Left Breast Irradiation Research Articles

Reducing Cardiac Radiation Dose From Breast Cancer Radiation Therapy With Breath Hold Training and Cognitive Behavioral Therapy.

The delivery of radiation therapy shares many of the challenges encountered in imaging procedures. As in imaging, such as MRI, organ motion must be reduced to a minimum, often for lengthy time periods, to effectively target the tumor during imaging-guided therapy while reducing radiation dose to nearby normal tissues. For patients, radiation therapy is frequently a stress- and anxiety-provoking medical procedure, evoking fear from negative perceptions about irradiation, confinement from immobilization devices, claustrophobia, unease with equipment, physical discomfort, and overall cancer fear. Such stress can be a profound challenge for cancer patients' emotional coping and tolerance to treatment, and particularly interferes with advanced radiation therapy procedures where active, complex and repetitive high-level cooperation is often required from the patient.In breast cancer, the most common cancer in women worldwide, radiation therapy is an indispensable component of treatment to improve tumor control and outcome in both breast-conserving therapy for early-stage disease and in advanced-stage patients. High technological complexity and high patient cooperation is required to mitigate the known cardiac toxicity and mortality from breast cancer radiation by reducing the unintended radiation dose to the heart from left breast or left chest wall irradiation. To address this, radiation treatment in daily deep inspiration breath hold (DIBH), to create greater distance between the treatment target and the heart, is increasingly practiced. While holding the promise to decrease cardiac toxicity, DIBH procedures often augment patients' baseline stress and anxiety reaction toward radiation treatment. Patients are often overwhelmed by the physical and mental demands of daily DIBH, including the nonintuitive timed and sustained coordination of abdominal thoracic muscles for prolonged breath holding.While technologies, such as DIBH, have advanced to millimeter-precision in treatment delivery and motion tracking, the "human factor" of patients' ability to cooperate and perform has been addressed much less. Both are needed to optimally deliver advanced radiation therapy with minimized normal tissue effects, while alleviating physical and cognitive distress during this challenging phase of breast cancer therapy.This article discusses physical training and psychotherapeutic integrative health approaches, applied to radiation oncology, to leverage and augment the gains enabled by advanced technology-based high-precision radiation treatment in breast cancer. Such combinations of advanced technologies with training and cognitive integrative health interventions hold the promise to provide simple feasible and low-cost means to improve patient experience, emotional outcomes and quality of life, while optimizing patient performance for advanced imaging-guided treatment procedures - paving the way to improve cardiac outcomes in breast cancer survivors.

Evaluation of the Irradiated Volume of the Heart and Cardiac Substructures After Left Breast Radiotherapy.

Twenty-five patients were enrolled in our study. We retrospectively assessed the radiation doses to the whole heart, left anterior descending artery (LAD) and left ventricle (LV). The mean heart dose (MHD) was 152 cGy (SD=50.56 cGy) and the range was 74-279 cGy. The LAD was the most exposed structure, with a mean dose of 448.91 cGy (SD=490.53 cGy) and range of 120-2,057cGy. Finally, the mean LV dose was 149.12 cGy (SD=69.57) with a range of 63-317 cGy. The early results of our study showed low radiation exposure of the whole heart and left ventricle, and higher exposure of the LAD. The data that will emerge from the evaluation of strain echo parameters should show whether these associations might be useful in clinical practice for the prediction of early subclinical cardiac changes.

118P Should DIBH (deep inspiration breath-hold) be the standard of care in LBC (left breast cancer)?

