Breathing adapted radiotherapy of breast cancer: reduction of cardiac and pulmonary doses using voluntary inspiration breath-hold

Evaluating Danish Breast Cancer Group locoregional radiotherapy guideline adherence in clinical treatment data 2008-2016: The DBCG RT Nation study

BACKGROUND AND PURPOSE

Guideline adherence in radiotherapy is crucial for maintaining treatment quality and consistency, particularly in non-trial patient settings where most treatments occur. The study aimed to assess the impact of guideline changes on treatment planning practices and compare manual registry data accuracy with treatment planning data.

MATERIALS AND METHODS

This study utilised the DBCG RT Nation cohort, a collection of breast cancer radiotherapy data in Denmark, to evaluate adherence to guidelines from 2008 to 2016. The cohort included 7448 high-risk breast cancer patients. National guideline changes included, fractionation, introduction of respiratory gating, irradiation of the internal mammary lymph nodes, use of the simultaneous integrated boost technique and inclusion of the Left Anterior Descending coronary artery in delineation practice. Methods for structure name mapping, laterality detection, detection of temporal changes in population mean lung volume, and dose evaluation were presented and applied. Manually registered treatment characteristic data was obtained from the Danish Breast Cancer Database for comparison.

RESULTS

The study found immediate and consistent adherence to guideline changes across Danish radiotherapy centres. Treatment practices before guideline implementation were documented and showed a variation among centres. Discrepancies between manual registry data and actual treatment planning data were as high as 10% for some measures.

CONCLUSION

National guideline changes could be detected in the routine treatment data, with a high degree of compliance and short implementation time. Data extracted from treatment planning data files provides a more accurate and detailed characterisation of treatments and guideline adherence than medical register data.

Prospective Randomized Trial Comparing 2 Devices for Deep Inspiration Breath Hold Management in Breast Radiation Therapy: Results of the BRAVEHeart Trial

Purpose

The Breast Radiotherapy Audio Visual Enhancement for sparing the Heart (BRAVEHeart) trial prospectively randomized patients with left-sided breast cancer to 1 of 2 deep inspiration breath hold biofeedback devices: a novel chest surface tracking system and an abdominal block tracking system. The primary hypothesis was that the accuracy of chest tracking would be higher than that of abdominal tracking as the chest is a more direct surrogate of the breast target.

Methods and Materials

Patients with left-sided breast cancer were treated in deep inspiration breath hold with intensity modulated radiation therapy delivery. Patients were randomized to either the novel chest surface system or abdominal block system for active management of breath hold with visual feedback. On both trial arms, the unallocated system was monitored passively. A total of 239,296 cine electronic portal imaging device images were analyzed retrospectively to extract the chest wall position. Treatment accuracy was quantified as the deviation of the internal chest wall during treatment relative to the planned position from the digitally reconstructed radiograph. The correlation between motion of the external surrogate and internal chest wall was calculated per-breath hold. Ease of use was assessed with questionnaires for both radiation therapists and patients and appointment length recorded.

Results

Data from 26 participants were available for analysis. No difference was found in delivered treatment accuracy between arms. Across all patients and fractions, the median correlation between internal chest wall movement and external surrogate was 0.69 for the chest surface and 0.17 for the abdominal block. Patients found it easy to follow visual feedback from both systems. No difference was found in appointment length between arms.

Conclusions

No statistical evidence was found for superior treatment accuracy, satisfaction, or appointment length for the novel chest surface tracking device compared with the abdominal block system. During deep inspiration breath hold, the median per-breath hold correlation of internal chest wall movement to the motion of the chest surface was higher than the median correlation of the abdominal block to the chest surface.

Can physical parameters from radiation simulation scan with deep inspiratory breath hold predict magnitude of heart dose reduction?

INTRODUCTION

Deep inspiratory breath hold is one of the techniques for reducing the heart doses for left breast cancers. This study was conducted to confirm use of physical parameters from DIBH simulation CT scan like DIBH amplitude alongside several novel parameters to predict the heart dose reduction.

MATERIALS AND METHODS

Segmentation and planning of radiation to the left breast on the free breathing (FB) and DIBH simulation scan was performed for 50 left-sided breast cancer patients treated with DIBH technique. Physical parameters, namely DIBH amplitude, anterior sternal displacement, diaphragmatic excursion, ratio of lung volume (cc) in DIBH scan to lung volume in FB scan (cc), and delta heart volume in field (DHVIF), were extracted and were compared with magnitude of heart dose reduction (mean heart dose, V30Gy, and D5%).

