Energy response of radiophotoluminescent glass dosimeter for diagnostic kilovoltage x-ray beams

PurposeThis study aimed to investigate the energy response of a radiophotoluminescent glass dosimeter (RGD) for diagnostic kilovoltage x-ray beams by Monte Carlo (MC) calculations and measurements.MethodsThe uniformity and reproducibility of GD-352M (with Sn filter) and GD-302M (no filter) were tested with 45 RGDs in free air. Subsequently, the RGD response was obtained as a function of an Al-HVL using the parameter, quality index (QI), which is defined as the ratio of the effective energy (keV) to the maximum energy (keV) of the photons. The x-ray fluence spectra with QI of 0.4, 0.5, and 0.6 were set for tube voltages of 50 ~ 137.6 kVp. The RGD response was calculated in free air using the MC method and verified by the air kerma, K_air, measured using an ionization chamber.ResultsThe uniformity and reproducibility of the 45 RGDs were ± 2.3% and ± 2.7% for GD-352M and ± 0.7% and ± 1.6% for GD-302M at the one standard deviation level, respectively. The calculated RGD response was 0.965 to 1.062 at Al-HVL 2.73 mm or more for GD-352M and varied from 3.9 to 2.8 for GD-302M. Both RGD responses exhibited a good correlation with the Al-HVL for the given QI. K_air measured by RGDs for each beam quality with a QI of 0.5 was in the range of −5%~0.8% for GD-352M and −1.8%~3% for GD-302M, relative to the chamber measurements.ConclusionsThe RGD response was indicated as a function of the Al-HVL for the given QI, and it presented a good correlation with the Al-HVL.     

Confidence interval estimation of the difference between two sensitivities to the early disease stage

Although most of the statistical methods for diagnostic studies focus on disease processes with binary disease status, many diseases can be naturally classified into three ordinal diagnostic categories, that is normal, early stage, and fully diseased. For such diseases, the volume under the ROC surface (VUS) is the most commonly used index of diagnostic accuracy. Because the early disease stage is most likely the optimal time window for therapeutic intervention, the sensitivity to the early diseased stage has been suggested as another diagnostic measure. For the purpose of comparing the diagnostic abilities on early disease detection between two markers, it is of interest to estimate the confidence interval of the difference between sensitivities to the early diseased stage. In this paper, we present both parametric and non‐parametric methods for this purpose. An extensive simulation study is carried out for a variety of settings for the purpose of evaluating and comparing the performance of the proposed methods. A real example of Alzheimer's disease (AD) is analyzed using the proposed approaches.     

Estructura diagnóstica y funcional de una consulta de alta resolución de nódulo tiroideo

Appearance of a thyroid nodule has become a daily occurrence in clinical practice. Adequate thyroid nodule assessment requires several diagnostic tests and multiple medical appointments, which results in a substantial delay in diagnosis. Implementation of a high-resolution thyroid nodule clinic largely avoids these drawbacks by condensing in a single appointment all tests required for adequate evaluation of thyroid nodule. This paper reviews the diagnostic and functional structure of a high-resolution thyroid nodule clinic.     

Médicaments radiopharmaceutiques : du diagnostic au théranostique des tumeurs neuroendocrines

Neuroendocrine tumors (NET) are a heterogeneous group originating from endocrine cells, which have the ability to develop themselves on various organs. Most of NET are well differentiated and have the capacity to produce different hormones and biogenic amines. NETs usually appear sporadically and can also be associated with different syndromes (multiple endocrine neoplasia). For the majority of NETs, surgical resection is the treatment of choice requiring the precise location of the tumor before surgery as well as the determination of the stage, followed by monitoring the progression of the disease. In the diagnostic process, nuclear medicine with molecular imaging plays a fundamental role. The secretory functions of these tumors enable the use of molecular imaging by targeting specific metabolic pathways or receptors. In addition, nuclear medicine also plays an important role in the field of therapy by replacing in one radiopharmaceutical drugs, the imaging suited radionuclide by replacing with a radionuclide emitting radiation suitable for therapy, also called vectorized internal radiotherapy. The activity of nuclear medicine, which enables diagnosis and treatment to be carried out using the same structures specific to the molecular targets of neuroendocrine tumors, is fully integrated into the new theragnostic approach, and constitutes one of its main pillars. The objective of this work is to describe the molecular targets expressed by NETs and corresponding radiopharmaceuticals, validated for human use (diagnosis and therapy).