Arms-down Position Research Articles

Optimal Positioning of Load-Distributing Band CPR Device by Body Mass Index.

Background: Research investigating the optimal compression position for load-distributing bands (LDBs) in treating cardiac arrest is limited This study aimed to determine the optimal LDB position based on body mass index (BMI). Methods: A simulation study was conducted using chest and abdominal computed tomography imaging data collected with patients in the arms-down position. Participants were categorized into three BMI groups: low (<18.5 kg/m2), normal (18.5-25 kg/m2), and high (≥25 kg/m2). The assumed compression area was 20 cm below the axilla. The optimal compression position was identified by adjusting the axilla to maximize the thorax-to-abdomen volume ratio (TAR) and the covered heart volume ratio (CHR), defined as the ratio of heart volume compressed by the LDB to total heart volume. Optimal compression positions were compared across BMI groups. Results: Among 117 patients, TAR was significantly lower in the low BMI group compared to the normal and high BMI groups (p < 0.001), while CHR differences were not significant (p = 0.011). The distance between the optimal position and axilla height was significantly greater in the normal and high BMI groups than in the low BMI group (46.5 cm vs. 66.0 cm vs. 72 cm, respectively; p < 0.001). For each unit increase in BMI, the optimal position shifted significantly cephalad relative to axilla height (β coefficient 2.39, adjusted p < 0.001). Conclusions: Significant differences in TAR were observed among BMI groups. As BMI increased, the optimal LDB position shifted progressively cephalad.

Effect of posture on position of subcutaneous implantable cardioverter-defibrillator

BackgroundThe PRAETORIAN score was developed as an alternative for defibrillation testing after subcutaneous implantable cardioverter-defibrillator implantation to assess 3 aspects of implant position on a bidirectional chest radiograph. The score is validated on a standard standing chest radiograph with arms elevated in the lateral view. ObjectiveWe aimed to evaluate the effect of different anatomic positions on the PRAETORIAN score. MethodsThirty patients with a subcutaneous implantable cardioverter-defibrillator underwent standard posterior-anterior and lateral chest radiography, including additional lateral views in 2 positions: standing with arms down and supine with arms alongside the body. PRAETORIAN score and weighted κ coefficient were calculated for each position. ResultsIn 8 of 30 patients, the PRAETORIAN score was ≥90 in standard position. The agreement in PRAETORIAN score was substantial (κ = 0.677) for the position with the arms down and fair (κ = 0.399) for the supine position. With the arms down, the PRAETORIAN score decreased in 10 patients (33%), 4 of whom changed to a lower risk category. In supine position, the PRAETORIAN score decreased in 16 patients (53%), 7 of whom changed to a lower risk category, 1 from high to low risk. ConclusionA supine or arms-down position during chest radiography can result in lower PRAETORIAN scores and underestimation of associated risk on defibrillation testing failure. This emphasizes the importance of correct anatomic positioning (arms up) during chest radiography when the PRAETORIAN score is used.

Optimal Landmark for Chest Compressions during Cardiopulmonary Resuscitation Derived from a Chest Computed Tomography in Arms-Down Position.

Compressions at the left ventricle increase rate of return of spontaneous circulation. This study aimed to identify the landmark of the point of maximal left ventricular diameter on the sternum (LVmax) by using chest computed tomography (CCT) in the arms-down position, which was similar to an actual cardiac arrest patient. A retrospective study was conducted between September 2014 and November 2020. We included adult patients who underwent CCT in an arms-down position and measured the rescuer’s hand. We measured the distance from the sternal notch to LVmax (DLVmax), to the lower half of sternum (DLH), and to the point of maximal force of hand, which placed the lowest palmar margin of the rescuer’s reference hand at the xiphisternal junction. Thirty-nine patients were included. The LVmax was located below the lower half of the sternum; DLVmax and DLH were 12.6 and 10.0 cm, respectively (p < 0.001). Distance from the sternal notch to the point of maximal force of the left hand, with the ulnar border located at the xiphisternal junction, was close to DLVmax; 11.3 and 12.6 cm, respectively (p = 0.076). In conclusion, LVmax was located below the lower half of the sternum, which is recommended by current guidelines.

