Left-sided Breast Cancer Radiotherapy Research Articles

A comparative study in left-sided breast cancer treated with moderate deep inspiratory breath hold versus free breathing

BackgroundThe moderate deep inspiratory breath hold (mDIBH) is a modality famed for cardiac sparing. Prospective studies based on this are few from the eastern part of the world and India. We intend to compare the dosimetry between mDIBH and free-breathing (FB) plans.MethodsThirty-two locally advanced left breast cancer patients were taken up for the study. All patients received a dose of 50 Gy in 25 fractions to the chest wall/intact breast, followed by a 10-Gy boost to the lumpectomy cavity in the case of breast conservation surgery. All the patients were treated in mDIBH using active breath coordinator (ABC). The data from the two dose volume histograms were compared regarding plan quality and the doses received by the organs at risk. Paired t-test was used for data analysis.ResultsThe dose received by the heart in terms of V5, V10, and V30 (4.55% vs 8.39%) and mean dose (4.73 Gy vs 6.74 Gy) were statistically significant in the ABC group than that in the FB group (all p-values < 0.001). Also, the dose received by the LADA in terms of V30 (19.32% vs 24.87%) and mean dose (32.99 Gy vs 46.65 Gy) were significantly less in the ABC group. The mean treatment time for the ABC group was 20 min, while that for the free-breathing group was 10 min.ConclusionsIncorporating ABC-mDIBH for left-sided breast cancer radiotherapy significantly reduces the doses received by the heart, LADA, and left and right lung, with no compromise in plan quality but with an increase in treatment time.

Dosimetric Comparison of CPAP and DIBH for Left-sided Breast Cancer Radiotherapy

PurposeDespite the increasing interest in using continuous positive airway pressure (CPAP) in radiotherapy (RT), direct comparisons with the more widely employed deep inspiration breath-hold (DIBH) have been limited. This planning study aimed to offer comprehensive geometric and dosimetric evidence by comparing CPAP and DIBH-based RT plans. Materials and MethodsA retrospective dataset of 35 left-sided breast cancer patients with planning CT (pCT) scans under three breathing conditions (free breathing, CPAP with 10 cmH2O pressure, and DIBH) was collected. Volumetric arc therapy plans aimed for 95% dose coverage to 95% of the planning target volume with a maximum dose below 107%. A comparative dosimetric analysis among the three plans was conducted. Additionally, geometric differences were assessed by calculating the minimum distance between the heart and the clinical target volume (CTV) in each pCT. ResultsCPAP and DIBH plans demonstrated comparable mean heart doses (1.05 Gy), which were significantly lower than the FB plan (1.34 Gy). The maximum dose to the left anterior descending artery was smallest in the CPAP plan (4.44 Gy), followed by DIBH (4.73 Gy) and FB (7.33 Gy). Other organ-at-risk doses for CPAP and DIBH were similar, with mean contralateral breast doses of 2.27 and 2.21 Gy, mean ipsilateral lung doses of 4.09 and 4.08 Gy, V20 at 6.11 and 6.31%, and mean contralateral lung doses of 0.94 and 0.92 Gy, respectively. No significant difference was found in the minimum heart-to-CTV distance between CPAP and DIBH. DIBH exhibited the greatest lung volume (3908 cc), followed by CPAP (3509 cc), and FB (2703 cc). ConclusionThe comparison between CPAP and DIBH shows their similarity in both geometric and dosimetric aspects, providing strong evidence for CPAP's effectiveness and feasibility in RT. This suggests its potential as an alternative to DIBH for left-sided breast cancer patients.

Chest Wall to Heart Distance Reproducibility in Postoperative Deep Inspiration Breath-Hold Radiotherapy for Left-Sided Breast Cancer Using an Anzai Laser Sensor With Visual Feedback.

