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Vol . 8 No. 3 June 2000  

Technical Facilities

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:

Production of Technetium-99m

Various Tc-99m generators including one produced at BARCThe 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.

Other Radionuclides

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
liquid (milliCurie dose-therapy dose). Thallium-201 chloride, used for cardiac studies, is a cyclotron produced
compound and is presently imported. It does not require any radiopharmaceutical modification.

Radiopharmacy Laboratory

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 are:
Tc-99m Based

Tc-99m DTPA, DMSA(III and V), Tc-99m GHA, Tc-99m MDP,
Tc-99m, DISIDA, Tc-99m sulphur colloid, Tc-99m RBC, etc.

I-131 Based

I-131 HSA (and other proteins), I-131 amino acids

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
Tc-99m HES, Tc-99m ciprofloxacin, Tc-99m citrate, Tc-99m glucaric acid, Tc-99m BFCA, Tc-99m starch, Tc-99m
glutathione etc.

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.

Other Related Technical Facilities

DRDO also possesses other facilities allied to nuclear medicine, like radioimmuno assay laboratory, radioiodine therapy work area and an experimental animal study facility.