Optimal landmark for chest compression during cardiopulmonary resuscitation derived from a chest computed tomography in arms-down position

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): The Faculty of Medicine, Chiang Mai University Fund Background Recently evidence, compression at the maximal left ventricular diameter on sternum (LVmax) maximises cardiac output, stroke volume and rate of return of spontaneous circulation. However, there is insufficient evidence for the specific landmark on the chest for high-quality chest compression. Although cardiac arrest patients are usually in the arms-down position, previous studies used chest computed tomography (CCT) of the patient with arms-up position. It might alter the left ventricular position. Purpose This study aimed to identify the landmark of LVmax and to propose the new hand placement to optimise the chest compression by using CCT in arms-down position. Methods A retrospective, cross-sectional study conducted at a university-based, tertiary care hospital between September 2016 and November 2020. We included adult patients who underwent CCT in arms-down position. We measured healthcare providers’ hand heel width and the cardiothoracic parameters in CCT to establish a new optimal landmark of chest compression. We defined the sternal notch as a reference point and measured the distance from the sternal notch to LVmax (DLVmax), to the lower half of sternum (DLH), and to the point of maximal force of hand which placed the palmar margin of the reference hand at the xiphisternal junction (lower end of the sternum). Results A total of 39 patients were enrolled to measure the cardiothoracic parameters. There were 22 male (56.4%) and the median age was 67 years. DLVmax was neither different in inspiratory-hold nor expiratory-hold (mean ± standard deviation: 12.1 ± 1.9 cm and 12.9 ± 2.7 cm, p = 0.386). LVmax was located lower than the lower half of the sternum (Figure 1); the median of DLVmax and DLH were 12.6 cm (interquartile range: 10.6, 13.5 cm) and 10.0 cm (9.5, 11.0 cm), respectively (p &amp;lt;0.001). We found that the distance from the sternal notch to the point of maximal force of the left hand which the ulnar border located at the xiphisternal junction (DLU) was not significantly different from DLVmax (Figure 2); the median of DLVmax and DLU were 12.6 cm (10.6, 13.5 cm) and 11.3 cm (10.6, 12.5 cm), respectively (p 0.076). Conclusions The maximal left ventricular diameter on sternum (DLVmax) in the arms-down position was located lower than the lower half of the sternum (lower than the standard guideline recommendation). We propose that the new hand placement for chest compression is placing the left hand down and the hand’s border located at the xiphisternal junction while approach at left side of the patient. Abstract Figure. Abstract Figure.

Feasibility Study of Dose Modulation for Reducing Radiation Dose with Arms-Down Patient Position in Abdominal Computed Tomography.

This study was carried out to demonstrate whether the radiation dose for patients in arms-down position can be reduced without affecting the diagnosis on abdominal computed tomography (CT). The patients were divided into two groups: group A, which included patients with arms-down position using dose modulation on, and group B, which included patients with arms-down position using dose modulation turned off. Quantitative evaluation was compared using Hounsfield units, standard deviation, and signal-to-noise ratio of the four regions. The qualitative evaluation was assessed for overall image quality, subjective image noise, and beam hardening artifacts. Dose evaluation for CT dose index (CTDI) and dose length product (DLP) was compared by comparing the CT images with dose modulation turned on and off. In the quantitative and qualitative evaluation, there was no statistically significant difference between groups A and B (p > 0.05). In the dose evaluation, the CT images with dose modulation turned off had significantly lower CTDI and DLP than the CT images with dose modulation turned on (p < 0.05). Our results suggest that, for the GE Revolution EVO CT scanner, turning off dose modulation and increasing the tube voltage can reduce the radiation dose for patients with the arms-down position without affecting the diagnosis. This study did not consider the change of tube potential according to the use of dose modulation, and we plan to conduct additional research in the future.