RESULTS

Forty-eight (96%) patients achieved reduction in the mean heart dose with DIBH technique, while all patients had reduction in V30Gy. The median reduction was 41%, 89.7%, and 63% in the mean dose, V30Gy, and D5%, respectively. While DIBH did not correlate with heart dose reduction, ratio of lung volumes and DHVIF showed a strong positive correlation with heart dose reduction (P < 0.05). Sternal displacement correlated weakly with heart dose reduction but strongly with DHVIF, demonstrating to be an indirect predictor.

CONCLUSIONS

Physical parameters like anterior sternal displacement, ratio of lung volumes of DIBH to FB, and possibly diaphragmatic movement can predict the dose reduction before the dose calculations by the physicist. These parameters can be used to construct a model to predict heart dose reduction.

Deep inspiratory breath-hold radiotherapy on a Helical Tomotherapy unit: Workflow and early outcomes in patients with left-sided breast cancer

INTRODUCTION

The clinical implementation of deep inspiratory breath-hold (DIBH) radiotherapy to reduce cardiac exposure in patients with left-sided breast cancer is challenging with helical tomotherapy(HT) and has received little attention. We describe our novel approach to DIBH irradiation in HT using a specially designed frame and manual gating, and compare cardiac substructure doses with the free-breathing (FB) technique.

MATERIAL AND METHODS

The workflow incorporates staggered junctions and a frame that provides tactile feedback to the patient and monitoring for manual cut-off. The treatment parameters and clinical outcome of 20 patients with left-sided breast cancer who have undergone DIBH radiotherapy as a part of an ongoing prospective registry are reported. All patients underwent CT scans in Free Breathing (FB) and DIBH using the in-house Respiframe, which incorporates a tactile feedback-based system with an indicator pencil. Plans compared target coverage, cardiac doses, synchronizing treatment with breath-hold and avoiding junction repetition. MVCT scans are used for patient alignment.

RESULTS

The mean dose (Dmean) to the heart was reduced by an average of 34 % in DIBH-HT compared to FB-HT plans (3.8 Gy vs 5.7 Gy). Similarly, 32 % and 67.8 % dose reduction were noted in the maximum dose (D0.02 cc) of the left anterior descending artery, mean 12.3 Gy vs 18.1 Gy, and mean left ventricle V5Gy 13.2 % vs 41.1 %, respectively. The mean treatment duration was 451.5 sec with a median 8 breath-holds; 3 % junction locations between successive breath-holds were replicated. No locoregional or distant recurrences were observed in the 9-month median follow-up.

CONCLUSION

Our workflow for DIBH with Helical-Tomotherapy addresses patient safety, treatment precision and challenges specific to this treatment unit. The workflow prevents junction issues by varying daily breath-hold durations and avoiding junction locations, providing a practical solution for left-sided breast cancer treatment with HT.

Quantitative analysis of the impact of respiratory state on the heartbeat-induced movements of the heart and its substructures

PURPOSE

This study seeks to examine the influence of the heartbeat on the position, volume, and shape of the heart and its substructures during various breathing states. The findings of this study will serve as a valuable reference for dose-volume evaluation of the heart and its substructures in radiotherapy for treating thoracic tumors.

METHODS

Twenty-three healthy volunteers were enrolled in this study, and cine four-dimensional magnetic resonance images were acquired during periods of end-inspiration breath holding (EIBH), end-expiration breath holding (EEBH), and deep end-inspiration breath holding (DIBH). The MR images were used to delineate the heart and its substructures, including the heart, pericardium, left ventricle (LV), left ventricular myocardium, right ventricle (RV), right ventricular myocardium (RVM), ventricular septum (VS), atrial septum (AS), proximal and middle portions of the left anterior descending branch (pmLAD), and proximal portion of the left circumflex coronary branch (pLCX). The changes in each structure with heartbeat were compared among different respiratory states.

RESULTS

Compared with EIBH, EEBH increased the volume of the heart and its substructures by 0.25-3.66%, while the average Dice similarity coefficient (DSC) increased by - 0.25 to 8.7%; however, the differences were not statistically significant. Conversely, the VS decreased by 0.89 mm in the left-right (LR) direction, and the displacement of the RV in the anterior-posterior (AP) direction significantly decreased by 0.76 mm (p < 0.05). Compared with EIBH and EEBH, the average volume of the heart and its substructures decreased by 3.08-17.57% and 4.09-20.43%, respectively, during DIBH. Accordingly, statistically significant differences (p < 0.05) were observed in the volume of the heart, pericardium, LV, RV, RVM, and AS. The average DSC increased by 0-37.04% and - 2.6 to 32.14%, respectively, with statistically significant differences (p < 0.05) found in the right ventricular myocardium and interatrial septum. Furthermore, the displacements under DIBH decreased in the three directions (i.e.,- 1.73 to 3.47 mm and - 0.36 to 2.51 mm). In this regard, the AP displacement of the heart, LV, RV, RVM, LR direction, LV, RV, and AS showed statistically significant differences (p < 0.05). The Hausdorff distance (HD) of the heart and its substructures under the three breathing states are all greater than 11 mm.

