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PURPOSE: Polymethylmethacrylate (PMMA) slab is one of the mostly used phantoms for studying breast dosimetry in mammography. The purpose of this study was to evaluate the equivalence between exposure factors acquired from PMMA slabs and patient cases of different age groups of Taiwanese women in mammography. METHODS: This study included 3910 craniocaudal screen/film mammograms on Taiwanese women acquired on one mammographic unit. The tube loading, compressed breast thickness (CBT), compression force, tube voltage, and target/filter combination for each mammogram were collected for all patients. The glandularity and the equivalent thickness of PMMA were determined for each breast using the exposure factors of the breast in combination with experimental measurements from breast-tissue-equivalent attenuation slabs. Equivalent thicknesses of PMMA to the breasts of Taiwanese women were then estimated. RESULTS: The average +/- standard deviation CBT and breast glandularity in this study were 4.2 +/- 1.0 cm and 54% +/- 23%, respectively. The average equivalent PMMA thickness was 4.0 +/- 0.7 cm. PMMA slabs producing equivalent exposure factors as in the breasts of Taiwanese women were determined for the age groups 30-49 yr and 50-69 yr. For the 4-cm PMMA slab, the CBT and glandularity values of the equivalent breast were 4.1 cm and 65%, respectively, for the age group 30-49 yr and 4.4 cm and 44%, respectively, for the age group 50-69 yr. CONCLUSIONS: The average thickness of PMMA slabs producing the same exposure factors as observed in a large group of Taiwanese women is less than that reported for American women. The results from this study can provide useful information for determining a suitable thickness of PMMA for mammographic dose survey in Taiwan. The equivalence of PMMA slabs and the breasts of Taiwanese women is provided to allow average glandular dose assessment in clinical practice.

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OBJECTIVE: The currently used model breast for mammographic dosimetry assessment lacks the flexibility to change dimensions. The aim of this study was to develop an adjustable model breast for mammographic dosimetry assessment of Taiwanese women. MATERIALS AND METHODS: A retrospective review of 4226 craniocaudal (CC) views was conducted. The geometry of the model breast was defined as a semielliptical cylinder. Breast parameters, including compressed breast thickness, chest wall-to-nipple distance, compressed breast width, and percentage glandular content, were measured and analyzed. To validate the adjustable model breast, 44 mammograms were obtained. The expected values from the adjustable model breast were compared with the measured values. RESULTS: The average values of compressed breast thickness, chest wall-to-nipple distance, compressed breast width, and percentage glandular content of the women studied were 4.1 cm, 6.9 cm, 16.9 cm, and 54%, respectively. Variations of chest wall-to-nipple distance, compressed breast width, and percentage glandular content can be expressed as functions of compressed breast thickness, and the adjustable model breast developed was based on compressed breast thickness. The average area of the CC view obtained is a factor of 0.81 lower than that defined by the American College of Radiology protocol. For validation, the difference in average values between the expected and measured did not exceed 0.5 cm in breast dimensions and 6% in percentage glandular content. CONCLUSION: Compressed breast thickness is useful for quantifying dimensions and percentage glandular content of a model breast. The adjustable model breast developed in this study can offer greater flexibility in the determination of breast dimensions for mammographic dosimetry assessment of Taiwanese women.

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The aim of this study was to investigate the bone status of hemodialysis patients and identify factors that have influence on bone quality. Four hundred eighty-nine subjects (213 males and 276 females) on maintenance hemodialysis and 696 healthy subjects (309 men, 387 women) were enrolled in this study. Speed of sound (SOS), broadband ultrasound attenuation (BUA) and quantitative ultrasound index (QUI) were assessed by quantitative ultrasound (QUS) at the right calcaneus in both groups. Serum levels of intact parathyroid (iPTH), total alkaline phosphatase (ALP), calcium and phosphate were measured to determine their influence on bone status in hemodialysis patients. All QUS parameters were significantly lower in hemodialysis patients than in controls (p < 0.0001). Stepwise multiple linear regression analysis in male patients indicated that age, weight, calcium-phosphate product and ALP were significant predictors of QUS parameters (adjusted R(2) = 0.15 in SOS; adjusted R(2) = 0.17 in BUA and QUI). In female patients, same findings including number of parity were observed in SOS only (adjusted R(2) = 0.25 in SOS). In postmenopausal patients, the duration of menopause was significant negatively correlated with all QUS parameters (p < 0.01). In conclusion, patients on maintenance hemodialysis had additional risk of bone loss. Advanced age, low body weight, high calcium-phosphate product and high ALP level were important risk factors for deterioration of bone quality.

