RESUMO
Background: This study evaluated whether IMRT using fewer beams and segments could reduce delivery time without compromising plan quality in gastric cancer adjuvant radiotherapy
Materials and Methods: Fifteen patients with advanced gastric cancer who underwent D2, R0 surgery were included in this study. IMRT plans for each patient were designed as 7 equal beams with 40 segments, 5 beams with 25 segments and 4 beams with 20 segments. The dosimetric parameters were compared for the planned target volume [PTV]. The dose of normal organs at risk [OARs] was also assessed. The monitor units and treatment times of the different IMRT plans were calculated
Results: The 20-segment IMRT plan significantly reduced the PTV maximum dose compared to the 40-segment IMRT plan. The 20-segment IMRT plan improved left kidney and liver dose sparing in V20 and V30 as well as the 40-segment IMRT plan did and provided be4er protection for the V20 [13.86+/-7.78] of the right kidney, the V30 [9.25+/-4.04] of the le kidney, the D mean [19.68+/-2.47] of liver and D max [38.79+/-3.57] of the spinal cord. Irradiation times in the 20-segment and 25-segment plans decreased by 2.5 and 1.9 min, respectively, compared to the 40-segment IMRT plan
Conclusion: IMRT using fewer beams and segments reduced delivery time without compromising plan quality in gastric cancer adjuvant radiotherapy. Fewer segments IMRT plans lowered the monitor units and the treatment time
RESUMO
To compare different indicators of iodine deficiency disorders [IDD] in school children from study sites in Bangladesh Indonesia, Guatemala, and the United States. Cross-sectional surveys were performed in Savar, Bangladesh; Sukabumi, Indonesia; San Pedro Sacatepequez, Guatemala; and Atlanta, United States. In each study site, school children were assessed for thyroid size by palpation and thyroid volume by ultrasonography, urine specimens collected for iodine concentration, and finger stick blood specimens spotted onto filter paper for assessment of thyroid stimulating hormone [TSH] and thyroglobulin [Tg]. Weights and heights were collected in all sites except Guatemala. Between 305 to 518 school children were surveyed in each site. Indicators based on thyroid size tended to indicate more severe levels of iodine deficiency compared to urinary iodine based on WHO/UNICEF/ICCIDD criteria. TSH levels appeared to correlate well with other indicators of IDD whereas Tg did not. In these study sties, it appeared that urinary iodine, thyroid volume [based on body surface area], palpation, and TSH were consistent in identifying the Bangladesh site as having the highest prevalence of IDD, followed by sites in Indonesia, Guatemala, and the United States. The prevalence of goiter indicated more severe levels of IDD compared to urinary iodine levels. Tg was not significantly different between the study sites