CONCLUSION

The variations in the displacement and shape alterations of the heart and its substructures during cardiac motion under various respiratory states are significant. When assessing the dose-volume index of the heart and its substructures during radiotherapy for thoracic tumors, it is essential to account for the combined impacts of cardiac motion and respiration.

Carbon-fiber alternative to the commercial gating surrogate for the Varian Truebeam™

BACKGROUND

In this study we present the Tracking Accessory 3 (TA3) as an alternative to the commercial gating block (GB) surrogate for the Varian Truebeam™ gating system (TGS). The TGS requires three visible reflectors to track the surrogate, presenting an opportunity for a surrogate to be made with less material and thus smaller dosimetric footprint than the commercial four reflector model.

MATERIALS AND METHODS

Relative dose and depth dose profiles below the TA3 and the GB were measured with radiosensitive film. Accuracy and reproducibility of the detected motion amplitude for three TA3s and one GB were determined using a respiratory phantom with surrogate to determine the camera's tracking volume. Clinical performance was evaluated prospectively in 10 breast cancer patients treated with deep inspiration breath hold monitored with TA3 and compared to previously published results. Non-parametric statistics were applied to test for significance.

RESULTS AND CONCLUSIONS

Surface doses were increased up to 94% and 187% for the TA3 and GB, respectively, compared to no surrogate. The surface area influenced by at least 25% increase in dose was 12 cm2 and 105 cm2 for the TA3 and GB, respectively. The water equivalent thickness of the surrogates was found to be 1 mm for the TA3 and 3 mm for GB. The difference in measured amplitude were <0.2 mm for TA3 compared to the GB. The TA3s and GB were detected at all extremes of the clinically relevant tracking volume of the TGS. Clinical performance showed no significant differences. The TA3 caused less surface dose increase compared to the commercial GB. In the tested range all surrogates measured motion amplitude within 0.2 mm of reference value, which is not a clinically relevant difference. The TA3 showed no significant differences in clinical performance to similarly positioned surrogates.

Regional nodal irradiation in breast cancer patients: Effects of deep inspiration breath hold on the internal mammary chain location

The purpose of this study was to investigate the impact of deep inspiration breath hold (DIBH) on the positioning of thoracic structures and provide treatment planning recommendations for internal mammary chain (IMC) irradiation in breast cancer patients. Thirty-two breast cancer patients from our database underwent both DIBH and free breathing (FB) treatment planning. Contouring of the axillary lymph node clinical target volumes (CTVs: level I, II, III, IV, and IMC according to ESTRO), the internal mammary artery (IMA), the heart, and the left anterior descending artery (LAD) was performed. The following were then analyzed: the distance between the IMA and the heart, the craniocaudal distance in which IMC-CTV and heart coexist, the craniocaudal distance between the lower end of the of level III and IV and the upper end of the heart. Several significant geometric differences were observed between DIBH and FB that explain the efficacy of the DIBH for regional nodal irradiation. In >80% of patients the cranial origin of the LAD lies below the lower edge of the IMC-CTV in DIBH. In addition the slices in which the heart/LAD and IMC-CTV coexist decrease during DIBH. The IMA-heart distance is significantly larger in DIBH. Also the craniocaudal distance between the lower border of the CTV level III and IV and the upper border of the heart is larger in DIBH. The observed mechanisms during DIBH contribute significantly to the dose reduction in regional nodal irradiation. To further enhance the benefits of DIBH for the irradiation of the IMC-CTV, it is recommended to implement steep dose gradients in the caudal plane.

ESTRO-ACROP guideline: Recommendations on implementation of breath-hold techniques in radiotherapy

The use of breath-hold techniques in radiotherapy, such as deep-inspiration breath hold, is increasing although guidelines for clinical implementation are lacking. In these recommendations, we aim to provide an overview of available technical solutions and guidance for best practice in the implementation phase. We will discuss specific challenges in different tumour sites including factors such as staff training and patient coaching, accuracy, and reproducibility. In addition, we aim to highlight the need for further research in specific patient groups. This report also reviews considerations for equipment, staff training and patient coaching, as well as image guidance for breath-hold treatments. Dedicated sections for specific indications, namely breast cancer, thoracic and abdominal tumours are also included.