Dosimetric Comparison of Arms Up Versus Arms Down Positions for Lung SBRT

<h3>Purpose/Objective(s)</h3> Reproducible patient positioning is integral to the safe and accurate delivery of radiation therapy. Commonly, lung patients are simulated with their arms up (AU) to improve dose conformality by utilizing lateral gantry angles. However, the AU position can be uncomfortable and difficult to maintain, especially in the early stage lung SBRT patient cohort, who tend to be older and less physically fit. For these patients, the physical discomfort from the AU position can lead to decreased accuracy in patient positioning and possibly treatment delivery. We sought to evaluate any potential dosimetric differences between simulating and treating SBRT lung patients in the standard AU position versus a more comfortable arms down (AD) position. <h3>Materials/Methods</h3> A sample of 10 patients undergoing lung SBRT on a noncoplanar robotic radiosurgery platform were selected. Patients were originally simulated, planned, and treated in the AD position. For ease of comparison, all treatments were replanned to 50 Gy (10 Gy x 5 fractions) regardless of tumor location. For each patient a new plan was then generated subtracting out the arms to reproduce the commonly used AU simulation position. Dosimetric quantities such as PTV coverage, PTV conformality, and other commonly accepted normal tissue constraints were compared. <i>Paired t-tests</i> of various plan metrics were calculated with a <0.05 threshold of significance. <h3>Results</h3> All plans were able to achieve adequate target coverage without violating any standard normal tissue constraints. There was no statistically significant differences observed for plans calculated in the AD versus AU positions for PTV V50Gy, lung V20Gy, esophagus D0.03cc, chest wall V30Gy, proximal bronchus D0.03cc, and distal bronchus D0.03cc. There was a statistically significant difference observed for the cord 0.03cc and cord 0.35cc doses in favor of the AD position, though in all cases the cord constraints were met. The median cord D0.35cc was 557cGy for AU verses 216cGy for AD. The median cord D0.03cc was 606cGy for AU verses 252cGy for AD. <h3>Conclusion</h3> There is no major dosimetric difference between treatment plans generated in the AU and AD positions. The exception was cord dose metrics, which showed a favorable decrease in median D0.03cc and D0.35cc in the AD position. Given the increased ease of positioning, which we believe leads to improved reproducibility and ultimately accuracy of treatment, we believe that simulating and treating patients in the AD position can be advantageous for lung SBRT treatments.

Considerations and Experience in the Treatment of Lung Cancer with VMAT SBRT + DIBH in Arms-Down Position

The arms-up position is the most common treatment position adopted for lung cancer patients treated with radiation therapy. However, many elderly or frail patients have shoulder problems and cannot tolerate such an overstretched position for an extended period. Therefore, the arms-down position becomes the only alternative for this group of patients during radiation therapy. Even though the arms-down position is not ideal, it does provide a stable and comfortable patient immobilization position for radiation treatments that require a longer delivery time, such as stereotactic body radiation therapy (SBRT). In this study, we designed a protocol to treat lung cancer patients with VMAT stereotactic body radiation therapy (VMAT SBRT) and deep inspiration breath-hold (DIBH) in the arms-down position. Our initial clinical experience with this protocol indicates that it is reliable for patient immobilization and accurate in delivered dosimetry.

PET/CT Image Artifacts Caused by the Arms.

PET/CT images are usually obtained in the arms-up position in patients with no head and neck pathology and in the arms-down position to image the head and neck area. The arms usually cause artifacts regardless of up or down positioning. These artifacts include beam hardening, scatter, truncation, and cold areas (cold artifacts) in obese or large patients; motion artifacts; implanted-metal-object artifacts; and artifacts related to radiotracer extravasation at the injection site. In this review article, we will discuss the mechanisms of these artifacts and suggest solutions to reduce or eliminate them, such as reviewing the non-attenuation-corrected PET images, performing extended-field-of-view reconstruction, not applying scatter correction, and using software to correct beam-hardening, scatter, and truncation artifacts. We will present various PET/CT images before and after corrections for such artifacts.

Arms positioning in post-mastectomy proton radiation: Feasibility and development of a new arms down contouring atlas.