Background Left-sided breast cancer radiotherapy may increase the risk of cardiovascular death due to possible heart irradiation. Thereproducibility of the chest wall to heart distance in deep inspiration breath-hold (DIBH) was studied using a laser sensor with visual feedback. Methodology A total of 10 consecutive postoperative left-sided breast cancer cases receiving DIBH radiotherapy between December 2022 and September 2023 were retrospectively investigated. The prescribed dose was 50 Gy in 25 fractions. An Anzai respiratory gating system, AZ-733VI (Anzai, Tokyo, Japan), was employed that has a laser displacement sensor and a visual feedback device. An Elekta linac with a cone-beam CT unit, Axesse (Elekta AB, Stockholm, Sweden), was used in this study. The interfractional changes in the chest wall to heart distance among 25 fractions were analyzed for each of the 10 patients in each coordinate axis. In addition, the median with the 95% confidence interval (CI) and interquartile range (IQR) for all 250 fractions were calculated in each axis to assess the reproducibility of our DIBH technique. Results The medians of the interfractional changes in the chest wall to heart distance in each of the 10 patients ranged from -2 mm to 3 mm, -1 mm to 3 mm, and -2 mm to 1 mm in the lateral (X), superior-inferior (Y), and anterior-posterior (Z) directions, respectively. For all 10 cases, the medians were 1 mm (95% CI = 0.72 to 1.28 mm) in X, 1 mm (95% CI = 0.76 to 1.24 mm) in Y, and 0 mm (95% CI = -0.20 to 0.20 mm) in Z directions, whereas the IQRs were 4 mm in X, 2 mm in Y and 2 mm in Z directions. The measured IQRs were two to three times smaller than those shown in a previous report without visual feedback, suggesting a clinical advantage of the visual feedback in DIBH for left-sided breast cancer radiotherapy. The DIBH solution shown in this study required approximately 10 minutes from room-in to room-out, thereby not reducing the daily number of patients. Conclusions Our DIBH approach with visual feedback achieved better distance reproducibility between the chest wall and heart by a factor of two to three in terms of IQR compared to the previously reported data without visual feedback. Patient throughput was also favorable. To our knowledge, this is the first report demonstrating the chest wall to heart distance reproducibility in DIBH with visual feedback.

Setup margins based on the inter- and intrafractional setup error of left-sided breast cancer radiotherapy using deep inspiration breath-hold technique (DIBH) and surface guided radiotherapy (SGRT).

The use of volumetric modulated arc therapy (VMAT), simultaneous integrated boost (SIB), and hypofractionated regimen requires adequate patient setup accuracy to achieve an optimal outcome. The purpose of this study was to assess the setup accuracy of patients receiving left-sided breast cancer radiotherapy using deep inspiration breath-hold technique (DIBH) and surface guided radiotherapy (SGRT) and to calculate the corresponding setup margins. The patient setup accuracy between and within radiotherapy fractions was measured by comparing the 6DOF shifts made by the SGRT system AlignRT with the shifts made by kV-CBCT. Three hundred and three radiotherapy fractions of 23 left-sided breast cancer patients using DIBH and SGRT were used for the analysis. All patients received pre-treatment DIBH training and visual feedback during DIBH. An analysis of variance (ANOVA) was used to test patient setup differences for statistical significance. The corresponding setup margins were calculated using the van Herk's formula. The intrafractional patient setup accuracy was significantly better than the interfractional setup accuracy (p<0.001). The setup margin for the combined inter- and intrafractional setup error was 4, 6, and 4mm in the lateral, longitudinal, and vertical directions if based on SGRT alone. The intrafractional error contributed ≤1mm to the calculated setup margins. With SGRT, excellent intrafractional and acceptable interfractional patient setup accuracy can be achieved for the radiotherapy of left-sided breast cancer using DIBH and modern radiation techniques. This allows for reducing the frequency of kV-CBCTs, thereby saving treatment time and radiation exposure.

Exploring Helium Ions' Potential for Post-Mastectomy Left-Sided Breast Cancer Radiotherapy.

Proton therapy presents a promising modality for treating left-sided breast cancer due to its unique dose distribution. Helium ions provide increased conformality thanks to a reduced lateral scattering. Consequently, the potential clinical benefit of both techniques was explored. An explorative treatment planning study involving ten patients, previously treated with VMAT (Volumetric Modulated Arc Therapy) for 50 Gy in 25 fractions for locally advanced, node-positive breast cancer, was carried out using proton pencil beam therapy with a fixed relative biological effectiveness (RBE) of 1.1 and helium therapy with a variable RBE described by the mMKM (modified microdosimetric kinetic model). Results indicated that target coverage was improved with particle therapy for both the clinical target volume and especially the internal mammary lymph nodes compared to VMAT. Median dose value analysis revealed that proton and helium plans provided lower dose on the left anterior descending artery (LAD), heart, lungs and right breast than VMAT. Notably, helium therapy exhibited improved ipsilateral lung sparing over protons. Employing NTCP models as available in the literature, helium therapy showed a lower probability of grade ≤ 2 radiation pneumonitis (22% for photons, 5% for protons and 2% for helium ions), while both proton and helium ions reduce the probability of major coronary events with respect to VMAT.

