Semi-quantification of the minimum detectable difference of imaging quality of gamma camera SPET for four radionuclides via an innovative PMMA phantom with a V-shaped slit: interpretation of a feasibility study.

OBJECTIVE: An indigenous polymethyl metacrylate (PMMA) phantom with a V-shaped slit and a correlated technique for semi-quantifying the minimum detectable difference (MDD) of single photon emission tomography (SPET) via gamma camera scanning are proposed and validated using four radionuclides. MATERIALS AND METHODS: Radio-actinide solutions of gallium-67 (67Ga), technetium-99m (99mTc), iodine-131 (131I) and thallium-201 (201Tl) were diluted to 11c.c. and thoroughly injected into the continuous zig zag slit of the PMMA phantom. Either depth or edge of the slit between two lines of the V-shape was customized from deep or wide to change into shallow or narrow gradually. Thus, the quantified MDD could be easily evaluated, according to the revised Student's t-test evaluation. The revised Student's t-test was calculated by both full width at half maximum (FWHM) and edge width between two adjacent peaks that were acquired from the original data matrix of SPET. The derived MDD was indicated as for radionuclide, depth, width in mm: For 67Ga, 2.9, 2.13, for 99mTc, 2.5, 0.66, for 131I, 4.7, 2.38 and for 201Tl, 3.3, 2.00, respectively. RESULTS: Technetium-99m had the highest and 131I had the lowest MDD among the four radionuclides. Furthermore, two adjacent peaks of 67Ga could be easily identified with fewer counts than for 201Tl (depth, 2.9 vs. 3.3mm), but its MDD was poorer (width: 2.13 vs.2.00mm). The revised Student's t-test analysis proved to be an acceptable technique for the MDD identification. CONCLUSION: The proposed new combination of PMMA phantom with a V-slit and the revised Student's t-test proved to be instrumental in the MDD of SPET optimization analysis.

Taguchi's analysis to optimize descending aortography for patent ductus arteriosus, with clinical verification.

OBJECTIVE: Taguchi's analysis was adopted to optimize the various factors referring to cardiac angiographic examination used to delineating ductus arteriosus in pediatric patients. SUBJECTS AND METHODS: Thirty-six pediatric patients, 9 male and 27 female, mean age of 6.5±4.7yrs, range 0.6 to 16.6 years were included in the study from January 2004 to April 2005. All patients had patent ductus arteriosus (PDA). Taguchi's L9 orthogonal array was used to generate nine different designs of angiographic levels. Four control factors were selected: a) body surface area (BSA), b) projection angle, c) catheter location, and d) the volume of contrast medium. Each factor was set to three different levels. Statistical analysis, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) were used to estimate the optimum level of each control factor and to analyze the effect of each factor. RESULTS AND CONCLUSION: The optimal combinations that obtained the highest image quality for PDA were: a) at <0.65m(2) of BSA, b) right anterior oblique (RAO) position at 30(o) plus cranial position (Cr) at 15(o) and lateral view, c) catheter location at T2-3 and d) contrast medium volume: 1.0cc/kg. The projection angle was found to be the most significant factor to delineate ductus arteriosus using the ANOVA test and was not influenced by other factors. The setting of RAO at 30(o) plus Cr at 15(o) and the LAT view obtained the optimal image quality for PDA during descending aortography.

Evaluation of the occupational X-rays dose of the medical staff in a cardiac catheterization laboratory using an acrylic phantom and semiconductor dosimeter.

