Objective: To assess the average glandular doses (AGD) from full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT). Material and Methods: Radiographic exposure parameters target/filter, tube voltage, and tube current were collected from 50 patients. Patient information including age, breast thickness, entrance surface air kerma (ESAK) and AGD from the monitor display were also recorded. The tube outputs (tube voltage and tube loadings) at the reference points in both FFDM and DBT modes were measured. The AGD was calculated from ESAK by using the correction factors following the Technical Report Series no. 457 protocol. For the DBT mode, the AGD was calculated and corrected for the X-ray gantry rotation following the Dance et al. method. Results: The radiation doses to breasts in terms of ESAK and AGD from FFDM were 4.97±2.29 and 1.36±0.48 milligray (mGy) respectively. The third quartiles were 6.5 mGy and 1.67 mGy, findings which were lower than the standard Dose Reference Levels reported by the International Atomic Energy Agency recommendation (AGD 3 mGy/view for standard breast thickness with grid). For the DBT mode, ESAK and AGD were 6.49±2.10 mGy and 1.63±0.51 mGy. The third quartiles were 7.68 mGy and 1.81 mGy which were more than the FFDM mode by 23.0% and 17.0%, respectively. Conclusion: This study found that the AGD received from the DBT mode was higher than from the FFDM mode. Patients who underwent combination modes of mammographic examination increasingly received AGD up to 1.74 mGy. However, the AGD in our institute was still lower than the standard AGD recommendations.

Introduction In this study, we aimed to investigate the feasibility of gadoxetate low‐temporal resolution (LTR) DCE‐MRI for voxel‐based hepatic extraction fraction (HEF) quantification for liver sparing radiotherapy using a deconvolution analysis (DA) method. Methods The accuracy and consistency of the deconvolution implementation in estimating liver function was first assessed using simulation data. Then, the method was applied to DCE‐MRI data collected retrospectively from 64 patients (25 normal liver function and 39 cirrhotic patients) to generate HEF maps. The normal liver function patient data were used to measure the variability of liver function quantification. Next, a correlation between HEF and ALBI score (a new model for assessing the severity of liver dysfunction) was assessed using Pearson's correlation. Differences in HEF between Child‐Pugh score classifications were assessed for significance using the Kruskal–Wallis test for all patient groups and Mann–Whitney U ‐test for inter‐groups. A statistical significance was considered at a P ‐value <0.05 in all tests. Results The results showed that the implemented method accurately reproduced simulated liver function; root‐mean‐square error between estimated and simulated liver response functions was 0.003, and the coefficient‐of‐variance of HEF was <20%. HEF correlation with ALBI score was r = −0.517, P < 0.0001, and HEF was significantly decreased in the cirrhotic patients compared to normal patients ( P < 0.0001). Also, HEF in Child‐Pugh B/C was significantly lower than in Child‐Pugh A ( P = 0.024). Conclusion The study demonstrated the feasibility of gadoxetate LTR‐DCE MRI for voxel‐based liver function quantification using DA. HEF could distinguish between different grades of liver function impairment and could potentially be used for functional guidance in radiotherapy.

Objective: Intratumoral heterogeneity is associated with poor outcomes in head and neck cancer (HNC) patients owing to chemoradiotherapy resistance.[ 18 F]-FDG positron emission tomography (PET) / Magnetic Resonance Imaging (MRI) provides spatial information about tumor mass, allowing intratumor heterogeneity assessment through histogram analysis. However, variability in quantitative PET/MRI parameter measurements could influence their reliability in assessing patient prognosis. Therefore, to use standardized uptake value (SUV) and apparent diffusion coefficient (ADC) parameters for assessing tumor response, this study aimed to measure SUV and ADC's variability and assess their relationship in HNC. Methods: First, ADC variability was measured in an in-house diffusion phantom and in five healthy volunteers. The SUV variability was only measured with the NEMA phantom using a clinical imaging protocol. Furthermore, simultaneous PET/MRI data of 11 HNC patients were retrospectively collected from the National Cyclotron and PET center in Chulabhorn Hospital. Tumor contours were manually drawn from PET images by an experienced nuclear medicine radiologist before tumor volume segmentation. Next, SUV and ADC's histogram were used to extract statistic variables of ADC and SUV: mean, median, min, max, skewness, kurtosis, and 5 th , 10 th , 25 th , 50 th , 75 th , 90 th , and 95 th percentiles. Finally,the correlation between the statistic variables of ADC and SUV,as well as Metabolic Tumor volume and Total Lesion Glycolysis parameters was assessed using Pearson's correlation. Results: This pilot study showed that both parameters' maximum coefficient of variation was 13.9% and 9.8% in the phantom and in vivo, respectively. Furthermore, we found a strong and negative correlation between SUV max and ADV med (r = −0.75, P = 0.01). Conclusion:The SUV and ADC obtained by simultaneous PET/MRI can be potentially used as an imaging biomarker for assessing intratumoral heterogeneity in patients with HNC. The low variability and relationship between SUV and ADC could allow multimodal prediction of tumor response in future studies.

Objective: The main purpose of this study was to investigate the typical dose for standard-sized patients in chest (posteroanterior; PA) and abdomen (anteroposterior; AP) digital radiography.Material and Methods: The air kerma was measured by the ionization chamber (Radical Corporation, model 10X6-6) in X-ray equipment manufactured by General Electric Healthcare Definium 8000 System for different kilovoltage peak (kVp) settings in each X-ray examination. The entrance surface air kerma (ESAK) was determined in 422 mediumsized patients in different projections: chest (PA) and abdomen (AP), according to the recommended protocol of the International Atomic Energy Agency Technical Report Series Number 457 (Technical Reports Series No. 457 “Dosimetry in Diagnostic Radiology: An International Code of Practice).Results: The mean entrance surface air kerma values for chest (PA) radiography in female and male patients were 0.08 milligray (mGy) and 0.09 mGy, respectively and for abdomen (AP) radiography for both genders were 0.98 mGy and 1.06 mGy, respectively.Conclusion: The mean entrance surface air kerma values of this study were less than the diagnostic reference levels from the IAEA 1996, Korea 2007, United Kingdom 2010 and Japan 2015, in all projections. Patient doses (ESAK) in chest (PA) and abdomen (AP) digital radiography at Chulabhorn Hospital were less than the other guidelines, because of the use of a high kVp technique for the chest and the automatic exposure control for the abdomen. Furthermore, Thai people are smaller than Westerners. We studied in digital radiography only that literally provides lowest radiation dose compares with screen film and computed radiography.