Radiotherapy is the most effective treatment to eradicate the residual locoregional disease after breast cancer surgery with significative survival improvements after 15 years post diagnostic. For women receiving left-breast radiotherapy (DIBH) is used to further mitigate mortality and morbidity due to late cardiac toxicity, with a demonstrated linear relationship with Mean Heart Dose (MHD). The risk increases 7.4% per Gy, starting within the first 5 years and continuing into the third decade after radiotherapy. The aim of this study was to evaluate the effect of DIBH irradiation on MHD, V16, V8, V4 and mean, maximum and D10% left anterior descending coronary artery (LADCA) dose. 75 patients with left breast cancer (LBC), after radical mastectomy or conservative surgery, that were able to maintain voluntary DIBH ≥ 20 seconds, were irradiated with this cardiac sparring approach. All patients received hypofractionated radiotherapy (total dose of 40.05Gy / 2.67Gy per fraction) with 58 receiving a concomitant boost (total dose of 48Gy / 3.2Gy per fraction) and 9 patients having axillary nodes irradiated. The target volume was delineated on CT in DIBH and Free Breathing (FB) according to the ESTRO consensus guideline and heart according to the CT-based atlas by Feng et al. Tangent-based intensity modulated radiation therapy (n: 71) or VMAT (n: 4) plans were developed for both datasets. Patient set-up and tracking in FB/DIBH was monitored by Surface Guided Radiation Therapy (VisionRT, London, UK), after daily validation by cone beam CT matching. DIBH reduces significantly MHD, V16, V8, V4 and mean, maximum and D10% LAD dose compared to FB (p = 0.001). This difference is irrespective of breast PTV volume (797±367.6 cm3) or boost PTV volume (75.3 ± 30.3cm3). DIBH average MHD was 1.20 Gy (0.87-1.62) and average LADCA Dmean of 4.95 Gy (2.79-9.14) with respectively in FB 3.18 Gy (2.47-4.26) and 20.20Gy (12.29.-25.40). DIBH in LBC does lead to a significant reduction in heart and LADCA doses by increasing the distance between target and heart. These reductions could contribute to increase cardiovascular health of LBC. These findings apply to all patients and further studies will indicate to which subgroups the benefits are more pronounced.

Abstract P4-12-29: Utility of surface guide radiation therapy (SGRT) in radiation therapy for breast cancer

Abstract Purpose: Radiation therapy has been shown to be a highly effective treatment for breast cancer. Historically, patient setup for daily treatment has required a set of permanent tattoos. However, due to a variety of reasons, it may be hard to align patients to these marks and the marks can also cause distress in many patients. National Comprehensive Cancer Network’s (NCCN) radiation therapy guidelines recommend weekly radiation ports films; however, many centers perform daily image guidance using x-rays for breast treatments prior to radiation delivery, increasing both radiation dose and treatment time. Surface Guided Radiation Therapy (SGRT) is a technique which is being adopted by radiation therapy centers to aid in patient’s setup and treatment delivery accuracy. SGRT is safe and non-invasive, using visible light to compare the patient’s skin surface in the treatment room to the planned treatment position with sub-millimeter accuracy. SGRT can also automatically signal for the treatment delivery system to pause radiation if the patient moves out of the desired position. The aim of this study was to evaluate the AlignRT (Vision RT, Ltd, London, United Kingdom) SGRT system for patient setup accuracy in comparison to a 3-point tattoo setup and daily KV pair imaging. Methods: A total of 20 breast cancer patients (600 radiation fractions) were setup using a 3-point tattoo technique and then positioned using AlignRT. Inter-fraction positions were analyzed between all three techniques, namely tattoo, AlignRT and kV imaging. In addition, the AlignRT system was used to evaluate that patient’s position during breath hold. This deep inspiration breath hold (DIBH) technique is designed to provide cardiac sparing during left breast radiotherapy. Results: Using 3-point tattoo setup, an average magnitude of 5.7±3 mm error from isocenter was measured, compared to 2.4±1 mm using surface guidance. Statistically significant 3d shift vectors were found between patient setup using 3-point tattoo and SGRT techniques, however between SGRT and daily KV imaging 3d shift vectors were not statistically significant. AlignRT based DIBH showed the distance between the heart and chest-wall at the mid tangential beam level, based on weekly port films, to be within 2±1 mm of the planned level. Conclusion: SGRT has been shown to improve the accuracy of patient setup compared to 3-point tattoos and is comparable to daily KV imaging for isocentric setup. SGRT can be used in clinics to reduce the frequency of KV imaging and therefore additional radiation exposure. SGRT can also remove setup tattoo requirements which are placed during simulation which provide a permanent reminder to patients of their cancer and treatment. SGRT has also been demonstrated to ensure adequate and reproducible breath hold for DIBH left sided breast treatments. Citation Format: Snehal Desai. Utility of surface guide radiation therapy (SGRT) in radiation therapy for breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-12-29.