Evaluation of Heart Substructures as a Function of Dose and Radiation-Induced Toxicities in Left-Sided Breast Cancer Radiotherapy

Background. A group of cardiopathies (ischemic, arrhythmic, and pericardial cardiac events) were shown to be associated with doses received by heart substructures following radiotherapy, alerting about the importance of dosimetric evaluation of cardiac structures besides the heart. The aim of this study was to assess the dosimetry of heart and heart substructures of left-sided breast cancer radiotherapy to evaluate possible radiation-induced complications. Methods and Materials. The study enrolled 20 patients treated with 3D-conformal radiotherapy (3DCRT), while intensity-modulated (IMRT) and volumetric-modulated arc radiotherapy (VMAT) plans were simulated for comparative purposes. The organs at risk (OARs) of interest were the heart, ascending aorta, descending aorta, left ventricle, left atrium, right ventricle, right atrium, superior vena cava, inferior vena cava, and pulmonary artery. Results. The percentage of left ventricle included in the radiation field was &gt;5% for all plans (8.92% 3DCRT, 8.30% IMRT, and 6.84% VMAT). A strong correlation between mean heart dose and the percentage of left ventricle overlapping with the radiation fields was observed in 3DCRT (r = 0.784) and IMRT (r = 0.755) plans, and a moderate correlation was shown between tumor volume and the percentage of left ventricle included in the radiation field for all plans. A moderate correlation was observed between body mass index and cardiac structures for the mean dose to the right ventricle (r = 0.640) in conformal plans and V5 of heart (r = 0.528) and left ventricle (r = 0.669) in volumetric-modulated plans. Additionally, moderate to strong correlations were found between maximum heart distance and heart dose in both conformal and modulated plans. Conclusions. Considering possible occurrences of cardiac events during or postradiotherapy, monitoring the heart and its substructures and setting dosimetric thresholds for healthy tissues must be a priority to achieve a personalized and effective treatment.

VMAT with DIBH in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery: results of a non-inferiority clinical study.

The purpose of this study was to show the safety of volumetric modulated arc therapy (VMAT) with deep inspiration breath-hold (DIBH) in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery in a clinical setting. Twenty-five Japanese women, aged 20-59years, who were enrolled in this prospective non-inferiority study received VMAT under the condition of DIBH with 42.4Gy/16 fractions for whole-breast irradiation (WBI) ± boost irradiation for the tumor bed to show the non-inferiority of VMAT with DIBH to conventional fractionated WBI with free breathing. The primary endpoint was the rate of occurrence of radiation dermatitis of Grade 3 or higher or pneumonitis of Grade 2 or higher within 6months after the start of radiotherapy. This study was registered with UMIN00004321. All of the enrolled patients completed the planned radiotherapy without interruption. The evaluation of adverse events showed that three patients (12.0%) had Grade 2 radiation dermatitis. There was no other Grade 2 adverse event and there was no patient with an adverse event of Grade 3 or higher. Those results confirmed our hypothesis that the experimental treatment method is non-inferior compared with our historical results. There was no patient with locoregional recurrence or metastases. In conclusion, VMAT under the condition of DIBH in hypofractionated radiotherapy for left-sided breast cancer after breast-conserving surgery can be performed safely in a clinical setting.

Even the presence of minimal changes in regional wall motion abnormalities with exercise stress echocardiography predicts MACE and all-cause mortality in patients with previous chest radiotherapy

