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Purpose: To investigate the influence of translational and rotational errors on prostate intensity-modulated radiotherapy (IMRT) with an integrated boost to the tumor and to evaluate the effect of the use of an on-line correction protocol. Methods and Materials: For 19 patients, who had been treated with prostate IMRT and fiducial marker-based position verification, highly inhomogeneous IMRT plans, including an integrated tumor boost, were made using varying margins (2, 4, 6, and 8 mm). The measured translational and rotational errors were used to calculate the dose using two positioning strategies: an off-line and an on-line protocol to correct the translational shifts. The estimated dose to the targets and the organs at risk was compared with the intended dose. Results: Residual deviations after off-line correction led to statistically significant, but very small, reductions in dose coverage. Even when a 2-mm margin was used, the average reduction in dose to 99% of the volume was 1.4 ± 1.9 Gy for the tumor, 1.5 ± 1.5 Gy for the prostate without seminal vesicles (boost volume), and 4.3 ± 4.6 Gy, including the seminal vesicles (clinical target volume). Patients with large systematic rotational errors demonstrated a substantial decrease in dose, especially for the clinical target volume. If an on-line correction protocol was used, the average mean dose and dose to 99% of the volume of the targets improved. However, the extensive dose reduction for patients with large rotational errors barely recovered with on-line correction. Conclusion: For complex prostate IMRT with an integrated tumor boost, the use of an on-line correction protocol yields little improvement without the correction of rotational errors. [Copyright &y& Elsevier]

Purpose: To calculate the generic planning target margin (GPTM) for patients receiving radiation therapy (RT) for rectal cancer placed in a prone position with a customized cradle for small–bowel exclusion. Methods and Materials: A total of 25 consecutive rectal cancer patients were treated for 25 or 28 fractions in a prone position using a cradle to maximize small bowel exclusion. Treatment planning computed tomography (CT) scans were used to create orthogonally digitally reconstructed radiographs (DRRs) for portal image registration, which were compared with daily portal images from an electronic portal–imaging device (EPID). Translation values needed to align the DRRs and EPIDs were recorded for the superior to inferior (SI), right to left (RL), and anterior to posterior (AP) directions, and used to calculate the GPTM using the four–parameter model. Age, weight, and body mass index were tested compared with the setup variation using a Pearson correlation and a t test for significance. Gender versus setup variation was compared with a t test. Results: A total of 1,723 EPID images were reviewed. The GPTM was 10 mm superior, 8 mm inferior, 7 mm RL and 10 mm AP. Age and gender were unrelated to setup variation. Weight was significantly associated with systematic AP variation (p < 0.05). BMI was significantly associated with systematic SI (p < 0.05) and AP (p < 0.01) variation and random RL variation (p < 0.05). Conclusions: The GPTM for rectal cancer is asymmetric with a maximum of 10 mm in the superior, anterior and posterior dimensions. Body mass index may effect setup variation. Research using advanced treatment planning should include these margins in the planning target volume definition. [Copyright &y& Elsevier]

Data from pQCT sections at the forearm were examined to assess the impact of positioning on measurements. Two thousand five hundred fifty one scans were analysed. The results showed 25% of scans were not performed in the same anatomical location at follow-up when one section was scanned. These results have implications for accurate follow-up BMD measurements. pQCT of the distal radius is routinely performed using a single section of 2 mm thickness. Accurate positioning is essential to maximise long-term repeatability. We perform two adjacent sections which, permits us to select sections at baseline and follow-up that are in the most similar anatomical site for calculating longitudinal change. This study aimed to assess baseline and follow-up pQCT forearm data to examine variability and determine whether performing two sections, as opposed to one section, improved accuracy when monitoring long-term change in BMD. Two adjacent 1.2 mm pQCT radial sections were performed at: baseline n = 2,551 (1,896F:655M) and follow-up n = 335F. Baseline: difference between adjacent 1.2 mm forearm sections: total BMD 19.3 mg/cm3 (females) and 16.7 mg/cm3 (males); trabecular BMD 3.1 mg/cm3 (females) and 2.35 mg/cm3 (males); CSA 16.2 mm2 (females) and 17.7 mm2 (males) (all significant). Follow-up: percentage of scans at baseline and follow-up performed in the same anatomical location: one section performed—75%, two sections performed—95%. When performing a single section at the distal radius it is difficult to perform scans in the same anatomical location at visits. Performing two or more sections can overcome this problem in some individuals and provide more accurate BMD measurements. [ABSTRACT FROM AUTHOR]

The article focuses on the study which evaluates the effectiveness of lateral radiographic positioning techniques to acquire reliable and functional representation of sagittal balance. Sagittal alignment of the spine such as kyphosis, lordosis and sagittal vertical axis (SVA) is measured by positioning the reflective markers attached to the surface of the pelvis. It is stated that the movement of arms anterior to the spine is more appropriate on overall sagittal balance.