Difference between planned and delivered radiotherapy dose to the internal mammary nodes in high-risk breast cancer patients

Background and purpose

Chest wall movement during radiotherapy can impact the delivered dose to the internal mammary nodes (IMN) in high-risk breast cancer patients. Using portal imaging and dose reconstruction we aimed to examine the delivered IMN dose coverage.

Material and methods

Cine MV images were recorded for 39 breast cancer patients treated with daily image-guided radiotherapy (IGRT) in deep-inspiration breath-hold (DIBH). On the final frame of each cine MV recording the chest wall was matched with the Digitally Reconstructed Radiograph (DRR) from the treatment plan. The geometrical chest wall error was determined in the imager-plane perpendicular to the cranio-caudal direction, rounded to integer millimeters, and binned. For each 1 mm bin, an isocenter-shifted treatment plan was recalculated assuming that the projected error observed in the cine MV image was caused by anterior-posterior chest wall movement in the IMN region. A weighted plan sum yielded the IMN clinical target volume receiving at least 90% dose (V90_CTVn_IMN).

Results

The mean number of cine MV observations per patient was 36 (range 26-55). Most patients (67%) had on average a posterior chest wall position at treatment compared to planned. This translated into a change in the delivered median V90_CTVn_IMN of -0.7% (range, -11.9-2.9%; p < 0.001). The V90_CTVn_IMN reduction was greater than 9% in three patients. No clinically relevant differences were found for the mean lung dose or mean heart dose.

Conclusion

Using cine MV images, we found that the delivered V90_CTVn_IMN was significantly lower than planned. In 8% of the patients, the V90_CTVn_IMN reduction exceeded 9%.

The Efficacy of Multi-Leaf Collimator in the Reduction of Cardiac and Coronary Artery Dose in Left-Sided Breast Cancer Radiotherapy

Background

Multi-leaf collimator (MLC) is one of the efficient and cost-effective methods for protecting sensitive tissues around the target. This study aimed to evaluate the protective effect of MLC on the protection of sensitive organs in patients with left breast cancer.

Materials and Methods

This study was performed on computed tomography (CT) scans of 45 patients with left breast cancer. Two treatment plans were completed for each patient. Only the heart and left lung were considered organs at risk in the first treatment plan, and in the second treatment plan, the left anterior descending artery (LAD) was also considered the organ at risk. It was covered as much as possible by the MLC. Dosimetric results of tumor and organ at risk (OARs) were extracted from the dose-volume histogram and compared.

Results

The results showed that more LAD coverage by MLC leads to a significant reduction in the mean dose of OARs (P-value <0.05). The mean dose for heart, LAD, and left lung decreased by 11%, 7.4%, and 4.9%, respectively. The values of V₅ (volume received the dose of 5 Gy) and V₂₀ for the lung, V₁₀, V₂₅, and V30 for LAD, and V₅, V₂₀, V₂₅, and V₃₀ for the heart also decreased significantly (P-value <0.05).

Conclusions

In general, better protection of LAD, heart, and lungs can be achieved by maximal shielding organs at risk by MLC in radiation therapy for patients with left breast cancer.

Dose coverage and breath-hold analysis of breast cancer patients treated with surface-guided radiotherapy

BACKGROUND

Surface-guided radiotherapy (SGRT) is used to ensure a reproducible patient set-up and for intra-fraction motion monitoring. The arm position of breast cancer patients is important, since this is related to the position of the surrounding lymph nodes. The aim of the study was to investigate the set-up accuracy of the arm of patients positioned using SGRT. Moreover, the actual delivered dose was investigated and an extensive breath-hold analysis was performed.

METHODS

84 patients who received local or locoregional breast radiation therapy were positioned and monitored using SGRT. The accuracy of the arm position, represented by the clavicle position, was studied on the anterior-posterior kV-image. To investigate the effect of changes in anatomy and patient set-up, the actual delivered dose was calculated on cone-beam CT-scans (CBCT). A deformable registration of the CT to the CBCT was applied to deform the structures of the CT onto the CBCT. The minimum dose in percentage of the prescribed dose that was received by 98% of different CTV volumes (D98) was determined. An extensive breath-hold analysis was performed and definitions for relevant parameters were given.

