RESUMO
Purpose: The study purpose included dosimetric comparison of cobalt 60 (60Co) and iridium 192 (192Ir) high dose rate (HDR) source used in brachytherapy treatment of cervical cancer. Materials and Methods: Computed tomography (CT) scans for 15 patients of carcinoma of uterine cervix using 3-mm slice thickness were considered for the study The contouring of high-risk clinical target volume (HRCTV), bladder, and rectum on CT images was done as per the GEC ESTRO guidelines with the help of magnetic resonance imaging images in the treatment planning system. All parameters were kept the same for 60Co (3.5 mm active length, 0.5 mm active dia, Bebig) and 192Ir (3.5 mm active length, 0.6 mm active dia, Bebig) HDR source with 2.5-mm step size and dose prescription to Point A. As per the International Commission on Radiation Unit (ICRU)-89 guidelines, the dose–volume parameters such as D50(Gy), D90(Gy), and D98(Gy) for HRCTV and D0.1cc (Gy), D1cc (Gy), D2cc (Gy), and D5cc (Gy) to the bladder and rectum were calculated for both the HDR sources. Results: The difference in dose–volume histogram parameters such as D50,D90,and D98 of HRCTV was 3.19%, 1.13%, and 0.50%, respectively, for the two radioisotopes. The difference in dose values of D0.1cc, D1cc, D2cc, D5cc, and ICRU reference points of bladder was –0.58%, –0.67%, –0.99%, –0.94%, and –1.75%, respectively. On the other hand, dose difference for D0.1cc, D1cc, D2cc, D5cc, and ICRU reference points of rectum was 0.67%, 0.26%, 0.56%, 0.63%, and –0.33%, respectively. Conclusions: The present study results show that all the dose parameters of HRCTV, bladder, and rectum with 60Co were comparable with those of 192Ir HDR source. The isodose distribution is more bulge out for 60Co in cranial-caudal direction compared to that of 192Ir. However, these differences can be reduced by treatment planning optimization techniques. The clinical plan evaluation in each slice and plane is necessary to explore the logistic and financial benefits of miniaturized 60Co source over 192Ir HDR source
RESUMO
Manganese deficiency in wheat has become an important nutritional disorder particularly in alkaline calcareous soils where rice-wheat rotation is followed. This experiment was aimed to study the mechanism of Mn efficiency during various developmental stages in six wheat cultivars grown at two Mn levels viz. 0 and 50 mg Mn kg-1soil (Mnapplied as MnSO4.H20) in pots. The Mn vegetative efficiency calculated on the basis of shoot dry weight at anthesis indicated HD 2967 and PBW 550 (bread wheat) as Mn efficient and durums as Mn inefficient. The efficient cultivars recorded highest values for influx, uptake, shoot dry weight, leaf area/plant, SPAD index, Fv/Fmratio and root length that explained their higher efficiencies whereas inefficiency of durum cultivars was attributed to their smaller roots and lower influx. Under Mn deficiency, PDW 314 and PDW 291 retained 68% and 64%, respectively, of total Mn uptake in vegetative parts (stem and leaves) and lowest in grains 7% and 5%, respectively, whereas PBW 550, BW 9178 and HD 2967 retained 29, 37 and 34% in vegetative parts, and 21, 17 and 15 % in grains, respectively at maturity. Higher utilization efficiency of efficient genotypes also indicated that increased Mn uptake with Mn supply produced more efficiently grains in efficient genotypes but vegetative parts in inefficient genotypes. Hence Mn efficiency of a cultivar could be explained by longer roots, higher uptake, influx and efficiency index during vegetative phase and higher grain yield and utilization efficiency during generative phase.