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PURPOSE: 4-[(18)F]-ADAM is a potent serotonin transport imaging agent. We studied its toxicity in rats and radiation dosimetry in monkeys before human studies are undertaken. METHODS: Single and multiple-dosage toxicity studies were conducted in Sprague-Dawley rats. Male and female rats were injected intravenously with 4-F-ADAM as a single dose of 1,023.7 microg/kg (1,000 times the human dose) or as five consecutive daily doses of 102.37 microg/kg (100 times the human dose). PET/CT scans were performed in seven Formosa Rock monkeys (four males and three females) using a Siemens Biograph scanner. After injection of 4-[(18)F]-ADAM (182+/-8 MBq), a low dose CT scan and a series of eight whole-body PET scans were performed. Whole-body images were acquired in 3-D mode. Time-activity data of source organs were used to calculate the residence times and estimate the absorbed radiation dose using OLINDA/EXM software. RESULTS: In the rats neither the single dose nor the five daily doses of 4-F-ADAM produced overt adverse effects clinically. In the monkeys the radiation doses received by most organs ranged between 7.1 and 35.7 microGy/MBq, and the urinary bladder was considered to be the critical organ. The effective doses extrapolated to male and female adult humans were 17.4 and 21.8 microSv/MBq, respectively. CONCLUSION: Toxicity studies in Sprague-Dawley rats and radiation dosimetry studies in Formosa Rock monkeys suggested that 4-[(18)F]-ADAM is safe for use in human PET imaging studies.

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An improved synthesis of N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM, 2) as a potent serotonin transporter (SERT) imaging agent is described. Molecular orbital (MO) calculation predicts that N,N-dimethyl-2-(2-nitro-4-trimethylammoniumtrifluoromethanesulfonylphenylthio)benzamide (8) is probably a better precursor than N,N-dimethyl-2-(2,4-dinitrophenylthio)benzylamine (1) for preparing 2. Radioligand 2 was synthesized by the reaction of either precursor 1 or precursor 8 with K[(18)F]/K(2.2.2) at 120 degrees C followed by reduction with BH(3) at 80 degrees C. The radiochemical yield (EOB) of 2 synthesized from precursor 1 and 8 was 5.7+/-2.4% (n=6) and 14.8+/-4.0% (n=5), respectively, in a synthesis time of 120 min from EOB. The specific activity of 2 was 3 Ci/micromol or 111 GBq/micromol (EOB). Thus, this new synthetic method has significantly improved the radiochemical yield of 4-[(18)F]-ADAM and makes this radioligand more accessible to PET Centers without a cyclotron.

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Small cell carcinoma of the uterine cervix (SCCUC) is an uncommon, aggressive disease accounting for less than 5% of all cervical cancers. Due to its rarity, definitive treatment strategies have not been developed. Our aim was to analyze the clinical factors, treatment modalities, sites of relapse, and overall survival of women with early stage SCCUC and thus determine prognostic factors. The clinical records of 18 women diagnosed with stage IB1 to IIA SCCUC were reviewed, and patient characteristics and treatment modalities were analyzed to determine the prognostic factors for disease-free survival (DFS) and overall survival (OS). DFS and OS were 39% and 44% at 2 years. Lymph node metastasis was a significant prognostic factor of DFS. International Federation of Gynecology and Obstetrics (FIGO) stage and lymph node metastasis were significant prognostic factors of OS as determined by multivariate analysis (p < 0.05). Radical hysterectomy followed by adjuvant chemotherapy resulted in higher 2-year survival rates compared to radical hysterectomy followed by adjuvant radiotherapy (62.5% vs. 16.7%); however, the difference was not statistically significant due to the small sample size. FIGO stage and lymph node metastasis are significant indicators of OS in patients with early stage SCCUC. Further larger scale analysis is warranted to determine whether adjuvant chemotherapy may facilitate a better prognosis than adjuvant radiotherapy.