RESULTS

The arm position of 77 out of 84 patients in total was successful, based on the clavicle rotation. The mean clavicle rotation was 0.4° (± 2.0°). For 89.8% of the patients who were irradiated on the whole-breast D98 was larger than 95% of the prescribed dose (D98 > 95%). D98 > 95% applied for 70.8% of the patients irradiated on the chest wall. Concerning the lymph node CTVs, D98 > 95% for at least 95% of the patients. The breath-hold analysis showed a mean residual setup error of - 0.015 (± 0.90), - 0.18 (± 0.82), - 0.58 (± 1.1) mm in vertical, lateral, and longitudinal direction, respectively. The reproducibility and stability of the breath-hold was good, with median 0.60 mm (95% confidence interval (CI) [0.66-0.71] mm) and 0.20 mm (95% CI 0.21-0.23] mm), respectively.

CONCLUSIONS

Using SGRT we were able to position breast cancer patients successfully, with focus on the arm position. The actual delivered dose calculated on the CBCT was adequate and no relation between clavicle rotation and actual delivered dose was found. Moreover, breath-hold analysis showed a good reproducibility and stability of the breath-hold. Trial registration CCMO register NL69214.028.19.

Dosimetric impact of different multileaf collimators on cardiac and left anterior descending coronary artery dose reduction

Introduction

Radiotherapy (RT) may increase the dose of heart structure like left anterior descending coronary artery (LAD). The purpose of this paper was to evaluate the impact of various multileaf collimators (MLCs) in shielding organ at risks (OARs), especially LAD, of patients with left breast cancer.

Materials and Methods

Forty-five patients with left breast cancer were selected. The treatment plans were created applying three techniques for all patients. In the first plan (uncovered LAD), the treatment plan was made without considering LAD as OARs. In the two other plans, two MLCs with different leaf widths (6.8 mm and 5 mm) were used to shield the LAD. For all plans, MLC was shielded as much of OAR as possible without compromising planning target volume (PTV) coverage. Dosimetric parameters of the heart, LAD, and ipsilateral lung were assessed.

Results

Compared to other plans, the covered LAD plan 1(CL1) obtained lower lung, cardiac, and LAD doses with the same PTV coverage. On average, the mean heart dose decreased from 6.2 Gy to 5.4 Gy by CL1, and the average mean dose to the LAD was reduced from 36.4 Gy to 33.7 Gy, which was statistically significant. The average lung volume receiving >20 Gy was significantly reduced from 24.6% to 23.4%. Moreover, the results show that covered LAD plan 2(CL2) is less useful for shielding OARs compared to CL1.

Conclusion

CL1 plans may reduce OAR dose for patients without compromising the target coverage. Hence, the proper implementation of MLC can decrease the side effects of RT.

Deep inspiration breath-hold radiation therapy in left-sided breast cancer patients: a single-institution retrospective dosimetric analysis of organs at risk doses

BACKGROUND

Radiotherapy can induce cardiac injury in left-sided breast cancer cases. Cardiac-sparing irradiation using the deep inspiration breath-hold (DIBH) technique can achieve substantial dose reduction to vulnerable cardiac substructures compared with free breathing (FB). This study evaluated the dosimetric differences between both techniques at a single institution.

METHODS

From 2017 to 2019, 130 patients with left-sided breast cancer underwent breast-conserving surgery (BCS; n = 121, 93.1%) or mastectomy (ME; n = 9, 6.9%) along with axillary lymph node staging (n = 105, 80.8%), followed by adjuvant irradiation in DIBH technique; adjuvant systemic therapy was included if applicable. 106 (81.5%) patients received conventional and 24 (18.5%) hypofractionated irradiation. Additionally, 12 patients received regional nodal irradiation. Computed tomography (CT) scans in FB and DIBH position were performed for all patients. Intrafractional 3D position monitoring of the patient surface in deep inspiration and breath gating was performed using Sentinel and Catalyst HD 3D surface scanning systems (C-RAD, Catalyst, C‑RAD AB, Uppsala, Sweden). Individual coaching and determination of breathing amplitude during the radiation planning CT was performed. Three-dimensional treatment planning was performed using standard tangential treatment portals (6 or 18 MV). The delineation of cardiac structures and both lungs was done in both the FB and the DIBH scan.

