Breath Hold Breast Research Articles

186: Prospective study on impact of CBCT on heart dose variation in breath hold breast RT(NCT03459898)

186: Prospective study on impact of CBCT on heart dose variation in breath hold breast RT(NCT03459898)

Failure mode and effects analysis in consensus-based GDM for surface-guided deep inspiration breath-hold breast radiotherapy for breast cancer under the framework of linguistic Z-number

Most of the cancer patients cannot get the usual treatment in the advanced stage of the disease. In particular, for breast cancer, it is to use a special kind of radiation that targets the tumor while the patient holds their breath. This is called surface-guided (SG) breast radiotherapy (RT) with deep inspiration breath-hold (DIBH). This treatment is very complicated and different from the normal way of treating breast cancer. It can also have many errors and problems that are not well-studied or understood. To prevent these problems, we need to use a method called failure mode and effects analysis (FMEA). This method helps us find and rank the possible risks and how to avoid them. In keeping with this aim, this paper studies consensus-reaching process-based group decision-making (GDM) with completely unknown risk factors' weights and the gained-lost dominance score (GLDS)-based ranking process. We cannot avoid the uncertainty related to relativity information in medical science. Therefore, in this study, we offer the experts to provide their opinions using the linguistic Z number (LZN) because LZN is designed to capture such types of information in medical science. For the consensus-reaching process (CRP), the relativity among experts is considered for consensus measurement, and the minimum adjustment sum with group consensus opinion-based feedback is offered. For unknown weight of risk factors, we don't know how much each risk factor weighs. So, we use a method that combines two ways of calculating weights. One way is a subjective weight computation process, and the other way is based on the data using entropy and division. Finally, we applied our proposed CRP-based GDM approach for ranking the identified FMs related to the SG DIBH RT process. We conduct sensitive, comparative, and statistical assessments to ensure our method is reasonable and practical.

Initial end-to-end testing of the ExacTrac dynamic deep inspiration breath hold workflow using a breath hold breast phantom

ExacTrac Dynamic (ETD) provides a Deep Inspiration Breath Hold (DIBH) workflow for breast patients. Stereoscopic x-ray imaging combined with optical and thermal mapping allows localisation against simulation imaging, alongside surface guided breath hold monitoring. This work aimed to determine appropriate imaging parameters, the optimal Hounsfield Unit (HU) threshold for patient contour generation and workflow evaluation via end-to-end (E2E) positioning using a custom breast DIBH phantom. After localisation via existing Image Guidance (IG), stereoscopic imaging was performed with a range of parameters to determine best agreement. Similarly, residual errors in prepositioning were minimised using a range of HU threshold contours. E2E positioning was completed for clinical workflows allowing residual isocentre position error measurement and existing IG comparison. Parameters of 60 kV and 25mAs were determined appropriate for patient imaging and HU thresholds between −600 HU and −200 HU enabled adequate prepositioning. The average and standard deviation in residual isocentre position error was 1.0 ± 0.9 mm, 0.4 ± 1.0 mm and 0.1 ± 0.5 mm in the lateral, longitudinal and vertical directions, respectively. Errors measured using existing IG were −0.6 ± 1.1 mm, 0.5 ± 0.7 mm and 0.2 ± 0.4 mm in the lateral, longitudinal and vertical directions, and 0.0 ± 1.0o, 0.5 ± 1.7o and −0.8 ± 1.8o for pitch roll and yaw. The use of bone weighted matching increased residual error, while simulated reduction of DIBH volume maintained isocentre positioning accuracy despite anatomical changes. This initial testing indicated suitability for clinical implementation during DIBH breast treatments.