Breast cancer patients receiving radiation are traditionally positioned with both arms up, but this may not be feasible or comfortable for all patients. We evaluated the treatment planning and positioning reproducibility differences between the arms up and arms down positions for patients receiving post-mastectomy radiation therapy (PMRT) using proton pencil beam scanning (PBS). Ten PMRT patients who were scheduled to receive PBS underwent CT-based treatment planning in both an arms down and a standard arms up position. An arms down contouring atlas was developed for consistency in treatment planning. Treatment plans were performed on both scans. A Wilcoxon test was applied to compare arms up and arms down metrics across patients. Five patients received treatment in the arms-down position at our institution while others were treated with the arms up. Residual set-up errors were recorded for each patient's treatment fractions and compared between positions. Target structure coverage remained consistent between the arms up and arms down positions. In regard to the OAR, the heart mean and maximum doses were statistically significantly lower in the arms up position versus the arms down position, however, the absolute differences were modest. Patients demonstrated similar setup errors, less than 0.5mm differences, in all directions. PBS for PMRT in the arms down position appeared stable and reproducible compared to the traditional arms up positioning. The degree of OAR sparing in the arms down group was minimally less robust but still far superior to conventional photon therapy.

Investigating the impact of patient arm position in an MR-linac on liver SBRT treatment plans.

The superior soft-tissue contrast offered by the integrated magnetic resonance imaging (MRI) of the Unity MR-linac compared to the x-ray-based image guidance on conventional linacs potentially allows for liver stereotactic body radiation therapy (SBRT) without the need for implanted markers or other surrogates. On conventional linacs, liver SBRT patients are typically positioned with their arms above their heads (arms-up) to minimize exposure to healthy tissue. However, the spatial confinement of the MRI-bore and increased treatment delivery times can make the arms-up position straining. Therefore, we assessed the plan quality for MR-linac treatment plans with the patient in the arms-up and in the arms-down position. Additionally, we compared the MR-linac plans with clinically used arms-up treatment plans made for a conventional linac. Fifteen consecutively treated patients with oligometastatic liver disease were included in this retrospective study. For each patient, a planning computed tomography (CT) with delineations, a diagnostic MRI, and a 3×20Gy dual-arc volumetric modulated arc therapy (VMAT) plan, which was used to treat the patient in an arms-up position on the conventional linac, were available. For the MR-linac, 15-beam step-and-shoot intensity-modulated radiation therapy (IMRT) plans were created for four patient positioning scenarios: arms-up, mimicking current clinical practice; arms-down, with treatment beams avoiding the arms on the entrance side; arms-through, arms are down but not avoided, and right-arm-up; only the right arm is up and the left arm is avoided on the entrance side. Resulting treatment plans were compared. Bonferroni-corrected two-sided Wilcoxon signed-ranks tests were used to assess statistical significance (P<0.05). No significant differences were found in gross tumour volume (GTV) coverage (D , D , and D ) or liver sparing (liver-GTV V ) between the clinical plans and any of the MR-linac plans. The median target conformity [exterior V /planning target volume (PTV)] was significantly better in the clinical plans (5.8) than in the MR-linac scenarios (arms-down: 6.6, arms-up/right-arm-up: 6.2, arms-through: 6.3). No MR-linac plan violated any additional organ-at-risk (OAR) constraint that was not already violated in the clinical plans. In the arms-down scenario a significantly increased median spinal cord D (14.5Gy) was detected compared to the clinical setup (7.2Gy). For the arms-down (arms-through) scenario, the median left arm D was 1.5 (2.7)Gy, the median right arm D was 5.8 (22.7)Gy, and the median right arm V was 0.0 (14.7) cc. These differences were statistically significant. For the right-arm-up scenario, the median left arm D (2.3Gy) and V (0.0) were not significantly different compared to the arms-down scenario. Mimicking the current clinical practice by treating patients in the arms-up/right-arm-up position on the MR-linac leads to plans which are dosimetrically very similar to the conventional linac plans. Treating in the arms-down position is expected to increase patient comfort at the cost of a small reduction in OAR sparing for individual patients. Treating through the arms is not encouraged due to substantial dose deposition in the arms.

Radical radiotherapy for locally advanced non-small cell lung cancer-what's up with arm positioning?