The article offers guidelines for interpretation of chest radiographs of the critically ill patients in intensive care units (ICUs). Particular focus is given to cardiopulmonary disorders diagnosed through chest radiographs. The normal position of monitoring devices and other line placements, including the endotracheal tube, nasogastric tube and pulmonary capillary wedge pressure monitors, are described. The definitions and characterizations of cardiopulmonary disorders including pneumothorax, pneumomediastinum and pleural effusions are provided.

Abstract: Purpose: To evaluate the efficiency of combining on-line and off-line corrections for the positioning of patients receiving external beam radiotherapy for prostate cancer. Materials and methods: Daily portal images were acquired during the treatment of 102 patients to verify and correct the position of the prostatic gland using implanted gold markers. In addition to an existing off-line procedure, on-line corrections were applied in the anterior–posterior (AP) direction only, to limit the increase in daily workload. The possible increase in workload of the combined correction procedure for on-line corrections in either two or three directions was further investigated by simulating the required position corrections for 500 treatments. Results: The combined correction procedure in AP-direction resulted in a systematic dispersion and random variation of 0.3mm (1 SD) and 1.0mm (1 SD), respectively. Application of off-line corrections during pre-treatment setup reduced the number of required on-line corrections from 22±4 (1 SD) to 17±4 (1 SD), at the cost of 1.4±1.0 (1 SD) off-line corrections. For on-line corrections in two or three directions, application of a combined on-line/off-line procedure did not noticeably reduce the number of setup corrections. Conclusions: The on-line procedure is feasible and significantly improves both systematic and random errors to below 1 mm with a limited impact on the workload and treatment time. The application of off-line setup corrections during pre-treatment patient positioning only marginally reduces the number of on-line setup corrections. [Copyright &y& Elsevier]

Abstract: Background and purpose: The Micropos 4DRT system is being developed to provide accurate, precise, objective, and continuous target localization during radiotherapy. This study involves the first in vivo use of the system, aiming to evaluate the localization accuracy of this electromagnetic positioning technique compared with radiographic localization and to assess its real-time tracking ability. Material and methods: An active positioning marker was inserted in the prostatic urethra of 10 patients scheduled to receive radiotherapy for localized prostate cancer. A receiving sensor plate (antennae system) was placed at a known position in the treatment tabletop. Initial in vivo system calibrations were performed in three subjects. Ten additional patients were then enrolled in a study arm that compared radiographic transponder location to radiotransponder location simultaneously acquired by the Micropos 4DRT system. Frontal and side radiographs were taken with the radiopaque transponder located at three different positions within the prostatic urethra. Results: The transponder insertions were all successful and without complications. Comparison of the transponder location as per the Micropos 4DRT system with the radiographic transponder localization showed an average (±SD) absolute and relative 3D difference of 2.7±1.2 and 1.7±1.0mm, respectively. Continuous transponder tracking capability was also demonstrated. Conclusions: Electromagnetic positioning using the Micropos transponder system is feasible in vivo. Evaluation of this novel non-ionizing localization system, in this study using a transponder positioned in the prostatic urethra, indicates transponder localization accuracy to isocenter comparable with X-ray localization of a radiopaque marker. [Copyright &y& Elsevier]

Radiographic interpretation and diagnosis of dental impactions and different associated pathology have long posed a challenge to the clinician. Dental impactions can occur due to pathologic or developmental factors, both of which can be evaluated more accurately using cone beam computed tomography (CBCT) imaging. Three-dimensional localization of the impacted teeth and determination of the type of impaction can be performed using the multiplanar reformats of the CBCT data, as well as three-dimensional reconstruction to give the clinician a sense of the position of the teeth in the bone and their relationship to their adjacent structures, In the event of treatment planning for extraction, the location of vital structures can be determined accurately. The advent of CBCT has been a monumental event for improving the diagnostic options and capabilities of the orthodontist. Familiarity and full utilization of its many options can provide the dentist with a valuable treatment planning tool. [Copyright &y& Elsevier]