OBJECTIVE: The occupational X-rays doses of medical staff in a cardiac catheterization laboratory were evaluated. METHODS: Four customized acrylic phantoms were used to simulate a patient, medical doctor, assistant, and radiologist to evaluate the in-situ X-rays exposure dose using semiconductor dosimeters. The exposure dose was measured under three scenarios that were preset to imply: no shielding, moderate shielding and complete shielding for the medical staff in the laboratory. The doses were applied by changing the dose area product (DAP) from 11,000 to 500,000mGy·cm(2) in 14 increments. RESULTS: The estimated annual occupational doses for doctors, assistants and radiologists in scenarios I, II, and III were: I) 35.03, 7.78, 1.95; II) 1.95, 0.78, 0.06; and III) 0.19, 0.10, 0.05cSv, respectively. The derived linear regression line of the exposure dose with respect to the DAP were extrapolated to obtain the minimum detectable level (MDL) of DAP for triggering the staff dosimeters. Accordingly, the minimum annual dose was estimated as 0.05cSv. Additional shielding provided measurable protection to the staff. The protective clothing used in scenarios II and III can reduce the original dose from scenario I to ∼3% (scenario II) and ∼0.5% (scenario III). The annual occupational dose also changed with the various X-rays energy settings. The annual dose increased to 126% when the preset X-rays energy was changed from 70 to 100kVp. CONCLUSION: The semiconductor dosimeter proved to be an adequate tool for measuring low doses and low dose rates under these circumstances. The dose can be reduce of I) 35.03, 7.78, 1.95; to II) 1.95, 0.78, 0.06 (∼3%); or III) 0.19, 0.10, 0.05 (∼0.5%)cSv, respectively according to different protective scenarios.

Enhanced acrylic gauge with five eccentric circles for optimizing CT angiography spatial resolution via Taguchi's methodology.

BACKGROUND: Cerebral examination via CTA is always the first choice for patients with unexpected brain injury or different types of brain lesions to detect ruptured hemangiomas, vascular infarcts, or other brain tissue lesions. OBJECTIVE: This study innovated the acrylic gauge with five eccentric circles for computed tomography angiography (CTA) analysis to optimize the spatial resolution via Taguchi's methodology. METHODS: The customized gauge was revised from the V-shaped slit gauge and transferred into five eccentric circles' slit gauge. The gauge was assembled with another six acrylic layers to simulate the human head. Taguchi's L18 orthogonal array was adopted to optimize the spatial resolution of CTA imaging quality. In doing so, six essential factors of CTA are kVp, mAs, spiral rotation pitch, FOV, rotation time of the CT and reconstruction filter, and each factor has either two or three levels to organize into eighteen combinations to simulate the full factor combination of 486 (21 × 35 = 486) times according to Taguchi's recommendation. Three well-trained radiologists ranked the gauge's 18 CTA scanned imaging qualities according to contrast, sharpness, and spatial resolution and derived the unique fish-bone-plot of six factors for further analysis. The optimal factor combination of CTA was proven by follow-up verification and ANOVA to obtain this study's dominant or minor factor. RESULTS: The optimal factor combination of CTA was A2 (120 kVp), B3 (200 mAs), C1 (Pitch 0.6), D2 (FOV 220 mm2), E1 (rotation time 0.33 s), and F3 (Brain sharp, UC). Furthermore, deriving a quantified MDD (minimum detectable difference) to imply the spatial resolution of CTA, a semiauto profile analysis program run in MATLAB and OriginPro was recommended to evaluate the MDD and to suppress the manual error in calculation. Eventually, the derived MDDs of the conventional and optimal factor combinations of CTA were 2.35 and 2.26 mm, respectively, in this study. CONCLUSION: Taguchi's methodology was found applicable for quantifying the CTA imaging quality in practical applications.

The optimum Ga-67-citrate gamma camera imaging quality factors as first calculated and shown by the Taguchi's analysis.

