Monte Carlo study on beam hardening effect of physical wedges

Physical wedges are still widely used as beam modifiers in external beam radiotherapy. However the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. The aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value layer, mean energy and tissue-phantom ratio. The effect of physical wedges on the photon beam quality of a 6-18MV Varian 2100C/D accelerator was studied with the BEAMnrc Monte Carlo code. Good agreements were obtained between measured and calculated depth doses and beam profiles for open and wedged photon beams at both energies. It was noticed that for 6 MV photon beams, physical wedges have more significant effects on beam quality than for 18 MV. Also it was obtained that at 18 MV photon beam as the wedge angle increased, the effect of wedge on beam quality becomes reversed and beam softening occurred. According to these results, it is recommended that beam hardening and softening of physical wedges should be considered in treatment planning systems in order to increase the accuracy in dose delivery

[Frequency of depression in 207 patients with copd in Qom city, 2008]

Depression is one of the common problems of patients with chronic obstructive pulmonary disease [COPD]. Depending on the severity of lung disease in patients and the kind of study, the prevalence of depression has been reported to lie between 10%-80%. Depression may not be diagnosed in routine examinations, so the patients may not receive appropriate treatment. Due to the lack of similar studies in Iran, the main purpose of this study was to determine the prevalence of depression in COPD patients in Qom. In this cross-sectional study, 207 known cases of COPD were evaluated for depression and its severity by using standardized tests of Beck depression screening. Other variables in the study such age, sex, educational level, marital status and smoking rates were taken into account. SPSS version 15 and Chi square test were utilized for data analysis [p<0/05]. Data analysis showed that 83.3% of patients suffer edfrom varying degrees of depression, of whom 12.9% had severe or very severe depression. Moreover, a significant relationship was found between depression and education level. Depression is one of the common problems in COPD patients reducing their quality of life. It can be treated by physicians which can lead to improved quality of life for these patients