Factors Affecting Heart and Anterior Descending Coronary Artery Radiation Dose during Left Breast Irradiation (Dosimetric Retrospective study)

Background: Breast cancer is the commonest cancer in females. Radiotherapy is one of the important factors in treatment of breast cancer. Heart and coronary artery are radio-biologically serial organs. Radiation toxicity in the treatment of breast cancer showed significant clinical problem and increased cardiac morbidity and mortality. Aim of the Work: Assessing Factors affecting heart and anterior descending coronary artery dose during left breast irradiation in 3D technique. Patients and Methods: This study included 69 patients with left breast cancer received radiotherapy to the chest wall or breast tissue at Clinical Oncology Department, Al-Hussein University hospital. Results: heart size and Maximum heart distance included in tangential fled had a relation between mean of heart and ADCA. Heart size rang (442.4 -898.9) with mean 623±104 cm3 we found when heart size increase the mean dose to heart and ADCA decrease with significant p value 0.017 and 0.016 respectively. Maximum heart distance that when if it was ≤3cm, the mean of the ADCA was 18.5±10.9 Gy while when if it was >3cm, the mean of the ADCA was 27.9±9.1 Gy with a p-value 0.030 which is statistically significant. Conclusion: Maximum heart distance included in tangential field and Heart size were only Factors can Affect mean of Heart and ADCA Radiation Dose During Left Breast Irradiation while BSA, WT, BMI, HT, RTH dose, Number of fractions, number of segments, para sternal tissue thickness, Breast Size, Shortest distance between heart and ANT chest wall, Site, Extent, Type surgery, Boost, Bolus and stage were insignificant.

Myocardial dysfunction in long-term breast cancer survivors treated at ages 40-50 years.

AimsAnthracyclines increase heart failure (HF) risk, but the long‐term prevalence of myocardial dysfunction in young breast cancer (BC) survivors is unknown. Early measures of left ventricular myocardial dysfunction are needed to identify BC patients at risk of symptomatic HF.Methods and resultsWithin an established cohort, we studied markers for myocardial dysfunction among 569 women, who were 5–7 years (n = 277) or 10–12 years (n = 292) after BC treatment at ages 40–50 years. Left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) were assessed by echocardiography. N‐terminal pro‐brain natriuretic peptide (NT‐proBNP) was measured in serum. Associations between patient‐related and treatment‐related risk factors and myocardial dysfunction were evaluated using linear and logistic regression. Median ages at BC diagnosis and cardiac assessment were 46.7 and 55.5 years, respectively. Anthracycline‐treated patients (n = 313), compared to the no‐anthracycline group (n = 256), more often had decreased LVEF (10% vs. 4%), impaired GLS (34% vs. 27%) and elevated NT‐proBNP (23% vs. 8%). GLS and LVEF declined in a linear fashion with increasing cumulative anthracycline dose (GLS: +0.23 and LVEF: −0.40 per cycle of 60 mg/m2; P < 0.001) and GLS was worse for patients with left breast irradiation. The risk of NT‐proBNP >125 ng/L was highest for patients who received 241–300 mg/m2 anthracycline dose compared to the no‐anthracycline group (odds ratio: 3.30, 95% confidence interval: 1.83–5.96).ConclusionImpaired GLS and increased NT‐proBNP levels are present in a substantial proportion of young BC survivors treated with anthracyclines. Whether this will lead to future cardiac disease needs to be evaluated by longitudinal assessment.

Predictors of cardiac and lung dose sparing in DIBH for left breast treatment

This retrospective study of left breast radiation therapy (RT) investigates the correlation between anatomical parameters and dose to heart or/and left lung in deep inspiration breath-hold (DIBH) compared to free-breathing (FB) technique. Anatomical parameters of sixty-seven patients, treated with a step-and-shoot technique to 50 Gy or 50.4 Gy were included. They consisted of the cardiac contact distances in axial (CCDax) and parasagittal (CCDps) planes, and the lateral heart-to-chest distance (HCD). Correlation analysis was performed to identify predictors for heart and lung dose sparing. Paired t-test and linear regression were used for data analysis with significance level of p = 0.05. All dose metrics for heart and lung were significantly reduced with DIBH, however 21% of patients analyzed had less than 1.0 Gy mean heart dose reduction. Both FB-CCDpsdistance and FB-HCD correlated with FB mean heart dose and mean DIBH heart dose reduction. The strongest correlation was observed for the ratio of FB-CCDpsand FB-HCD with heart dose sparing. A FB-CCDps and FB-HCD model was developed to predict DIBH induced mean heart dose reduction, with 1.04 Gy per unit of FB-CCDps/FB-HCD. Variation between predicted and actual mean heart dose reduction ranged from −0.6 Gy to 0.6 Gy. In this study, FB-CCDps and FB-HCD distance served as predictors for heart dose reduction with DIBH equally, with FB-CCDps/FB-HCD as a stronger predictor. These parameters and the prediction model could be further investigated for use as a tool to better select patients who will benefit from DIBH.