In this work gallium-67 ((67)Ga) gamma camera imaging quality was optimized using the Taguchi's analysis and a planar phantom. The acrylic planar phantom was LASER-cut to form groups of slits 1mm wide and 5mm deep, to determine the spatial resolution and contrast ratio that could be achieved in a (67)Ga citrate nuclear medicine examination. The (67)Ga-citrate solution was injected into the slits to form an active radioactive line source which was placed between regular acrylic plates for optimization. Then, nine combinations of four operating factors: L9 (3((4)), of the gamma camera imaging system were used and followed the Taguchi's analysis. The four operating factors were: a) the type of collimator in front of the NaI(Tl) detector, b) the region of interest of (67)Ga gamma rays spectrum, c) the scanning speed of NaI(Tl) detector head and d) the activity of (67)Ga. The original judged grade of the planar phantom image quality was increased 36% and factors a) and b) were confirmed to dominate. The cross interaction among factors was also discussed. Our results showed that the optimal factor settings of the gamma camera imaging system were verified by performing a routine nuclear medicine examination in ten cases. Nine cases showed the same optimal settings as estimated by three highly trained radio-diagnostic physicians. Additionally, the optimal setting yielded clearer images with greater contrast than did the conventional settings. In conclusion, this work suggests for practical use an optimized process for determining both the spatial resolution and the contrast ratio of a gamma camera imaging system using Taguchi's optimal analysis and a planar phantom. The Taguchi's method is most effective in targeting a single quality characteristic but can also be extended to satisfy multiple requirements under specific conditions by revising the definition of signal to noise ratio.

Treatment and mortality risk of older adults with non-small cell cancer in Taiwan: A population-based cohort study.

BACKGROUND: Older patients tend to have decreased physical functions and more comorbidities than younger patients. At present, the best management for very elderly patients with lung cancer is not known. In this study, we aimed to investigate treatment and mortality risk of older adults with non-small cell cancer (NSCLC) in Taiwan. METHODS: This study analyzed data from the Taiwan Cancer Registry database. Patients aged ≥80 years with newly diagnosed NSCLC between 2010 and 2017 were included. Treatment options were categorized as curative, palliative, and no treatment. Patients were followed up until death or December 31, 2020. Univariable and multivariable Cox proportional hazards models were used to estimate mortality risk, and Kaplan-Meier survival curves were drawn. RESULTS: A total of 11 941 patients, aged ≥80 years, with newly diagnosed NSCLC between 2010 and 2017 were identified from the Taiwan Cancer Registry and followed up until 2020. The mean age was 84.4 ± 3.7 years old, and 7468 (62.54%) were men. The Kaplan-Meier survival curves showed significant differences across the three treatment options (log-rank p < 0.001). Results from multivariate Cox regression demonstrated that patients on palliative treatment (adjusted HR: 0.52, 95% CI: 0.48-0.56, p < 0.001) and curative treatment (adjusted HR: 0.45, 95% CI: 0.42-0.48, p < 0.001) had a significantly lower mortality risk than those with no treatment. The subgroup analyses stratified by cancer stages also showed consistent findings. CONCLUSION: Elderly patients with NSCLC had significantly decreased mortality risk when receiving curative or palliative treatment compared with those without treatment. In the future, further studies are warranted to investigate complications and quality of life of elderly patients with NSCLC during palliative or curative treatment.

Potential risk quantification from multiple biological factors via the inverse problem algorithm as an artificial intelligence tool in clinical diagnosis.

BACKGROUND: The inverse problem algorithm (IPA) uses mathematical calculations to estimate the expectation value of a specific index according to patient risk factor groups. The contributions of particular risk factors or their cross-interactions can be evaluated and ranked by their importance. OBJECTIVE: This paper quantified the potential risks from multiple biological factors by integrated case studies in clinical diagnosis via the IPA technique. Acting as artificial intelligence field component, this technique constructs a quantified expectation value from multiple patients' biological index series, e.g., the optimal trigger timing for CTA, a particular drug in blood concentration data, the risk for patients with clinical syndromes. METHODS: Common biological indices such as age, body surface area, mean artery pressure, and others are treated as risk factors upon their normalization to the range from -1.0 to +1.0, with a non-dimensional zero point 0.0 corresponding to the average risk factor index. The patients' quantified indices are re-arranged into a large data matrix. Next, the inverse and column matrices of the compromised numerical solution are constructed. RESULTS: This paper discusses quasi-Newton and Rosenbrock analyses performed via the STATISTICA program to solve the above inverse problem, yielding the specific expectation value in the form of a multiple-term nonlinear semi-empirical equation. The extensive background, including six previous publications of these authors' team on IPA, was comprehensively re-addressed and scrutinized, focusing on limitations, stumbling blocks, and validity range of the IPA approach as applied to various tasks of preventive medicine. Other key contributions of this study are detailed estimations of the effect of risk factors' coupling/cross-interactions on the IPA computations and the convergence rate of the derived semi-empirical equation viz. the final constant term. CONCLUSION: The main findings and practical recommendations are considered useful for preventive medicine tasks concerning potential risks of patients with various clinical syndromes.

