Survey on fan-beam computed tomography for radiotherapy: Current implementation and future perspectives of motion management and surface guidance devices.

Background And Purpose: This work reports on the results of a survey performed on the use of computed tomography (CT) imaging for motion management, surface guidance devices, and their quality assurance (QA). Additionally, it details the collected user insights regarding professional needs in CT for radiotherapy. The purpose of the survey is to understand current practice, professional needs and future directions in the field of fan-beam CT in radiation therapy (RT).

Survey on fan-beam computed tomography for radiotherapy: Imaging for dose calculation and delineation.

Background And Purpose: To obtain an understanding of current practice, professional needs and future directions in the field of fan-beam CT in RT, a survey was conducted. This work presents the collected information regarding the use of CT imaging for dose calculation and structure delineation.

Materials And Methods: An online institutional survey was distributed to medical physics experts employed at Belgian and Dutch radiotherapy institutions to assess the status, challenges, and future directions of QA practices for fan-beam CT.

Limited short-term effect of palliative radiation therapy on quantitative computed tomography-derived bone mineral density in femora with metastases.

Purpose: The aim of this study was to determine the effect of single fraction (SF) and multiple fraction (MF) radiation therapy (RT) on bone mineral density (BMD) in patients with cancer and bone metastases in the proximal femur. We studied this effect in the radiation field and within metastatic lesions, and differentiated between lytic, blastic, and mixed lesions.

Methods And Materials: This prospective cohort study comprised 42 patients with painful bone metastases, including 47 irradiated femora with 52 metastatic lesions in the proximal femur.

Two-dimensional measurement of photon beam attenuation by the treatment couch and immobilization devices using an electronic portal imaging device.

In our institution, an individualized dosimetric quality assurance protocol for intensity modulated radiotherapy (IMRT) is being implemented. This protocol includes dosimetric measurements with a fluoroscopic electronic portal imaging device (EPID) for all IMRT fields while the patient is being irradiated. For some of the first patients enrolled in this protocol, significant beam attenuation by (carbon fiber) components of the treatment couch was observed.

Detection of organ movement in cervix cancer patients using a fluoroscopic electronic portal imaging device and radiopaque markers.

Purpose: To investigate the use of a fluoroscopic electronic portal imaging device (EPID) and radiopaque markers to detect internal cervix movement.

Methods And Materials: For 10 patients with radiopaque markers clamped to the cervix, electronic portal images were made during external beam irradiation. Bony structures and markers in the portal images were registered with the same structures in the corresponding digitally reconstructed radiographs of the planning computed tomogram.

Clinical thermometry, using the 27 MHz multi-electrode current-source interstitial hyperthermia system in brain tumours.

Background And Purpose: In interstitial hyperthermia, temperature measurements are mainly performed inside heating applicators, and therefore, give the maximum temperatures of a rather heterogeneous temperature distribution. The problem of how to estimate lesion temperatures using the multi-electrode current-source interstitial hyperthermia (MECS-IHT) system in the brain was studied.

Materials And Methods: Temperatures were measured within the electrodes and in an extra catheter at the edge of a 4 x 4 x 4.

An electric field measurement system, using two-dimensional array of diodes.

In hyperthermia induced by electromagnetic applicators, one way to obtain information about the energy absorption is by measurement of electric field strength (E). This paper describes a system which can measure E-distributions, using a two-dimensional array of diodes. It was designed to be used on patient skin, during hyperthermia treatments of superficial tumours, providing additional data for applicator power control.

Temperature measurement errors with thermocouples inside 27 MHz current source interstitial hyperthermia applicators.

The multielectrode current source (MECS) interstitial hyperthermia (IHT) system uses thermocouple thermometry. To obtain a homogeneous temperature distribution and to limit the number of traumas due to the implanted catheters, most catheters are used for both heating and thermometry. Implications of temperature measurement inside applicators are discussed.

Renal volume measurements: accuracy and repeatability of US compared with that of MR imaging.

Purpose: To determine the accuracy and repeatability of ultrasonography (US) with the ellipsoid formula in calculating the renal volume.

Materials And Methods: The renal volumes in 20 volunteers aged 19-51 years were determined by using US with the ellipsoid formula and magnetic resonance (MR) imaging with the voxel-count method by two independent observers for each modality. The observers performed all measurements twice, with an interval between the first and second examinations.

Spatial steering with quadruple electrodes in 27 MHz capacitively coupled interstitial hyperthermia.

Purpose: The 27 MHz Multi Electrode Current Source (MECS) interstitial hyperthermia system uses probes consisting of multiple independent electrodes, 10-20 mm long, to steer the 3-D power deposition. Seven point thermocouples integrated into the probes provide matching 3-D temperature feedback data. To improve spatial steering the number of independent segments was increased; the feasibility and reliability of four independent electrodes integrated into a single probe were evaluated, with special attention to efficiency and to interference between separate electrodes.

Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomised trial.

Background: Percutaneous transluminal angioplasty (PTA) for ostial atherosclerotic renal-artery stenosis has poor results. Angioplasty with stent placement (PTAS) may be more effective. We undertook a randomised prospective study to compare PTA with PTAS in patients with ostial atherosclerotic renal-artery stenosis.

In vitro measurement of kidney size: comparison of ultrasonography and MRI.

In this in vitro study, the accuracy and repeatability of magnetic resonance imaging (MRI) and ultrasound (US) in assessing renal length and volume were determined. US and MR images of 20 cadaver pig kidneys were obtained twice and evaluated by two observers for each modality. The fluid displacement method provided the "gold standard.

