A Case Report of Delayed Presentation of a Carotid-Jugular Fistula Caused by Blunt Injury from an Arrow.

BACKGROUND: Acquired arteriovenous fistulas (AVFs) are most commonly caused by direct arterial trauma, with 90% of traumatic AVFs due to penetrating trauma. Post-traumatic common carotid artery-internal jugular vein fistulae are rare, with an incidence of 4% to 7% of all traumatic AVFs. CASE REPORT: We present a case of delayed presentation of a patient with shortness of breath, neck pain, and worsening right upper extremity paresthesias 10 days after a blunt injury to the neck by an arrow. He was subsequently found to have a common carotid artery-internal jugular vein fistula and a common carotid pseudoaneurysm on computed tomography angiography. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Post-traumatic common carotid-jugular AVFs are uncommon, especially in patients with delayed presentations and a blunt injury mechanism. If left untreated, AVFs may progress to high-output cardiac failure, atrial fibrillation, and embolization. Clinicians must be aware of this finding, given the potential for significant morbidity.

Design and testing of a microcontroller that enables alpha particle irradiators to deliver complex dose rate patterns.

There is increasing interest in using alpha particle emitting radionuclides for cancer therapy because of their unique cytotoxic properties which are advantageous for eradicating tumor cells. The high linear energy transfer (LET) of alpha particles produces a correspondingly high density of ionizations along their track. Alpha particle emitting radiopharmaceuticals deposit this energy in tissues over prolonged periods with complex dose rate patterns that depend on the physical half-life of the radionuclide, and the biological uptake and clearance half-times in tumor and normal tissues. We have previously shown that the dose rate increase half-time that arises as a consequence of these biokinetics can have a profound effect on the radiotoxicity of low-LET radiation. The microcontroller hardware and software described here offer a unique way to deliver these complex dose rate patterns with a broad-beam alpha particle irradiator, thereby enabling experiments to study the radiobiology of complex dose rate patterns of alpha particles. Complex dose rate patterns were created by precise manipulation of the timing of opening and closing of the electromechanical shutters of an α-particle irradiator. An Arduino Uno and custom circuitry was implemented to control the shutters. The software that controls the circuits and shutters has a user-friendly Graphic User Interface (GUI). Alpha particle detectors were used to validate the programmed dose rate profiles. Circuit diagrams and downloadable software are provided to facilitate adoption of this technology by other radiobiology laboratories.