RESULTS

All dosimetric parameters for cardiac structures were significantly reduced (p < 0.01 for all). The mean heart dose (Dmean) in the DIBH group was 1.3 Gy (range 0.5-3.6) vs. 2.2 Gy (range 0.9-8.8) in the FB group (p < 0.001). The Dmean for the left ventricle (LV) in DIBH was 1.5 Gy (range 0.6-4.5), as compared to 2.8 Gy (1.1-9.5) with FB (p < 0.001). The parameters for LV (V10 Gy, V15 Gy, V20 Gy, V23 Gy, V25 Gy, V30 Gy) were reduced by about 100% (p < 0.001). The LAD Dmean in the DIBH group was 4.1 Gy (range 1.2-33.3) and 14.3 Gy (range 2.4-37.5) in the FB group (p < 0.001). The median values for LAD such as V15 Gy, V20 Gy, V25 Gy, V30 Gy, and V40 Gy decreased by roughly 100% (p < 0.001). An increasing volume of left lung in the DIBH position resulted in dose sparing of cardiac structures.

CONCLUSION

For all ascertained dosimetric parameters, a significant dose reduction could be achieved in DIBH technique.

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

BACKGROUND

Deep 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).

METHODS

BRAVEHeart 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.

DISCUSSION

The 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 REGISTRATION

ClinicalTrials.gov NCT02881203 . Registered on 26 August 2016.

Development of deep-inspiration breath-hold system that monitors the position of the chest wall using infrared rangefinder

We conducted a prospective study to quantitatively evaluate the movement of the chest wall to establish the simple and reproducible deep-inspiration breath-hold (DIBH) method. The left nipple position was monitored to confirm the inspiratory state. Planning computed tomography (CT) was performed under DIBH and free-breath. We conducted radiation plans with DIBH and free-breath CT and evaluated organ at risk (OAR) and target doses according to two different plans. The relationship between positioning errors of the chest wall and patient factors was evaluated using univariate analysis and fixed-effects models. Twenty-three patients aged ≤ 60 years were enrolled during January-August 2021; 358 daily radiation treatments were evaluated. The median time of treatment room occupancy was 16 minutes (interquartile range, 14-20). The area of the planning target volume (PTV) surrounded by the 95% isodose line was more extensive in DIBH than in free breathing (71.6% vs 69.5%, P < 0.01), whereas the cardiac and left anterior descending (LAD) artery doses were lower (both P < 0.01). In the fixed-effects model analysis, the occupation time of the treatment room was correlated with positioning error. The difference between the planned and irradiated dose was the largest in the LAD branch of the coronary artery (-2.5 Gy), although the OAR dose decreased owing to positional error. The current DIBH method, wherein a single point on the chest wall is monitored to confirm that the patient is in an inspiratory state, allows radiation to be performed in a short time with a small dose error.

Surface-guided DIBH radiotherapy for left breast cancer: impact of different thresholds on intrafractional motion monitoring and DIBH stability

PURPOSE

To compare two left breast cancer patient cohorts (tangential vs. locoregional deep-inspiration breath-hold - DIBH treatment) with different predefined beam gating thresholds and to evaluate their impact on motion management and DIBH stability.

METHODS

An SGRT-based clinical workflow was adopted for the DIBH treatment. Intrafractional monitoring was performed by tracking both the respiratory signal and the real-time displacement between the isocenter on the daily reference surface and on the live surface ("SGRT shift"). Beam gating tolerances were 5 mm/4 mm for the SGRT shifts and 5 mm/3 mm for the gating window amplitude for breast tangential and breast + lymph nodes locoregional treatments, respectively. A total of 24 patients, 12 treated with a tangential technique and 12 with a locoregional technique, were evaluated for a total number of 684 fractions. Statistical distributions of SGRT shift and respiratory signal for each treatment fraction, for each patient treatment, and for the two population samples were generated.

RESULTS

Lateral cumulative distributions of SGRT shifts for both locoregional and tangential samples were consistent with a null shift, whereas longitudinal and vertical ones were slightly negative (mean values < 1 mm). The distribution of the percentage of beam on time with SGRT shift > 3 mm, > 4 mm, or > 5 mm was extended toward higher values for the tangential sample than for the locoregional sample. The variability in the DIBH respiration signal was significantly greater for the tangential sample.

CONCLUSION

Different beam gating thresholds for surface-guided DIBH treatment of left breast cancer can impact motion management and DIBH stability by reducing the frequency of the maximum SGRT shift and increasing respiration signal stability when tighter thresholds are adopted.