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The effect of cigarette smoking in relation to bone mineral density (BMD) remains inconclusive, especially in middle-aged men. This cross-sectional study was conducted to examine the effect of smoking on BMD in 837 healthy Taiwanese males (532 never-smokers, 258 current smokers, 47 former smokers; aged 46-64 yr), recruited at their routine health examination. Subjects with suspected conditions affecting bone metabolism or receiving any medications affecting bone metabolism were excluded. BMD of the lumbar spine (LSBMD) and femoral neck (FNBMD) was measured with dual-energy X-ray absorptiometry. After adjustment for confounding variables (age, weight, physical activity, alcohol consumption, and caffeine intake), we found that the mean value of LSBMD was significantly (2.9%) lower in current smoker compared with never-smokers (p=0.024), but no significant difference was observed in FNBMD. No statistically significant association was observed between former smokers and never-smokers in any of the BMD sites, indicating that quitting smoking did have a positive effect on bone density. Compared with never-smokers, current heavy smokers who consumed at least 20 cigarettes/d (n=94) had 3.8% lower LSBMD (p=0.04), but no significant difference was observed in FNBMD. In the correlation analysis, the duration of smoking was negatively associated with LSBMD (r=-0.166, p=0.004), but no association was shown in FNBMD. Our results suggested that both smoking status and duration of smoking were deleterious factors on the bone density of the lumbar spine, and the effect was cumulative with duration and quantity.

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Activity concentrations and distributions of natural and man-made radionuclides in soil samples collected around nuclear power plant IV, Taiwan, were investigated for five years to assess the environmental radioactivity and characterisation of radiological hazard prior to commercial operation. The activity concentrations of radionuclides were determined via gamma-ray spectrometry using an HPGe detector. Data obtained show that the average concentrations of the (238)U and (232)Th series, and (40)K, were within world median ranges in the UNSCEAR report. The (137)Cs ranged from 2.46 +/- 0.55 to 12.13 +/- 1.31 Bq kg(-1). The terrestrial absorbed dose rate estimated by soil activity and directly measured with a thermoluminescence dosemeter (excluding cosmic rays), and the annual effective doses, were 45.63, 57.34 nGy h(-1) and 57.19 microSv, respectively. Experimental results were compared with international recommended values. Since the soil in this area is an important building material, the mean radium equivalent activity, external and inhalation hazard indices and the representative level index using various models given in the literature for the study area were 98.18 Bq kg(-1), 0.27, 0.34 and 0.73, respectively, which were below the recommended limits. Analytical results demonstrate that no radiological anomaly exists. The baseline data will prove useful and important in estimating the collective dose near the new nuclear power plant under construction in Taiwan.

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Extraction chromatographic separation techniques based on U/TEVA and TEVA resins were utilized to separate uranium and thorium isotopes in complex matrices from environmental samples. This approach has the advantages of ease of quantitative analysis, small sample size, an absence of mixed waste solvents, complete separation of U/Th isotopes, acceptable chemical yields and good energy resolution in the alpha spectrum. The procedure for analyzing alpha-emitting isotopes of uranium and thorium in geothermal water from Peito, Taiwan, is illustrated in detail. It involves sample pre-concentration, filtration and separation by highly selective extraction chromatographic resins, followed by electroplating and alpha-spectroscopy. The analytical results show a chemical recovery exceeding 55% for U and 65% for Th, respectively, under optimized conditions. The efficient and cost-effective use of recyclable columns makes the analytical methods simple, accurate, rapid, reliable and robust.

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We describe a rapid, simple, and highly efficient capillary electrophoresis (CE)-based method for the analysis of nanoparticles (NPs). In this study, we used the reversed electrode polarity stacking mode (REPSM) of CE to assess the feasibility of enhancing the detection of Au NPs and Au/Ag NPs, optimizing parameters such as the length of time for which the REPSM was applied, the concentrations of the buffer and the sodium dodecylsulfate (SDS) surfactant, and the pH. Under the optimized on-line enhancement conditions [buffer: SDS (40 mM) and 3-cyclohexylamino-1-propanesulfonic acid (CAPS; 10 mM) at pH 10.0; applied voltage: 20 kV; REPSM applied for 24s], the detection limits of the Au NPs and Au/Ag NPs increased by ca. 30- and 140-fold, respectively. In addition, when the NPs were subjected to on-line enhancement and separation by CE using diode array detection (DAD), this approach allowed chemical characterization of the NP species. Our results suggest that such CE analyses will be useful for accelerating the rates of fabrication and characterization of future nanomaterials.