Inverse Problem Algorithm-Based Time-Resolved Imaging of Head and Neck Computed Tomography Angiography Contrast Kinetics with Clinical Testification.

This study mitigated the challenge of head and neck CT angiography by IPA-based time-resolved imaging of contrast kinetics. To this end, 627 cerebral hemorrhage patients with dizziness, brain aneurysm, stroke, or hemorrhagic stroke diagnosis were randomly categorized into three groups, namely, the original dataset (450), verification group (112), and in vivo testified group (65), in the Affiliated BenQ Hospital of Nanjing Medical University. In the first stage, seven risk factors were assigned: age, CTA tube voltage, body surface area, heart rate per minute, cardiac output blood per minute, the actual injected amount of contrast media, and CTA delayed trigger timing. The expectation value of the semi-empirical formula was the CTA number of the patient's left artery (LA). Accordingly, 29 items of the first-order nonlinear equation were calculated via the inverse problem analysis (IPA) technique run in the STATISTICA 7.0 program, yielding a loss function and variance of 3.1837 and 0.8892, respectively. A dimensionless AT was proposed to imply the coincidence, with a lower AT indicating a smaller deviation between theoretical and practical values. The derived formula was confirmed for the verification group of 112 patients, reaching high coincidence, with average ATavg and standard deviation values of 3.57% and 3.06%, respectively. In the second stage, the formula was refined to find the optimal amount of contrast media for the CTA number of LA approaching 400. Finally, the above procedure was applied to head and neck CTA images of the third group of 65 patients, reaching an average CTA number of LA of 407.8 ± 16.2 and finding no significant fluctuations.

Quantitative Prediction of SYNTAX Score for Cardiovascular Artery Disease Patients via the Inverse Problem Algorithm Technique as Artificial Intelligence Assessment in Diagnostics.

The quantitative prediction of the SYNTAX score for cardiovascular artery disease patients using the inverse problem algorithm (IPA) technique in artificial intelligence was explored in this study. A 29-term semi-empirical formula was defined according to seven risk factors: (1) age, (2) mean arterial pressure, (3) body surface area, (4) pre-prandial blood glucose, (5) low-density-lipoprotein cholesterol, (6) Troponin I, and (7) C-reactive protein. Then, the formula was computed via the STATISTICA 7.0 program to obtain a compromised solution for a 405-patient dataset with a specific loss function [actual-predicted]2 as low as 3.177, whereas 0.0 implies a 100% match between the prediction and observation via "the lower, the better" principle. The IPA technique first created a data matrix [405 × 29] from the included patients' data and then attempted to derive a compromised solution of the column matrix of 29-term coefficients [29 × 1]. The correlation coefficient, r2, of the regression line for the actual versus predicted SYNTAX score was 0.8958, showing a high coincidence among the dataset. The follow-up verification based on another 105 patients' data from the same group also had a high correlation coefficient of r2 = 0.8304. Nevertheless, the verified group's low derived average AT (agreement) (ATavg = 0.308 ± 0.193) also revealed a slight deviation between the theoretical prediction from the STATISTICA 7.0 program and the grades assigned by clinical cardiologists or interventionists. The predicted SYNTAX scores were compared with earlier reported findings based on a single-factor statistical analysis or scanned images obtained by sonography or cardiac catheterization. Cardiologists can obtain the SYNTAX score from the semi-empirical formula for an instant referral before performing a cardiac examination.

Optimizing cardiac CT angiography minimum detectable difference via Taguchi's dynamic algorithm, a V-shaped line gauge, and three PMMA phantoms.