Abstract: To date, Doppler myocardial imaging (DMI) is no longer an intriguing new research tool only, but is rather on the verge of becoming a routinely used diagnostic method in adult and pediatric cardiology. Clinical studies have proven its diagnostic relevance for global left and right ventricular function. Concerns about reliability and reproducibility of DMI functional analysis, however, rely on lacking standards for the acquisition and analysis of DMI parameters. This study focuses on the effect of sample volume positioning during the cardiac cycle on the absolute myocardial velocities. Our hypothesis was that systolic sample volume placement leads to altered diastolic measurements, and diastolic placement vice versa to altered systolic measurements, when compared with continuous systolic and diastolic tracking. The effect of tracking on intra- and interobserver variability was a second endpoint of the study. Twenty healthy women underwent color-coded Doppler myocardial imaging. Clips of three heart cycles were stored in digital format for off-line analysis, administering sector angles of approximately 30° and a mean frame rate of 280 frames per second. Using the Echopac software (GE, Germany), the sample volume was positioned immediately below the atrioventricular valvar annulus within the basal segments of the right and left ventricular free wall and the interventricular septum. Three conditions were investigated: conventional end-systolic or end-diastolic placement of the Doppler probe, or continuous tracking to the ideal position during systole or diastole. Descriptive statistics, intra and interobserver variabilities and Bland-Altman analyses were performed. Tracking revealed higher values of early diastolic myocardial velocities compared with measurements during systolic sample volume placement only, and higher systolic myocardial velocities, preejection acceleration and late diastolic myocardial velocities using diastolic sample volume placement. Inter and intraobserver reproducibility improved remarkably with the new procedure with the exception of isovolumic acceleration (IVA), which could not be reproduced satisfactorily at all. In summary, tracking is a promising method that helps to improve reproducibility of DMI-derived myocardial velocities. It helps to minimize the effect of changing myocardial velocities during the natural longitudinal cardiac movement, and should be considered as standard method during DMI. (E-mail: oberhoffer@sp.tum.de) [Copyright &y& Elsevier]

Background Currently used positioning landmarks for the lateral scapula and Y projections often yield inconsistent results and lead to repeats. Objective To determine whether new positioning landmarks can help radiographers position the lateral scapula and Y projections more accurately. Methods Following laboratory experimentation on dry bone specimens, a small pilot study was conducted in the clinical setting to test the new landmarks. Results Laboratory and clinical testing of the use of the acromial tip and superior angle of the scapula suggest that these landmarks are easier to use and improve accuracy of positioning. [ABSTRACT FROM AUTHOR]

Abstract  We asked whether radiographic angles and signs of hip osteoarthrosis differ between radiographs of the pelvis taken in standing and supine positions. We retrospectively reviewed the radiographs of 61 patients (72 hips) with developmental dislocation of the hip. The minimum followup after closed reduction was 15 years (mean, 44 years; range, 15–64 years). We used pelvic radiographs in supine and standing positions taken at the same time and determined the following parameters: minimal joint space width, acetabular roof obliquity (AC angle), depth of the acetabulum (ACM angle), and center-edge angle. Osteoarthrosis was assessed according to Kellgren and Lawrence. Two independent observers measured all radiographs manually with a goniometer. AC angle, center-edge angle, and minimum joint space width differed between the radiographs taken in supine and standing positions at followup, whereas osteoarthrosis grading and the ACM angle did not. The AC angle depended on patient position and predicted development of osteoarthrosis. The minimum joint space width was influenced by the radiographic position with greater values in the supine position. ACM angle and the osteoarthrosis grade according to Kellgren and Lawrence were unaffected by the patient’s position. Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Purpose: To compare two “four-dimensional” methods for image-guided target localization in the presence of respiration. Methods and Materials: Four-dimensional image guidance was performed with two methods. A respiration-correlated computed tomography (RCCT) was acquired on a CT simulator, and an average CT (AVG-CT) image was generated from the RCCT. A respiration-correlated cone-beam CT (RC-CBCT) and a free-breathing cone-beam CT (FB-CBCT) were acquired. The “RCCT method” consisted of calculating the mean target position on both the RCCT and RC-CBCT, registering the RCCT to the RC-CBCT, and determining the shift in the mean target position from the planned mean position. The “AVG-CT method” consisted of registering the AVG-CT to the FB-CBCT. The ability of each to measure the shift in the mean target position was compared, both in a respiratory phantom and in 8 patients. Results: In phantom, the RCCT and AVG-CT methods were able to measure the true mean target position to within 0.15 cm and 0.10 cm, respectively. In the patient study, the mean error between the methods was 0.13 cm (left–right), 0.14 cm (anterior–posterior), and 0.10 cm (cranio–caudal). The error was not observed to vary with tumor position or magnitude of tumor motion. Conclusions: Respiration may impact the on-line image guidance process. The RCCT method enables localization of the mean tumor position and measurement of changes in the motion pattern, whereas the AVG-CT method is simple, fast, and easily implemented. We found the methods to be nearly equivalent in detecting shifts in the mean tumor position. [Copyright &y& Elsevier]