Left breast irradiation with tangential intensity modulated radiotherapy (t-IMRT) versus tangential volumetric modulated arc therapy (t-VMAT): trade-offs between secondary cancer induction risk and optimal target coverage

BackgroundAdjuvant radiotherapy is the standard treatment after breast-conserving surgery. According to meta-analyses, adjuvant 3d-conventional irradiation reduces the risk of local recurrence and thereby improves long-term survival by 5–10%. However, there is an unintended exposure of organs such as the heart, lungs and contralateral breast. Irradiation of the left breast has been related to long-term effects like increased rates of coronary events as well as second cancer induction. Modern radiotherapy techniques such as tangential intensity modulated radiotherapy (t-IMRT) and tangential volumetric modulated arc therapy (t-VMAT) and particularly deep inspiration breath hold (DIBH) technique have been developed in order to improve coverage of target volume and to reduce dose to normal tissue. The aim of this study was to compare t-IMRT-plans with t-VMAT-plans in DIBH position for left-sided breast irradiation in terms of normal tissue exposure, i.e. of lungs, heart, left anterior descending coronary artery (LADCA), as well as homogeneity (HI) and conformity index (CI) and excess absolute risk (EAR) for second cancer induction for organs at risk (OAR) after irradiation.MethodsTwenty patients, diagnosed with left-sided breast cancer and treated with breast-preserving surgery, were included in this planning study. For each patient DIBH-t-IMRT plan using 5 to 7 beams and t-VMAT plan using four rotations were generated to achieve 95% dose coverage to 95% of the volume. Data were evaluated on the basis of dose-volume histograms: Cardiac dose and LADCA (mean and maximum dose, D25% and D45%), dose to ipsilateral and contralateral lung (mean, D20%, D30%), dose to contralateral breast (mean dose), total monitor units, V5% of total body and normal tissue integral dose (NTID). In addition, homogeneity index and conformity index, as well as the excess absolute risk (EAR) to estimate the risk of second malignancy were calculated.ResultsT-IMRT showed a significant reduction in mean cardiac dose of 26% (p = 0.002) compared to t-VMAT, as well as a significant reduction in the mean dose to LADCA of 20% (p = 0.03). Following t-IMRT, mean dose to the left lung was increased by 5% (p = 0.006), whereas no significant difference was found in the mean dose to the right lung and contralateral breast between the two procedures. Monitor units were 31% (p = 0.000004) lower for t-IMRT than for t-VMAT. T-IMRT technique significantly reduced normal tissue integral dose (NTID) by 19% (p = 0.000005) and the V5% of total body by 24% (p = 0.0007). In contrast, t-VMAT improved CI and HI by 2% (p = 0.001) and 0.4% (p = 0.00001), respectively. EAR with t-IMRT was significantly lower, especially for contralateral lung and contralateral breast (2–5/10,000 person years) but not for ipsilateral lung.ConclusionCompared to t-VMAT, t-IMRT in left-sided breast irradiation significantly reduced dose to organs at risk as well as normal tissue integral dose, and V5% total body. EAR with t-IMRT was significantly lower for contralateral lung and contralateral breast. T-VMAT, however, achieved better homogeneity and conformity. This may be relevant in individual cases where sufficient coverage of medial lymphatic target volumes is warranted.

Evaluating a potential technique with local optical flow vectors for automatic organ-at-risk (OAR) intrusion detection and avoidance during radiotherapy

