Determination of absorbed dose of organs [thyroid, sternum, cervical vertebra] in thyroid cancer patients following radioiodine therapy

In patients with thyroid carcinoma, radiation absorbed doses of the thyroid and surrounding tissues is important to weigh risk and benefit considerations. In nuclear medicine, the accuracy of absorbed dose of internally distributed radionuclides is estimated by different methods such as MIRD and direct method using TLD. The aim of this study is using TLD and a phantom to determine the amount of cumulated activity in thyroid and surrounding tissues. Thermoluminescent dosimeter [TLD] measurements were performed on 27 patients on the skin over the thyroid, sternum and cervical vertebra. There were 5 TLDs for each organ which they were taken after 4, 8, 12, 20 and 24 hr. To calculate the amount of activity in the thyroid a head and neck phantom with a source of 10 mCi of [131] I was used. Several TLDs were placed putted on the surface of thyroid on phantom [similar to patients] for 24 hr and then compared the dose of phantom and patients followed by calculation of the activity in patient's thyroid. TLD measurements showed cumulated radiation absorbed doses [cGy] of 315.6, 348.1 and 361.9 for thyroid with administration of 100, 150 and 175 mCi of [131] I, respectively. For sternum the values found to be 201.5 cGy, 275.2 cGy and 242.6 cGy. For cervical vertebra results were 311.5 cGy, 184.1 cGy and 325.9 cGy. The average of measurements was 33.3 cGy using of TLDs on phantom and absorbed activity in thyroid were 94.9, 104.6 and 108.8 mCi in 24 hr for mentioned doses administration. In this work a method to obtain the absorbed activity in the thyroid and other surrounding tissues is described. By this method, the amount of [131] I needed for each patient also could be determined. The results of this work can be used in estimation of absorbed dose in thyroid and other organs using of MIRD method

Evaluation of the relation between breast glandular absorbed dose and radiographic quality in mammography

Breast is one of the main radiological sensitive organs, hence it is important to evaluate absorbed dose to this organ especially to the glandular parts. It is the aim of this study to measure mean glandular dose and image contrast in terms of different mammographic parameters. In this study two mammography machines located at Said-al Shohada [Giotto] and Shahid Behesti [GE] hospitals were used. According to the recommendations of ACR and MQSA, breast phantoms were constructed and used for this study. For dose evaluation TLD dosimetry method was used. The TLD dosimeters were of LiF type and the reader was a Solaro TLD reader. To obtain a constant contrast when increasing kVp from 22 to 24, it was necessary to reduce mAs by 12 percent. The obtained relation between these two parameters is: contrast=0.2829D-0.2427. It was also found that there is a linear relationship between contrast and image quality. The relation between these two parameters is: Image quality = 28.117 Contarst + 20.134. Increasing kVp and hence decreasing mAs results a reduction to the glandular dose, especially in patients with large breast. Increasing kVp from 28 to 30 results in reduction of dose from 6.8mGy to 5mGy. It was found that there has been a linear relationship between contrast and image quality. It was also found that increasing kVp necessitate to reduce mAs for a constant contrast and hence reduction of glandular dose

Solar ultraviolet radiation on the ground level of Isfahan

Ultraviolet [UV] radiation affects human organs such as skin, eyes and immune system, as well as animals and plants. The main natural source of UV radiation is the Sun. To study the effects of solar UV radiation there is a need to quantify variations of solar energy received on the earth surface at different intervals. To measure UV radiation a broadband fiber optic UV spectrometer was used. With the spectrometer, the energy received at earth surface was measured from wavelength 100 to 400 nm [the UV spectrum]. Measurement duration was from January first to the end of December 2003, and from sunrise to sunset. The received UVC at the ground level was too low to be measured. The measured UVA was between 11 to 21 times higher than UVB energy during the measurement period. The minimum UV received on the ground level was in January and it was 14.5x10[5] J/m[2] while the maximum was in July and it was 80.14x10[5] J/m[2]. Total UV radiation received on the ground level was during the year of measurement period 579 x10[5] J/m[2]. The measurement showed that UVC intensity on the earth surface was negligible. As the wavelength increased the receiving UV energy at the ground level also increased. From the results, it has become clear that the main health consequences of solar UV were related to UVA band. As the intensity of the UVR during summer is too high, a method of UV health risk reduction should be devised

Improvement of renal function after relief of chronic partial upper urinary tract obstruction

Kidney's functional and anatomical changes reversibility of after treatment of partial ureteropelvic junction obstruction [UPJO] is not defined well. Therefore, in this clinical trial study, we've evaluated these changes. In a clinical trial study with non randomized-simple sampling, 32 patients with chronic partial obstruction of urinary tract due to unilateral UPJO were studied. In each patient, IVU, DMSA, DTPA, and bilateral kidney sonography were down pre and post operatively. Paired t-test, Wilcoxon, and McNemar tests analyzed data. P-value less than 0.05 was considered significant. Mean age of the patients was 5.44 +/- 0.47 years old and 40.6% of the patients were male. Split function mean in DMSA had significant difference, comparing pre and post operatively [P<0.05]. There also was a significant difference in mean of retention time and T1/2 of DTPA [P<0.05], comparing pre and post operatively [P<0.05]. Mean of kidney pelvis diameter had significant difference, comparing pre and post operatively [P<0.05]. Our study showed that operation of chronic partial obstruction of kidney, could improve kidney function. We also showed that sonographic evaluation of kidneys could help to evaluate kidney function in these patients

value of thyroglobulin [tg] measurement in different thyroid disorders

Thyroglobulin is a glycoprotein which is synthesized by the thyroid follicular cells. The blood level of this protein is changed in different physiologic and pathologic thyroid conditions. In this papar, the usefulness of thyroglobulin assay, methods of measurement, problems in evaluation and interpretation of the results in physiologic and disease processes are reviewed