ntroduction: total body irradiation is a type of external radiotherapy which allows the delivery of a homogenous dose to the entire body while the critical organs such as lung, etc. can be shielded, if needed. The role of TBI is to suppress the patient's immune system prior to bone marrow transplantation in order to avoid the rejection of the donor bone marrow. in this study, some basic dosimetric parameters (percentage depth dose and dose rate) were measured under TBI condition for 60Co machine. A Perspex water phantom having dimensions of 30´30´30 cm and a farmer type ionization chamber (0.6 cc) were used to measure some parameters such as percentage depth dose.For the measurement of surface dose, a parallel plate ionization chamber was used. All the chambers in this study were used with a UNIDOS electrometer. A human phantom consisting of 3 sections (head and neck, trunk and hip) was used to check the accuracy of the dose delivered. The dose in the midpoint of the phantom was measured by a farmer type ionization chamber (0.3 cc) which was placed at the umbilicus level. The dose to be delivered was calculated by two 1. using the measured percentage depth dose and the dose rate under TBI condition 2. using the calculated percentage depth dose based on Mayneord factor and the dose rate for the TBI condition which was derived from the inverse square law.P-type Silicon diodes while being connected to a multi channel electrometer was used to investigate the dose uniformity throughout the whole body. For this purpose, the diodes were taped at several locations on the entrance and the exit side of the human phantom. there is an agreement between the measured and the calculated dose within 2.6 and 3% for the first and second method, respectively. The mean difference between the calculated and measured percentage depth dose was 0.71% with standard deviation of 0.96%. The dose uniformity through the whole body at the anterior and posterior side was within 6 and 5%, respectively. The measured dose in the midlobe of the lung shows that the delivered dose to the lungs was 14.14 Gy which is higher than the prescribed dose of 13.5 Gy. Discussion and the results of the dose delivered by both methods show that the difference between the calculated and measured values are within the acceptable level (±5%).The second method is recommended for the use in TBI calculation than the first one because it is simpler to use. Although the obtained result from the first method is in a better agreement with the measured data than the one from the second method.One of the main objectives in TBI is to achieve dose uniformity throughout the whole body. The results of this work on the human phantom show that dose uniformity was achieved. The measured dose in the midlobe of the lung shows that the delivered dose to the lung was higher than the prescribed dose, thus appropriate shielding should be used to reduce the lung dose. Based on the dose uniformity obtained in this work it is recommended that TBI treatment can be implemented in the radiotherapy centers throughout the country using Cobalt-60, provided proper lung shield is used.

Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy.
A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calculation accuracy of TPS in these regions.
The confidence limit values for the central axis, build-up, off-axis, and out-of-field regions were 1.01, 8.62, 1.79, and 55.24, respectively. Furthermore, the results showed that TiGRT TPS underestimated the dose of build-up and out-of-field regions for most points.
According to the results of the present study, it can be concluded that the dose calculation accuracy of TiGRT TPS for physical wedged fields in the central axis, build-up, and off-axis regions is adequate, while it is insufficient for out-of-field regions.

In vivo measurements of applied dose during radiotherapy treatment, is important to ensure accurate dose delivery to patients. Uncertainty in dose delivery should fall within ±5% of the prescribed dose as recommended by ICRU. Assessment of dose for radiotherapy applications performed with various types of detectors. In this study, semiconductor diodes were used which have some advantages for clinical dosimetry. The brain tumors have generally treated with two fields using SSD technique. Entrance and exit dose were measured for each patient with diodes during treatment. Entrance and exit dose measurements have converted to midline dose. Measured entrance and exit doses have compared with calculated ones and large deviations (more than 5%) have observed. A farmer ionization chamber (0.6 cm) was used as the reference dose detector and a Perspex water phantom (30 30cm2 area and thickness ranging from 5 cm to 30 cm) were used to determine calibration and correction factors. Correction factors were determined and variations more than 1% have used to obtain correct doses. Large deviations between measured and calculated for entrance (5.3%), exit (42%) and midline (47%) were detected. The difference was not found to be significant when comparing the measured entrance dose with the calculated one (p=0.696) and the measured exit dose with calculated one (p=0.643) and measured midline dose with calculated one (p=0.104). In vivo dosimetry is very useful to check the dose delivered to the patient. A high precision obtained when the calibration and correction factors for each parameter of influence on the diode response are carefully determined and applied to convert the diode signal in the adsorbed dose. In this study, the target-absorbed doses were estimated from the measured entrance dose and the measured transmission.