Radical thoracic radiotherapy is ideally delivered in the arms-up (AU) position; however, patient comfort may only allow for arms-down (AD) positioning to be feasible. Objectives of this study were (I) to evaluate the dosimetric impact of changing arm position during treatment and (II) to compare plan quality for optimization in AU vs. AD positions. In this retrospective planning study, stage III lung cancer patients (n=10) who received 60 Gy in 30 fractions using volumetric modulated arc therapy (VMAT) were identified. To simulate AD treatment, a PET/CT (acquired AD) was registered to the planning CT (acquired AU) for arm delineation. The clinically delivered plan (AU) was recalculated with a density override to 1 g/cm3 for one or both arm contours (AD). Plans were also re-optimized for the AD position. Dose-volume parameters were compared for each scenario. Moving from AU to AD without re-optimization resulted in a mean 3.7% reduction in PTV D95; in all cases, this caused 95% of the PTV to receive ≤57 Gy. The mean arms D2cc were 23.1 and 4.0 Gy for the ipsilateral and contralateral, respectively. Dosimetric consequences of ipsilateral arm only were similar to both AD, whereas contralateral arm only had less than 1% effect on PTV D95. Re-optimizing to account for both AD recovered PTV D95 coverage with acceptable doses to all organs at risk. Arm D2cc were also decreased to 5.5 and 2.3 Gy for ipsilateral and contralateral, respectively. There was a significant difference in heart V25 and mean heart dose (P<0.001), but the magnitude was small at 4.1% for V25 and 1.7 Gy for mean heart dose and the plans still met institutional dose constraints. This planning study suggests that it is feasible to plan radiotherapy for locally advanced lung cancer patients in the AD position using VMAT, when necessary, with only a modest dosimetric impact.

Feasibility of radiation dose reduction with iterative reconstruction in abdominopelvic CT for patients with inappropriate arm positioning.

BackgroundThe arms-down position increases computed tomography (CT) radiation dose. Iterative reconstruction (IR) could enhance image quality without increasing radiation dose in patients with arms-down position.AimTo investigate the feasibility of reduced-dose CT with IR for patients with inappropriate arm positioningMethodsTwenty patients who underwent two-phase abdominopelvic CT including standard-dose and reduced-dose CT (performed with 80% of the radiation dose of the standard protocol) with their arms positioned in the abdominal area were included in this study. Reduced-dose CT images were reconstructed using filtered back projection (FBP), hybrid IR, and iterative model reconstruction (IMR). These images were compared with standard-dose CT images reconstructed with FBP. Objective image noise in the liver and subcutaneous fat was measured by standard deviation for the quantitative analysis. Then, two radiologists qualitatively assessed beam hardening artifacts, artificial texture, noise, sharpness, and overall image quality in consensus.ResultsReduced-dose CT with all IR levels had lower objective image noise compared to standard-dose CT with FBP reconstruction (P < 0.05). Quantitatively measured beam hardening artifacts were similar in reduced-dose CT with iDose levels 5–6 and fewer with IMR compared to standard-dose CT. In the qualitative analysis, beam hardening artifacts and noise decreased as the IR levels increased. However, artificial texture was significantly aggravated with iDose 5–6 and IMR, and overall image quality significantly worsened with IMR.ConclusionsIR algorithms can reduce beam hardening artifacts in a reduced-dose CT setting in patients with arms-down position, and an intermediate level of hybrid IR allows radiologists to obtain the best image quality. Because the retrospective and single-center nature of our study limited the number of patients, multicenter prospective clinical studies are required to validate our results.

A Monte Carlo study of arms effect in myocardial perfusion of normal and abnormal cases utilizing STL heart shape

Arms influence in myocardial perfusion single photon emission computed tomography (SPECT) imaging has been studied for the last two decades. These studies suggested that arms positioning next to the patient would not show cardiac abnormalities or perfusion defects in SPECT imaging while it would not affect the scan during positron emission tomography (PET) scans. As a recent improvement in Geant4 Application for Tomographic Emission (GATE), -a Monte Carlo simulation toolkit- a new feature was added to enable the use of STereoLithography (STL). STL files are implanted as an input geometry for most human organs, which would give superior advantages in details compared to analytical geometry shapes. This study is adopting this recent improvement in GATE to study arms effect in SPECT imaging with the consideration of four scenarios; normal heart perfusion imaging with and without arms positioned next to the patient and two of the same scenarios with a perfusion myocardial defected. The results showed that perfusion defect could be observed with arms next to the patient. For image reconstruction, both filtered backprojection (FBP) and iterative technique – maximum likelihood expectation maximization (MLEM) were used. The MLEM was performed to analyse the four different patient scenarios. The difference in counts between arms-up and arms-down position for the abnormal case was shown to be less than 6%. The conclusion from this paper is that arm influence during abnormal heart SPECT imaging can be measured and has a minimal contribution to the reconstructed images.

