Evaluation and Comparison of Dosimetric Characteristics of Semiflex®3D and Microdiamond in Relative Dosimetry under 6 and 15 MV Photon Beams in Small Fields.

Background: In modern radiotherapy techniques, the frequently small and non-uniformed fields can increase treatment efficiency due to their highly conformal dose distribution. Particular features including lack of Lateral Charge Particle Equilibrium (LCPE) lead to detectors with high resolution since any error in obtained dosimetric data could cause patient mistreatments. Objective: This study aims to evaluate and compare two small detectors (Semiflex®3D and microdiamond) dosimetric characteristics in small field relative dosimetry. Material and Methods: In this experimental study, the dosimetric properties of Semiflex®3D and microdiamond were assessed under 6 and 15 MV photon beams. The linearity and stability of the detector's response and dose rate were measured. Square-field sizes ranging from 0.6×0.6 - 5×5 cm2 were used for obtaining percentage depth dose curves (PDDs) and in-plane profiles. The angular and temperature dependence of both detectors' responses were also studied. Results: The detector response shows good stability, no deviation from linearity, and low dose rate dependence (≤1.6%). PDDs and in-plan profiles of both detectors are in good agreement and no significant difference was observed except for the high dose gradient regions (P-value≤0.017). Both detectors demonstrated low angular dependence (<0.3%) with temperature dependence lower than 1% for both detectors. Conclusion: The results indicate both investigated detectors were well performed in small field relative dosimetry and for measuring penumbra, it is better to use microdiamond detector.

Gender difference in motor impairments induced by chronic administration of vinblastine.

OBJECTIVES: Neurotoxicity of anticancer drugs complicates treatment of cancer patients. Vinblastine (VBL) is reported to induce motor and cognitive impairments in patients receiving chronic low-dose regimen. MATERIALS AND METHODS: The effects of VBL treatment on motor, learning and memory functions of male and female Wistar rats were studied by behavioral related tests. Animals were given chronic intraperitoneal injections of VBL (0.2 mg/kg/week for 5 weeks) from postnatal day 23 to 52. Motor function was evaluated using grasping test and balancing was evaluated by the rotarod. Spatial learning and memory and anxiety-like behavior were determined using Morris water maze (MWM) task and open field test, respectively. RESULTS: Administration of VBL caused severe damage to motor and balance function of male rats in comparison to female rats treated with VBL and rats treated with saline. Memory and locomotion were affected in both male and female rats compared with saline treated rats, while a sex difference was also observed in these parameters; male rats showed more impairment compared with female ones. Both male and female rats showed cognitive impairments in MWM task and no sex differences were observed in these functions. CONCLUSION: Results revealed that VBL is a potent neurotoxic agent and despite the profound effect of VBL on motor and cognitive functions, it seems that male rats are more susceptible to motor deficits induced by VBL.

Markov's modeling for screening strategies for colorectal cancer.

Economic decision models are being increasingly used to assess medical interventions. Advances in this field are mainly due to enhanced processing capacity of computers, availability of specific software to perform the necessary tasks, and refined mathematical techniques. We here estimated the incremental cost-effectiveness of ten strategies for colon cancer screening, as well as no screening, incorporating quality of life, noncompliance and data on the costs and profit of chemotherapy in Iran. We used a Markov model to measure the costs and quality-adjusted life expectancy of a 50-year-old average-risk Iranian without screening and with screening by each test. In this paper, we tested the model with data from the Ministry of Health and published literature. We considered costs from the perspective of a health insurance organization, with inflation to 2011, the Iranian Rial being converted into US dollars. We focused on three tests for the 10 strategies considered currently being used for population screening in some Iranians provinces (Kerman, Golestan Mazandaran, Ardabil, and Tehran): low-sensitivity guaiac fecal occult blood test, performed annually; fecal immunochemical test, performed annually; and colonoscopy, performed every 10 years. These strategies reduced the incidence of colorectal cancer by 39%, 60% and 76%, and mortality by 50%, 69% and 78%, respectively, compared with no screening. These approaches generated ICER (incremental cost-effectiveness ratios) of $9067, $654 and $8700 per QALY (quality-adjusted life year), respectively. Sensitivity analyses were conducted to assess the influence of various scales on the economic evaluation of screening. The results were sensitive to probabilistic sensitivity analysis. Colonoscopy every ten years yielded the greatest net health value. Screening for colon cancer is economical and cost-effective over conventional levels of WTP8.

Evaluation of destructive effects of exposure to cisplatin during developmental stage: no profound evidence for sex differences in impaired motor and memory performance.

We have elucidated the alteration in hippocampal and cerebellum function following chronic cisplatin treatment in male and female rats. Hippocampus and cerebellum related behavioral dysfunction in cisplatin-treated [intraperitoneally, 5 mg/(kg/week) for 5 weeks from 23-day-old] rats were analyzed using explorative, motor function, learning, and memory tasks (grasping, rotarod, open field, and Morris water maze tests). Exposure to cisplatin impaired the motor coordination in male and female rats. Exposure to cisplatin was reflected by a decrease in grasping time compared to vehicle-treated controls (saline) only in male rat while there were not any differences in female rats. When the rearing frequency, total distance moved and velocity of their recorded in open fieldtest, both males and females were dramatically affected by exposure to cisplatin. Compared to the saline, male and female rats trained 5 weeks after cisplatin injection showed significant memory deficits in the Morris water maze test. However, hippocampal and cerebellum functions of male and female rats were profoundly affected by exposure to cisplatin while no sex differences in the most variable were evident.

Profound destructive effects of adolescent exposure to vincristine accompanied with some sex differences in motor and memory performance.

Vincristine, an anticancer drug, is known to induce neuronal cell damage. We have elucidated the alteration in performance of the hippocampus and cerebellum following chronic vincristine treatment (0.2 mg·(kg body mass)(-1)·week(-1)) in male and female rats. Intraperitoneal injection of vincristine in adolescent rats caused impairment of motor and cognitive behavior. In the probe test, the length of path traveled and percent swimming time for vincristine-treated rats in the correct quadrant was significantly less than for the saline-treated (control) groups. The path length and time latency at the 2nd and 3rd blocks of trials for the male vincristine-treated group was significantly higher than that for the female saline- and the vincristine-treated rats. In the rod test, vincristine exposure impaired the motor coordination in both male and female rats. Exposure to vincristine caused a significant decrease in hanging time in male rats, compared with the saline- and the vincristine-treated female rats, while there were no differences between the female vincristine-treated rats and the saline-treated rats of both sexes. The rearing frequency, total distance moved, and velocity for both male and female rats were dramatically affected by exposure to vincristine. We have observed that the hippocampal and cerebellar functions of male and female rats were profoundly affected by exposure to vincristine, especially the male rats, suggesting a sexual dimorphism in the developing central nervous system that is affected by chemicals such as anticancer drugs.