comparison of contralateral breast dose due to breast cancer radiotherapy using two different treatment machines in a radiotherapy center

Background: The radiation dose received by contralateral breast [CLB] is one of the concerns of breast radiotherapy, because it may lead to the induction of secondary breast cancer. The aim of this study was to evaluate the CLB surface dose in the breast treatment in Yazd radiotherapy center

Materials and Methods: The surface dose of CLB was measured using TLD dosimetry in 50 cancer breast patients. The TLD chips were placed at four points on the each of CLBs. The patients were treated by 6MV photon beams of Oncor [physical wedge] and Compact [motorized wedge] LINAC. The TLD chips were placed on the surfaces of CLB during the medial and lateral tangent radiation fields in one of radiotherapy fractions

Results: The mean percent of prescription dose of the CLB surface doses on the point 1 in the two Linac [Oncor and Compact] were significantly different. The mean of CLB surface doses of point 1 in the physical and the motorized wedge techniques were 5.78 and 7.84 percent of prescription dose of breast cancer, respectively. The medial and lateral fields' contribution from 7.4% surface dose of CLB were 5.8% and 1.6%, respectively

Conclusion: In Shahid Ramezanzadeh radiotherapy center, the CLB surface dose due to breast cancer radiotherapy by the Compact machine [7.84 %] was significantly more than the allowable value [6% prescription dose]. The CLB does due to the medial field beam was more than the lateral field

Measurement of solar ultraviolet radiation in Yazd, Iran

Ultraviolet [UV] radiation is divided into three regions: UVA, UV[B], and UVC. Both the quality and quantity of solar UV radiation vary with various factors including the elevation of the sun above the horizon, as well as absorption and scattering of UV photons by molecules in the atmosphere, notably ozone and clouds. It is clear that whereas a moderate amount of UV exposure is beneficial, too much is detrimental, so there is a need to quantify variations of solar UV on the earth surface, at different time intervals. The measurement of solar UV radiation in Yazd city was achieved by two radiometers: 1] a special UVA light meter with maximum sensitivity to 365nm in the range of 320- 390nm and 2] a radiometer with a probe for 280-320 nm in UV[B] radiation. Measurement duration was from 1rst January to the end of December 2008 and from sunrise to sunset, every one hour. Daily integral UVA radiation in December with the lowest [0.38×10[5]Jm[-2]] and July with the highest intensity [5.26×10[5]Jm[-2]] were found. The minimum and maximum monthly UVA radiation on the ground level of Yazd city were 25.8×10[5]Jm[-2] in December and 128.7×10[5]Jm[-2] in July, respectively. Based on UV[B] /UV[A] ratio the UV[B] intensity at 12 o'clock is 25 times lower than the UV[A]. Therefore, the integrated hourly UV[B] in this time is equal to 3.13 kjm-2and almost the effective UV[B] is 1.56 kJm[-2] so the minimum required exposure time of UV[B] radiation for one SDD and MED by hands and head are about 22 and 110 minutes respectively

Evaluation of cancer risk of the patients undergoing coronary angiography in Yazd, Iran

Coronary angiography is a commonly performed diagnostic procedure with life saving benefits for the patient. However, this procedure involves relatively high radiation dose. The purpose of this study was to determine the average effective dose of patients undergoing coronary angiography and to estimate the associated radiation risk in terms of fatal malignancy. Radiation doses received by 103 patients who underwent coronary angiography [CA] at one hospital of Yazd province in Iran were measured in terms of Kerma Area Product [KAP]. KAP values were then used to determine the effective dose and the organ doses using the NRPB-S262 conversion factors and to estimate the radiation cancer risk based on the population averaged probability coefficients given in ICRP-60 and BEIR-VII report. A mean KAP value was found to be 29.15 +/- 16.97Gy. Cm[2] and the estimated mean values of effective dose was 5.0 +/- 3.18mSv. The dose of lung, esophagus, bone marrow, skin, stomach and female breast were 24.99 +/- 14.93 mSv, 14.01 +/- 9.47 mSv, 3.72 +/- 2.61 mSv, 2.9 +/- 1.8 mSv, 2.17 +/- 1.62 mSv and 1.46 +/- 0.32 mSv, respectively. The estimated total annual collective dose and caput dose were 17.52 man-Sv and 0.018mSv respectively. The frequency of examinations per 1000 population in Yazd was 3.5 which is lower than UK and the health care level I countries. Taking into account the ICRP risk factors, radiation dose arising from CA examinations could lead to 239 fatal cancers per million cases. Although the mean values of effective dose found in this study was lower than most of the published results, however CA examinations should be justified

