introduction to radiological devices ultrasound

                                                                 In  the  19 th century   many women  died during childbirth  .  There were many causes for these deaths but  doctors often had no instrument to diagnose the cause .   Some of the causes like  abnormal position of the baby , abnormal position of placenta  etc  produced deadly complications during delivery.  But  ,because they were not diagnosed early often treatment was delayed and many pregnant women died  due to uterus  rupture( due to abnormal baby position  )or severe bleeding (due to abnormal placental position)      A remarkable  invention helps us nowadays  to diagnose these problems   months before the actual time  of birth thereby  preventing complications .  What is more the same device can even  predict the date of  birth with some degree of accuracy .  We often hear  pregnant women telling other people about their “due date “  . This due date is also calculated by the images produced by this great invention .

This  remarkable instrument is called an ultrasound machine  . As  the name implies it works by ultra –sound  . Using sound  frequencies above the audible range of 20000 hertz  ultrasound is produced  by the  machine .These  sound waves  travel inside the body and get reflected from  the  organs inside our body.  In  the case of pregnancy, sound waves are reflected by the  baby inside the  mothers uterus

The ultrasound probe is the part of the ultrasound machine which contains most important part of the machine .  It contains crystal made of quartz which works on the principle of pressure electricity or piezoelectric effect  . When a small current is applied on this quartz crystal it undergoes a rapid change of shape . This rapid change or vibrations produce high frequency ultrasound waves They are transmitted into the body . Different body organs reflect these waves back into the ultrasound probe.  These reflected waves produce mild electric current in the crystal . This minimal electric current is amplified and processed by the computer inside the ultrasound machine  .This processed signals are displayed as an image or   picture  in a display like a television screen   producing an ultrasound image  .

  Ultrasound image  is very useful  to  find pregnancy complications  . Not only is it used to study pregnant women it is used to study  the  inside of the abdomen  to find  diseases of liver ,gall bladder ,appendix etc  .It is also used for fast screening of abdominal injury in road traffic accident victims by emergency trauma care teams .  Nowadays we have ultrasound machines of all sizes from the pocket sized portable  ultrasound to  machines which have  different frequency probes to study different parts of the body . The advantage of ultrasound over other imaging modalities like CT scan and MRI scan is it is cheaper , easily available and portable.  3D ultrasound is relatively new where the images produced are more lifelike due to their 3 Dimensional nature They are useful to see the face of an unborn baby . Imagine the joy when a pregnant mother sees her unborn childs face on the computer screen .  .

. The world of oceanography has a similar machine called sonar .The advantage  of ultrasound  is that it does not produce harmful radiation  . Also ,  ultrasound waves are used by bats to locate their prey even in total darkness.

                                                Cardiologists  or the doctors who treat  heart diseases  use a type  of ultrasound called cardiac ultrasound or  echocardiography  . Here  sound waves  are  used  like  ultrasound  but  the  frequency shift  of the  reflected  beam is used to find the  velocity  of  moving structures  like blood  moving in the heart or valve motion in the heart  .  These  frequency  shifts can  be colour coded and  valve  problems like narrowing or leaks in heart valves can be accurately seen .

The  frequency shift  or Doppler  effect  is also  used  in doppler  ultrasonography  to study  all the arteries and veins  in the body  .This helps us to know the blockages within artery  and veins .Unlike the public municipal drainage system we cannot cut open the body  whenever  a block is suspected . By using  Doppler ultrasound without cutting open we can diagnose the  blockage of artery and veins  .

In short  this remarkable machine  helps us in seeing the inside of body  and helps doctors in diagnosing a lot of diseases before they can cause harm  .