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Experiments on the archival-overwrite performance of GeSnSb phase-change discs are described. A mechanism explaining the poor archival-overwrite performance is proposed and it is found that this could be greatly improve by optimization of the phase-change material, based on reflectivity measurements and transmission electro microscopy (TEM) experiments.

Purpose: To gain insight into the accuracy of brachytherapy treatments, the accuracy of implant reconstruction and dose delivery was investigated in 33 radiotherapy institutions in The Netherlands and Belgium., Materials and Methods: The accuracy of the implant reconstruction method was determined using a cubic phantom containing 25 spheres at well-known positions. Reconstruction measurements were obtained on 41 brachytherapy localizers, 33 of which were simulators. The reconstructed distances between the spheres were compared with the true distances. The accuracy of the dose delivery was determined for high dose rate (HDR), pulsed dose rate (PDR) and low dose rate (LDR) afterloading systems using a polymethyl methacrylate cylindrical phantom containing a NE 2571 ionization chamber in its centre. The institutions were asked to deliver a prescribed dose at the centre of the phantom. The measured dose was compared with the prescribed dose., Results: The average reconstruction accuracy was -0.07 mm (+/-0.4 mm, 1 SD) for 41 localizers. The average deviation of the measured dose from the prescribed dose was +0.9% (+/-1.3%, 1 SD) for 21 HDR afterloading systems, +1.0% (+/-2.3%, 1 SD) for 12 PDR afterloaders, and +1.8% (+/-2.5%, 1 SD) for 15 LDR afterloaders., Conclusions: This comparison showed a good accuracy of brachytherapy implant reconstruction and dose delivery in The Netherlands and Belgium.

Opportunities for medical service abound throughout the world. These experiences can allow development of clinical skills in the absence of advanced technology. We describe an eight-month experience in Papua New Guinea, including the most frequent illnesses treated and procedures performed.

Evaluation of breast masses is a frequent dilemma encountered by a primary care physician. Adding fine-needle aspiration biopsy to the work-up of these lesions adds an inexpensive, highly accurate test with high patient acceptance. At our institution a technique using a butterfly needle has yielded a sensitivity of 91% and a specificity of 100%.

The value of a high-fiber diet in preventing and treating colonic diverticula is firmly established. Although the diagnosis of diverticulosis is usually made with colonoscopy or barium enema examination, computed tomography has become the test of choice during acute diverticulitis, when the diagnosis cannot be confidently made clinically. Recently developed surgical principles for diverticulitis include radiographically directed drainage with delayed operation for peridiverticular abscess, resection of the site of disease in patients with general peritonitis, and primary anastomosis in most cases requiring urgent intervention. Diverticulosis accompanied by abdominal pain or irregular bowel habits is by itself rarely an indication for surgery. Diverticular bleeding usually resolves spontaneously, but persistent bleeding can usually be successfully treated with segmental colectomy after localization of the bleeding site with colonoscopy or arteriography.

Four patients with heparin-associated antiplatelet antibodies who were not receiving platelet function-inhibiting agents received heparin during surgery, angiography, or hemodialysis. Three of the four patients had complications that were attributed to heparin-induced platelet aggregation. The complications included a superficial femoral artery thrombosis, a thrombotic stroke after a carotid endarterectomy, and recurring thrombosis of a graft inserted for dialysis. Nine patients received aspirin (325 mg b.i.d.) or dipyridamole (Persantine) (200 to 300 mg daily) before reexposure to 5000 to 12,000 units of heparin during 11 vascular procedures. The procedures included two carotid endarterectomies, three aortofemoral bypasses, one femoropopliteal bypass, two femorotibial in situ saphenous vein bypasses, one iliofemoral thrombectomy, one bilateral iliac artery angioplasty, and one axillobifemoral bypass. Platelet counts averaged 173,000/mm3 before heparin reexposure, fell to an average of 86,000/mm3 within 24 hours of heparin reexposure, and returned to normal within 48 hours after the reexposure. None of these patients had a thromboembolic or hemorrhagic complication. Patients with heparin-associated antiplatelet antibodies are at risk for developing thrombocytopenia and thromboembolic complications on reexposure to heparin. The platelet function-inhibiting agents, aspirin and Persantine, protect the patients from the thromboembolic complications but not the thrombocytopenia associated with limited heparin reexposure.