There are various Regulatory Bodies at the international and National level, which lay down norms for radiation protection. These are the International Commission for Radiation Protection (ICRP) the National Commission for Radiation Protection (NCRP) in America, and the Atomic Energy Regulatory Board (AERB) in India. These bodies recommend norms for permissible doses of radiation from X ray tubes and the shielding required for the walls of an X ray room. Data is also available from the work of Investigators regarding the room shielding required in a CT suite. The recommended lead equivalent in shielding apparel to be worm by radiation workers is 0.5 mm. The regulatory bodies also lay down safe dose limits for radiation workers and for the general public. The duties of the Radiation Safety Officer (RSO) are also specified by the regulatory bodies, as are the radiation surveillance and radiation safety programmers.

To retrieve the true color of the internal organs and various tissues of the CT images obtained in gray scale, by determining the value of color components, density, CT (attenuation) value, refractive index (RI) and gray value of various tissues in vivo thereby revealing physics of true color sensation of tissue in various path-physiological states and to digitize the tissue and parenchyma by R.I. Materials and Methods: Physical density, CT value (No.) and refractive index of the tissues of goat and biopsy materials of various patients are determined in the laboratory and integrating such data with gray value of CT images. A computer generated color image of the organs and tissue are thus retrieved. Value of the red (R), green, blue (B) components (out of 256 shades) of true color of the tissues are obtained by a special technique of optics. Results: From all these experimental data a mathematical equation has been derived to show the relationship of CT No., refractive index and density of tissue which explains the underlying physics of true color sensation (wave length) of tissue in different patho-physiologic states. The refractive index is found to be unique for each tissue. Conclusion: All these determined values are assigned for gray value to produce a computer generated true color image of various tissue of CT images obtained in gray scale. Color of the tissue in turn determines R. I. a tool for tissue characterization.

Objectives: To evaluate the utility of gadolinium enhanced three dimensional magnetic resonance angiography for different vascular territories of the body in comparison to x-ray angiography and to present our preliminary experience in the optimal use of the technique. Materials and Methods: The study evaluated 30 consecutive patients who underwent contrast enhanced MR angiography for different indications. Contrast enhanced MRA was performed on 1.5 Tesla MR system (Magnetom Vision, Germany) using 3D-Flash sequences. Coronal dynamic MRa was performed after injection of the contrast bolus and the images obtained were reconstructed using maximum intensity projections. Twenty patients underwent DSA of 23 vascular territories after CE MRA. Five patients underwent surgery. All the studies were interpreted by two qualified radiologists in consensus. Results: CEMRA was 100 per cent sensitive in picking up aneurysmal and stenotic lesions. The specificity for complete occlusion and aneurysmal disease was also 100 percent, but for partial stenosis the specificity was 83.3 percent related to overestimation of stenosis. CEMRA offered a global view of vascular pathology precisely vessel stenosis, collateral formation and distal run-off, aneurysmal disease and the relation of different branches to the aneurysm from multiple projections. Conclusion: CEMRA should be considered an attractive and artifact-free advancement of MRA techniques, which besides surpassing the old unenhanced MRA techniques should tend to replace DSA for diagnostic purposes.

Objectives: To distinguish between neoplastic and non-neoplastic lesions showing ring enhancement or ring like lesions in the brain in CT or MRI with the help of correlative Nuclear imaging. Material and Methods: Twenty seven patients with various ring enhancing lesions in the brain detected in CT and/ or MRI were correlated with cerebral first pass study, Planar and SPECT imaging using different radiotracers like 99m Tc-HMPAO. TI-201, 99m Tc-DTPA/GHA, 99m mTc-MIBI or Tetrofosmin Results: Nuclear scanning was helpful in distinguishing between neoplastic and non-neoplastic conditions in 42 percent of cases in this study where C T or MRI were doubtful. Conclusion: Nuclear imaging coupled with CT or MRI provides a fairly accurate diagnosis in differentiating neoplastic conditions from non-neoplastic conditions without any MR Spectroscopic or Sterotactic biopsy technique applied on the patients.

Present study was based on 'Folkman's theory of neovascularisation' , according to which malignant neoplasms elaborate a factor named Tumor Angiogenesis factor (TAF), which stimulates rapid formation of new capillaries. The study aimed at evaluating the efficacy of Color and Spectral Doppler in diagnosing the ovarian malignancy. In all, 121 patients with adnexal masses were examined over a period of 2 years, out of which 60 patients with neoplastic ovarian tumors were retained as the study subject. Color Doppler showed blood flow in 92.59 percent of malignant tumors in contrast to only 42.24 per cent of benign tumors. Absent blood flow in a solid tumor almost always ruled out the possibility of malignancy. Spectral Doppler helped to assess the nature of the blood vessels picked up on Color Doppler. In the present study. 96.29 per cent of malignant tumors had PI less thsn 0.8 in contrast to only 6.06 per cent of benign tumors. Similarly, 92.59 percent of malignant tumors showed RI less than 0.6 in contrast to only 9.09 per cent of benign tumors. Thus, Color Doppler and Spectral Doppler tremendously increased the reliability in diagnosing a malignant ovarian tumor. Color Doppler served as an important tool to rule out malignancy in solid tumors if they failed to show any intratumoral vascularity. B-Mode USG in combination with Color Doppler and Spectral Doppler is proposed as the first and foremost diagnostic modality in patients with ovarian tumor, so as to establish the definite diagnosis of malignancy early in the course of the disease.

Primary extradural hydatid disease of the spine is a very rare condition. A 9 year old boy presented to the hospital with paraplegia of sudden onset. MRI study revealed an oval, unilocular, well-defined extradural cyst posterior to the thecal sac opposite to D4-D6 vertebrae in the middle. it was hypointense on T1W and uniformly hyperintense on T2W images. An operation was performed and histopathological findings confirmed the diagnosis of a hydatid cyst. Primary extradural hydatid disease should be considered in the differential diagnosis of a unilocular extradural cyst on MRI.

Objective: This prospective study was done to compare the role of the multi fraction (MF) and single fraction (SF) radiotherapy in the management of bone secondaries as regards potency for pain relief and resultant early toxicities. Materials and Methods: Seventy three out of eight five patients with bone metastases, who fulfilled the inclusion criteria were randomly divided into two groups to be treated by External radiation either by 3000 cGy over 2 weeks in 10 Fractions i.e. multiple fraction (MF) or by 8000 cGy in single fraction (SF). Pre and Post radiation pain relief potential and early toxicities due to the treatment were compared. Results: No significant difference (P>0.50) was observed as regards pain relief which was 84% in Gr-I (MF) and 76% in Gr - II (SF). Similarly incidence of complete pain relief, (42% VS - 35%) no response (16% VS 24%) and early toxicities also show marginal difference. Conclusion: Though both the radiation schedules resulted in considerable reduction of Bone pain in majority of the patients, no significant difference was observed as regards pain relief and early toxicities.