Patient dose values during interventional cardiology examinations in Yazd hospital, Iran

The number of interventional cardiology [IC[procedures has increased rapidly, coronary angiography [CA] and percutaneous transluminal coronary angioplasty [PTCA] are now widely performed as a matter of routine, and they are considered safe procedures for experienced cardiologists. However, it is also known that these procedures are associated with high radiation doses due to long fluoroscopy time [T], and large number of cineradiography frames [F]. These levels of radiation may even lead to radiation skin injuries under certain conditions. A detailed study of radiation doses received by 168 patients who underwent coronary angiography [CA], and 84 patients who underwent percutaneous transluminal coronary angioplasty [PTCA] using 3 angiography X-ray systems in two hospitals of Yazd-Iran is presented. An air kerma-area product [KAP] meter was used for patient dosimetry. KAP, fluoroscopy time and total number cine frames for CA and PTCA prodecures were recorded for each patient. Mean +/- SD of KAP in CA and PTCA were 33 Gy.cm[2] +/- 18.8 Gy.cm[2] and 80.3 Gy.cm[2] +/- 65.6 Gy.cm[2] respectively. The comparison showed that CA KAP [33Gy.cm[2]], fluoroscopy time [2.7 +/- 2.4 min], and cine frames number [571 +/- 149] except of on case, were lower than [P<0.001] the results of other studies an mean KAP due to PTCA procedures, except for three cases, were not significantly different from the other references' results. The high level expert cardiologists couldn't have a significant effect on the decrease of patient dose since they should also teach angiography examinations to medicine students. With increasing patient BMI the value of KAP increased, but the fluoroscopy time and cineframes number did not change significantly. In addition, the results showed that the use of flat detector was not sufficient for decreasing patient dose, and system's adjustment was more important

Radon level in dwellings basement of Yazd-Iran

Indoor radon gas [[222]Rn] has been recognized as one of the health hazards for human. Air radon comes mainly from basement soil and construction materials. Saghand region with rich uranium mines lies 180 km from Yazd, so the indoor radon concentration can be high. Yazd, with population of about 457000, is the biggest city near Saghand, thus, indoor gamma background radiation of Yazd could be more than the other cities of Yazd province. In this study the air radon level of 84 dwellings basement from various regions of Yazd were measured during the year 2007. To do so, a portable radon gas surveyor was used which is an active measurement method. Using this device, alpha radiation of each basement was measured by a solid state detector for 24 hours. Radon concentrations of the basements were between 5.55 to 747.4 Bq/m[3] with mean of 137.36 Bq/m[3]. The mean radon concentration wasn't significantly different from the EPA guide line that is mitigation recommendations level [148 Bq/m[3]]. However, more than 30% of the basements had radon concentration more than EPA guide line. Using good air conditioning system in the dwelling basements is suggested