Purpose: Motion-adapted radiotherapy with gated irradiation or tracking of tumor positions requires dedicated imaging techniques such as four-dimensional (4D) helical computed tomography (CT) for patient selection and treatment planning. The objective was to evaluate the reproducibility of spatial information for small objects on respiratory-gated 4D helical CT using computer-assisted volumetry of lung nodules in a ventilated ex vivo system. Methods and Materials: Five porcine lungs were inflated inside a chest phantom and prepared with 55 artificial nodules (mean diameter, 8.4 mm +/- 1.8). The lungs were respirated by a flexible diaphragm and scanned with 40-row detector CT (collimation, 24 x 1.2 mm; pitch, 0.1; rotation time, 1 s; slice thickness, 1.5 mm; increment, 0.8 mm). The 4D-CT scans acquired during respiration (eight per minute) and reconstructed at 0-100% inspiration and equivalent static scans were scored for motion-related artifacts (0 or absent to 3 or relevant). The reproducibility of nodule volumetry (three readers) was assessed using the variation coefficient (VC). Results: The mean volumes from the static and dynamic inspiratory scans were equal (364.9 and 360.8 mm3, respectively, p = 0.24). The static and dynamic end-expiratory volumes were slightly greater (371.9 and 369.7 mm3, respectively, p = 0.019). The VC for volumetry (static) was 3.1%, with no significant difference between 20 apical and 20 caudal nodules (2.6% and 3.5%, p = 0.25). In dynamic scans, the VC was greater (3.9%, p = 0.004; apical and caudal, 2.6% and 4.9%; p = 0.004), with a significant difference between static and dynamic in the 20 caudal nodules (3.5% and 4.9%, p = 0.015). This was consistent with greater motion-related artifacts and image noise at the diaphragm (p <0.05). The VC for interobserver variability was 0.6%. Conclusion: Residual motion-related artifacts had only minimal influence on volumetry of small solid lesions. This indicates a high reproducibility of spatial information for small objects in low pitch helical 4D-CT reconstructions. [ABSTRACT FROM AUTHOR]

The present paper illustrates our attempt to design and test the reproducibility of low-cost patient positioning devices prepared in-house in our radiotherapy department. Rigid thermocole boards with angulations, scales and support were designed as breast, pelvis and head positioning devices. Reproducibility and accuracy were tested by serial electronic portal imaging detector imaging. The positioning devices (with or without superimposed moulds) showed variations within 2-3 mm on serial treatment days which were within acceptable limits. It is therefore concluded that low-cost patient positioning devices for head, breast and pelvis (the common sites of treatments in radiotherapy) can be fabricated from available materials in-house. These have been shown to be resulting in accurate immobilization, can be customized for particular techniques and are considerably cheaper than commercially available solutions. [ABSTRACT FROM AUTHOR]

Rationale: Superimposition of the rims of the medial tibial plateau to within 1mm is an aim of fluoroscopic knee positioning protocols for osteoarthritic (OA) knee radiography and has also been proposed as a measure of quality for non-fluoroscopic methods.Objective: To evaluate the effect of tibial rim alignment (TRA) on reproducibility of joint space width (JSW) measurement, both were measured from radiographs taken with each tibial plateau at a range of angles determined by different non-fluoroscopic views.Methods: TRA and JSW measurements were taken from both knees of 100 OA patients each radiographed in fully extended, schuss/tunnel, and MTP views. Degree of TRA was compared with JSW reproducibility using correlation, and between groups defined both by the 1mm threshold and by TRA-defined quartiles.Results: JSW reproducibility was dependent on the degree of TRA in the fully extended and schuss/tunnel flexed knee views, although the use of the specific TRA threshold of 1mm was not supported. In the MTP view, JSW measurement was found to be highly reproducible across the full range of TRA values.Conclusion: These results contradict claims that TRA to within 1mm is essential for useful measurement of JSW. It is an arbitrary threshold, of use in quality control (QC) for protocols which explicitly require such alignment, and the choice of QC criteria for other protocols should be evaluated on a view-by-view basis. The results confirm previous studies showing the MTP view to afford highly reproducible JSW measurement. [ABSTRACT FROM AUTHOR]

Provides information on a method to minimize errors of laterality in medical radiography by knowing the exposure side of the image. Circumstances in which the lateral erroneous interpretation of an image occurs; Words that are applied to the surface of the screen facing the cassette front to positively identify the side of the image that received the exposure; Information on the way patients are positioned for radiographic exposures.