Deep Inspiratory Breath-Hold Radiation for Left-Sided Breast Cancer using Novel Frame-based Tactile Feedback

A frame providing tactile feedback for the reproducibility of deep inspiratory breath-hold (DIBH) is described. The frame, fitted across the patient, comprises a horizontal bar, parallel to the patient's long axis, and holds a graduated pointer perpendicular to it. The pointer provides individualized tactile feedback for reproducibility of DIBH. Within the pointer is a movable pencil, bearing a 5 mm coloured strip which becomes visible only during DIBH, and acts as a visual cue to the therapist. The average variation in separation in the planning and pretreatment cone-beam computed tomography of 10 patients was 2 mm (confidence interval 1.95-2.05). Frame-based tactile feedback is a novel, reproducible technique for DIBH.

Three-dimensional conformal radiotherapy (3D-CRT) vs. volumetric modulated arc therapy (VMAT) in deep inspiration breath-hold (DIBH) technique in left-sided breast cancer patients-comparative analysis of dose distribution and estimation of projected secondary cancer risk

PURPOSE

The purpose of this study was to compare two techniques of irradiation of left-sided breast cancer patients who underwent breast-conserving surgery, three-dimensional conformal radiotherapy technique (3D-CRT) and volumetric modulated arc therapy (VMAT), in terms of dose distribution in the planning target volume (PTV) and organs at risk (OARs). The second aim of the study was estimation of the projected risk of radiation-induced secondary cancer for both radiotherapy techniques.

MATERIALS AND METHODS

For 25 patients who underwent CT simulation in deep inspiration breath-hold (DIBH), three treatment plans were generated: one using a three-dimensional conformal radiotherapy technique and two using volumetric modulated arc therapy. First VMAT-DIBH geometry consisted of three partial arcs (ARC-DIBH 3A) and second consisted of four partial arcs (ARC-DIBH 4A). Cumulative dose-volume histograms (DVHs) were used to compare dose distributions within the PTV and OARs (heart, left anterior descending coronary artery [LAD], ipsilateral and contralateral lung [IL, CL], and contralateral breast [CB]). Normal tissue complication probabilities (NTCPs) and organ equivalent doses (OEDs) were calculated using the differential DVHs. Excess absolute risks (EARs) for second cancers were estimated using Schneider's full mechanistic dose-response model.

RESULTS

All plans fulfilled the criterium for PTV V95% ≥ 95%. The PTV coverage, homogeneity, and conformity indices were significantly better for VMAT-DIBH. VMAT showed a significantly increased mean dose and V5Gy for all OARs, but reduced LAD D_max by 15 Gy. For IL, CL, and CB, the 3D-CRT DIBH method achieved the lowest values of EAR: 28.38 per 10,000 PYs, 2.55 per 10,000 PYs, and 4.48 per 10,000 PYs (p < 0.001), compared to 40.29 per 10,000 PYs, 15.62 per 10,000 PYs, and 23.44 per 10,000 PYs for ARC-DIBH 3A plans and 41.12 per 10,000 PYs, 15.59 per 10,000 PYs, and 22.73 per 10,000 PYs for ARC-DIBH 4A plans. Both techniques provided negligibly low NTCPs for all OARs.

CONCLUSION

The study shows that VMAT-DIBH provides better OAR sparing against high doses. However, the large low-dose-bath (≤ 5 Gy) is still a concern due to the fact that a larger volume of normal tissues exposed to lower doses may increase a radiation-induced risk of secondary cancer.

Deep inspiration breath hold in post-operative radiotherapy for right breast cancer: a retrospective analysis

Background

The aim of our study is to determine whether deep inspiration breath hold (DIBH) is effective for reducing exposure of the heart, left coronary artery (LAD) and both lungs in right breast radiotherapy.

Materials and methods

We have analyzed 10 consecutive patients with right-sided breast cancer (BC), simulated during free breathing (FB) and in DIBH modality. For all patients we contoured breast PTV and organs at risk (right and left lungs, heart, LAD) on both CT scans (FB and DIBH). Finally, 5 patients were treated with IMRT and 5 with VMAT techniques.

Results

All patients were able to end the treatments in DIBH modalities regardless of the longer treatment time in comparison to FB. The maximum and mean dose to the heart are lower in the DIBH modality. The mean values of the heart mean dose were 1.76 Gy in DIBH and 2.19 Gy in FB. The mean heart maximum dose in DIBH and FB were, respectively, 9.3 Gy and 11 Gy. Likewise, the maximum dose to the LAD is lower in DIBH; 2.57 Gy versus 3.56 Gy in FB. Noteworthy, 3 patients with hepatomegaly treated with the DIBH technique showed a higher ipsilateral lung dose than FB, but a decrease of liver dose.