Effect of arm position, presence of medical devices, and off-centering during acquisition of scout image on automatic tube voltage selection and current modulation in pediatric chest CT.

PurposeTo evaluate the patients’ morphologic factors affecting radiation dose in pediatric chest CT.Materials and methodsFrom November 2013 to May 2015, 315 pediatric chest CT scans were obtained using a CT scanner, and classified into 5 groups according to the patients’ age. For each age group, the chest CT scans were divided into two subgroups. A cut-off value used was the 75th percentile of size-specific dose estimates (SSDE), age-specific diagnostic reference level (DRL): less than the 75th percentile of SSDE (Group A, n = 238) and greater than the 75th percentile of SSDE (Group B, n = 77). All CT scans were performed with the same protocol using automatic tube voltage selection and current modulation techniques. The morphologic factors of the patients including body mass index (BMI), arm angles, presence of medical devices in the scan field, and degree of off-centering within the CT gantry were compared between groups A and B.ResultsGroup B showed narrower arm angles on scout and coronal reformatted images, higher frequency of the presence of devices and higher BMI than group A (P < 0.001, P < 0.001; P = 0.018, and P < 0.001, respectively). In multivariate analysis, narrower arm angles, the presence of devices on the scout images and higher BMI were independently associated with higher SSDE (P = 0.001, P = 0.037, and P < 0.001, respectively).ConclusionsDuring acquisition of the scout images, arms-down position and the presence of medical devices were associated with a high radiation dose above age-specific DRLs in pediatric chest CT, regardless of repositioning before the actual scanning. In addition, off-centering had no clinical impact on radiation dose in the routine practice.

Stereotactic ablative body radiotherapy for non-small-cell lung cancer: setup reproducibility with novel arms-down immobilization.

A clinical evaluation of the intrafraction and interfraction setup accuracy of a novel thermoplastic mould immobilization device and patient position in early-stage lung cancer being treated with stereotactic radiotherapy at the Beatson West of Scotland Cancer Centre, Glasgow, UK. 35 patients were immobilized in a novel, arms-down position, with a four-point Klarity™ (Klarity Medical Products, Ohio, US) clear thermoplastic mould fixed to a SinMed (CIVCO Medical solutions, lowa, US) head and neck board. A knee support was also used for patient comfort and support. Pre- and post-treatment kilovoltage cone beam CT (CBCT) images were fused with the planning CT scan to determine intra- and interfraction motion. A total of 175 CBCT scans were analysed in the longitudinal, vertical and lateral directions. The mean intrafraction errors were 0.05 ± 0.77 mm (lateral), 0.44 ± 1.2 mm (superior-inferior) and -1.44 ± 1.35 mm (anteroposterior), respectively. Mean composite three-dimensional displacement vector was 2.14 ± 1.2 mm. Interfraction errors were -0.66 ± 2.35 mm (lateral), -0.13 ± 3.11 mm (superior-inferior) and 0.00 ± 2.94 mm (anteroposterior), with three-dimensional vector 4.08 ± 2.73 mm. Setup accuracy for lung image-guided stereotactic ablative radiotherapy using a unique immobilization device, where patients have arms by their sides, has been shown to be safe and favourably comparable to other published setup data where more complex and cumbersome devices were utilised. There was no arm toxicity reported and low arm doses. Advances in knowledge: We report on the accuracy of a novel patient immobilization device.

The effect of arm position on the dosimetry of thoracic stereotactic ablative radiation therapy using volumetric modulated arc therapy

