Metals in medicine
Metals in medicine

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Metals in medicine

Other X-ray contrast agents

An alternative to barium sulfate for imaging of the gastro-intestinal tract is a tri-iodinated benzenoid compound which goes under the trade name Gastrografin® (Structure 1). Iodine is also used in intravenous contrast agents for imaging blood vessels and organs such as the heart (angiogram).

Structure 1

Polymetallic tungsten complexes such as K3[PW12O40] have also been investigated for some applications.

  • Why do you suppose that such compounds are being studied as contrast agents?

  • Iodine and tungsten are heavy elements, so compounds containing a number of these atoms will absorb X-rays well.

  • When having an X-ray taken, you are asked not to use talcum powder (a magnesium silicate) or antiperspirant (typically containing aluminium and often zirconium) on the day of the appointment. Why might this be so?

  • Magnesium, silicon, aluminium and zirconium are heavier elements than those contained in body tissue, and so show up as spots on the image where they absorb the X-rays.

Now watch the following short video which shows a CT scan of the head using a tri-iodated contrast agent. In this example, the contrast agent has been preferentially taken up in the blood.

Download this video clip.Video player: Video 2
Video 2  CT scan of the head. (Note that there is no soundtrack on this sequence.) (0:33 min)
Interactive feature not available in single page view (see it in standard view).

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371