[en] Computerized Treatment Planning System (TPS) play an important role in radiotherapy with the intent to maximize tumor control and minimize normal tissue complications. Treatment planning during earlier days was generally carried out through the manual summations of standard isodose charts on to patient body contours that were generated by direct tracing or lead wire representation, and relied heavily on the careful choices of beam weights and wedging. Since then there had been tremendous advances in field of Radiation Oncology in last few decades. The linear accelerators had evolved from MLC's to IGRT, the techniques like 3DCRT, IMRT has become almost routine affair. The simulation has seen transition from simple 2D film/fluoroscopy localization to CT Simulator with added development in PET, PET- CT and MR imaging. The Networking and advances in computer technology has made it possible to direct transfer of Images, contours to the treatment planning systems

[en] Last decade has been tremendous advances in the field of radiotherapy. In India itself many new centres have come up with linear accelerators, HDR units and other modern facilities. One of the important developments is introduction of networking. The networking in radiation oncology in its current form supports the integration of all image manipulation, processing and acquisition, data transfer, record and verification

[en] Full text: Introduction. To meet the growing need of teletherapy machines in the country, BARC has taken up the development of Cobalt teletherapy machines. Isocentrically mounted, 80 cm SSD telecobalt machine having fully electronic operations and computerized control console was designed by the Division of Remote Handling and Robotics (DRHR), BARC. The Tata Memorial Centre has been in the Task Group and provided expertise on many clinical and technical aspects. For commercial manufacturing, the know-how was passed on to M/s Panacea Medical Technology, Bangalore. The first machine Bhabhatron-I produced by them was installed for clinical evaluation at Advanced Centre for Treatment Research and Education in Cancer (ACTREC), Tata Memorial Centre (TMC), Mumbai. Acceptance tests Quality assurance tests for the acceptance of the machine were carried out by scientists from RP and AD, BARC and physicists from TMC. All safety features like door interlock, emergency stop and other functional safety interlocks are available and working properly. Optical and collimator axis coincidence, orthogonality and parallelism of jaws, accuracy of collimator and gantry scale are well within specified limits. Shift in isocentre due to collimator, couch and gantry rotation are well within BARC specified limit (≤ 4mm dia Sphere). This needs to be improved as many other commercial telecobalt machines in market have this parameter within ≤ 2mm diameter sphere. Optical field size accuracy for field ≤ 10x10 cm² and ≥ 10x10 cm² is well within specified limit. Optical and radiation field congruence are within acceptable limit. Timer reproducibility is acceptable. All the radiation leakage levels Such as head leakage (source on and off condition) and collimator transmission are well within limit. The profiles for smaller field sizes (5x5 and less) showed lot of coning effect. This was later improved after necessary modifications.Another important safety features of Bhabhatron-1 is whenever there is any emergency situation or any interlocks are activated, the jaws will close to 0x0 cm. It will minimize the radiation level in the room if the source is struck,and RSO has to go to push the source to the safe position with T rod. Beam data generation. Measurement of beam data was carried out using Radiation Field Analyser PTW-MP3S System. Percentage Depth Doses (PDD) were taken for field sizes 5x5 cm, 10x10 cm, 15x15 cm, 20x20 cm, 25x25 cm and 30x30 cm. The value of PDD for standard 10x10 cm at depth of 10 cm were found to be 56.2%, which is in agreement with standard cobalt PDD value (56.4%) quoted by BJR 25 within- 0.3%. X and Y profiles for all above fields were taken for 5 standard depths. Analysis of profiles showed flatness of 14% and symmetry of 8% for field size of 10x10 cm and above. This was later improved to 5% and 2% respectively. Penumbra for 10x10 cm was found to be about 12 mm. The data was also verified using Linear Diode profiler and values were matching with RFA measurements. The absolute output measurement for various field sizes was carried out using 0.6cc (FC65- G) chamber and Dose-1 Electrometer (Scanditronix Wellhofer). Output of the machine for 170 RMM source at 80.5cm for standard 10x10 cm field was 235 cGy/ min. Technical improvements. During and after commissioning, there have been several design modifications leading to improvements in the technical beam parameters. Software upgrades have made the control console more user friendly and easy to handle. The machine beam data has been configured into the Treatment Planning System and data on beam modifiers (wedges) has been generated. Wedge filters of standard angles (15, 30, 45 and 60) for varying field sizes have made using high density lead alloy. The beam profiles for wedges were generated for different wedge angles and field sizes. Wedge angles are verified by generating isodose charts .Wedge factors are measured at two different field sizes and two different depths. Dependence of wedge factors on field sizes and depths are studied. Before using clinically,wed ge factors are verified by comparing the dose calculated and dose measured at 5 cm depth using 0.6cc (FC65- G) chamber and Dose-1 Electrometer (Scanditronix Wellhofer) and solid water phantom. They were found to be satisfactory and have been implemented in clinical use. Several software upgrades have been provided which have made the control console remarkably user friendly. Database of the patient treatment can be stored in the computer. Patient setup notes can be written which will appear on the monitor in the treatment room along with the treatment parameters for the patient to be set up. Treatment record is maintained for the future verification. Around 125 patients of various anatomic sites, mostly head and neck, cervix and chest wall irradiation have been treated on the machine on clinical trials since the commissioning of the unit. Currently 30-40 patients are being treated daily with multi field treatments. Conclusions Indigenously developed telecobalt machine Bhabhatron-I satisfies all the required specifications needed for clinical acceptance. Continuous interactions between BARC scientists and manufacturer and clinical inputs from the Tata Memorial Centre have resulted in the development of a very good, user friendly and cheaper telecobalt unit in India. (author)