Various techniques of deep inspiration breath hold (DIBH) have been used to mitigate the likelihood and risk of exposing the heart, an organ-at-risk (OAR) for unintended radiation during left breast radiotherapy. However, issues of reproducibility of these techniques warrant further investigation into the feasibility of detecting the intrusion of an OAR into the treatment field during intra-fractional treatment delivery. The increase of high-dose, low-fraction radiotherapy treatments makes it important to immediately adapt treatment once an OAR is detected in the treatment field. This proof-of-concept implementation includes an algorithm that detects and tracks the motion at the edges of a treatment field and a control algorithm that adapts the treatment aperture according to the motion detected. In accordance to the AAPM Task-Group (TG-132) report, image registration techniques should be verified with virtual and physical phantoms prior to clinical application. Since most OARs move as a result of respiration-induced motion, we have used a lung phantom to generate images of a generic OAR intruding into a treatment field with known velocity. The phantom was programmed to move with sinusoidal and lung patient tumor motion patterns and the accuracy of intrusion tracking and MLC adaptation were benchmarked with the ground truth—programmed motion of the OAR. The motions were recorded with an electronic portal imaging device (EPID). An optimal cluster size of 9 × 9 motion vectors was found to provide the smallest average absolute position error of 0.3 mm. A strong linear correlation between the adapted MLC leaves and the actual OAR position was observed. The algorithm had a mean position tracking error of −0.4 ± 0.3 mm and a precision of 1.1 mm. It is possible to adapt MLC leaves based on the motion detected at the edges of the irradiated field, and it would be feasible to shield an unplanned intrusion of an OAR into the treatment field.

A Broad Evaluation of Left Breast Radiotherapy

A Broad Evaluation of Left Breast Radiotherapy

EP-1916 Predictive model of the dose to the heart based on geometry evaluation in left breast radiotherapy

EP-1916 Predictive model of the dose to the heart based on geometry evaluation in left breast radiotherapy

Accuracy and stability of deep inspiration breath hold in gated breast radiotherapy – A comparison of two tracking and guidance systems

PurposeTo characterize reproducibility of patient breath-hold positioning and compare tracking system performance for Deep Inspiration Breath Hold (DIBH) gated left breast radiotherapy. Methods29 consecutive left breast DIBH patients (655 fractions) were treated under the guidance of Calypso surface beacons with audio-feedback and 35 consecutive patients (631 fractions) were treated using C-RAD Catalyst HD surface imaging with audiovisual feedback. The Calypso system tracks a centroid determined by two radio-frequency transponders, with a manually enforced institutional tolerance, while the surface image based CatalystHD system utilizes real-time biometric feedback to track a pre-selected point with an institutional tolerance enforced by the Elekta Response gating interface. DIBH motion data from Calypso was extracted to obtain the displacement of breath hold marker in ant/post direction from a set-zero reference point. Ant/post point displacement data from CatalystHD was interpreted by computing the difference between raw tracking points and the center of individual gating windows. Mean overall errors were compared using Welsh’s unequal variance t-test. Wilcoxon rank sum test were used for statistical analysis with P < 0.05 considered significant. ResultsMean overall error for Calypso and CatalystHD were 0.33 ± 1.17 mm and 0.22 ± 0.43 mm, respectively, with t-test comparison P-value < 0.034. Absolute errors for Calypso and CatalystHD were 0.95 ± 0.75 mm and 0.38 ± 0.30 mm, respectively, with Wilcoxon rank sum test P-value <2×10-16. Average standard deviation per fraction was found to be 0.74 ± 0.44 mm for Calypso patients versus 0.54 ± 0.22 mm for CatalystHD. ConclusionReduced error distribution widths in overall positioning, deviation of position, and per fraction deviation suggest that the use of functionalities available in CatalystHD such as audiovisual biofeedback and patient surface matching improves accuracy and stability during DIBH gated left breast radiotherapy.

OC-0605 Is DIBH more robust than FB in VMAT left breast irradiation? Multicenter and multivendor analysis

OC-0605 Is DIBH more robust than FB in VMAT left breast irradiation? Multicenter and multivendor analysis

Comparison of deep inspiration breath hold and free breathing technique in left breast cancer irradiation: a dosimetric evaluation in 40 patients

To analyze the reduction of dose to organs at risk between deep inspiration breath hold (DIBH) and free breathing (FB) techniques in left breast irradiation. Forty left-sided breast cancer patients received adjuvant radiotherapy and were retrospectively analyzed. Treatment plans were generated on both DIBH and FB computed tomography (CT) scans. The patients were monitored by the Varian RPM™ respiratory gating system. The treatment planning was performed with conformal tangential fields by means of 6 and 10 MV photon fields. Treatment schedule were 50 Gy in 25 fractions (conventional schedule) or 40.05 Gy in 15 fractions (hypofractionated schedule), with or without sequential boost to tumor bed. Dose-volume histograms were compared for all plans. For the comparison, we considered cardiac and ipsilateral lung doses and volumes. Quantitative statistical analyses of plans dose differences were generated. In order to correlate the mean cardiac dose difference between the FB and DIBH techniques with maximum heart distance (MHD), a linear regression model was used. A statistically significant reduction of cardiac and pulmonary doses using the DIBH technique was achieved compared with FB plans, maintaining an equal coverage of planning target volume (PTV). A positive correlation was found between MHD and mean heart dose difference. Our study confirms the DIBH technique advantage in reducing cardiac and pulmonary doses for tangentially treated left-sided breast cancer patients. Further research is warranted to evaluate potential long-term clinical implications of these relevant dosimetry results.

