ABSTRACT
Background: commissioning tests are recommended before implementing Intensity Modulated Radiation Therapy. This study evaluated five different plans of IMRT mocks for different modulation indices
Materials and Methods: IMRT tests were done in slab phantom for both 6MV and 15 MV photon energies using a 2D array ion chamber dosimeter
Results: the acceptance criteria were based on 3% /3mm. All tests passed the gamma criteria except for the prostate test with 15 MV photon beams and C shape test for both 6 MV and 15 MV energies. The Ratio passing points for Multi target test in 6 MV and 15 MV plans were 93.1% and 91.5%, respectively. The results of the prostate tests with 3%/3mm was 92.3% for 6MV and 91.2% for 15 MV in 4%/4 mm tolerance limit. For Head and Neck test with the same gamma criteria, the percentages of the points were 93.2 and 94 for 6 MV and 15 MV plans, respectively. For C shape tests, the used gamma criteria were 4%/ 4 mm. The ratio passing points were 94.9% and 94.3% for 6MV and 15MV plans, respectively. However, C shape hard test could not pass the gamma criteria of 4%/ 4mm for 6MV
Conclusion: results showed that by increasing the complexity of the IMRT plan, the verification test must be done in a more strict-manner, because a small change in dose delivery can cause a large discrepancy between planned and real dosimetry and may produce hot spots in organs or a cold spot in the target volume
ABSTRACT
Background: To compare the dosimetric coverage of the planning target volume [PTV] and the dose delivered to the main Organs at Risk [OARs] in 5 and 7-field techniques of Intensity Modulated Radiation Therapy [IMRT] in patients with local prostate cancer
Materials and Methods: Twelve patients with local prostate cancer underwent 5 and 7-field IMRT planning. The delivery of IMRT was carried out using the sliding technique. The dose coverage for PTV was designated to >/= 98% of the PTV covered by 95% of the prescribed dose. Dose conformity was evaluated by comparing the volume of nontarget tissue receiving maximum, and average of the prescribed dose and the dose of 33%, 50%, and 66% of the volumes on both planning sets. For target, this evaluation was made with comparing the Conformity Index [CI] and Inhomogeneity Index [HI]. In addition, we compared the monitor units used for dose delivery in both planning techniques
Results: All the 5 and 7-field IMRT plans differed slightly in the measured parameters, and none of them have statistically significant differences with each other except for the monitor units where significant differences were observed in favor of the 5-field IMRT plans [p=0.000]. In all of the 5-field IMRT plans the mean dose delivered to OARs were very similar or less than that of the 7-field plans
Conclusion: In comparison to the 7-field technique, the 5-field IMRT technique has resulted in improved IMRT dose conformity, homogeneity, and lesser MUs used for radiation therapy. However, this difference was not significant
ABSTRACT
Next to lung cancer, breast cancer is the second cause of mortality among women. Although the prevalence of this disease has been increased, but the rate of mortality has not been changed during last three decades, this may be due to early diagnosis at the first stage of disease. The aim of this study is to determine fertility risk factor of breast cancel in women. This research is a case-control study which was performed in 1999 on three educational treatment centers related to Ministry of Health and Medical Education in Tehran. Personal, fertile characteristics in women with breast cancer were determined and compared with control group. 120 patients with breast cancer were selected randomly and compared with 120 healthy women. Results showed that majority [70%] of women with breast cancer were between 35 to 54 years old and there was significant relation between marital status and breast cancer [P < 0.006]. There was no relation between cancer and age of first menstruation, marriage age, number of pregnancy, age of first and last pregnancy, history of multiple pregnancy, history of breast feeding, duration of using OCP and age of menopause. But there was significant relation between number of abortion [P < 0.046]. In this study, risk factors of breast cancer were marital status, and there was a weak relation between number of abortion and breast cancer. Unfortunately some of this factors are not preventable, but for those factors which are manageable, proper program should be provided in order to make people aware of risk factors and ways of their prevention