[en] Radiation polymerization of methyl methacrylate (NMA) was studied in the presence of two liquid crystals: N-(p-methoxybenzylidene)-p-butylaniline (MBBA, nematic) and cholesteryl 2-(ethoxy-ethoxy) ethyl carbonate (CHEECO, cholesteric). For comparison, polymerization was also carried out in the presence of benzene and cholesterol. Tacticities of the resultant poly(methyl methacrylate) were determined from nuclear magnetic resonance spectroscopy. Enhancement of syndiotacticity of the polymer obtained in the presence of cholesteric liquid crystal was observed. The rates of polymerization of pure MMA and MMA with different additives at various concentrations were studied. The viscosity-average molecular weights at one dose were also determined. Replica polymerization in the presence of preformed isotactic poly(methyl methacrylate) [i-PMMA] or syndiotactic poly(methyl methacrylate) [s-PMMA] with and without CHEECO was studied. Enhancement of syndiotacticity was observed in the presence of i-PMMA with and without CHEECO. (author)

[en] Radiation polymerisation of methylmethylacrylate (MMA) was studied in the presence of two liquid crystals, viz. N-(p-methoxybenzilidine)-p-butylaniline (MBBA : nematic phase) and cholesteryl-2-(ethoxy ethoxy)ethyl carbonate (CHEECO : cholesteryl phase). For comparison, polymerisation is also carried in presence of benzene and cholesterol. Significant differences in tacticities of the polymer formed in the presence of the two liquid crystals were observed as compared with the tacticities of the polymer formed with other additives or in the absence of anyone. For this purpose, various physical properties of the polymer were studied and compared with those of standard iso- and syndio-PMMA samples. With increasing concentration of benzene, the rate of polymerisation of MMA decreases slightly; in the case of cholesterol, there is no significant difference while in the case of MBBA, there is a drastic decrease in the rate of polymerisations. All these measurements are at 30deg C. With CHEECO addition at 30deg in isotropic phase, as well as at 12.5deg in cholesteryl phase, the rate first decreases and then increases with increasing amounts of CHEECO. The degree of polymerisation (DP) was found to be decreasing linearly with increasing concentration of benzene. In the case of other additives however, the decrease in DP was much less. (author)

[en] Cancer of the uterine cervix is the leading cancer among the female population in India. Radical external chemoradiotherapy and brachytherapy is the treatment of choice for locally advanced cervical cancers. Brachytherapy plays a pivotal role for its ability to deliver very high dose to the tumor while reducing the dose to the surrounding critical organs. In the last decade, external beam radiotherapy (EBRT) has seen technological advances in terms of intensity modulated radiotherapy (IMRT), image guided radiotherapy (IGRT), etc. However, the advances in brachytherapy for cervical cancers are not as rapid as EBRT, which have shown significant potential to improve local control rates and reduce toxicities

[en] The advantage of Brachytherapy is the ability to deliver very high dose to the tumour while sparing the surrounding critical organs. The Brachytherapy has evolved tremendously over past few decades. High Dose Rate (HDR) remote after-loading coupled with advances in treatment planning systems has ensured well defined protocols and methods for Brachytherapy dose analysis. Recently use of imaging techniques for 3-D data acquisition for Brachytherapy application, contouring and treatment planning has made significant contribution for better Brachytherapy dose delivery

[en] Copolymerization of N-vinyl-2-pyrrolidone (NVP) with vinyl acetate (VAC) was carried out using gamma-ray radiation. The compositions of the copolymers were determined from elemental analysis and the monomer reactivity ratios have been calculated using YBR method. The glass transition temperature and the intrinsic viscosities of the copolymers have been determined. All the experimental results were discussed in terms of the nature of the monomers. (author)

[en] Efficiency of neutron radiation against factors responsible for radioresistance is well established. Californium neutron source (₉₈²⁵²Cf) is being efficiently used in developed nations for interstitial and intracavitary brachytherapy (Seaborg therapy). Results of intracavitary Seaborg therapy have been very encouraging in advanced carcinoma cervix cases. In this preview we discuss the various advantages offered by Seaborg therapy and its efficacy in the treatment of advanced cancer of cervix, which is the most common type of malignancy found among females in India. (author). 28 refs., 2 figs., 1 tab

[en] Quality assurance (QA) in brachytherapy is as important as quality assurance in external beam radiation therapy. Not much literature is available on QA of PC-based treatment planning systems to improve the accuracy of dose computations. In this paper, some useful quality assurance tests for brachytherapy are suggested for proper evaluation and use of treatment planning systems (TPS). (author). 12 refs., 3 figs., 5 tabs