المدينة الطبية · مختبر الأجهزة · الجهاز 13 من 69
الموجات فوق الصوتية داخل الأوعية
IVUS
الموجات فوق الصوتية داخل الأوعية في مختبر الأجهزة في المدينة الطبية من BMEssentia. افتحه بتقنية ثلاثية الأبعاد تفاعلية، وفكّكه قطعةً قطعة، وتعرّف إلى طريقة عمله، ثم تعلّمه على منصة BMEssentia واسأل إسنشيا عنه.
محتوى مختبر الأجهزة في هذه الصفحة باللغة الإنجليزية، كما هو داخل المدينة الطبية.
- عدد الأجزاء: 10
- عدد التكوينات في مختبر الأجهزة: 2
- يُعرف أيضًا باسم: Intravascular Ultrasound
مختبر الأجهزة
IVUS
One piezoelectric element, six tenths of a millimetre across, cemented to the end of a flexible torque shaft and spun inside a sealed sheath at eighteen hundred revolutions a minute. It fires two hundred and fifty-six times per turn, so one revolution is one cross-sectional frame and thirty turns a second are thirty frames. The sheath stays still while the shaft inside it rotates, and the space between them has to be filled with saline, because a bubble of air in that gap reflects essentially the whole beam.
التكوينات
نسخ الجهاز في مختبر الأجهزة.
Mechanically rotated single transducer
One piezoelectric element, six tenths of a millimetre across, cemented to the end of a flexible torque shaft and spun inside a sealed sheath at eighteen hundred revolutions a minute. It fires two hundred and fifty-six times per turn, so one revolution is one cross-sectional frame and thirty turns a second are thirty frames. The sheath stays still while the shaft inside it rotates, and the space between them has to be filled with saline, because a bubble of air in that gap reflects essentially the whole beam.
Solid-state phased array around the tip
Sixty-four elements in a ring around the catheter tip, with the multiplexer and the preamplifiers on a chip immediately behind them, because sixty-four coaxial cores will not fit down a one-millimetre catheter and a signal of a few microvolts will not survive being sent down them if they did. Groups of fourteen adjacent elements are fired together to form one beam, and the group is stepped around the ring electronically. Nothing moves, nothing has to be flushed, and the frame rate is whatever the electronics choose.
كيف يعمل
استكشفه في مختبر الأجهزة.
The cosine that divides every area
Set the tilt to zero, note the area, then step it out in five degree increments and watch two things: the number, and how plausible the picture continues to look.
The error that costs nothing, and the one that costs everything
Set the tilt to zero and the eccentricity to eighty per cent, and watch the area. Then set the eccentricity back to zero and the tilt to twenty degrees, and watch it again.
A revolution that closes and is wrong everywhere
On the rotational configuration, introduce a binding shaft and watch the shape of the lumen, then watch the area.
Sixteen times the speckle for twice the frequency
Turn the flush down to zero on each configuration in turn, and compare the speckle index against the wall line.
A third dimension made of time
Put the system into a pullback, introduce a slipping carriage, and watch what happens to the lengths. Then switch between a continuous pullback and a gated one and watch the frame spacing.
الأجزاء
قطعةً قطعة.
Mains inlet, isolation and protective earth
An appliance inlet, a fuse, an equipotential stud and a rating plate on the back of the rack, and behind them a transformer whose entire purpose is to make sure that no fault anywhere in this machine can put a voltage on the conductor that runs to a transducer inside somebody heart.
Transmit pulser
A high-voltage switch that slams a few tens of volts across a piece of piezoelectric ceramic for about fifty nanoseconds and then stops, and then waits for eight microseconds doing nothing at all. On one configuration there is one of them.
Preamplifier and time-gain compensation
A low-noise amplifier whose gain climbs while it is listening, and on one of the two configurations it is not in the console at all, it is on a chip inside the catheter tip, a millimetre from the elements, because a signal of a few microvolts will not survive a metre of anything.
Digitiser
The most expensive board in the rack, and the reason this device costs what it does. A forty megahertz pulse two cycles long has a bandwidth to match, and sampling it faithfully means converting at a rate that most medical electronics never approaches.
Envelope detection, compression and polar scan conversion
The stage that turns a numbered series of echoes into a disc. It rectifies and smooths each line into an envelope, compresses a hundred and twenty decibels of amplitude into the thirty a screen can show, and then writes each line outwards from the centre at the angle the reconstruction believes it was taken at.
Cross-sectional display and measurement calipers
A screen showing a disc with a hole in the middle of it, and two tools for tracing a border on that disc and reporting the area it encloses. The number those tools produce is the deliverable of the entire device, and it is the number the one idea of this device is about.
Longitudinal display and pullback reconstruction
A second screen showing the vessel along its length, assembled out of the cross-sections by stacking one diameter from each of them side by side. It is the only view on this device that has a length in it, and that length is not measured.
Console control panel
A deck of keys, two rotary controls and a trackball, with a small strip above it showing the last area that was measured. Four keys matter: area, distance, bookmark and pullback, and the bookmark is the one that decides whether anybody can find the frame again.
Patient interface module
A box about the size of a paperback on a stand beside the table, with a socket in one end that the catheter plugs into and a screened cable out of the other end that runs to the rack. On one configuration it contains a motor.
Motorised pullback sled
A rail about a hundred millimetres long with a lead screw, a carriage that grips the catheter, and a scale printed along the side in millimetres. It travels at half a millimetre a second, which looks like nothing at all happening, and it is the only reason this device has a third dimension.
ملاحظات الطُّرز
طُرز حقيقية، بعد المراجعة.
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