CT is a diagnostic imaging modality giving higher patient dose in comparison with other radiological procedures, so the calculation of organ dose in CT exams is very important. While methods to calculate the effective dose have been established (ICRP 26 and ICRP 60), they depend heavily on the ability to estimate the dose to radiosensitive organs from the CT procedure. However, determining the radiation dose to these organs is problematic, direct measurement is not possible and comparing the dose as functions of scan protocol such as mA is very difficult. One of the most powerful tools for measuring the organ dose is Monte Carlo simulation. Today the predominant method for assessment of organ absorbed dose is the application of conversion coefficients established by the use of Monte Carlo simulations. One of the most famous dose calculation software is CTDOSE, which we have used it for calculation of organ dose. In this work we measured the relationship between the mA, KV and scanner type with the equivalent organ dose and effective dose in mathematically standard phantom (Hermaphrodite 170cm/70Kg) in an abdomen-pelvis CT exam by Monte Carlo method. For this measurement we increased the mA in steps of 10 mA and plot curves for organ dose as a function of mA for different KV setting. As expected, with increasing mA, patient organ dose increased, but the simulation results showed that the slope of organ dose as a function of mA increased with KV increasing. By increasing KV from 120 to 140 the increase in slope of curves representing patient organ dose versus mA for different scanner types show almost similar behavior whereas the slope of the corresponding curves in scanners which equipped xenon detectors was almost 22% more than the slope of scanners equipped with scintillation detectors. Our research showed that regarding equivalent dose the system incorporating scintillation detector has a superior performance. Incorporating such software in various CT scanners, marketed by different vendors, will offer the ability to get a print out of patient organ dose in any examination according to the imaging parameters used for imaging any part of the body

Computed tomography (CT) is one of the most used imaging modalities and is one of the main sources of population exposure. Recently, patient doses are estimated through CT dose index (CTDI) phantoms as a reference to calculate CTDI volume (CTDIvol) values followed by calculating equilibrium dose (Deq). This study aimed to improve measurement methods for equilibrium dose and the effective dose using the American Association of Physicists in Medicine-Task Group Report No. 111 (AAPM-TG111).
Using standard phantom of polymethylmethacrylate (PMMA) and pencil ionization chamber, the values of CTDI100 and ε(CTDI100), and DL(0) were calculated followed by calculating equilibrium dose, hence obtaining the total effective dose.
Findings: The average equilibrium dose in according to the CTDI100 and CTDIvol was found to be 26.11 and 58.99, respectively; which was based on the value of 19.4 and 42.4 mGy recorded by CT console. Differences between CTDIvol and Deq were 34.58% and 39.12% based on the experiments setting up by the CT-weighted and volume dose index, respectively.
Differences between values of CTDIvol and Deq were consistent with the literature results. Overall, weighted dose index of CT systems is not sufficient to determine patient’s dose and using new recommended indices are required.

Colorectal carcinoma is a common malignancy، in treatment of which pelvic radiotherapy plays an important role. But this may lead to azospermia. We designed a study to determine the delivered dose to the testis with thermoluminescence dosimetry (TLD) and compare it to the dose calculated by the Three-dimensional planning software. We measured the testicular doses by TLD; the TLDs were fixed to the scrotum in six points anteriorly and posteriorly in two random fractions of the radiation course. All patients received a 50-50. 4 Gy radiation dose to the pelvis in a prone position with standard fractionation and 3-dimensional planning، through three or four fields. The average dose of the TLD measurements was compared to the average of 6 relevant point doses calculated by the planning software. In 33 patients with a mean age of 56 years، the mean testis dose of radiation measured by TLD was 3. 77 Gy، equal to 7. 5% of the total prescribed dose. The mean of point doses calculated by the 3-dimensional planning software was 4. 11 Gy، equal to 8. 1% of the total prescribed dose. A significant relationship was seen between the position of the inferior edge of the fields and the mean testis dose (P= 0. 04). Also body mass index (BMI) was inversely related with the testicular dose (P= 0. 049). In this study، the mean testis dose of radiation was 3. 77 Gy، similar to the dose calculated by the planning software (4. 11 Gy). This dose could be significantly harmful for spermatogenesis، though low doses of scattered radiation to the testis in fractionated radiotherapy might be followed with better recovery. Based on above findings، careful attention to testicular dose in radiotherapy of rectal cancer for the males desiring continued fertility seems to be required.