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This paper demonstrates that capillary electrophoresis (CE) can be employed for characterizing the sizes of a series of Au/Ag core/shell nanoparticles (NPs). We effected the CE separation of Au/Ag core/shell NPs using a mixed buffer of sodium dodecyl sulphate (SDS) (40 mM) and 3-(cyclohexylamino)propanesulfonic acid (10 mM) at pH 9.7 and an applied voltage of 20 kV. A linear relationship (R(2)>0.99) existed between the electrophoretic mobilities and the sizes of the Au/Ag core/shell NPs within the diameter range from 25 to 90 nm; the relative standard deviations of these electrophoretic mobilities were <0.9%. From the good correlation between the results obtained by CE and those provided by scanning electron microscopy, we confirmed that this CE method is a valid one for characterizing the sizes of Au/Ag core/shell NP samples. In addition, when the Au/Ag core/shell NPs were separated through CE and detected using an on-line photodiode array detector, this approach allowed the chemical characterization of the NP species. This CE approach should allow the rapid and cost-effective characterization of a number of future nanomaterials.

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We demonstrate a novel approach for the production of patterned films of nanometer-sized Au/Ag bimetallic core/shell nanoparticles (NPs) on silicon wafers. In this approach, we first self-assembled monodisperse Au NPs, through specific Au...NH(2) interactions, onto a silicon substrate whose surface had been modified with a pattern of 3-aminopropyltrimethoxysilane (APTMS) groups to form a sandwich structure having the form Au NPs/APTMS/SiO(2). These Au NPs then served as seeds for growing the Au/Ag bimetallic core/shell NPs: we reduced silver ions to Ag metal on the surface of Au seeds under rapid microwave heating in the presence of sodium citrate. Energy-dispersive X-ray analysis confirmed that the Au/Ag bimetallic core/shell NPs grew selectively on the regions of the surface of the silicon wafer that had been patterned with the Au seeds. Scanning electron microscopy images revealed that we could synthesize well-scattered, high-density (>82%) thin films of Au/Ag bimetallic core/shell NPs through the use of this novel strategy. The patterned structures that can be formed are simple to produce, easily controllable, and highly reproducible; we believe that this approach will be useful for further studies of nanodevices and their properties.

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BACKGROUND: In current combined positron emission tomography/computed tomography (PET/CT) systems, high-quality CT images not only increase diagnostic value by providing anatomic delineation of hyper- and hypometabolic tissues, but also shorten the acquisition time for attenuation correction compared with standard PET imaging. However, this technique potentially introduces more radiation burden to patients as a result of the higher radiation exposure from CT. METHODS: In this study, the radiation doses delivered from typical germanium-based and CT-based transmission scans were measured and compared using an anthropomorphic Rando Alderson phantom with insertions of thermoluminescent dosimeters. Image geometric distortion and quantified uptake values in PET images with different manipulating CT acquisition protocols for attenuation correction were also evaluated. RESULTS: It was found that radiation doses during germanium-based transmission scans were almost negligible, while doses from CT-based transmission scans were significantly higher. Using a lower radiation dose, the CT acquisition protocol did not significantly affect attenuation correction and anatomic delineation in PET. CONCLUSIONS: This study revealed the relation between image information and dose. The current PET/CT imaging acquisition protocol was improved by decreasing the radiation risks without sacrificing the diagnostic values.

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This paper describes the feasibility of employing capillary electrophoresis (CE) to separate silver particles in nanometer regimes. We have found that the addition of an anionic surfactant, sodium dodecyl sulphate (SDS), to the running electrolyte prevents coalescence of the silver particles during the process, which improves the separation performance; the concentration of SDS required for optimal silver nanoparticle separation is ca. 20 mM. By monitoring the electropherograms using a diode-array detection (DAD) system, we have also investigated the separation of suspended silver nanorods with respect to their shapes. Our results demonstrate that the combination of CE and DAD is a powerful one for the separation and characterization of various silver nanoparticles.

