Vol . 8 No. 3 June 2000
Nuclear medicine technical
facilities in DRDO have shown both vertical and horizontal upgradation of equipment
throughout its period of functioning. Presently, the facilities include the following:
The radiolabel preferred for nuclear medicine imaging is
Technetium-99 m Various Tc-99m generators including one pro (Tc-99m) because of its
favourable half-life of 6 hr, iDEAL monochromatic gamma photon energy (140 kev) suited for
imaging, and absence of alpha- or beta-raDIATion emissions that are responsible for almost
all radiobiological damages ascribed to raDIATion exposure. Tc-99m is not found in nature
due to its short half-life. It is the daughter radionuclide produced by the decay of
molybdenum 99 (Mo-99). Mo-99 is obtained from the nuclear reactor as a fission by-product
or produced from Mo-98, a naturally occurring metal, by neutron flux exposure. Tc-99m is
generated at the site of its use from its parent radionuclide (Mo-99) by a chemical
process called solvent extraction method. The basic Tc-99m compound obtained from this
method is sodium pertechnetate (NaTcO). About 200 milliCurie (mCi) of Tc-99m is produced
at DRDO and consumed for 10-15 patient studies per day along with experimentation on
animals. Many nuclear medicine studies use pertechnetate in its basic form. However, most
procedures require it to be labelled to a suitable chemical (radiopharmaceutical) which
determines the site (or organ) of its uptake in the human body.
Besides Tc-99m, lodine-131 (I-131) continues to be used as a diagnostic and therapeutic
agent particularly for thyroid disorders. Again a nuclear reactor product, it comes in
capsules (in microCurie-diagnostic dose) or as a
DRDO possesses a fully equipped functioning radiopharmacy laboratory specialising in labelling various radionuclides with radiopharmaceuticals (Tc-99m or 1-131) for human use and formulating these to kit forms using standard protocols. The kits can be stored for future human use and have varying shelf-life of a few weeks to six months depending upon the chemical ingredients. The laboratory is equipped with quality control measures to ensure the injectable product to be pure and properly labelled. It labels all the radiopharmaceuticals required to meet in-house needs and has the infrastructural capability of producing more for use by other institutes for research and medical purposes. The laborartory is equipped with the state-of-the-art radiolabelling technology.
DRDO has the technology to make many routinely used formulations. Notables among these
Besides, DRDO has also developed indigenous technology to make many new Tc-99m based
agents, including Tc-99m platelets, Tc-99m denatured RBC, Tc-99m dextran, Tc-hlgG and
other proteins, Tc-99m somatostatin
New compounds and peptides are also synthesised that are tailor-made for ultimate human use. The laboratory is planning to add a Genetic Division to enable DRDO to take lead in producing radiolabelled nucleic acids, the ultimate in molecular nuclear medicine by the end of the new millenium year. The well-known specificity of antisense RNA is used to carry the radiolabel (for imaging or for therapeutic purpose) to the diseased cell right at the molecular level.
Nuclear Medicine Imaging Instrumentation
Imaging hardware constitutes the core of nuclear medicine technology. From the modest
beginning, made from the days of thyroid probe giving quantitative information about I-131
uptake in the thyroid, and renogram probe giving time-activity curve produced by both the
kidneys in handling I-131 hippuran, a rectilinear scanner and a first-pass cardiac scanner
have been acquired. Also, a Gamma Camera and SPECT systems have been set up as
state-of-the-art technology for nuclear medicine imaging. Using complex software to
perform difficult operations like Fourier transformation, these systems are capable of
acquiring data by rotating round the patient in a circular or elliptical fashion and
producing images in cut section of organs in any plane.
DRDO also possesses other facilities allied to nuclear medicine, like radioimmuno assay laboratory, radioiodine therapy work area and an experimental animal study facility.