[Evaluation of radiation dose received by operating room personnel during radiological procedures]

Utilization of ionizing radiation in some surgery operations [especially orthopedic operations] is inevitable. One of the main occupational hazards of physicians and other personnel could be radiation exposure risks. This study aimed to evaluate the exposure doses received by operating room personnel in such surgery operations. 30 personnel of operation room in university affiliated hospitals of Hamadan city [excluding physicians and nurses] were studied as they received radiation doses. 3 TLD [thermoluminescent dosimet ers] chips were fixed on the apron of each staff member. To estimate the high risk examinations, staff members also completed a questionnaire about the type and number of the radiological examinations that they had participated. Minimum and maximum level of doses received by the participants were between 0.24 and 0.56 mSv in a four month period. Therefore, amount of annual doses received by the personnel would be between 0.73 and 1.7 mSv, respectively [without reduction of background radiation]. As the accuracy of TL dosimeters is normally about 0.1 mSv; therefore, it can be claimed that the received doses by the personnel was very low and comparable with background radiation. The results indicated that the radiation doses received by operating room personnel were very low. They were less than maximum predicted doses reported by the International Commission of Radiation Protection. However, the use of dose recording systems for awareness about absorbed doses beyond permitted limits is necessary

[Maximum dose] points in cervical and endometrial cancer medium dose rate brachytherapy

Best dose distribution in target volume and control of Organ at Risk [OAR] dose are the two main goals in brachytherapy. In this study in vivo dosimetry in 4 rectal points was performed by Transillumination Dosimeter [TLD] s and the measured doses were compared in different patients. One point was reported to have the maximum dose in each patient and the very dose was considered as rectal dose according to ICRU-38 prescription; however, the next higher dose was also considered the same as the highest point when the difference was not more than 10% of the highest value. In more than 50% of the cases the 1[st] and 2[nd] highest points were in the same range with less than 10% variation. There were 3 points in approximately equal dose in 7% of cases. These findings are challenging with the IVTU-38 recommendations reporting the existence of a sole maximum rectal dose. So it seems wise to consider an isodose plate of maximum doses instead of one point only

[Testes doses and sex hormone changes using different radiotherapy machines to treat rectal cancer]

Complications of pelvic irradiation have gained more attention because of increased survival of patients. CO-60 Teletherapy has wide penumbra in comparison with linear accelerator that can cause testes irradiation during radiotherapy in vicinity of lower border of pelvic portal when treated for rectal cancer. In this study we compared testicular doses of testes when pelvis is irradiated for rectal cancer and its effect on sex hormone levels. In a cohort study, rectal cancer patients treated by pelvic irradiation concomitant with chemotherapy in two group. A group treated by Co-60 Teletherapy and another group by Linear Accelerator [LINAC]. Sex hormones serum levels were measured immediately before and 3 to 6 weeks after finishing irradiation. Testicular doses were measured by TLD [LiF], 3 times during whole course of irradiation in 5 patients of each group. T test and Mann-Whitney were used to compare data. 28 patients entered in study but 2 patients died early in course of radiotherapy [1 in each group], and one patient excluded because testes was inside of treatment portals. Patients and disease characteristics were similar between groups. Testes doses in patients treated by LINAC [55 +/- 24.7 mGy] was significantly lower than Co-60 [120 +/- 23 mGy] [p <0.001]. FSH and LH serumic level increased after irradiation in both groups and there is not a relation between FSH and LH levels with treatment machine [p<0.2] for LINAC and p<0.6 for Co-60. Decrease in serumic levels of testosterone was significant in patients treated by CO-60 [p<0.05], but was not significant in LINAC group [p<0.3]. It seems using LINAC in treating patient with rectal cancer can decrease testes doses but can not prevent hormonal changes. We suggest extra shield to decrease testes doses below the toxic dose

Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry

OBJECTIVE: The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom. MATERIALS AND METHODS: An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus. RESULTS: There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 (micro)Gy and 1.81 (micro)Gy, respectively. Also, the scan center dose in the women was 5.70 (micro)Gy. There was correlation between the thyroid and uterus surface doses, and the scan center dose. CONCLUSION: We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.

[Estimation of absorbed dose of uterus and thyroid in women based on scan center dose in radiation with DEXA pencil-beam system]

Dual energy X-ray absorptiometery [DEXA] is presently considered as the standard technique for diagnosis of osteoporosis. Since there is still no evaluation based on the correlation between scan center dose and critical organs doses, in this study after measuring surface doses of thyroid and uterus as critical organs the correlation between scan center dose and thyroid and uterus surface doses were calculated in order to assess the rate of radiation doze to patients. In this study, 40 women underwent bone densitometry of Lunar DPX-MD system with pencil beam in two scan modes of AP spine and femur, simultaneously. Then surface doses of thyroid, uterus, scan center, and background were measured by placing 433 TLDs-400 at the surface of thyroid and uterus and also scan center. Then correlation between scan center dose and critical organs surface dose were analyzed and regression functions with significant level were determined. In AP spine and femoral scanning, average surface doses of thyroid [91 TLD-400] and uterus [84 TLD-400] were 1.88 +/- 1.36 and 1.81 +/- 1.03 micro Gy, respectively. Scan center dose in this scanning mode was 5.70 +/- 2.38 micro Gy. There was significant correlation between surface doses of thyroid and uterus and scan center dose. Therefore, regression functions and correlation coefficients were calculated. The observed significant correlation between critical organs surface dose and scan center dose showed that Lunar DPX-MD with pencil beam has very low radiation, similar to background doses

Evaluation of basic parameters of real-time diagnostic ultrasound systems

Today, diagnostic ultrasound imaging is utilized immensely, vast utilization of this method in clinic necessitate the implementation of a quality control program for diminishing diagnostic errors. In this study, by using the test object and proposed performance protocol, Seventy nine real time ultrasound system have been evaluated in different hospitals in Tehran. The ultrasound systems were selected have evaluated randomly and evaluated in aspect of quality control essential parameters. The results were compared to AAPM [American Association of Physicists in Medicine] recommended values. The data showed that of total tested equipments 20.3% in dead zone, 64.6% in depth measurements, 54.4% in horizontal measurements, 19.0% in axial resolution, 12.7% in lateral resolution, 20.2% in focusing number and 30.4% in uniformity had no performance as compared to AAPM recommended values. These results showed that the maximum error was related to lateral and depth measurements and least error was related to lateral resolution. The presence of these considerable errors highlighted the necessity of performing a comprehensive quality control program routinely for real-time diagnostic ultrasound imaging equipments