P198 - Cardiac sparing radiotherapy in left tangential breast irradiation: geometric conformity of chest wall and heart volume as useful clinical parameters for a tailored radiation approach

P198 - Cardiac sparing radiotherapy in left tangential breast irradiation: geometric conformity of chest wall and heart volume as useful clinical parameters for a tailored radiation approach

Application of retrospective data analysis to clinical protocol design: can the potential benefits of breath-hold techniques for breast radiotherapy be assessed without testing on patients?

The advantages, in terms of heart dose sparing, resulting from using a breath-hold technique when treating supine left breast radiotherapy patients are widely accepted, and increasing numbers of radiotherapy departments are implementing breath-hold techniques. However, due to differences in patient setup and treatment planning protocols between radiotherapy departments, it is important to assess the benefits of using a breath-hold technique within each department, before or during implementation. This study investigated the use of retrospective analysis of past patient treatment plans, as a means to identify the potential for breath-hold techniques to benefit patients. In-house "Treatment and Dose Assessor" code was used to complete a bulk retrospective evaluation of dose-volume metrics for 708 supine and 13 prone breast and chest wall radiotherapy treatments, that were planned using the same clinical protocols, which did not utilise a breath hold technique. For supine patients, results showed statistically significant differences between heart doses from left and right breast treatment plans, in the absence of significant differences between lung doses from left and right breast treatment plans, confirming the potential benefit of using a breath-hold technique for supine left breast radiotherapy patients. Fewer than 1% of the right breast treatment plans showed heart doses high enough to suggest a possible benefit from using a breath-hold technique. Approximately 50% of the prone left breast treatment plans included very low heart doses without intervention, and may therefore have shown no noticeable dosimetric benefit from the use of a breath hold. This study demonstrated the extent of information that can be obtained using retrospective data analysis, before or instead of obtaining multiple CT images of patients and completing a process of dual planning and prospective dose evaluation.

Dosimetric comparison of VMAT with integrated skin flash to 3D field-in-field tangents for left breast irradiation.

Volumetric modulated arc therapy (VMAT) has been implemented for left breast irradiation to reduce prescription dose to the heart and improve dose homogeneity across the targeted breast. Our in‐house method requires application of a bolus during the optimization process with a target outside of the body, then removing the bolus during the final calculation in order to incorporate skin flash in VMAT plans. To quantify the dosimetric trade‐offs between traditional 3D field‐in‐field tangents and VMAT with integrated skin flash for these patients, we compared nine consecutive patients who recently received radiation to their entire left breast but not their regional lymphatics. Tangent plans used non‐divergent tangents of mixed energies and VMAT plans utilized four 6 MV arcs of roughly 260°. Mean dose to the heart, contralateral lung, and contralateral breast and their volume receiving 5%, 10%, and 20% of the prescription dose were higher in all nine VMAT plans than in the static tangential beam plans. For all critical structures, the mean VMAT DVH was higher in the low‐dose region and crossed the 3D field‐in‐field DVH between 23.13% and 34.18% of the prescription dose (984.75‐1454.70 cGy). However, the volume of the contralateral breast and heart receiving the prescription dose was slightly lower in the VMAT plans, but not statistically significant. VMAT provided superior homogeneity, with a mean homogeneity index of 9.41 ± 1.64 compared to 11.05 ± 1.82 for 3D tangents. Results indicate that VMAT spares the heart, contralateral lung, and contralateral breast from prescription dose at the cost of increasing their mean and low‐dose volume and delivers a more homogenous dose distribution to the breast. For these reasons, VMAT is selectively applied at the request of the physician for left breast radiation without respiratory gating to spare the heart from prescription dose in cases of poor anatomical geometry.