Patient motion during cardiac SPECT imaging can cause diagnostic imaging artifacts. We investigated the feasibility of monitoring patient motion using the Polaris motion-tracking system. This system uses passive infrared reflection from small spheres to provide real-time position data with vendor stated 0.35 mm accuracy and 0.2 mm repeatability. In our configuration, the Polaris system views through the SPECT gantry toward the patient's head. List-mode event data were temporally synchronized with motion-tracking data utilizing a modified Lab VIEW virtual instrument that we have employed in previous optical motion-tracking investigations. Calibration of SPECT to Polaris coordinates was achieved by determining the transformation matrix necessary to align the position of four reflecting spheres as seen by Polaris, with the location of Tc-99m activity placed inside the sphere mounts as determined in SPECT reconstructions. We have successfully tracked targets placed on volunteers in simulated imaging positions on the table of our SPECT system. We obtained excellent correlation (R² > 0.998) between the change in location of the targets as measured by our SPECT system and the Polaris. We have also obtained excellent agreement between the recordings of the respiratory motion of four targets attached to an elastic band wrapped around the abdomen of volunteers and from a pneumatic bellows. We used the axial motion of point sources as determined by the Polaris to correct the motion in SPECT image acquisitions yielding virtually identical point source full-width at half-maximum and full-width at tenth-maximum values, and profiled maximum heart wall counts of cardiac phantom images, compared to the reconstructions with no motion. [ABSTRACT FROM AUTHOR]

A position-sensitive γ-camera is being currently designed at IASA. This camera will be used experimentally (development mode) in order to obtain an integrated knowledge of its function and perhaps to improve its performance in parallel with an existing one, which has shown a very good performance in phantom, small animal, SPECT technique and is currently being tested for clinical applications. The new system is a combination of a PSPMT (Hamamatsu, R2486-05) and a PMT for simultaneous or independent acquisition of energy and position information, respectively. The resistive chain technique resulting in two signals at each (X,Y) direction will perform the readout of the PSPMT''s anode signals; the system is based on PCI electronics. Status of the system''s development and the ongoing progress is presented. [Copyright &y& Elsevier]

In this paper, a new positioning system is proposed for the 3-D ultrasound (US). This system combines the image registration technique and speckle decorrelation algorithm to accurately position sequential ultrasonic images without any additional positioning hardware. The speckle decorrelation algorithm estimates the relative distance of two neighboring frames and the image registration technique gets the range of the whole 3-D ultrasonic data set and makes slight modification on each frame’s position. The image registration technique is based on the reference image, which is perpendicular to the 3-D ultrasonic data set. This reference image intersects each frame of the 3-D ultrasonic data set in a line. For each frame, the intersectional line is first found and then the location in the reference image can be used to estimate the position of this frame. This system uses the data set of consecutive 2-D freehand-scanned US B-mode images to construct the 3-D US volume data, and it can be integrated into the 3-D US volume rendering system. (E-mail: dlchen88@ms13.hinet.net) [Copyright &y& Elsevier]

Because the degree and duration of lumbar flexion during sewage work have only been assessed on the basis of subjective reports, the purpose of this study was to investigate the usability of a measurement system for the non-invasive assessment of lumbar sagittal posture during sewage work using ultrasound. The validity of an ultrasonic measurement device was investigated in 16 healthy individuals by comparing the measurements obtained with the device with both Schober and electronic inclinometer measurements. To determine the intra-rater reliability of the ultrasonic device, short-term, medium-term, and long-term test-retest data were collected. Moreover, the percentage of the work time sewage workers spend in each of seven lumbar flexion categories within their individual lumbar flexion range of motion was assessed. Pearson's correlation coefficients of ≥ 0.88 indicate high validity between the methods. The intraclass correlation coefficients between tests and retests (≥ 0.88) demonstrate high reproducibility of the measurement procedures. Sewage workers spend about 25% of their work day in the most extreme of the seven lumbar posture categories. Also, testing did not interfere with the workers' normal work routine. The validity and reliability data as well as the trouble-free technical performance of the ultrasonic device support its usability for the continuous measurement of lumbar posture during sewage work. [ABSTRACT FROM AUTHOR]