Recommendations to immunize healthcare workers (HCWs) against hepatitis B are well known. However, a proportion of individuals do not respond to the primary standard three-dose HB vaccination schedule. The current study aimed to evaluate whether a double-dose HB booster vaccine could induce better protective anti-HB titers than a single-dose booster in non-protected HCWs. This was a randomized clinical trial. A total of 91 HCWs not responding to the primary vaccine series in 2014 were enrolled. The participants were randomized into two groups that received a double dose of the HB vaccine containing 40 µg of antigen or a single dose of the HB vaccine containing 20 µg of antigen in three doses (at zero, one and six months after vaccination). Blood samples were collected before vaccinations and 28 days after the third dose to assess the seroconversion rate, according to the anti-HB antibody titer threshold of > 10 mIU/mL. The seroconversion rates were 93.2% and 87.2% after the first booster doses of the double-dose and single-dose HB vaccines, respectively (P = 0.64). In the double-dose HB vaccine group, the seroconversion rate was 97.8% compared with 89.6% in the single-dose group following the second vaccine dose (P = 0.83). All of the participants in both groups were seroprotected after the third HB vaccine dose. Both the single- and double-dose HB vaccines were adequately immunogenic, and the double-dose HB vaccine was not significantly more immunogenic than the single-dose vaccine in terms of the seroconversion rates of HCWs who had not responded to the primary vaccine series.

Given the importance of CT imaging in the diagnosis and treatment of diseases, the concern of the dose that patients are receiving while undergoing CT examination and the lack of information about the situation in the centers CT scan was conducted at Shahid Beheshti University of Medical Sciences. A descriptive study was conducted. A list of CT scans of patients who are still under the supervision of Shahid Beheshti University of Medical Sciences were prepared (the public sector). Exposure data were collected via referring to the centers (kV voltage level and mA and scan time) and two methods were used and back up CT scan of the patient's history was carried. Dosimetry on phantoms, phantom head and body with the same exposure conditions (radiation) was performed and the organ dose and effective dose received by mili Gary was calculated according mili Sivert. The research was conducted in five centers with CT scan. In CT scan of the head (head CT) brain dose, the highest dose (31.55 mG) and bladder lowest dose (zero) and in CT scan of the chest (chest CT), breast highest dose (20.67 mG) and bladder lowest dose (0.005 mG) and in CT scan of the abdomen and pelvis (abdominal pelvis) bladder highest dose (16.44 mG) and brain lowest dose (0.002 mG) was calculated. Furthermore, effective dose received by patients for three protocols of the head, chest, abdomen pelvis centers surveyed, respectively. The lowest effective dose for the patient CT scan of the head (0.16 ± 1.55 mSv) and the lowest effective dose for the patient CT scan of the chest (0.3 ± 3.4 mSv) and the highest effective dose received by patients CT scan of the abdomen pelvis (0.3 ± 6.8 mSv), respectively. It seems organ dose and effective dose in some higher centers of the world standard (ICRP) and the overall dose exposure is a concern.

Gafchromic films are utilized for two-dimensional dose distribution measurements, especially in radiotherapy. In this study, we investigated a close connection between energy and dose rate of Gafchromic EBT3 films irradiating with 6 MV and Co-60 photon beams over a broad dose range. EBT3 films were exposed to 6 MV and Co-60 photon beams using 4 and 2 Gy/min dose rates over a 10-400 cGy dose range. The films were scanned in red, green, and blue channels to obtain the optical density (OD)-dose curves. The OD-dose curves resulted from three-color scans for different photon energies and dose rates were compared by statistical independent t-test. For the radiations of Co-60 and 6 MV photon beams, the highest correlation was obtained between the 2 and 4 Gy/min dose rates with red and green channels, respectively. Moreover, the red channel had a greater OD response per dose value, following the green and blue channels. There was no significant difference between different photon energies' (Co-60 and 6 MV) and dose rates' (2 and 4 Gy/min) dependence on OD-dose response of EBT3 films over a broad domain of radiation dose, except for different photon energies in the blue channel. Our results revealed that the OD-dose response of EBT3 films is independent on photon energies (Co-60 and 6 MV) and dose rate (2 and 4 Gy/min) in the evaluated dose range (10-400 cGy). Therefore, the EBT3 films are suitable, consistent, and reliable instruments for dose measurements in radiotherapy.