Spiral CT angiography of the renal arteries: should a scan delay based on a test bolus injection or a fixed scan delay be used to obtain maximum enhancement of the vessels?

Purpose: The purpose of this work was to assess the optimal scan delay for spiral CT angiography (SCTA) of the renal arteries in achieving optimal vascular contrast enhancement and to compare the utility of a delay based on these bolus injection versus that of a fixed scan delay.

Method: Seventy patients underwent renal artery SCTA with a 140 ml bolus of contrast agent injected a 3 ml/s. In 35 patients (Group A), a fixed scan delay of 27 s was used; in the other 35 (Group B), the scan delay was based on the transit time (TTest) of a test bolus injection.

Angiotensin converting enzyme inhibitor-induced renal dysfunction in atherosclerotic renovascular disease.

Ischemic nephropathy due to bilateral renovascular disease (RVD) is increasingly recognized as cause of end-stage renal failure in the elderly, but a reliable non-invasive method of detection is nor available. Angiotensin converting enzyme inhibition (ACEi) may impair renal function in such patients, but a prospective study of its diagnostic validity has not been undertaken. We studied the effects of controlled exposure to ACEi on plasma creatinine in 108 patients at risk for severe bilateral atherosclerotic RVD, and compared the findings with subsequent angiography.

Renal artery stenosis: detection and quantification with spiral CT angiography versus optimized digital subtraction angiography.

Purpose: To compare spiral computed tomographic (CT) angiography with optimized digital subtraction angiography (DSA) for accurate detection and quantification of renal artery stenosis.

Materials And Methods: In 71 consecutive patients with possible renovascular hypertension, spiral CT angiography was performed of the renal arteries before DSA. Optimized DSA (performed with projection angles calculated from axial spiral CT source images) was used as the standard.

Renal artery origins: best angiographic projection angles.

Purpose: To determine the best projection angles for imaging the renal artery origins in profile.

Materials And Methods: A mathematical model of the anatomy at the renal artery origins in the transverse plane was used to analyze the amount of aortic lumen that projects over the renal artery origins at various projection angles. Computed tomographic (CT) angiographic data about the location of 400 renal artery origins in 200 patients were statistically analyzed.

Computed tomographic angiographic imaging of abdominal aortic aneurysms: implications for transfemoral endovascular aneurysm management.

Purpose: To describe anatomic features pertinent to patient selection and graft design for transfemoral endovascular aneurysm management (TEAM) of the infrarenal aorta using computed tomographic (CT) angiography.

Methods: A prospective noncomparative analysis of 102 spiral CT scans of the abdominal aorta of patients with abdominal aortic aneurysms was performed. From the original CT data set, slices were reconstructed perpendicular to the vessel axis (central lumen line) at a 10 mm interval.

Design of applicators for a 27 MHz multielectrode current source interstitial hyperthermia system; impedance matching and effective power.

In interstitial heating one of the main requirements for achieving a certain elevated temperature in a tumour is that the effective power per applicator (Peff), i.e. the power which is actually deposited in the tissue, is sufficiently high.

Complications during renal artery stent placement for atherosclerotic ostial stenosis.

Purpose: To describe short-term complications during stent placement for atherosclerotic renal artery ostial stenosis.

Methods: Sixty-one arteries in 50 patients were treated with Palmaz stents. Nineteen patients had a single functioning kidney, 23 had a bilateral stenosis, which was stented bilaterally in 11, and 8 had a unilateral stenosis.

Implications of using thermocouple thermometry in 27 MHz capacitively coupled interstitial hyperthermia.

The 27 MHz Multi Electrode Current Source (MECS) interstitial hyperthermia system uses segmented electrodes, 10-20 mm long, to steer the 3D power deposition. This power control at a scale of 1-2 cm requires detailed and accurate temperature feedback data. To this end seven-point thermocouples are integrated into the probes.

Renal artery origins: location and distribution in the transverse plane at CT.

Purpose: To determine the in situ location and distribution of the renal artery origins in the transverse plane with computed tomography (CT).

Materials And Methods: CT scans of the paired main renal arteries in 200 patients (89 men, 111 women) were retrospectively reviewed. The locations of the renal artery origins, defined on the basis of their optimal profile angles, and the angle between them were measured.

Spatial temperature control with a 27 MHz current source interstitial hyperthermia system.

Purpose: This article gives an overview of the properties of a 27 MHz current source interstitial hyperthermia system, affecting temperature uniformity.

Methods And Materials: Applicators can be inserted in standard flexible afterloading catheters. Maximum temperatures are measured with seven-point constantan-manganin thermocouple probes inside each applicator.

CT-angiography of abdominal aortic aneurysms after transfemoral endovascular aneurysm management.

Objective: To evaluate short-term effect of Transfemoral Endovascular Aneurysm Management (TEAM) on aortic diameters and volumes after aneurysm exclusion, using CT-angiography.

Design: Analysis of preoperative, 1 week postoperative and 6 months postoperative CT measurements.

Setting: University Hospital.

Atherosclerotic renal artery stenosis: ostial or truncal?

Purpose: To evaluate a discrepancy between the location of renal artery stenoses on intraarterial digital subtraction angiographic (DSA) images and that on spiral computed tomographic (CT) angiograms.

Materials And Methods: The spiral CT angiograms and intraarterial DSA images of 40 consecutive patients with atherosclerotic renal artery stenoses were examined retrospectively. Stenoses were classified as truncal or ostial.