PurposePatient comfort and positioning stability may be improved in the arms down (AD) compared with the typical arms up (AU) position in thoracic stereotactic ablative radiation therapy (SABR). We compared plan quality for AD vs AU when using volumetric modulated arc therapy (VMAT), and evaluated the sensitivity of AD plans to arm positioning variability. Methods and materialsWe took plans of 14 patients with 17 lung tumors treated with thoracic SABR using VMAT in the AD position and simulated the same treatments in the AU position by re-optimizing after digitally removing the ipsilateral arm. To evaluate the sensitivity of AD plans to arm positioning variability, all plans were recalculated without re-optimization after assigning water density to the ipsilateral arm (AD-W) and then digitally shifting the arm 2.5 cm anterolaterally (AD-WS). ResultsBetween AD and AU plans, statistically significant but clinically insignificant (all original planning constraints met) differences were found for the following parameters: mean planning target volume maximum dose, difference of 2.3% of prescription dose (P = .049); mean intermediate dose conformity index, difference of 0.27 (P = .012); median percent lung volume receiving a minimum of 10, 20, and 30 Gy (V10, V20, and V30), differences of 0.5%, 0.2%, and 0.1%, respectively (P = .040, .007, and .001); and median spinal cord maximum dose, difference of 33.5 cGy (P = .017). Similarly, between AD-W and AD-WS plans, statistically significant but clinically insignificant differences were found for median lung V20 and V30, difference of 0.0% for both (P = .034 and .016, by matched pair analysis). ConclusionsOur exploratory planning study suggests that when using VMAT for lung tumor SABR, AD and AU positioning achieve clinically equivalent plan quality, and AD plans are insensitive to relatively large variability in arm position.

Whole-body CT in polytrauma patients: The effect of arm position on abdominal image quality when using a human phantom

For a considerable number of emergency computed tomography (CT) scans, patients are unable to position their arms above their head due to traumatic injuries. The arms-down position has been shown to reduce image quality with beam-hardening artifacts in the dorsal regions of the liver, spleen, and kidneys, rendering these images non-diagnostic. The purpose of this study was to evaluate the effect of arm position on the image quality in patients undergoing whole-body CT. We acquired CT scans with various acquisition parameters at voltages of 80, 120, and 140 kVp and an increasing tube current from 200 to 400 mAs in 50 mAs increments. The image noise and the contrast assessment were considered for quantitative analyses of the CT images. The image noise (IN), the contrast-to-noise ratio (CNR), the signal-to-noise ratio (SNR), and the coefficient of variation (COV) were evaluated. Quantitative analyses of the experiments were performed with CT scans representative of five different arm positions. Results of the CT scans acquired at 120 kVp and 250 mAs showed high image quality in patients with both arms raised above the head (SNR: 12.4, CNR: 10.9, and COV: 8.1) and both arms flexed at the elbows on the chest (SNR: 11.5, CNR: 10.2, and COV: 8.8) while the image quality significantly decreased with both arms in the down position (SNR: 9.1, CNR: 7.6, and COV: 11). Both arms raised, one arm raised, and both arms flexed improved the image quality compared to arms in the down position by reducing beam-hardening and streak artifacts caused by the arms being at the side of body. This study provides optimal methods for achieving higher image quality and lower noise in abdominal CT for trauma patients.

Change in thez-axis location of the sternal notch in an arms-raisedvsarms-down position on CT examinations

The aim of the study was to determine whether the sternal notch changes in its z-axis position in the arms raised vs arms down position on CT scans. A retrospective study was made of 132 consecutive CT scans of the neck and chest. We recorded the table position of the sternal notch and the most inferior slice through the thyroid gland on both scans, and the table position on the chest CT where the configuration of the head and neck vessels most closely corresponded to their configuration on the sternal notch slice of the neck CT. The sternal notch moved up an average of 8.4 mm (p<0.0001) when the arms were raised. In 44 cases (33.3%), the sternal notch moved up by > or =10 mm. In 6% of cases, the sternal notch moved upwards > or =20 mm. There was a slightly greater upward movement of the sternum in males of 2.57 mm (p = 0.0208). Mean upward motion of the sternal notch relative to the vessels was 7.74 mm (p<0.0001). Mean upward motion of the sternal notch relative to the thyroid was 8.98 mm (p<0.0001). In conclusion, the sternal notch moves upwards relative to the CT table and soft tissues in the neck and upper mediastinum when the arms are raised; the degree of upward motion is greater in males. This may have implications when categorizing nodes at the cervicothoracic junction on staging CT examinations, when deciding if nodes might be accessible to ultrasound-guided biopsy, and in classifying goitres.

42. ‘Raise your arm if you think it makes a difference!’ Arms-up versus arms-down position for myocardial perfusion studies

42. ‘Raise your arm if you think it makes a difference!’ Arms-up versus arms-down position for myocardial perfusion studies