Objectives: To investigate the accuracy in position-matching in the upper limb in two groups of subjects who were physically movement aware. Design: A mixed-group design was used. Objective measurement of the accuracy in position-matching at the shoulder and elbow in both dominant and nondominant arms consisted of photographic record of the position-matching test, with goniometric measurement. Settings: Physiotherapy department at the Birmingham Royal Ballet and School of Health Science, University of Birmingham. Subjects: Two subject groups: physiotherapy students (n = 10), professional ballet dancers (n = 10). Results: A mixed design analysis of variance found significant differences between the accuracy in position-matching at both the shoulder and elbow joints in the two groups (p < 0.05), with the ballet dancers having greater accuracy then the physiotherapy students. A significant difference in the joint positions tested were demonstrated (p < 0.05) with the positions of abduction at the shoulder and extension of the elbow showing greatest accuracy in matching. There was no significant difference found between the dominant and nondominant upper limb in position-matching. Conclusion: Professional ballet dancers demonstrated greater accuracy in position-matching the upper limb, implying that mass and continuing practice can improve a motor sensory skill. [ABSTRACT FROM AUTHOR]

Introduction: Precise localization of target sites for radiofrequency catheter ablation (RFCA) of arrhythmias is hampered by the relative inaccuracy of X-ray localization procedures. This study evaluated the efficacy of a three-dimensional (3D) real-time position management system in guiding RECA procedures in patients. Methods and Results: Patients (n = 30, age 59 ± 20 years) referred for ablation of either atrial flutter (n = 10), ventricular tachycardia (n = 15), or accessory pathways (n = 5) were studied. The real-time position management system uses ultrasound ranging techniques to track the position of an ablation catheter relative to two multitransducer reference catheters, positioned in the right atrium or coronary sinus and the right ventricle. Each catheter contains three or four ultrasound transducers. The distance between the transducer(s) Is determined by calculating the time necessary for an ultrasound pulse to reach other transducers, assuming the speed of sound in blood is 1,550 m/sec. The proximal His bundle was marked at the beginning and the end of the procedure as an electrical landmark to verify reproducibility. After identification of target sites, the position of each lesion created with the ablation catheter was marked. Successful ablation was achieved in 94% of the patients. The distance between the location of the proximal His bundle as marked at the beginning and at the end of the procedure was 2.0 ± 1.2 mm (range 1.5 to 3.5). conclusion: The new 3D real-time position management system facilitated RFCA procedures as it allowed accurate and reproducible 3D tracking of the mapping and ablation catheter. [ABSTRACT FROM AUTHOR]

The article focuses on the advancement in image diagnosis in dentistry. It discusses the practical use of magnetic resonance imaging and computed tomography in 1972 and 1980. It also cites the utilization of scintigraphy, ultrasonography and three-dimensional (3-D) reconstructed images which have become vital tools for diagnosis in the oral and maxillofacial treatment.

The article explains radiographic technique for producing images of the temporomandibular joint. Topics include: orientation of the head in relation to the condyle, fossa, and x-ray source; orientation in relation to anatomic obstructions; radiographic characteristics of normal temporomandibular joint and interpretation of interarticular space; the term "approximate symmetry"; and the condylar movements from a position of rest to occlusion.

Background In about one-fifth of radiographs performed in neonates, no exact gastric feeding tube position can be defined. Objectives To determine whether injection of air via feeding tube before taking radiographs improves radiological assessment of its position. Methods In the study group (n=153), air was injected via gastric feeding tube before taking a radiograph. The tube position on radiographs was compared with a blinded control group (n=381) with no injection of air. Results The definition of exact gastric tube position was possible in 95% of the study group compared with 78% in the control group (p<0.001). Conclusion Injection of air before taking a radiograph significantly improves the definition of exact gastric feeding tube position in neonates. [ABSTRACT FROM AUTHOR]