Abstract Background Exercise stress echocardiography (ESE) is a non-invasive, radiation-free, and widely available technique that has demonstrated a reliable accuracy for the detection of coronary artery disease (CAD). Chest radiotherapy (RT) is associated with accelerated age-related atherosclerosis and fibrosis in a dose-dependent manner. ESE plays a role as a screening tool of RT induced heart disease, however, the prognostic value of changes in regional wall motion abnormalities in this population during ESE has not been evaluated. Methods This is a retrospective cohort study of breast cancer survivors treated with adjuvant RT that underwent ESE from 2000-2020 after treatment completion. Outcomes evaluated were: major adverse cardiovascular events (MACE: cardiovascular death, myocardial infarction, revascularization and stroke); and all-cause mortality. A univariate analysis was performed to characterize the population. Continuous variables were presented as means ± standard deviation (SD) or median with quartile 1 and 3 (Q1, Q3), and categorical variables as numbers and percentages. A Cox regression model adjusted by age and cardiovascular risk factors was used to evaluate variables associated with outcomes, and a time to first event approach was used. A p-value of &amp;lt;0.05 was considered statistically significant. Results From 2000-2020, 507 patients, with a mean age 66 ± 10 years, underwent ESE at a median of 5.8 years after RT completion. The most prevalent comorbidities were dyslipidemia (59%), HTN (55%) and obesity (37%). 55% underwent RT for left-sided breast cancer and 45% for right-sided, and median RT dose was 6000 cGy. Baseline characteristics are presented in Table 1. Most patients underwent Bruce Protocol (92%). Patients exercised a mean time of 6.6 minutes achieving 7.3 METS and 109% of functional aerobic capacity (Table 2). At a median follow up of 7.8 years, 61 MACE events occurred. Predictors of MACE were double product, baseline and stress EF, baseline and peak regional wall motion abnormalities (RWMA), development of new ischemic RWMA, inability to reach 85% of maximum HR, and an abnormal EF response with stress after adjusting for age, HTN, DM, smoking history, dyslipidemia, obesity, prior MI and cancer staging (Fig 1). Predictors of all-cause mortality were METS, LV mass index, baseline and peak RWMA, development of new ischemic RWMA and an abnormal EF change with stress even after adjusting for variables described previously (Fig 2). Conclusions The development of new or worsening RWMA of just 2 segments with stress, was a significant predictor of MACE and all-cause mortality in a large cohort of breast cancer survivors undergoing multidisciplinary management including adjuvant RT. Special emphasis on management of cardiovascular comorbidities and closer surveillance are recommended for these patients.

Evaluation of the accuracy of heart dose prediction by machine learning for selecting patients not requiring deep inspiration breath‑hold radiotherapy after breast cancer surgery.

Increased heart dose during postoperative radiotherapy (RT) for left-sided breast cancer (BC) can cause cardiac injury, which can decrease patient survival. The deep inspiration breath-hold technique (DIBH) is becoming increasingly common for reducing the mean heart dose (MHD) in patients with left-sided BC. However, treatment planning and DIBH for RT are laborious, time-consuming and costly for patients and RT staff. In addition, the proportion of patients with left BC with low MHD is considerably higher among Asian women, mainly due to their smaller breast volume compared with that in Western countries. The present study aimed to determine the optimal machine learning (ML) model for predicting the MHD after RT to pre-select patients with low MHD who will not require DIBH prior to RT planning. In total, 562 patients with BC who received postoperative RT were randomly divided into the trainval (n=449) and external (n=113) test datasets for ML using Python (version 3.8). Imbalanced data were corrected using synthetic minority oversampling with Gaussian noise. Specifically, right-left, tumor site, chest wall thickness, irradiation method, body mass index and separation were the six explanatory variables used for ML, with four supervised ML algorithms used. Using the optimal value of hyperparameter tuning with root mean squared error (RMSE) as an indicator for the internal test data, the model yielding the best F2 score evaluation was selected for final validation using the external test data. The predictive ability of MHD for true MHD after RT was the highest among all algorithms for the deep neural network, with a RMSE of 77.4, F2 score of 0.80 and area under the curve-receiver operating characteristic of 0.88, for a cut-off value of 300 cGy. The present study suggested that ML can be used to pre-select female Asian patients with low MHD who do not require DIBH for the postoperative RT of BC.

Changes in myocardial blood flow in a canine model of left sided breast cancer radiotherapy.

Left-sided breast cancer patients receiving adjuvant radiotherapy are at risk for coronary artery disease, and/or radiation mediated effects on the microvasculature. Previously our laboratory demonstrated in canines with hybrid 18FDG/PET a progressive global inflammatory response during the initial one year following treatment. In this study, the objective is to evaluate corresponding changes in perfusion, in the same cohort, where resting myocardial blood flow (MBF) was quantitatively measured. In five canines, Ammonia PET (13NH3) derived MBF was measured at baseline, 1-week, 1, 3, 6 and 12-months after cardiac external beam irradiation. MBF measurements were correlated with concurrent 18FDG uptake. Simultaneously MBF was measured using the dual bolus MRI method. MBF was significantly increased at all time points, in comparison to baseline, except at 3-months. This was seen globally throughout the entire myocardium independent of the coronary artery territories. MBF showed a modest significant correlation with 18FDG activity for the entire myocardium (r = 0.51, p = 0.005) including the LAD (r = 0.49, p = 0.008) and LCX (r = 0.47, p = 0.013) coronary artery territories. In this canine model of radiotherapy for left-sided breast cancer, resting MBF increases as early as 1-week and persists for up to one year except at 3-months. This pattern is similar to that of 18FDG uptake. A possible interpretation is that the increase in resting MBF is a response to myocardial inflammation.