Artificial Intelligence-Based Patient Selection for Deep Inspiration Breath-Hold Breast Radiotherapy from Respiratory Signals

Purpose: to predict eligibility for deep inspiration breath-hold (DIBH) radiotherapy (RT) treatment of patients with left breast cancer from analysis of respiratory signal, using Deep Bidirectional Long Short-Term Memory (BLSTM) recurrent neural networks. Methods: The respiratory traces from 36 patients who underwent DIBH RT were collected. The patients’ RT treatment plans were generated for both DIBH and free-breathing (FB) modalities. The patients were divided into two classes (patient eligible or not), based on the decrease of maximum dose to the left anterior descending (LAD) artery achieved with DIBH, compared to that achieved with FB and ΔDL. Patients with ΔDL > median value of ΔDL within the patient cohort were assumed to be those selected for DIBH. A BLSTM-RNN was trained for classification of patients eligible for DIBH by analysis of their respiratory signals, as acquired during acquisition of the pre-treatment computed tomography (CT), for selecting the window for DIBH. The dataset was split into training (60%) and test groups (40%), and the hyper-parameters, including the number of hidden layers, the optimizer, the learning rate, and the number of epochs, were selected for optimising model performance. The BLSTM included 2 layers of 100 neural units, each followed by a dropout layer with 20% dropout, and was trained in 35 epochs using the Adam optimizer, with an initial learning rate of 0.0003. Results: The system achieved accuracy, specificity, and sensitivity of, F1 score and area under the receiving operating characteristic curve (AUC) of 71.4%, 66.7%, 80.1%, 72.4%, and 69.4% in the test dataset, respectively. Conclusions: The proposed BLSTM-RNN classified patients in the test set eligible for DIBH with good accuracy. These results look promising for building an accurate and robust decision system to provide automated assistance to the radiotherapy team in assigning patients to DIBH.

BRAVEHeart: a randomised trial comparing the accuracy of Breathe Well and RPM for deep inspiration breath hold breast cancer radiotherapy

BackgroundDeep inspiration breath hold (DIBH) reduces radiotherapy cardiac dose for left-sided breast cancer patients. The primary aim of the BRAVEHeart (Breast Radiotherapy Audio Visual Enhancement for sparing the Heart) trial is to assess the accuracy and usability of a novel device, Breathe Well, for DIBH guidance for left-sided breast cancer patients. Breathe Well will be compared to an adapted widely available monitoring system, the Real-time Position Management system (RPM).MethodsBRAVEHeart is a single institution prospective randomised trial of two DIBH devices. BRAVEHeart will assess the DIBH accuracy for Breathe Well and RPM during left-sided breast cancer radiotherapy. After informed consent has been obtained, 40 patients will be randomised into two equal groups, the experimental arm (Breathe Well) and the control arm (RPM with in-house modification of an added patient screen). The primary hypothesis of BRAVEHeart is that the accuracy of Breathe Well in maintaining the position of the chest during DIBH is superior to the RPM system. Accuracy will be measured by comparing chest wall motion extracted from images acquired of the treatment field during breast radiotherapy for patients treated using the Breathe Well system and those using the RPM system.DiscussionThe Breathe Well device uses a depth camera to monitor the chest surface while the RPM system monitors a block on the patient’s abdomen. The hypothesis of this trial is that the chest surface is a better surrogate for the internal chest wall motion used as a measure of treatment accuracy. The Breathe Well device aims to deliver an easy-to-use implementation of surface monitoring. The findings from the study will help inform the technology choice for other centres performing DIBH.Trial registrationClinicalTrials.govNCT02881203. Registered on 26 August 2016.

Spirometer-guided breath-hold breast VMAT verified with portal images and surface tracking