BACKGROUND: Radiologists widely use the minimum detectable difference (MDD) concept for inspecting the imaging quality and quantify the spatial resolution of scans. OBJECTIVE: This study adopted Taguchi's dynamic algorithm to optimize the MDD of cardiac CT angiography (CTA) using a V-shaped line gauge and three PMMA phantoms (50, 70, and 90 kg). METHODS: The phantoms were customized in compliance with the ICRU-48 report, whereas the V-shaped line gauge was indigenous to solidify the cardiac CTA scan image quality by two adjacent peaks along the V-shaped slit. Accordingly, the six factors A-F assigned in this study were A (kVp), B (mAs), C (CT pitch), D (FOV), E (iDose), and F (reconstruction filter). Since each factor could have two or three levels, eighteen groups of factor combinations were organized according to Taguchi's dynamic algorithm. Three welltrained radiologists ranked the CTA scan images three times for three different phantoms. Thus, 27 (3 × 3 × 3) ranked scores were summed and averaged to imply the integrated performance of one specific group, and eventually, 18 groups of CTA scan images were analyzed. The unique signal-to-noise ratio (S/N, dB) and sensitivity in the dynamic algorithm were calculated to reveal the true contribution of assigned factors and clarify the situation in routine CTA diagnosis. RESULTS: Minimizing the cross-interactions among factors, the optimal factor combination was found to be as follows: A (100 kVp), B (600 mAs), C (pitch 0.200 mm), D (FOV 280 mm), E (iDose 5), and F (filter XCA). The respective MDD values were 2.15, 2.32, and 1.87 mm for 50, 70, and 90 kg phantoms, respectively. The MDD of the 90 kg phantom had the most precise spatial resolution, while that of the 70 kg phantom was the worst. CONCLUSION: The Taguchi static and dynamic optimization algorithms were compared, and the latter's superiority was substantiated.

Evaluating environmental radiations of the tomotherapy facility by optimizing full factorial design of the TLD technique.

BACKGROUND: In the last 40 years, the number of deaths due to cancer has been the highest in TaiwanOBJECTIVE: To optimize the readout system of the thermoluminescent dosimeter (TLD)-100H, the radiation rates among the Tomotherapy (TOMO) facility of the Department of Radiology Oncology of Chung Shan Medical University Hospital (CSMUH) were calculated with a 32 full factorial design (FFD). METHODS: A ten-month survey of the facility was employed using the sensitive and accurate TLD method. The TLD system was optimized for maximum temperature, heat rate, and preheat temperature of Harshaw 3500 reader. Eight analyzed groups with different factors were tested. RESULTS: The TOMO facility had significantly different radiation rates. The farther away from the gantry head, environmental radiation rates. The half value layer (HVL) was also determined. These results were compared with published. No significant contributions of environmental gamma radiations were detected except in the treatment room. CONCLUSIONS: Those were far below the occupational doses recommended by ICRP 60.

Metal concentrations in sediments of the Tamsui River, flows through central metropolitan Taipei.

This work analyzed metal concentrations and potential sources of sediment pollutants in the Tamsui River, Taiwan, by instrumental neutron activation analysis. The Tamsui River, the second longest of Taiwan's three major rivers, flows through metropolitan Taipei City in northern Taiwan and is renowned for its preserved mangrove wetlands. In total 11 elements Al, As, Br, Cs, Fe, La, Mg. Mn, Na, Sc, and Ti were identified in 24 samples taken from three sites upriver, the mangrove area and estuary during the spring of 2004. Specifically, the most abundant Al metal concentration was 15.6-0.92 mg/g adopted as standard reference in this study. Only few sites had As at the statistical meaning (>DL). Furthermore, arsenic concentrations fluctuated at roughly 0.67 +/- 0.09 mg/kg based on variations in background counts in various gamma-ray spectra. Elemental concentrations of these elements were compared with those in other nations, and discussed in the context of enrichment factors calculated for elements using the earth crust of various sediments as references, based on elemental values of Al.

TLD environmental monitoring of new scanner facilities at the Nuclear Medicine Department of the Taiwan Medical University Hospital.

