Diodes and In Vivo Dosimetry

Diodes

Diodes are used during the first few occasions you attend for radiotherapy. They are basically small detectors attached to a long wire, and are used to measure the dose, you are receiving in 'real time', whilst having your radiotherapy treatment. They are normally attached to your body with tape at specific points, where the treatment beam enters your body. Many professionals feel they are important because they have the potential to detect any errors that may have slipped through the quality safety net. Every part of your radiotherapy treatment is checked and double checked and then checked again and even the treatment machine itself has a range of interlocks that activate should any parameter appear out of tolerance for even a moment. Therefore the chance of any error getting through this vigorous checking process, is incredibly unlikely. However, if the 'incredibly unlikely' did happen, then the diodes would detect the error so it could be rectified.

The argument against using diodes is that the quality process should pick up any error that may occur, which means the money needed to buy, calibrate and investigate the diode readings could be better used elsewhere.

Block diagram of in vivo dosimetry
 application

The dosimeter can be used as a tool for quantifying dose at depth, as well as to evaluate adherence between doses from the treatment planning and the delivered dose. Dependence of small filed sizes (less than 4 × 4 cm) would be of future interest, especially when small radiation segments are used during IMRT. The DVS dosimeter does not identify the specific cause of the difference in dose, but it can reliably alert the physician that a deviation between the planned and delivered dose has occurred. As such, the dosimeter can act as a fail-safe device with the potential to catch an over- or underdose situation before the mistake could be repeated.

There are important advantages to DVS dose verification. It can be reliably used for the verification of any possible change of the dose to the target or nearby organs. The system is capable of keeping a permanent patient dose record by monitoring the daily dose delivered. Based on the dosimeter readings and trends, the dose changes might be predicted. If the weekly average readings were outside the clinically implemented tolerance, the physician can investigate the patient position, clinical protocols, internal anatomy, and treatment plan, then apply corrections, if necessary. Furthermore, the DVS system provides medical physicists with an independent QA verification of machine performances. The extensive commissioning and implementation strategy detailed above can improve the usage of implantable dosimeters and may lead to improvements in patient treatment outcomes.

Gamma cameras

Principle of gama camera

The gamma camera is an imaging technique used to carry out functional scans of the brain, thyroid, lungs, liver, gallbladder, kidneys and skeleton.


Gamma cameras image the radiation from a tracer introduced into the patient’s body.

The most commonly used tracer is technetium-99m, a metastable nuclear isomer chosen for its relatively long half-life of six hours and its ability to be incorporated into a variety of molecules in order to target different systems within the body. As it travels through the body and emits radiation the tracer’s progress is tracked by a crystal that scintillates in response to gamma-rays.

The crystal is mounted in front of an array of light sensors that convert the resulting flash of light into an electrical signal. Gamma cameras differ from X-ray imaging techniques in one very important respect; rather than anatomy and structure, gamma cameras map the function and processes of the body.

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Hand glows convert action to words.now dumb people also can talk

Two sophomores at the University of Washington have been recognized for an invention that could break down communication barriers for the deaf.

Their invention, the Sign Aloud, is a pair of sensor-filled gloves that interpret the hand movements American Sign Language users use to communicate, and converts them into speech or text that the rest of us can understand.

The two students, Navid Azodi and Thomas Pryor, designed the gloves inside the CoMotion MakerSpace, a collaborative workshop on campus. They recently received the Lemelson-MIT Student Prize for their work, which is a yearly award given to undergraduates for innovative inventions. They won in the “Use It” category, and received a $10,000 grant along with the prize.

Angiogram

A Valve Job with Heart

Sapien transcatheter

The Sapien transcatheter aortic valve is a life-saving alternative to open-heart surgery for patients who need new a new valve but can't endure the rigors of the operation. Manufactured by Edwards Life Sciences (Irvine, CA), the Sapien has been available in Europe for some time but is only now finding its first use in U.S. heart centers—where it is limited only to the frailest patients thus far. The Sapien valve is guided through the femoral artery by catheter from a small incision near the grown or rib cage. The valve material is made of bovine tissue attached to a stainless-steel stent, which is expanded by inflating a small balloon when correctly placed in the valve space. A simpler procedure that promises dramatically shorter hospitalizations is bound to have a positive effect on the cost of care.

Tabletop scanning electron microscope (SEM)



Tabletop scanning electron microscope

The next generation TM3000 Tabletop microscope builds on the success of its predecessor, the TM-1000, and offers significantly improved performance, including magnification up to 30,000x and better resolution, in a unit that occupies 20% less space and has an energy saving design. The new TM3000 is a tabletop variable pressure scanning electron microscope, characterized by even easier operation, with a ‘one button’ auto start, auto focus and other automated onboard functions. These are all controlled through a laptop computer with an intuitive, Windows® 7-based user interface, designed for use by microscopists and non-specialists alike. Improved electron optics has not only allowed the maximum magnification to be extended to 30,000x with improved resolution, but also provides three easily selectable modes of operation: surface, normal, and high-brightness/contrast. The exceptional depth of focus, combined with the improved imaging capabilities makes the TM3000 even more versatile. A larger specimen stage means that larger samples can be examined. The inclusion of an adjustable pressure charge-up reduction mode means that samples can be imaged without any special sample preparation. Even insulating and uncoated materials can be easily imaged.