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BACKGROUND: The purpose of our study was to evaluate the outcome of unresectable hepatocellular carcinoma (HCC) patients, who had either failed with or were unsuited for transcatheter arterial chemoembolization (TACE), treated with three-dimensional conformal radiation therapy (3DCRT) and to determine the prognostic outcome factors. METHODS: From September 1999 to March 2003, 44 patients with unresectable HCC underwent 3DCRT. Thirty-seven patients were male and seven female. Mean age was 62 years, ranging from 34 to 88. Eastern Cooperative Oncology Group (ECOG) performance status was 0 in 10 patients, 1 in 19 patients, and 2 in 15 patients. According to Child-Pugh classification for cirrhosis of the liver, 32 patients were in class A and 12 patients in class B. There were 14 patients with main portal vein thrombosis. Twenty patients had alpha-fetoprotein (AFP) level >400 ng/ml. Tumor size was <5 cm in 16 patients, 5-10 cm in 16 patients, and >10 cm in 12 patients. Thirty-two patients had tumors of confluent type, the remaining patients presented a single hepatic tumor. Serum hepatitis antigen markers were positive for type B in 35 patients and type C in nine patients. Twenty-one patients had Okuda Stage I, 22 patients Stage II, and one patient Stage III. According to the AJCC staging system (5th edition), eight patients were in Stage II (T2N0M0), 19 in Stage IIIA (T3N0M0) and 17 in Stage IVA (T4N0M0). RESULTS: An objective response was observed in 27 of 44 patients, giving a response rate of 61.4%. The survival rates at 1, 2 and 3 years were 60.5%, 40.3% and 32.0%, respectively. In the analysis of prognostic factors, Okuda stage, AJCC stage, portal vein thrombosis, pretreatment AFP level, and total dose of radiotherapy all had significant impact on survival. CONCLUSIONS: 3DCRT induced a substantial tumor response rate of 61.4% with survival rates at 1, 2 and 3 years of 60.5%, 40.3% and 32.0%, respectively, and a median survival time of 15.2 months in patients with unresectable HCC who had either failed with or were unsuited for TACE. The complications are acceptable and can be managed with conservative treatment. Although we do not know whether there is a survival benefit through the use of this treatment, 3DCRT seems to be a practical method of salvage for this subset of patients. Further study is warranted to evaluate the survival of such patients with and without this treatment.

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Correlation between behavioral parameters and fMRI responses can provide an advanced understanding of the neuronal processes. A lexical decision task was employed to examine the correlation between the reaction time (RT) and the temporal parameters in event-related BOLD responses. Word frequency was manipulated in the experiment. RTs for high-frequency, low-frequency and pseudowords were measured during fMRI (417 +/- 9 ms, 631 +/- 22 ms and 658 +/- 15 ms, respectively). For high-frequency words, RTs were significantly shorter than that for low-frequency and pseudowords (p < 0.0005). In the left inferior frontal region, the FWHM of the fMRI responses was significantly correlated with RT (p < 0.001), which may correspond to areas with sustained activation during the whole processing.

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Functional magnetic resonance imaging (fMRI) based on both perfusion and blood oxygenation level-dependent (BOLD) contrasts has been widely applied in spatiotemporal mapping of the human brain function. Temporal resolving power of fMRI is limited by the smoothed hemodynamic response function dispersed from the neuronal activity. In this study, temporal modulation transfer functions were utilized to quantify the resolving powers of perfusion and BOLD fMR signals in time domain. The impulse response function was determined using brief visual stimulations and event-related image acquisition schemes. An important feature of arterial spin labeling techniques is that quantitative perfusion and BOLD signals could be simultaneously acquired. This simultaneous BOLD response may arise from signals that are more proximal to capillary beds, and its temporal resolution may be different from that of the typical BOLD response. Therefore, we assessed and compared the temporal resolving capabilities of perfusion, simultaneous BOLD, and the typical BOLD response obtained from the gradient echo EPI pulse sequence. Full-width-at-half-maximums of perfusion and simultaneous BOLD measurements were significantly smaller than that of BOLD ones (4.3+/- 0.6 s vs 5.5 +/- 0.9 s, p<0.02 and 4.7 +/- 1.3 s vs 5.5 +/- 0.9 s, p<0.01, respectively). The corresponding temporal resolving powers of perfusion and simultaneous BOLD signals were statistically better than that of BOLD signals (0.23 +/- 0.03 Hz vs 0.17 +/- 0.02 Hz, p<0.01 and 0.21 +/- 0.04 Hz vs 0.17 +/- 0.02 Hz, p<0.01, respectively). Our results showed that the typical BOLD response was significantly smoothed from the perfusion response, thus resulting in a degraded temporal resolving power. However, results from the simultaneous BOLD and perfusion measurements were not significantly different. Biophysical implications of the experimental outcomes were further investigated using a computer simulation based on the Balloon model. By fitting the measured data into the model, an apparently longer transit time was obtained for the typical BOLD signal (1.7 s), comparing to that for the simultaneous BOLD one (1.2 s). Therefore, the simultaneous BOLD signal was regarded as less susceptible to the variations from local draining veins. Combining the simulation result with the significantly discrepant resolving powers between the two BOLD signals, we speculated that the blurred effects from large vessels played a predominant role that further reduced the temporal resolution of the BOLD-based fMRI from the perfusion response.