Background and purpose It is unclear whether osteoarthritis (OA) of the knee is seen better in standing flexion position radiographs than in the standing extended view. We assessed the value of standing flexion views. Patients and methods We retrospectively evaluated 1,090 radiographs of 545 consecutive knees with non-traumatic knee pain, comparing standing fixed flexion view (FFV) and standing extended view (SEV). OA was classified according to the Kellgren-Lawrence (KL) radiographic grading scale and joint space widths were measured. Results Medial joint space width was lower on average in the FFV, with the greatest difference in KL II knees. Medial full-thickness loss of cartilage was also seen more often in the FFVs of knees with moderate OA (KL II–III) than in the SEVs (6% vs. 19%). Interpretation Using FFV, there is no need to measure the exact knee flexion angle to use fluoroscopy. In earlier studies, the FFV has been found to be reproducible and easy to use in clinical practice. We recommend using flexion views when deciding the appropriate type of intervention in patients with OA. Full-thickness loss of cartilage in particular is better seen in the flexion view, which may be helpful if planning unicompartmental knee arthroplasty. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to determine the perceived and actual chin position(s) used for radiotherapy of head-and-neck cancers in a variety of clinical settings. Dosimetrists were asked to describe the external landmarks used to set the chin position. The lateral treatment planning radiographic figures in Ang''s textbook, Radiotherapy for Head and Neck Cancers: Indications and Techniques, were analyzed for chin position by drawing a horizontal line from the tip of the chin to the cervical spine. The physicians at 7 departments were asked to rate the chin positions used in their departments for head-and-neck simulations. Choices included: (1) mildly flexed, (2) neutral, (3) mildly extended, and (4) hyperextended. In addition, each center was asked to select 2 representative cases to show routine chin position. The dosimetrists fixed the chin in neutral position by placing a virtual plane defined by 3 points (the base of the nasal septum [acanthus] and the external auditory canals) perpendicular to the table top. The type of head holder was irrelevant. Eighty-two percent (31/38) of the figures in Ang''s text showed positioning in the neutral position (tip of the chin intersected the cervical spine between C2-3/C3-4). Most (71.4%) of the radiotherapists thought their patients were treated in the hyperextended neck position but, in fact, 85.7% (12/14) of the simulations showed a neural neck position. Reproducible chin positioning can be obtained by using the acanthiomeatal line. Consistent use of this technique will create a uniformly positioned set of axial co-images that have consistent appearance of avoidance and lymphatic areas. This will simplify contouring on axial computed tomography (CT) images of the neck. Standardizing the chin position is an important step to developing a standardized atlas and developing an information tool for automated contouring. [Copyright &y& Elsevier]

The article presents a case study of a 66-year-old woman with type 2 diabetes mellitus and hypertension which developed the acute onset of severe unsteadiness. A computerized dynamic posturography (CDP) test showed severe vestibular deficit. The patient presented body lateropulsion due to a small rostral paramedian midbrain infarction. The article discusses the possible mechanism of body lateropulsion at the level of the rostral midbrain.

The article presents information on the construction and use of a device for obtaining accurate and reliable measurements of tooth length through radiography. A diagram of the device is presented, along with a series of equations which can be used to determine the length of teeth, based on a known distance between the radiographic film and the teeth in question.

The purpose of this study was to demonstrate the feasibility of using a commercial two-dimensional (2D) detector array with an inherent detector spacing of 5 mm to achieve submillimeter accuracy in localizing the radiation isocenter. This was accomplished by delivering the Vernier ‘dose’ caliper to a 2D detector array where the nominal scale was the 2D detector array and the non-nominal Vernier scale was the radiation dose strips produced by the high-definition (HD) multileaf collimators (MLCs) of the linear accelerator. Because the HD MLC sequence was similar to the picket fence test, we called this procedure the Vernier picket fence (VPF) test. We confirmed the accuracy of the VPF test by offsetting the HD MLC bank by known increments and comparing the known offset with the VPF test result. The VPF test was able to determine the known offset within 0.02 mm. We also cross-validated the accuracy of the VPF test in an evaluation of couch hysteresis. This was done by using both the VPF test and the ExacTrac optical tracking system to evaluate the couch position. We showed that the VPF test was in agreement with the ExacTrac optical tracking system within a root-mean-square value of 0.07 mm for both the lateral and longitudinal directions. In conclusion, we demonstrated the VPF test can determine the offset between a 2D detector array and the radiation isocenter with submillimeter accuracy. Until now, no method to locate the radiation isocenter using a 2D detector array has been able to achieve such accuracy. [ABSTRACT FROM AUTHOR]

The authors comment on two articles concerning prostate fiducials and margins in relation to radiation oncology. One of the articles compared online imaging using implanted fiducials and offline bony landmark positioning. The other article calculated the margin around the clinical target volume (CTV) of patients. According to the authors, the margin method used to calculate CTV in the later article is the most common. They concluded that both articles are significant to radiation oncology.