OBJECTIVE: Single-photon emission computed tomography (SPECT) as well as dual energy X-ray absorptiometry (DXA) scanners were designed in July 2018 at the Nuclear Medicine Department (NM), of the Taiwan Medical University Hospital. These scanners emit substantial X-rays from the target, which are tungsten, iron. Therefore, patients undergoing SPECT and DXA diagnosis, in addition to medical personnel, are exposed to undesirable photon leakage. METHODS: Following administration of radiopharmaceuticals, patients become radioactive sources; thus, it is necessary to evaluate a possible increase in the environmental gamma exposure rates in the NM as a result of the operation of the new scanners. A three month evaluation of environmental radiation in the NM was performed using the accurate and sensitive TLD-100H approach, which gives an error rate less than 10%. RESULTS: Detected exposure radiation rates in the NM ranged from 0.12 ± 0.02 to 1.00 ± 0.15 mSv per month, indicating that the imaging room had significantly different radiation rates. The results were compared with previous results, and no significant contribution to the enhancement of environmental gamma radiation was detected, which remained far below the occupational dose recommended by ICRP 60. The minimum detectable dose (MDD) for environmental radiation is also discussed herein to demonstrate the reliability of TLD-100H. CONCLUSION: Recommendations were sent to the authorities of AEC-ROC to implement actions that could reduce doses at these high-dose locations to meet the ALARA principle.

Biokinetic model of radioiodine I-131 in nine thyroid cancer patients subjected to in-vivo gamma camera scanning: A simplified five-compartmental model.

A five-compartmental biokinetic model of I-131 radioiodine based on in-vivo gamma camera scanning results was developed and successfully applied to nine thyroid cancer patients who were administered 1,110 MBq I-131 in capsules for the residual thyroid gland ablation. The I-131 solution activity among internal organs was analyzed via the revised biokinetic model of iodine recommended by the ICRP-30 and -56 reports. Accordingly, a five-compartmental (stomach, body fluid, thyroid, whole body, and excretion) model was established to simulate the metabolic mechanism of I-131 in thyroid cancer patients, whereas the respective four simultaneous differential equations were solved via a self-developed program run in MATLAB. This made it possible to provide a close correlation between MATLAB simulation results and empirical data. The latter data were collected through in-vivo gamma camera scans of nine patients obtained after 1, 4, 24, 48, 72, and 168 hours after radioactive I-131 administration. The average biological half-life values for the stomach, body fluid, thyroid, and whole body of thyroid cancer patients under study were 0.54±0.32, 12.6±1.8, 42.8±5.1, and 12.6±1.8 h, respectively. The corresponding branching ratios I12, I23, I25, I34, I42, and I45 as denoted in the biokinetic model of iodine were 1.0, 0.21±0.14, 0.79±0.14, 1.0, 0.1, and 0.9, respectively. The average values of the AT dimensionless index used to verify the agreement between empirical and numerical simulation results were 0.056±0.017, 0.017±0.014, 0.044±0.023, and 0.045±0.009 for the stomach, thyroid, body fluid + whole body, and total, respectively. The results obtained were considered quite instrumental in the elucidation of metabolic mechanisms in the human body, particularly in thyroid cancer patients.

Bubble technique for evaluating effective dose of diagnostic X-rays: a feasibility study.

This study examined the feasibility of applying the bubble technique to evaluate effective dose for diagnostic X-rays. A BTI-GAMMA bubble detector from Bubble Technology Industries was used for gamma detection. A multi-slab acrylic (PMMA) phantom was fabricated to quantify the effective dose E based on an ICRP-60 report. Accordingly, the bubble detectors were evaluated through preliminary tests to ascertain both the reproducibility of specific X-ray doses and the linearity of multiple X-ray doses. Qualified bubble detectors were then inserted into a multi-slab acrylic phantom. The positions of the inserted bubbles closely corresponded with the position of represented organs or tissues. The effective dose E of X-ray was determined in 12 organ and tissue samples. The bubble detector was maintained at either 21.5 degrees C (for abdomen AP) or 22 degrees C (for chest PA) to optimize counting, and the assessed effective doses for males and females were 66.75 +/- 10.23 microSv and 66.47 +/- 9.89 microSv, respectively, for each chest PA X-ray exposure. The abdominal AP X-ray exposure doses were 1183.73 +/- 124.29 microSv and 976.70 +/- 120.13 microSv for males and females, respectively. Controlling and holding the bubble detector at an optimal ambient temperature during X-ray exposure was the most important issue in practical application, and the optimal temperature had to be adjusted slightly with incident X-ray to effectively suppress the largest bubbles to enable easy reading.