Mean Heart Dose Prediction Using Parameters of Single-Slice Computed Tomography and Body Mass Index: Machine Learning Approach for Radiotherapy of Left-Sided Breast Cancer of Asian Patients.

Deep inspiration breath-hold (DIBH) is an excellent technique to reduce the incidental radiation received by the heart during radiotherapy in patients with breast cancer. However, DIBH is costly and time-consuming for patients and radiotherapy staff. In Asian countries, the use of DIBH is restricted due to the limited number of patients with a high mean heart dose (MHD) and the shortage of radiotherapy personnel and equipment compared to that in the USA. This study aimed to develop, evaluate, and compare the performance of ten machine learning algorithms for predicting MHD using a patient's body mass index and single-slice CT parameters to identify patients who may not require DIBH. Machine learning models were built and tested using a dataset containing 207 patients with left-sided breast cancer who were treated with field-in-field radiotherapy with free breathing. The average MHD was 251 cGy. Stratified repeated four-fold cross-validation was used to build models using 165 training data. The models were compared internally using their average performance metrics: F2 score, AUC, recall, accuracy, Cohen's kappa, and Matthews correlation coefficient. The final performance evaluation for each model was further externally analyzed using 42 unseen test data. The performance of each model was evaluated as a binary classifier by setting the cut-off value of MHD ≥ 300 cGy. The deep neural network (DNN) achieved the highest F2 score (78.9%). Most models successfully classified all patients with high MHD as true positive. This study indicates that the ten models, especially the DNN, might have the potential to identify patients who may not require DIBH.

Pre-treatment predictors of cardiac dose exposure in left-sided breast cancer radiotherapy patients after breast conserving surgery

Abstract Objectives This study aimed to identify high-risk factors for high cardiac radiation exposure, based on anatomical measurements taken from planning CT images of patients with left-sided breast cancer who underwent breast-conserving surgery and received radiotherapy. Methods We retrospectively analyzed 45 patients with left-sided breast cancer who underwent whole-breast radiotherapy, either under free breathing (27/45) or deep inspiratory breath-holding (DIBH) (18/45), after breast-conserving surgery. Six anatomical parameters were measured from planning CT images, including treatment planning target volume (PTV), cardiopulmonary volume ratio (CVR), maximum cardiac margin distance, the relative distance between inferior boundaries of heart and PTV (DBIB(H2P)), axial cardiac contact distance, and para-sagittal cardiac contact distance (CCDps). Multiple linear regression analysis was performed using SPSS software to explore the correlation between the six parameters, body mass index (BMI), and the mean heart dose (MHD). Receiver operating characteristic (ROC) analysis was performed to evaluate the predictive power of the selected predictor of cardiac dose exposure. Results Significant correlations were observed between the MHD of patients and the CVR, DBIB(H2P), and CCDps parameters. Among them, the CVR was the most important predictor of cardiac dose exposure, with an area under the curve of 0.915 and a cut-off value of 0.17. Conclusions The study results indicated that CVR, DBIB(H2P), and CCDps are the primary parameters associated with the risk of cardiac dose exposure, with CVR being the most significant predictor. Further prospective studies are required to determine whether these parameters can be used to identify patients who would benefit from the DIBH technique.

Recent Postoperative Radiotherapy for Left-sided Breast Cancer Does Not Increase Mortality of Heart Disease in Asians or Pacific Islanders: SEER Database Analysis.