Presents a letter to the editor regarding the need of consistency in viewing of lateral radiographs.

In geometric calibration of cone-beam computed tomography (CBCT), sphere-like objects such as balls are widely imaged, the positioning information of which is obtained to determine the unknown geometric parameters. In this process, the accuracy of the detector location of CB projection of the center of the ball, which we call the center projection, is very important, since geometric calibration is sensitive to errors in the positioning information. Currently in almost all the geometric calibration using balls, the center projection is invariably estimated by the center of the support of the projection or the centroid of the intensity values inside the support approximately. Clackdoyle’s work indicates that the center projection is not always at the center of the support or the centroid of the intensity values inside, and has given a quantitative analysis of the maximum errors in evaluating the center projection by the centroid. In this paper, an exact method is proposed to calculate the center projection, utilizing both the detector location of the ellipse center and the two axis lengths of the ellipse. Numerical simulation results have demonstrated the precision and the robustness of the proposed method. Finally there are some comments on this work with non-uniform density balls, as well as the effect by the error occurred in the evaluation for the location of the orthogonal projection of the cone vertex onto the detector. [ABSTRACT FROM AUTHOR]

A Whole Body Counter (WBC) is a facility to routinely assess the internal contamination of exposed workers, especially in the case of radiation release accidents. The calibration of the counting device is usually done by using anthropomorphic physical phantoms representing the human body. Due to such a challenge of constructing representative physical phantoms a virtual calibration has been introduced. The use of computational phantoms and the Monte Carlo method to simulate radiation transport have been demonstrated to be a worthy alternative.In this study we introduce a methodology developed for the creation of realistic computational voxel phantoms with adjustable posture for WBC calibration. The methodology makes use of different software packages to enable the creation and modification of computational voxel phantoms. This allows voxel phantoms to be developed on demand for the calibration of different WBC configurations. This in turn helps to study the major source of uncertainty associated with the in vivo measurement routine which is the difference between the calibration phantoms and the real persons being counted. The use of realistic computational phantoms also helps the optimization of the counting measurement. Open source codes such as MakeHuman and Blender software packages have been used for the creation and modelling of 3D humanoid characters based on polygonal mesh surfaces. Also, a home-made software was developed whose goal is to convert the binary 3D voxel grid into a MCNPX input file. This paper summarizes the development of a library of phantoms of the human body that uses two basic phantoms called MaMP and FeMP (Male and Female Mesh Phantoms) to create a set of male and female phantoms that vary both in height and in weight. Two sets of MaMP and FeMP phantoms were developed and used for efficiency calibration of two different WBC set-ups: the Doel NPP WBC laboratory and AGM laboratory of SCK-CEN in Mol, Belgium. [ABSTRACT FROM AUTHOR]

An abstract of the article "Persistent occipito-posterior position: outcomes following digital rotation. A pilot study," by K. Graham, H. Phipps, J. Hyett, J. Ludlow, A. Mackie, A. Marren and B. deVries is presented.

Purpose: To determine the use of surgical clips as a surrogate for localization of the excision cavity and to quantify the stability of the clips’ positions during the course of external beam radiotherapy for breast cancer patients, using cone beam computed tomography (CBCT) scans. Methods and Materials: Twenty-one breast cancer patients with surgical clips placed in the breast excision cavity were treated in a supine position with 28 daily fractions. CBCT scans were regularly acquired for a setup correction protocol. Retrospectively, the CBCT scans were registered to the planning CT scans, using gray-value registration of the excision cavity region and chamfer matching of the clips. Subsequently, residual setup errors (systematic [Σ] and random [σ]) of the excision cavity were estimated relative to the clips’ registration. Finally, the stability of the clips’ positions were quantified as the movement of each separate clip according to the center of gravity of the excision cavity. Results: When clips were used for online setup corrections, the residual errors of the excision cavity were Σleft-right = 1.2, σleft-right = 1.0; Σcranial-caudal  = 1.3, σcranial-caudal = 1.2; and Σanterior-posterior  = 0.7, σanterior-posterior = 0.9 mm. Furthermore, the average distance (over all patients) between the clips and centers of gravity of the excision cavities was 18.8 mm (on the planning CT) and was reduced to 17.4 mm (measured on the last CBCT scan). Conclusion: Clips move in the direction of the center of gravity of the excision cavity, on average, 1.4 mm. The clips are good surrogates for locating the excision cavity and providing small residual errors. [ABSTRACT FROM AUTHOR]