Estimation and clinical verification of the effective and skin doses for pediatric and adult patients undergoing the cardiac interventional examination using five PMMA phantoms and TLD/ionization chamber technique.

BACKGROUND: Effective and skin doses gain much attention since the cardiac catheterization laboratory (CCL) is a place where both patients and medical staff are exposed to X-ray or fluoroscopy environment and gain a cumulative dose during the cardiac interventional procedure. OBJECTIVE: These doses for pediatric and adult patients undergone cardiac interventional examination using five PMMA phantoms and thermoluminescence dosimeter (TLD)/ionization chamber technique were estimated in this work with the further clinical verification. METHODS: Five PMMA phantoms (10, 30, 50, 70, and 90 kg) were customized to represent baby, child, adult female, adult male, and overweight adult (by Asian complexion standards), respectively, in accordance with the ICRU-48 report. Each phantom could be disassembled into 31 plates to insert TLD chips for measuring X-ray exposed dose or assisted with an auxiliary plate to insert high-sensitivity ionization chamber for surveying low-energy fluoroscopy dose. RESULTS: The data acquired from five phantoms were integrated into four semi-empirical formulas, in order to fit the binary quadratic form "Dose = A⋅BMI2+B⋅DAP2+C⋅BMI+ D⋅DAP+E". The latter linked the X-ray and fluoroscopy effective/skin doses, respectively, with a high coefficient of determination R2(from 0.888 to 0.986). CONCLUSIONS: The model refinement with DAP share adjustment is envisaged.

Survival rate prediction of breast cancer patients of 0-IV stages with and without radiotherapy via a revised Taylor series expansion algorithm: A population-based study in Taiwan.

BACKGROUND: The morbidity of breast cancer has continuously achieved a global topicality. In particular, during the last decade several ten thousand female adults in Taiwan have been confirmed as breast cancer patients. OBJECTIVE: To predict the survival rate of breast cancer patients at various (0-IV) stages and provide efficient assessment of proposed radiotherapy for patients. METHODS: The prediction algorithm proposed is based on the revised hit and target model and implies the application of Taylor series expansion to the population-based survey dataset. The proposed algorithm features a specific function comprising a single simple exponential term exp⁡(-α⁢t) to imply the fundamental degradation of patient's health multiplied by an additional term P⁢(α⁢t), which specifies the recovery effect of a particular therapy. RESULTS: Its calculated values for breast cancer patients who undergone radiotherapy at different stages 0-IV were {0.0029, 0.0066, 0.0178, 0.0475, 0.1785} yr-1, respectively, while those for corresponding groups of patients with no radiotherapy were assessed as {0.0072, 0.0137, 0.0264, 0.0913, 0.2425} yr-1. CONCLUSIONS: The revised algorithm successfully interpreted the breast cancer patients' survival rate at stages 0-IV and evaluated the necessity of radiotherapy for patients at various stages as well.

Effective half life of iodine for five thyroidectomy patients using an in vivo gamma camera approach.