The purpose of this study was to evaluate the impact of recent radiotherapy on mortality from heart disease in Asians or Pacific islanders with breast cancer using the Surveillance, Epidemiology, and End Results (SEER) database. Asians or Pacific islanders with stage 0 or I (AJCC 6th) breast cancer between 2000 and 2015 were analyzed. The impact of radiotherapy for mortality from heart disease after treatment was evaluated by comparing patients who received radiotherapy for left-sided breast cancer, patients who received radiotherapy for right-sided breast cancer and patients who did not receive radiotherapy. In 25,684 Asians or Pacific islanders, the incidence of cardiac death was higher in patients who did not receive radiotherapy than in patients who received radiotherapy. Among patients who received external beam irradiation, the incidence of cardiac death was 2.00% for patients with left-sided breast cancer and 1.69% for patients with right-sided breast cancer, with no significant difference (chi-square test, p=0.427). In the period from 2000 to 2008, there was no significant difference between the cumulative heart-related death rates in patients who received radiotherapy and in patients who did not receive radiotherapy (Tarone-Ware test, p=0.406); however, in 2009-2015, the cumulative heart-related death rate in patients who did not receive radiotherapy was significantly higher than that in patients who received radiotherapy (log-rank test, p<0.001). Heart-related death after treatment for breast cancer is relatively rare in Asians or Pacific islanders. Since at least 2000, the cardiac impact of postoperative radiotherapy has not been significant.

Evaluation of Cardiac Substructures Exposure of DIBH-3DCRT, FB-HT, and FB-3DCRT in Hypofractionated Radiotherapy for Left-Sided Breast Cancer after Breast-Conserving Surgery: An In Silico Planning Study

Left-sided breast cancer radiotherapy can lead to late cardiovascular complications, including ischemic events. To mitigate these risks, cardiac-sparing techniques such as deep-inspiration breath-hold (DIBH) and intensity-modulated radiotherapy (IMRT) have been developed. However, recent studies have shown that mean heart dose is not a sufficient dosimetric parameter for assessing cardiac exposure. In this study, we aimed to compare the radiation exposure to cardiac substructures for ten patients who underwent hypofractionated radiotherapy using DIBH three-dimensional conformal radiation therapy (3DCRT), free-breathing (FB)-3DCRT, and FB helical tomotherapy (HT). Dosimetric parameters of cardiac substructures were analyzed, and the results were statistically compared using the Wilcoxon signed-rank test. This study found a significant reduction in the dose to the heart, left anterior descending coronary artery, and ventricles with DIBH-3DCRT and FB-HT compared to FB-3DCRT. While DIBH-3DCRT was very effective in sparing the heart, in some cases, it provided little or no cardiac sparing. FB-HT can be an interesting treatment modality to reduce the dose to major coronary vessels and ventricles and may be of interest for patients with cardiovascular risks who do not benefit from or cannot perform DIBH. These findings highlight the importance of cardiac-sparing techniques for precise delivery of radiation therapy.

Comparison of 3D-conformal and intensity-modulated radiation therapy for left-sided breast cancer

Background: We compared 3D-conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) planning for left-sided post-mastectomy patients. Aim: To compare the dose coverage of the planning target volume (PTV) and dose delivered to organs at risk (OAR) of 3D-CRT and IMRT plans. Setting: Department of Oncology, central South Africa. Methods: Twenty-six archived CT scans of patients with left-sided breast cancer were included. The 3D-CRT and IMRT plans were designed for each patient and compared using the Monaco © planning system (version 5.11.02). Statistical analysis was performed for PTV coverage (V 95% , V 98% , V 105% ) and radiation doses to the heart, ipsilateral lung, combined lungs, contralateral breast, and oesophagus. Results: The V 98% and V 105% target volume dose coverage for the 3D-CRT plans were 67.07% and 0.21%, respectively, compared to 92.32% and 1.10% of the IMRT plans. However, the IMRT plans’ mean volume of PTV, receiving 95% of the prescribed dose (PD), was 7.68% compared to the 3D-CRT’s 32.93%. The IMRT plans resulted in a V 22 Gy &lt; 10% for the heart, with a value of 4.15%. The V 18.87 Gy &lt; 45% values for the ipsilateral and combined lungs were 28.09% and 13.70%, respectively. The 3D-CRT plans showed a lower dose to the oesophagus (5.07 Gy) and contralateral breast (V 5 Gy &lt; 15% = 3.51%). Conclusion: It was shown that 3D-CRT and IMRT treatment planning can effectively achieve clinical goals for post-mastectomy left-sided breast cancer radiotherapy. Contribution: The findings underscore the continuing relevance of 3D-CRT planning in oncology for optimal PTV dose coverage and low OAR dose.

