis). No adverse events of grade ≥ 4 occurred. The mean and median tumor follow-up periods were 19.5 and 15.2 mo (range, 3.0-41.5 mo). Local progression occurred in two cases at 3 and 12 mo after treatment and was successfully treated with a second RF ablation procedure. The technique efficacy rates were 91.7% at 6 mo, 81.5% at 1 y, and 81.5% at 2 y. CONCLUSIONS The transosseous approach was feasible in computed tomographic fluoroscopy-guided RF ablation of select lung tumors when no other option was available.

Angio-CT–Assisted Balloon Dissection: Protection of the Adjacent Intestine during Cryoablation for Patients with Renal Cancer

The present study describes the technical feasibility of a combined-modality angiography/computed tomography (angio-CT)-assisted balloon dissection technique for bowel protection during renal cryoablation in six procedures in five patients. A retrospective review was performed to evaluate balloon dissection using the angio-CT system. Mean bowel-to-tumor distances before and after balloon dissection were 0.9 mm (range, 0-3 mm) and 13.0 mm (range, 11-17 mm), respectively. No bowel injury was observed during the mean follow-up period of 19 months (range, 7-44 mo). Our preliminary experience suggests that balloon dissection using the angio-CT system for bowel protection during renal cryoablation may be feasible and effective.

Percutaneous Creation of an Extraanatomic Splenoportal Shunt in a Patient with Bleeding Ectopic Varices

Editor: We report percutaneous creation of an extraanatomic splenoportal shunt in combination with a transjugular intrahepatic portosystemic shunt (TIPS) and variceal embolization to treat a patient with bleeding ectopic varices at the site of a previous choledochojejunostomy. Our hospital’s institutional review board did not require approval for this case report. A 74-year-old man with a history of chronic pancreatitis presented with melena and anemia requiring multiple transfusions, resulting in impaired performance status. Computed tomography (CT) and double-balloon endoscopy performed at the referring hospital revealed variceal bleeding in the jejunum, adjacent to the anastomotic site of previous choledochojejunostomy for occlusion of the bile duct caused by pancreatitis. Endoscopy could not control the bleeding, and surgery was deemed unsafe as a result of postsurgical adhesions. The patient was referred to our hospital to seek possible treatment. On admission, hematologic tests revealed a decrease in hemoglobin level (8.0 g/dL) and platelet count (133,000/ μL). Liver function test and coagulation profile results were normal except for decreased albumin level (2.5 g/ dL). Contrast-enhanced CT demonstrated occlusion of the portal venous system, involving the intrahepatic bilateral main portal trunks, extrahepatic portal vein, and the confluence of the superior mesenteric and splenic veins. Collateral vessels were identified around the choledochojejunostomy site (Fig 1). On the basis of these findings, recanalization of the portal vein was planned. An angiography/CT system (INFX-8000C/ Aquilion 16; Toshiba, Ohtawara, Japan) with a c-arm

Percutaneous Catheter and Port Placement for Hepatic Arterial Infusion Chemotherapy: Catheter Placement from Subclavian Artery

Abstract Hepatic arterial infusion chemotherapy (HAIC) has been performed for patients with life-threatening liver tumors resistant to standard therapies for more than 30 years. Placement of the port and catheter system for HAIC is performed by surgeons or interventional radiologists. Surgical placement requires laparotomy, whereas the interventional radiologic approach places a port and a catheter percutaneously. The interventional radiologic technique of implanting a port and catheter was originally developed in Japan in the 1980s. The procedure consists of arterial redistribution, catheter and port placement, and evaluation and management of the drug distribution. For the catheter and port placement, the subclavian artery, femoral artery, or inferior epigastric artery is used as an access route. We have used a subclavian artery for HAIC to have the stability of the system at the anterior chest wall and the ease to advance a catheter into hepatic arteries at the time of the placement; however, there are some risks, such as cerebral infarction, and the specific skills of a cutdown procedure are required to access the subclavian artery. No procedure can be perfectly appropriate for all patients, and we should consider what we choose on a case-by-case basis. With this video (available online at www.jvir.org), we hope many interventional radiologists will be aware that this could be within their scope of practice with training.

A stochastic improvement method for stochastic programming

Abstract This paper proposes a stochastic improvement method for a linear programming problem which has linear constraints that contain unknown coefficients. The unknown coefficients are estimated using multivariate regression analysis. We update the estimates of unknown coefficients as well as the solution by making use of an affine scaling method, whenever new statistical data are delivered. It is shown that this iteration of improvements finds the point that gives the optimal value with probability one, which is based on the fact that the consistency of the estimator assures that the estimated problem converges to the problem with true parameters.

Studies of optimal ordering policies for perishable commodities

Abstract Problems associated with perishable or outdating products arise in many areas of inventory and production man agement. Many commodities exist whose value does not remain constant over time during transportation, holding stock, etc. Significant work has been done to describe optimal ordering policies for items which have a fixed lifetime. In this paper, per ishable inventory models subject to stochastic procurement leadtinie both on LIFO (Last In First Out) and FIFO (First In First Out) issuing policies are considered with cither zero or 1 unit leadtinie. First, assumptions and notation used throughout the paper are given. FIFO and LIFO models are then con structed, and the existence of the optimal ordering policies and theirpropertiesare clarified. Finally, significantresults are illustrated for the relationship among inventory on hand, delay probability of procurement and optimal ordering policies.