Nuclear Medicine

       A positive aspect of nuclear is its medical usefulness, especially in the field of imaging.  Nuclear medicine uses radioactive substances to make interior images of the body and to fight disease.  Since discovery of the x-ray, the technology of image-making in medical science has positively flourished.  And as knowledge of x-rays expanded, radiation intensity was generally reduced.  Nuclear medicine in particular has advanced rapidly, making great strides in technology and technique with very little fanfare.


 PET – A Key Development in Nuclear Medicine

Positron Emission Tomography (PET) scans are in the forefront of innovative imaging technology.  A small fraction of radioactive material is combined with a selective medicine (pharmaceutical), one attracted to the part of the body being studied.  When that radiopharmaceutical is introduced into the body and migrates to the tissue or organ of interest, e.g., iodine to the thyroid gland, the gamma rays (like x-ray) emitted produce an image in a detector called a gamma camera.  The metabolic activity of the cell, based on its use of glucose, etcetera, informs the nuclear specialist of how efficiently or abnormally the cell is functioning.  These pictures are crucial to his/her accurate diagnosis and treatment plan for the patient’s illness. 

CT or Computed Tomography (also known as a CAT scan) creates extremely detailed x-ray images of the anatomy through planes of the body, disk-like virtual slices across or down in various orientations. 

The PET/CT combines the two, furnishing functional image scans, merged with fine anatomical images in multiple three-dimensional views.  Blending PET and CT advantages have taken accuracy of diagnosis and sophisticated treatment planning to levels that have revolutionized medical imaging.  State-of-the-art PET scans, coupled with computer tomography provide valuable two and three-dimensional images of the inside of the body from multiple viewpoints, very detailed.  When the problem calls for it, the PET/CT and its iterations are uniquely informative, often vital to the patient’s life.  However, nuclear is nuclear; it emits radiation.  That is its menace and its usefulness.  Too intense, and it is
dangerous or even deadly.  With optimum radioactivity, it provides wonderful, detailed pictures of the body, layer by layer, the inside of the body, showing how it’s working, while it is still magic.   And from these images and additional biochemical tests, doctors can often tell what’s wrong with the person, how bad it is, and how to get rid of it. 

But the use of radioactivity always comes at a price.  Because it’s action is incompatible with life....although tolerated within limits.  How do we know those limits?  We have empirical evidence, e.g., more than 60 years experience to help us judge.  But we still have much to learn.  If exposure causes burns, nausea and death, having exceeded the limit is obvious.  But when does another dental x-ray or one more chest x-ray reach a tipping point of radiation exposure danger?  When are PET/CT scans justified, at 50 to 500 times the radiation of a chest x-ray?  The dangers and benefits of exposure to radiation are not always clearly defined, but they are real and significant, requiring difficult judgment calls affecting our quality of life, and sometimes our children’s, and even not-yet-conceived children’s lives.

At the personal level, the best we can do is educate ourselves to the field and at least, learn the vocabulary, so we can understand the experts.  Then we need to question the experts (usually doctors) and get more than one opinion.  Otherwise, we are left with the hope that we have been lucky to choose a good medical person.  And if we have children, the knowledge that our pediatrician is informed regarding the cumulative nature of radiation in the body and the increased vulnerability of the child, will bring us confidence, or at least, less anxiety.

Nuclear medicine enables physicians to provide a quick, often accurate diagnosis of conditions, such as cancer, heart disease, thyroid disorder, and bone fractures.  It allows the appropriate treatment to begin early, which means it has a far greater chance of being effective.  It is especially useful determining whether organs are functioning normally, whether blood supply to the heart is adequate, and if the heart can pump blood adequately.  It is used to detect cancers at an early stage, measure the extent of cancer and assess the response of cancer to treatment.  It can identify brain lesions, show
if brain cells are functioning, check whether kidneys are functioning normally, and ascertain lung function and bone
density. (1)  “More than 20 million Americans benefit each year from nuclear medicine,” (2) which provides information that would otherwise require exploratory surgery, more costly and invasive.  Consider....whatever vital information can be accessed with non-invasive technology may inform the physician so that exploratory surgery won’t be necessary.

The other extremely important way radiation is used in nuclear medicine is non-imaging and it kills cancerous cells directly.  A radioactive substance is emplaced next to the cancer in a “seed.” (3)  The adjacent malignant cells will typically die or (often) self-destruct (apoptosis), when the radiation interrupts their cellular code.  Sometimes a “gun” is used to project a beam of radiation at the malignancy with a favorable result.


The PET—The Down Side

Despite the advantages of PET imaging, the disadvantages are daunting.  Though the actual radioactive components of PET imaging are not present for long periods in a patient’s body, the radioactive exposure means there is a very limited number of times a patient can undergo this procedure.  It may cause damage to DNA, the repository of the cellular coding, and, “10 to 20 years later [may] cause cancer.  CT scans alone, which deliver l00 to 500 times the radiation associated with an ordinary x-ray and now provide three-fourths of Americans’ radiation exposure, are believed to account for 1.5 percent of all cancers that occur in the United States.” (4)  The potential seriousness of this hazard has prompted “radiologists to call for more careful consideration before ordering tests that involve radiation.” (4)  It is presumed this warning applies to all medical (and dental) radiation.  But, you must be alert, and ask.  Let your physician know you prefer conservative use of exposure to radiation in your family’s treatment, if there is a choice.

Medical Nuclear Waste

The great majority of radioactive waste that can cause serious health problems is produced by the nuclear fuel cycle and weapons reprocessing.  It is extremely hazardous, due to the exceedingly long-lived and highly radioactive nature of the waste.

Medical radioactive waste tends to have a much shorter decay period, when it’s dangerous to human beings.  Yet, they are of concern during the time they are actively emitting radioactive rays or particle.  The rags, clothes, tools, syringes, and radiopharmaceutical “seeds” must be isolated and shielded to protect humans until their radioactivity dissipates, even if their half life is only a few days.

Then this contaminated material is usually disposed of by shallow land burials, some dumping at sea (until 1984) and/or incineration. (5)   If incineration of even low level radioactive material is still being used for disposal, it brings some interesting questions.

In addition to low level waste disposal, nuclear medicine presents two inherent problems:

  • The equipment for scanning is extremely expensive. 
  • At present, well-trained diagnostic “readers” who have the expertise to interpret the images of the new technology skillfully are in short supply. (6)
Finally, beyond the powerful technology, the nuclear medical physicians must be promoting as healthy a lifestyle as each patient can live.  Else, they’re medical improvements will be, at best, transitory.

Sources:  (1) “General Nuclear Medicine. RadiologyInfo Website: The Radiology Information Resources for Patients. 2 July 2012, 3 Oct. 2012<htttp://>; (2) “Radiation Safety.”  Discover Molecular Imaging Website.  SNM, 2012,  4 Oct. 2012<http://>; (3) Nina Morgan,  Nuclear Power (Austin, TX:  Steck-Vaughn, 1998) 37;  (4) Jane E. Brody, “Medical Radiation Soars, with Risks Often Overlooked.” New York Times Online  20 Aug. 2012, 20 Sept. 2012< /2012/08/20/ medical-radiation-soars-with-risks-often-overlo...>; (5) Kate Scarborough,  Nuclear Waste (Mankato, MN:  Capstone Press, 2003) 18;  (6)) “Negatives and Side Effects of Positron Emission Tomography and CT Scans.”  Radiology Website.  29 Sept. 2012< negatives-and-side-effects-of-PET/CT>

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