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In positron emission tomographic (PET) scanning, transmission measurements for attenuation correction are commonly performed by using external germanium-68 rod sources. Recently, combined PET and computed tomographic (CT) scanners have been developed in which the CT data can be used for both anatomical-metabolic image formation and attenuation correction of the PET data. The purpose of this study was to evaluate the difference between germanium- and CT-based transmission scanning in terms of their radiation doses by using the same measurement technique and to compare the doses that patients receive during brain, cardiac and whole-body scans. Measurement of absorbed doses to organs was conducted by using a Rando Alderson phantom with thermoluminescent dosimeters. Effective doses were calculated according to the guidelines in the International Commission on Radiation Protection Publication Number 60. Compared with radionuclide doses used in routine 2-[fluorine-18]-fluoro-2-deoxy-D-glucose PET imaging, doses absorbed during germanium-based transmission scans were almost negligible. On the other hand, absorbed doses from CT-based transmission scans were significantly higher, particularly with a whole-body scanning protocol. Effective doses were 8.81 mSv in the high-speed mode and 18.97 mSv in the high-quality mode for whole-body CT-based transmission scans. These measurements revealed that the doses received by a patient during CT-based transmission scanning are more than those received in a typical PET examination. Therefore, the radiation doses represent a limitation to the generalised use of CT-based transmission measurements with current PET/CT scanner systems.

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For diamond film the one-hit model that is used to interpret low-energy X-ray thermoluminescence (TL) will require some modifications. After the films were irradiated with a superficial X-ray machine with different peak voltages, a two-compartment model with three parameters, the target size, the microscopic saturation factor and the high-LET saturation factor, was used to more precisely describe the TL response to X-ray with energies down to 10 kV. The microdosimetric distribution was calculated using single-event Monte Carlo code developed by authors together with EEDL cross-section data library. Some mechanistic insight into the physical aspect of radiation interaction with solid detectors can be obtained. The sensitive size in diamond was found to be about 15 nm. The saturation of one group of sublevels combined with the activation of another group of sublevels caused the relative efficiency to have a local minimum near 20 keV. The relative efficiency becomes higher below 10 keV, which is similar to the increasing relative biological effectiveness when the linear energy transfer passing through a biological system increases. The similarity made this material to be a molecular-scale dosimeter in the future.

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The effect of light on polycrystalline diamond film that was produced by chemical vapor deposition and is used as a thermoluminescent dosimeter should be considered, although some researchers have indicated that such an effect was theoretically unlikely to happen. A 15 min exposure to a normal desk light bulb induces significant thermoluminescence (TL) comparable to a 0.5 Gy exposure to high-energy photons. This light-induced TL will be saturated within 2 h. The saturated TL intensity depends on the frequency of the light and the blue light dominates. The TL peak area at a temperature of 605 K is insensitive to light but is sensitive to high-energy photons. Another peak at about 410 K is caused by light only, because the TL from the ionization radiation at the same location is bleached. The effect of light could be easily distinguished by a numerical or an experimental method. Lamps with a green lampshade or pure red lights are suggested for use as indoor light sources. To reduce the effect of light, pre-heating treatment before readout is also suggested.

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