Background and purposeFast rotating closed-bore gantry linacs are ideally suited for breath-hold treatments due to reduced imaging and delivery times. We evaluated the reproducibility and stability of spirometer-guided breath-hold breast treatments, using intra-bore surface monitoring and portal imaging on Halcyon (Varian Medical Systems). Materials and methodsSeven left-sided breast cancer patients were treated in breath-hold using the SDX spirometer (Dyn’R) with an integrated boost volumetric arc protocol on Halcyon. A dual depth-camera surface scanning system monitored the left breast. The interfraction, intrafraction and intrabreath-hold motion was determined in the anterior-posterior (AP) and superior-inferior (SI) direction. Portal images (PI), acquired at a tangential gantry angle were manually registered to the planning-CT to determine inter- and intrafraction breath-hold errors for the SI and tangential-anterior-posterior (“AP”) axis. Correlations between PI and surface imaging deviations were investigated. To evaluate workflow efficiency, the total time and the number of breath-holds were recorded. ResultsSystematic and random variability of breath-hold amplitude was below 0.7 mm for the AP and below 1.2 mm for the SI component as detected by surface monitoring (N = 130). Systematic and random errors retrieved from portal images (N = 140) were below 1.2 mm for the “AP” and 2.1 mm for SI axis. A limited correlation was found between PI and surface monitoring deviations for both the SI and “AP” axes (R2 = 0.27/0.38, p < 0.01). 75% of fractions were completed using four breath-holds and 82% within 10 min. ConclusionSurface imaging indicated spirometer-guided breath-hold VMAT breast radiotherapy can be accurately and quickly performed on a closed-bore gantry linac. Intra-bore surface scanning proved a valuable technique for monitoring breathing motion in closed-bore systems.

PO-1593: Impact of left ventricular V5 on acute coronary event cumulative risk in breath-hold breast IMRT

PO-1593: Impact of left ventricular V5 on acute coronary event cumulative risk in breath-hold breast IMRT

PO-1590: Spirometer guided breathhold breast VMAT on Halcyon verified with portal images and surface tracking

PO-1590: Spirometer guided breathhold breast VMAT on Halcyon verified with portal images and surface tracking

PO-1594: Impact of mean heart dose on acute coronary event excess cumulative risk in breath-hold breast IMRT

PO-1594: Impact of mean heart dose on acute coronary event excess cumulative risk in breath-hold breast IMRT

Technical Note: Issues related to external marker block placement for deep inspiration breath hold breast radiotherapy

It has been suggested that the Real-time Position Management (RPM) marker block should be placed directly on the breast or sternum to verify deep inspiration breath hold (DIBH) level for breast radiotherapy. We explore three potential issues with this practice: (a) surface dose effect of placing the marker block in the primary beam; (b) effect of marker block tilt on the accuracy of the RPM system; and (c) correlation between marker block positions on the patient surface and internal chest wall position. (a) The surface dose under the two-, four-, and six-dot marker blocks was measured at incident angles of 0° and 30°; (b) the motion amplitude detected when using the two- and six-dot marker blocks was recorded for block tilts from 0° to 60° about the RPM camera line of sight; (c) the correlation between median displacement of the chest wall and median displacement of the surface contour between breath holds was investigated for superior, middle, and inferior block positions using contours extracted from portal images of eight left-sided breast cancer patients. (a) The marker blocks increased the surface dose for a 6 MV direct field by 48.2-52.2% of Dmax ; (b) at lateral tilts greater than 10°, the two-dot marker block overestimated the motion amplitude; however, the six-dot marker block amplitude remained accurate up to 60°; (c) the whole, superior, and middle surface positions were strongly correlated with chest wall displacement (R2 = 0.83; R2 = 0.90; R2 = 0.83), whereas the inferior position was moderately correlated (R2 = 0.36). The RPM marker block can be placed on the breast for DIBH treatments; however, caution should be used regarding surface dose effects. The two-dot marker block should not be used for block tilts beyond 20°. Marker block placement at a middle or superior position on the breast results in the strongest correlation with chest wall position.

Setup error and motion during deep inspiration breath-hold breast radiotherapy measured with continuous portal imaging