[60]Co gamma-ray attenuation coefficient of barite concrete

Recently uses of medium and high energy x-rays has been increased in Iran and radiotherapy centers along with a variety of accelerators have been installed in some provinces. In the other hand there is no sufficient skill in designing and making radiotherapy treatment rooms. This study was conducted to evaluate the efficacy of different mixtures of barite concrete for shielding the radiotherapy rooms. In this way we emphasized on determining the size and amount of barite aggregations to achieve the maximum radiation attenuation which leads to minimizing wall thickness in treatment room. To increase concrete density, the barite aggregation was added to concrete. Different size variations of barite aggregates mixed with different water/cement ratio were examined. The dimension of cubic concrete specimens for compression strength test was 15_15_15 cm. The rectangular barite concrete blocks with different compressions as used for strength test with cross section of 10_10 cm and thicknesses from 5 to 40 cm were used for radiation attenuation test. For this test concrete specimens were irradiated by gamma beam of [60]Co [Phoenix Theratron]. The transmission radiation through the blocks was measured by a Farmer ionization chamber [FC65P] in Yazd radiotherapy center. Our findings showed that in all specimens the highest mean compression strength was related to the specimens with equal ratio of fine to coarse barite aggregates but the lowest HVL was obtained from mixtures with fine to coarse ratio of 35/65. The concrete sample with a 0.45 water/cement ratio, 350 kg/m[3] cement and equal amounts of fine and coarse barite sands had nearly minimum half value layer[HVL] and maximum compression strength, so this sample was considered as the best barite concrete sample. Since HVL of the barite concrete specimens with the same compression strength is markedly lower than the conventional concrete and we have a plenty barite mines in our country it is recommended to use barite concrete with the best mixture condition based on our findings for shielding the radiotherapy rooms

Conventional and spiral CT dose indices in Yazd general hospitals, Iran

While the benefits of Computed Tomography [CT] are well known in accurate diagnosis, those benefits are not risk free. CT is a device with higher patient dose in comparison with other conventional radiological procedures. Is the reduction of exposures by requiring optimization of CT procedures [a principle concern in radiological protection]

Patient dose in routine X-ray examinations in Yazd state

Medical x-rays are the largest man-made source of public exposure to ionizing radiation. It is important to avoid conditions where the amount of radiation used is more than that needed for the procedure. Materials and The Entrance Skin Exposure [ESE] measurement was conducted for quality control of x-ray machines and survey of operator's experimental techniques. The ESEs were measured by UNFORS dosimeter for five common types [12 projections] of x-ray procedures in standard man for the 18 public hospitals of Yazd province. The median, 3rd quartile, minimum, and maximum values of each ESEs distributions are reported. The 12 histograms are presented showing wide distribution of measured ESE in each examination. The survey results are compared with guide levels that reported by CRCPD or NRPB. The sum of ESEs measurements such as in skull, Th-spine and L-spine are projection out of the guide levels. One of reasons of the wide ESEs distribution is miss unique role in selection of techniques for the same procedure and same patient size by operators in each center and even for one x-ray machine. The findings support the importance of the on-going quality assurance program to ensure doses are kept to a level consistence with optimum imaging quality

Effects of low-frequency pulsed electromagnetic fields on wound healing in rat skin

Pulsed electromagnetic field stimulators are used for promotion of healing in various conditions such as bone, cartilage and ligament injuries, but there are controversies about the use of these stimulators for skin wound healing. The aim of this study was to investigate the effects of different pulse rates of pulsed electromagnetic fields [PEMF] on skin wound healing in rats. Forty-eight male Wistar rats were used in this study. After anaesthetizing and shaving, a paired full thickness incision wound [35 mm in length] was made on each side of the dorsal midline of the rats. The animals were divided into eight groups [n=6] namely control, sham and six treatment groups which were exposed to10, 20, 40, 50, 60, and 80 Hz pulse rates. Treatment groups were exposed to PEMF [4 mT] for 30 minutes twice a day for ten days after surgery. Wound healing was evaluated by measuring the maximum length, the surface area of the wounds and the healing fractions every two-days. The full contraction period of the wounds and the tensile strength of scars were also measured. Results showed that: I -The absolute and normalized length of wounds in animals receiving PEMF [20 Hz] were significantly less than that of the sham [P<0.01]. II -The wound healing duration in this group [12.7 days] was significantly shorter than that of the sham group [P<0.02]. III - The wound tensile strength in this group was significantly greater than that of the sham group [P<0.01]. We can conclude that PEMF with 20 Hz pulse rate is effective in promoting of wound healing