The effect of breath-hold technique on conformal and intensity modulated radiotherapy techniques at right breast cancer radiotherapy including internal mammarian field

Background/Aim: Significantly lower heart doses can be achieved by breath-hold technique at left-sided breast cancer radiotherapy (RT). We see high doses at organs at risk such as lung, heart, and contralateral breast during right-sided breast cancer RT planning especially in the presence of RT indication for mammaria interna (MI) lymph nodes. This study compared RT-planning methods that are conformal with intensity-modulated RT (IMRT) with breath holding and free breathing for right-sided breast cancer RT including full axillary and MI lymph node fields. Methods: Computed tomography (CT) simulations were performed using free-breath (FB) and breath-hold (BH) methods in 10 patients with right-sided breast cancer. A total of 40 RT treatment plans were calculated. Right-sided breast, level 1-2-3 axillary regions, and MI regions served for the target-planning volume. Left-sided breast, heart, as well as right-sided and left lungs were contoured as critical organs according to the atlas of the "Radiation Therapy Oncology Group." We used a Varian Eclipse v.13 for treatment planning. Conformal “FieldinField” RT (FinFRT) and dynamic IMRT (dIMRT) planning were performed separately for each patient over breath-hold and free-breath images. For PTV, 50 Gy was prescribed in 25 fractions and optimized such that the planned target volume (PTV) remained between 95% and 110% of the dose. The mean and maximum doses of the heart, V5 and V20 of the lungs, as well as V95 doses for MI were recorded. Statistical analyses were performed with SPSS version 22, and a paired t-test was used for comparison. Results: Four treatment plans (FB FinFRT, BH FinFRT, FB dIMRT, BH dIMRT) were made separately for 10 patients. For comparison, common FB FinFRT plans were accepted as the baseline plan. As expected, there were no significant differences in PTV coverage. The mean dose received by 95% of the MI volume was between 42.27 Gy and 42.4 Gy. For the maximum heart dose, the breath hold technique had no significant effect on plans. The lowest average maximum heart dose was seen in the BH FinFRT group. Mean heart doses are between 1.28 Gy – 4.85 Gy. There was no significance between BH FinFRT and FB FinFRT plan (P=0.504), and there was a significant difference for heart mean dose versus dIMRT plans (P=0.001). The mean V20 of the lungs ranged from 11.9 to 17.8. There was a significant decrease in V20 with BH or FB dIMRT plans (P=0.001). There was no difference between BH FinFRT (P=0.138). On the contrary, lung V5 values were significantly higher in dIMRT plans, and the lowest mean V5 value was seen in BH FinFRT plan. Conclusion: With the BH method, lower doses (but not significantly lower doses) were obtained in critical organ doses. There was a significant decrease with FinFRT plans in terms of heart mean and maximum dose and lung V5 percentages. The dIMRT plans were significant only in lung V20 percentages. When planning RT, we recommend evaluating all treatment techniques individually for right-sided breast cancer patients to obtain lower doses in critical organs.

PO-2334 Cardiac conduction nodes exposure in hypofractionated left-sided breast cancer radiotherapy

PO-2334 Cardiac conduction nodes exposure in hypofractionated left-sided breast cancer radiotherapy

PO-2338 Does gastric volume impact lung’s exposure in loco-regional left-sided breast cancer radiotherapy?

PO-2338 Does gastric volume impact lung’s exposure in loco-regional left-sided breast cancer radiotherapy?

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.

Dosimetric Comparison of Different Fractionated 3D Radiotherapy Regimens for Breast Conservation

Background and Objectives This study compared conventional dose fractionation and hypofractionation in breast cancer radiotherapy to optimize treatment planning using different physical indices Subjects and Methods In this retrospective study, the treatment plans of 30 patients eligible for radiotherapy for left-sided breast cancer were investigated. Patients were treated with a conventional dose- interval regimen and three hypofractionated regimens. Dosimetry indexes such as the homogeneity index, conformity index, and mean dose to the left breast, lung, and heart were extracted from the dose-volume histogram and compared with each other to study the four different treatment regimens. Results According to the data obtained, the mean dose to the left breast (PTV), heart and ipsilateral lung was significantly reduced in hypofractionation methods compared to conventional regimen. The homogeneity and the conformity index values showed no significant difference in any of the treatment regimens. The dose received showed no difference in lung volume. For heart, the volume of 38 and 43% of the prescribed dose were significantly higher in the conventional method than in the three hypofractionation regimens. Conclusion Hypofraction treatment regimens with fewer treatment fraction and a dose per fraction greater than 2Gy compared to conventional dose fractionation led to a dose reduction for the heart and the same side of the lung.