Longitudinal Results of Cardiac MRI Left Ventricular Mapping Following Tangential Left Breast Radiotherapy

Longitudinal Results of Cardiac MRI Left Ventricular Mapping Following Tangential Left Breast Radiotherapy

4. Application of the FMECA analysis in breast radiotherapy with active breath hold

Purpose The Deep Inspiration Breath Hold (DIBH) technique was introduced in order to freeze the breathing motion in a mid-inhale position with a computer controlled valve, with the purpose of lowering heart dose in left breast radiotherapy. A training project with FMECA analysis was started, aiming to write and implement a protocol, improved by proactive clinical risk analysis and feedback from the operators (radiotherapists, radiographers and medical physicists). Methods and materials At first, few operators were involved to take knowledge and dexterity with the system. They became the tutors and the core of the improvement group for the subsequent training project. The project was comprised of four stages: (1) implementation of the technique (tutors); (2) field training (tutors and operators); (3) training course on FMEA/FMECA analysis (all operators and clinical governance department); (4) implementation of the FMECA analysis in left breast radiotherapy DIBH treatments (tutors and FMEA-workgroup; the FMEA workgroup consisted of these professional roles: radiotherapists, radiographers, medical physicists and clinical governance area’s physicians). Results The outputs for each stage were: (1) redact the protocol and the training checklist; (2) training of all operators and application of the self-evaluation checklist; (3) understanding the clinical risk principles; (4) application of the FMEA analysis, data processing and final report. The self-evaluation checklist was comprised of 37 targets, with achieved/partially-achieved/not-achieved check boxes. The FMEA table was comprised of 48 activities, subdivided in 5 phases (DIBH-suitable-patients detection, treatment simulation, planning, radiotherapy treatment delivery, quality control), with pertinent Risk Probability Numbers associated. Points 1–3 were completed, while completion of point 4 is expected for the first half of 2018. Conclusion The application of the FMEA/FMECA method allowed us to introduce proactive methods to analyze and manage the clinical risk related to the introduction of the new DIBH technique. The FMEA/FMECA method was included in a training project which allowed to obtain feedback from all the involved operators, improving the understanding of the work process, the skill and safety in the practical use and the redaction of a multidisciplinary protocol.

172. Predictors of cardiac dose reduction achieved with deep inspiration breath hold technique over free breathing technique in left breast radiotherapy

PurposeDeep inspiration breath-hold (DIBH) has been routinely applied in left breast radiotherapy to reduce cardiac exposure. The purpose of this study was to compare deep inspiration breath hold and free breathing techniques (FB) in terms of heart and left-lung doses and to determine possible predictors of the dose reduction achieved with DIBH (ΔDBH-FB). MethodsTen patients with left breast cancer have been treated with postoperative radiotherapy in Parma Hospital. For each patient both the FB and the DIBH planning CT were acquired. 3DCRT treatment plans using tangential field-in-field beams were developed for both FB and DIBH. FB and DIBH dose distributions were compared in terms of Dmean, V5Gy, V20Gy, V30Gy of the heart and V5Gy, V20Gy of the left-lung. Many geometric/anatomical parameters were measured in the FB condition: heart and left-lung volumes (Vheart, Vlung-L), maximum thickness of the same organs inside the tangential fields (dheart, dlung-L), axial and para-sagittal cardiac contact distances (CCDax, CCDps), maximum tangential distance between beam-entrance and beam-exit (dentrance-exit), maximum anteroposterior diameter of the chest. ResultsDIBH plans showed a significant reduction of Dmean (−60.9%), V5Gy (−82.5%), V20Gy (−93.6%) and (−95.8%) of the heart (p < 0.01, Wilcoxon signed-rank test), while no significant difference in target coverage and left-lung V5Gy, V20Gy. The parameters that significantly correlated with ΔDBH-FB were: Vheart (0.041 < p < 0.049, 0.63 < R < 0.65), dheart (p < 0.001, 0.96 < R < 0.97), CCDps (0.036 < p < 0.045, 0.64 < R < 0.66) and dentrance-exit (0.036 < p < 0.048, 0.64 < R < 0.67). ConclusionsThis study confirmed how DIBH for left breast cancer treatment can decrease cardiac dose. The benefit of DIBH over FB strictly depends on chest shape, heart size and heart position. However, most of the parameters showed a weak correlation with ΔDBH-FB, so they cannot be used to effectively predict ΔDBH-FB. Only dheart seems to be a good predictor of ΔDBH-FB, but more cases must be included to confirm/reject these findings.