A uniform treatment policy for carcinoma anal canal and lower third of rectum is difficult to define for various reasons. The present approach is to take into consideration the psychological impact of the colostomy and preserve anatomy and function without compromising on the results. Concomitant radiotherapy and chemotherapy is given now-a-days as an alternative to surgery. External radiotherapy (RT) alone can control early and intermediate disease, but produce serious side effects. Brachytherapy, because of its rapid fall off of dose, enables to deliver high local dose. From 1990 to 1997, we have treated 19 patients of anorectal cancer with external RT and intraluminal brachytherapy. Till 1994, the policy was to give high fraction dose with brachytherapy. 10 patents ere treated during this period and brchytherapy dose was 10-12 Gy/fraction. Radiotherapy was given to total dose of 60-65, Gy. Since the tolerance of the patients was poor with this dose, we changed the policy after 1994 and reduced the dose per fraction to 5-6 Gy/fraction by brachytherapy. Total fractions given were 2-3 depending upon dose received with external RT. 9 patients were treated during this period. Brachytherapy was given with Selectron remote afterloading system. At an approximate dose rate of 500-600 cGy/h. Dose was calculated at 5 cm from surface and 1.5-2 cm from the centre of the applicator. The patients who were followed for 6 months were assessed. In the first group (1 990-1 994). out of the 10 patients treated, 3 were lost for follow-up, 2 had complete response earlier but the disease recurred after 1 year. 5 had partial response for which APR was done in 3 patients and palliative colostomy in 2. Overall results were poor. In the 2nd group (1995-1997), out of the 9 patients treated, 1 was lost for follow-up and 8 had complete response., 1 out of these had local recurrence at 1 year and was advised APR. Complications were high in group 1 with a patient having rectal ulceration and 1, rectovesical fistula. In group 2, only 1 patient had stricture formation.

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Trace elements have had a recognized role in clinical medicine for many years. It has been suggested that the concentrations of trace elements present in the human body may change depending on disease formed in tissue such as cancer. Multi-element analysis of tissue samples by INAA is an adequate method to define the role of trace elements in formation of these diseases. In this study, the normal and malignant tissue samples of breast, throat and large intestines taken from 4 female and 3 male patients having the same and/or different cancer types were collected and the concentrations of Cs, K, Se, Te and Zn were investigated by using INAA method. The concentration levels obtained for these elements were significantly high in the malignant tissues compared to the normal ones.

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The quantities of trace elements and their changes in normal and malignant tissue samples taken from six cancerous patients have been investigated by instrumental neutron activation analysis method (INAA), 29 elements (Na, K, Br, Au, Mo, U, Zn, Cr, Sb, Sc, Rb, La, Fe, Co, Te, Ce, Ru, Zr, Se, Ag, Cs, Nd, Ca, Hg, Cu, Ba, Ni, Xe, As) were observed in different amounts in normal and malignant tissues. The amounts of some elements were found to be increased in the malignant tissues as compared to those of normal ones, while others decreased or remained constant. It is thought that the concentration ratios of an element in malignant tissues as compared to those of normal ones were affected by diseases.

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The international Atomic Energy Agency (IAEA) has recently started a service to provide calibration of brachytherpy sources, traceable to the International Measurement S stem, through IAEWHO network of secondary standard dosimetry laboratories (SSDLs). Two types of 13'Cs sources, CDCSJ type tube and CDC-1100 type miniature cylinder, calibrated at the National Institute of Standards and Technology (NIST), USA are used by the IAEA as reference standards for providing traceable calibration to SSDLs, using well-type ionization chamber. The work carried out at the IAEA to standardize the measurement and the procedure recommended to transfer the calibration from the IAEA to SSDLs and on to the users are documented in the IAEA-TECDOC-1079 published in 1999. The salient features of this document are explained in this paper.

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Fifty patients with cervix cancer were treated with teletherapy (15 MV photons, 2 Gy daily) up to the dose of 40-45 Gy. Low dose-rate (two fractions) brachytherapy followed teletherapy up to the dose of 50-60 Gy. Total dose distributions were calculated on the basis of simple summation of brachytherapy and teletherapy doses. A linear quadratic model was used to calculate biologically effective doses (BED) in the tumour and critical organs. BED'S were higher than total doses in the rectum by 24% to 2% and those in the bladder by 11% to 1 %. The clinical observation in a group of patients showed late reactions in the rectum, which occurred more frequently than those in the bladder, where BED was closer to physical dose than in rectum.

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A software system to display and process medical imagining data of MRI and gamma camera is developed on IBM compatible personal computer system at the institute of Nuclear Medicine and Allied Sciences. Microsoft Visual c++ compiler is used to develop a software on Pentium based 133 MHz PCs in Window 95 ' environment. The software is capable of displaying and processing medical image data of MRI in Siemens propriety image format, Dicom format and images from EClL gamma camera, Siemen's SPECT system. The processing feature includes pseudo coloring, reading pixel value at different points on the images and enlarging the images. The flow chart of the program and image data set as displayed on PCs in Window 95 are presented in the paper.

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Curve filtration in nuclear medicine is a common technique for quantitation of certain physiological parameters. The most common and acceptable methods are 3 point and 5 point smoothing, in which the value of each element is replaced with a symmetrically weighted average of the element itself and some juxtaposed points. Although this procedure is simple, selection of the number of filter elements and correct weighting factors is an extremely difficult task. Both the real signals and noise have a wide range of frequencies, which generally have some overlapping components. Removal of noise inevitably removes the common frequency components of the data and results in distortion of useful data. Incorrect weighting factor either leaves some noise untouched or unnecessarily distorts the data. We have devised an algorithm (window filter), which defines two nested windows (narrow and wide) around each element of the data. The location of each element is compared with the window limits before replacing its value by 3point smoothing. The points within narrow window are left untouched and those outside it are subjected to 3 point smoothing.

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