The Hounsfield units into density conversion for a commercial treatment planning system (TPS) is discussed. The impact of an average calibration table provided by the manufacturer on computed doses was investigated when a customer calibration could not be included in the TPS. The maximum error determined on the computed monitor units per Gy was found to be about 2%, being below 1% on average. T...

Bone mineral density [BMD] generally correlates with bone strength. BMD testing is used to assess bone density and diagnose osteoporosis. The HU scale is a linear transformation of the original linear attenuation coefficient measurement in to one in which the radio-density of distilled water at standard pressure and temperature is defined as Zero Hounsfield Unit while the radio-density of air a...

To guarantee the reliability of densitometric data in clinical trials on pulmonary emphysema a quality control procedure is presented, to prevent that a measured progression in lung density could be reflected by a gradual change in the maintenance of the computed tomographic scanner. For that purpose, a foam phantom has been developed, which mimicks the densities of emphysematous lung tissue, f...

Introduction: The performance of computed tomography is routinely checked using phantoms, which are known as important diagnostic imaging tools. Depending upon the aim of the study, different phantoms are designed, while trying to satisfy certain levels of diversities in their application. Material and Methods: The present study describes the...

The goal of this study was to present a method for physiologic validation and show results for a comparison of the 4D-CT ventilation and SPECT ventilation or perfusion. A 4D-CT and a SPECT ventilation/perfusion (V/Q) (VSPECT and QSPECT) scans were acquired for a lung cancer patient. Two 4D-CT ventilation images were created using two metrics: Hounsfield unit (HU)-change (V4D-CT) and Jacobian de...

We report a patient who developed subarachnoid hemorrhage (SAH) just after coronary angiography (CAG) with non-ionic contrast media (CM) and minimal dose of heparin. The 55-year-old man had a history of acute ST elevation myocardial infarction that had been treated with primary percutaneous coronary intervention and was admitted for a follow-up CAG. The CAG was performed by the transradial appr...

Ophthalmic examination yielded the following results: vision: OD: 20/40, OS: 20/40; intraocular pressure (IOP): OD: 15 mm Hg, OS: 15 mm Hg. Eye position and motion were normal. Slit lamp examination showed a purple-hued cystic mass nasally of the left eye, extending to the orbit with clear verge and slight congestion (Figure 1). Orbital magnetic resonance imaging (MRI) revealed a mass in front ...

Radiologic assessment of cochlear implants can be limited because of metallic streak artifacts and the high attenuation of the temporal bones. We report on 14 patients with 18 cochlear implants (17 Med-El standard 31.5-mm arrays, 1 Med-El medium 24-mm array) who underwent flat panel CT with the use of high-resolution secondary reconstruction techniques. Flat panel CT depicted the insertion site...

Impact of the various kVp settings used during computed tomography (CT) simulation that provides data for heterogeneity corrected dose distribution calculations in patients undergoing external beam radiotherapy with either high-energy photon or electron beams have been investigated. The change of the Hounsfield Unit (HU) values due to the influence of kVp settings and geometrical distribution o...