Weed management is an important agronomic practice. It would be takes 40% of time of small holder farmers, if carried out by hand. Farmers have being interested in more comprehensive programs for weed management that reduce weed populations over time and the use of reduced herbicide doses in order to diminish their production costs. Integrated weed management takes advantages of various methods to suppress weeds in a more common and environmental natural way. Today, it is understood that chemical herbicides are not free of problem. So researchers are working on integrated weed management, which brings all possible methods to control weeds. The use of reduced herbicide doses will cost a fraction of full dose and make them even more affordable to poor farmers who have a limited amount of resources. Researches indicate that there is good potential to reduce the number of herbicide applications and utilize lower herbicide doses within competitive cropping systems. Crop competitiveness advantage is a great potential for weed suppression that provides reducing herbicide dose to avoid its environmental and economic suffers. Therefore, a field experiment was conducted to evaluate the effect of reduced dose of imazethapyr on weed control when two bean cultivars grown in pure stand and intercropping together.
The field experiment was conducted as split plot based on randomized complete block design at the Research Farm of University of Tehran located in Karaj during 2013–2014. Main plots were five doses of imazethapyr (0, 25, 50, 75 and 100 percent of the recommended dose) and sub-plots comprised pure stands and intercropping of two bean cultivars include: Akhtar (the growth habit is upright) and Goli (the growth habit is creeping). Also there is a plot as weed free (control). When the plants were at the third trifoliate stage, determined doses of imazethapyr were sprayed. Weed dry weight and bean yield were analyzed by nonlinear regression. In order to obtain the response curves to the doses of imazethapyr, data were fitted by SigmaPlot software (version 11) according to the standard dose-response equation:Where W is the dependent variable, ED50 is equivalent to a dose of herbicide that reduces weed dry matter by 50 percent and b is the curve slope where the trend is linear. The yield data were fitted using a three-parameter logistic equation:where a is maximum yield, x0 represents a dose of herbicide in which the yield reaches 50 percent and b is the slope of the curve.
The community of weeds in the field mostly consisted of three species; Amaranthus retroflexus, Chenopodium album and Solanum nigrum that all are summer annual weeds. The dose-response model well described the effect of doses of herbicide on weed dry weight. Results indicated that weed species response to herbicide doses differently in bean cultivars and their intercropping. Among dominant weeds, A. retroflexus was determined high sensitive to increasing doses. Bean cultivars were solely different in competition with weeds, as creeping cultivar i.e. Goli with more competitive ability (like: fast early growth and area coverage) was more successful in weed suppression. Herbicide application at reduced dose could also be efficient when we used 75 percent of the recommended dose because led to a yield more than 4000 kg/ha in pure stand of Goli. Pure stand of Akhtar and intercropping showed yields of 3617 and 3641 kg/ha, respectively at 75 percent of the recommended dose. Relative yield total (RYT) for doses of 75 and 100 percent of the recommended dose and weed free control were 0.95, 0.87 and 1.03, respectively.
The results of experiment showed that weed sensitivity to herbicide doses vary differently by species. So that, A. retroflexus dry weight was more affected than C. album and S. nigrum in response to reduced doses of imazethapyr. The application of 25 percent of the recommended dose of this herbicide reduced A. retroflexus dry weight more than 50 percent. It seems that if the dominant weed in a field was the A. retroflexus, the farmer could greatly reduce dose of imazethapyr. However, usually weed community of fields are consisted of several species, therefore, to use reduced herbicide doses, sensitivity of all species should be considered. Also, using bean cultivars that potentially have high competitive ability, it could be a good supplement in combination with reduced doses of herbicide. In this experiment, Goli cultivar presented more potential to combine with reduced doses of imazethapyr.