Background. The position and residual motion of the chest wall of breast cancer patients during treatment in deep inspiration breath-hold (DIBH) were investigated.Material and methods. The study included 58 left-sided breast cancer patients treated with DIBH three-dimensional (3D) conformal radiotherapy in 15 or 25 fractions. The DIBH levels were monitored using an external marker block placed on the chest, either shifted 5 cm to the right at the level of the xiphoid process (Group 1, 27 consecutive patients) or placed medially on the inferior part of the sternum (Group 2, 31 consecutive patients). At every third treatment fraction, continuous portal images were acquired. The time-resolved chest wall position during treatment was compared with the planned position to determine the inter-fraction setup errors and the intra-fraction motion of the chest wall.Results. The DIBH compliance was 95% during both recruitment periods. A tendency of smaller inter-fraction setup errors and intra-fraction motion was observed for group 2 (medial marker block position). However, apart from a significantly reduced inter-field random shift (σ = 1.7 mm vs. σ = 0.9 mm, p = 0.005), no statistically significant differences between the groups were found. In a combined analysis, the group mean inter-fraction setup error was M = − 0.1 mm, with random and systematic errors of σ = 1.7 mm and Σ = 1.4 mm. The group mean inter-field shift was M = 0.0 (σ = 1.3 mm and Σ = 1.1 mm) and the group mean standard deviation of the intra-field motion was 0.5 mm. The absolute setup error had a maximum of 16.3 mm, exceeding 5 mm in 2.2% of the imaged fields.Conclusion. Compared to free breathing treatments, the primary benefit of the DIBH technique was the separation of the heart from the target rather than more accurate targeting. Despite a small gating window, occasional large errors in the chest wall position were observed for some patients, illustrating limitations of the external marker block as surrogate in a broad patient population.

Clinical Results of Image-Guided Deep Inspiration Breath Hold Breast Irradiation

To evaluate the feasibility, cardiac dose reduction, and the influence of the setup error on the delivered dose for fluoroscopy-guided deep inspiration breath hold (DIBH) irradiation using a cone-beam CT for irradiation of left-sided breast cancer patients. Nineteen patients treated according to the DIBH protocol were evaluated regarding dose to the ipsilateral breast (or thoracic wall), heart, (left ventricle [LV] and left anterior descending artery [LAD]), and lung. The DIBH treatment plan was compared to the free-breathing (FB) treatment planning and to the dose data in which setup error was taken into account (i.e., actual delivered dose). The largest setup variability was observed in the direction perpendicular to the RT field (μ = -0.8 mm, Σ = 2.9 mm, σ = 2.0 mm). The mean (D(mean)) and maximum (D(max)) doses of the DIBH treatment plan was significantly lower compared with the FB treatment plan for the heart (34% and 25%, p < 0.001), LV (71% and 28%, p < 0.001), and LAD (52% and 39.8%, p < 0.001). For some patients, large differences were observed between the heart D(max) according to the DIBH treatment plan and the actual delivered dose (up to 71%), although D(max) was always smaller than the planned FB dose (mean group reduction = 29%, p < 0.001). The image-guided DIBH treatment protocol is a feasible irradiation method with small setup variability that significantly reduces the dose to the heart, LV, and LAD.

SU‐FF‐J‐60: A Video Guided Breath Hold Treatment Technique for Cardiac Sparing Breast Radiotherapy

Purpose: The purpose of this work was to examine the reproducibility of the treatment position for a breath hold treatment technique for left sided breast cardiac sparing treatments. The feasibility of three dimensional video feedback for breath hold was also examined. Method and Materials: Patients with left sided breast cancer and unfavorable cardiac anatomy were treated with a breath hold cardiac sparing technique. One cohort of patients was treated without any feedback and with only simple verbal instructions. Three dimensional surface images during breath hold were obtained using the AlignRT system (VisionRT, London, UK). The reproducibility of the position of the breast surface was tested by registering the surfaces to a reference image taken on the first day. The daily surfaces were also registered with the skin surface generated from the CT simulation to check for systematic setup errors. The feasibility of a video‐based patient feedback system was tested using simple video goggles that interfaced with the AlignRT system. Patients were able to visualize the relationship of their current breast surface during breath hold relative to the CT‐based reference surface used for treatment planning in near real time. Results: The variation of the breath hold surface without feedback was significant. The overall standard deviation of the breath hold surface was approximately 3–4 mm, but the range of positions of the surface was in some cases as large as 10–15 mm. Surface registration with the CT‐based reference surface showed setup errors that were in some cases as large as 10 mm. Surface matching was shown to reduce the discrepancies between the daily and reference surface. Furthermore, video feedback appears promising as a method to reduce day‐to‐day breath hold variations. Conclusion: Surface imaging is a useful tool in image guided breath hold breast treatments.