The effective half-life of radioactive iodine for (near) thyroidectomy patients was evaluated using an in vivo gamma camera approach. Five patients with post administered iodine for remnant ablation of thyroid were thoroughly scanned in vivo for one to four weeks. Derived data were analyzed in a MATLAB program to revise the ICRP recommended effective half-life and, thus, to offer a more reliable dose predication protocol from a health physics viewpoint. A quantitative index, AT (Agreement), was also introduced to specify the deviation between the actual measurement and the results fitted in MATLAB for each patient. The ATs were evaluated as 1.52 +/- 1.54 and 14.05 +/- 11.01 for the thyroid compartment and the remainder, re-spectively, indicating a slight discrepancy between the computed and practical results for the remainder. The actual effective half-life of iodine in the thyroid or the body fluid compartment shifted from 7.3d or 0.24 d to only 0.61 +/- 0.50 d or 0.49 +/- 0.23 d, respectively. Additionally, the integrated T(eff) for the remainder (both body fluid and whole body compartments) was still about 5.8d, since the body fluid and the whole body compartment was inseparable in real whole body scanning. The branching ratio from body fluid compartment to the thyroid and the excretion compartment also changed from 30% and 70% to 11.6 +/- 14.0% and 88.4 +/- 14.6%, respectively. The thyroid was the dominant compartment for a healthy person in the traditional biokinetic model. However, this dominant compartment was shifted to both thyroid and body fluid, based on analyses of the data following thyroidectomy, for the patients herein.

Optimizing left anterior oblique (LAO) caudal imaging in coronary angiography using the Taguchi method: A phantom study with clinical verification.

The aim of this work tried to optimize the spider view of the coronary angiograph for the clinical diagnosis of cardiac artery disease by cardiologists. A qualified spider view in coronary angiography must be exactly a "quasi-spider" image, which can help to diagnose a lesion in left main coronary artery and related regions. Coronary artery phantom was placed in a 75 mm-thick acrylic box to model a 70 kg human thorax. Eighteen groups of various combinations of operating factors of the X-ray facility were organized based on a Taguchi analysis. The six factors that govern the imaging quality of X-ray were (A) whether the X-rays emitted through a filter, (B, C) the Left Anterior Oblique (LAO) and Caudal Angulation (CAU) projection angles, (D) X-ray peak voltage (kVp), (E) X-ray pulse duration and current (mAs) and (F) distance between X-ray source and intensifying plate (SID). The obtained X-ray spider view images of each group were graded to determine the optimal settings; X-ray emitted without filter, 70° LAO, 30° CAU, 110 kVp, 1.5 mAs and 108 cm of SID. X-ray imaging quality optimal result was confirmed based on a clinical diagnosis of 43 patients, to prove the effectiveness of this study.

A quantitative evaluation of multiple biokinetic models using an assembled water phantom: A feasibility study.

This study examined the feasibility of quantitatively evaluating multiple biokinetic models and established the validity of the different compartment models using an assembled water phantom. Most commercialized phantoms are made to survey the imaging system since this is essential to increase the diagnostic accuracy for quality assurance. In contrast, few customized phantoms are specifically made to represent multi-compartment biokinetic models. This is because the complicated calculations as defined to solve the biokinetic models and the time-consuming verifications of the obtained solutions are impeded greatly the progress over the past decade. Nevertheless, in this work, five biokinetic models were separately defined by five groups of simultaneous differential equations to obtain the time-dependent radioactive concentration changes inside the water phantom. The water phantom was assembled by seven acrylic boxes in four different sizes, and the boxes were linked to varying combinations of hoses to signify the multiple biokinetic models from the biomedical perspective. The boxes that were connected by hoses were then regarded as a closed water loop with only one infusion and drain. 129.1±24.2 MBq of Tc-99m labeled methylene diphosphonate (MDP) solution was thoroughly infused into the water boxes before gamma scanning; then the water was replaced with de-ionized water to simulate the biological removal rate among the boxes. The water was driven by an automatic infusion pump at 6.7 c.c./min, while the biological half-life of the four different-sized boxes (64, 144, 252, and 612 c.c.) was 4.8, 10.7, 18.8, and 45.5 min, respectively. The five models of derived time-dependent concentrations for the boxes were estimated either by a self-developed program run in MATLAB or by scanning via a gamma camera facility. Either agreement or disagreement between the practical scanning and the theoretical prediction in five models was thoroughly discussed. The derived biokinetic model represented the metabolic mechanism in the human body and helped to solidify the internal circulatory system into concert with numerical verification.