Conclusion

We report that the use of DIBH for right-sided BC allows the dose to the heart, LAD and to the liver to be reduced in case of hepatomegaly. This technique is well tolerated by patients, when adequately trained, and could be considered effective even in right sided BC.

Incidental irradiation of the regional lymph nodes during deep inspiration breath-hold radiation therapy in left-sided breast cancer patients: a dosimetric analysis

Background

Radiotherapy using the deep inspiration breath-hold (DIBH) technique compared with free breathing (FB) can achieve substantial reduction of heart and lung doses in left-sided breast cancer cases. The anatomical organ movement in deep inspiration also cause unintended exposure of locoregional lymph nodes to the irradiation field.

Methods

From 2017–2020, 148 patients with left-sided breast cancer underwent breast conserving surgery (BCS) or mastectomy (ME) with axillary lymph node staging, followed by adjuvant irradiation in DIBH technique. Neoadjuvant or adjuvant systemic therapy was administered depending on hormone receptor and HER2-status.

CT scans in FB and DIBH position with individual coaching and determination of the breathing amplitude during the radiation planning CT were performed for all patients. Intrafractional 3D position monitoring of the patient surface in deep inspiration and gating was performed using Sentinel and Catalyst HD 3D surface scanning systems (C-RAD, Catalyst, C-RAD AB, Uppsala, Sweden). Three-dimensional treatment planning was performed using standard tangential treatment portals (6 or 18 MV). The delineation of ipsilateral locoregional lymph nodes was done on the FB and the DIBH CT-scan according to the RTOG recommendations.

Results

The mean doses (D_mean) in axillary lymph node (AL) level I, II and III in DIBH were 32.28 Gy (range 2.87–51.7), 20.1 Gy (range 0.44–53.84) and 3.84 Gy (range 0.25–39.23) vs. 34.93 Gy (range 10.52–50.40), 16.40 Gy (range 0.38–52.40) and 3.06 Gy (range 0.21–40.48) in FB (p < 0.0001). Accordingly, in DIBH the D_mean for AL level I were reduced by 7.59%, whereas for AL level II and III increased by 22.56% and 25.49%, respectively.

The D_mean for the supraclavicular lymph nodes (SC) in DIBH was 0.82 Gy (range 0.23–4.11), as compared to 0.84 Gy (range 0.22–10.80) with FB (p = 0.002). This results in a mean dose reduction of 2.38% in DIBH.

The D_mean for internal mammary lymph nodes (IM) was 12.77 Gy (range 1.45–39.09) in DIBH vs. 11.17 Gy (range 1.34–44.24) in FB (p = 0.005). This yields a mean dose increase of 14.32% in DIBH.

Conclusions

The DIBH technique may result in changes in the incidental dose exposure of regional lymph node areas.

Influence of respiratory movement during post mastectomy radiotherapy on targets and heart for breast cancer

BACKGROUND/AIM

This study aimed to compare the dosimetric consequences of respiratory movement in volumetric-modulated arc therapy (VMAT) and three-dimensional conformal radiation therapy (3D-CRT) during postmastectomy radiation therapy, including internal mammary nodes (IMNs).

MATERIALS AND METHODS

Respiratory motion was implemented to a phantom using a dynamic device. The plans were delivered during cranial-caudal and ventral-dorsal movement in 5-mm (R05) and 10-mm (R10) amplitudes.

RESULTS

At the IMN, the dose errors were -2.8% (R05) and -6.2% (R10) for 3D-CRT and -4.9% (R05) and -8.5% (R10) for VMAT. The dose errors in chest wall were -.5% (R05) and -6.0% (R10) for 3D-CRT and -1.9% (R05) and -5.3% (R10) for VMAT. The left anterior descending doses showed significantly small absolute values. The gamma pass rates of VMAT were higher than those of 3D-CRT.

CONCLUSIONS

The benefit of VMAT technique in dose distribution was maintained, except in occasional instances of large breathing motion.

A Phase 2 trial of deep-inspiration breath hold in radiotherapy of gastric lymphomas

•

A Bayesian method is developed for the uncertainty quantification of FE models.

•

Expectation-Maximization strategies are combined with asymptotic approximations.

•

Identification uncertainty and test-to-test variability of parameters are included.

•

A new rationale to optimally weight the modal parameters is introduced.

Background and purpose

Radiotherapy (RT) is an important part in the treatment of gastric lymphomas and the prognosis after radiotherapy is very good with a good chance of long-term survival, so prevention of long-term adverse effects is important. In patients with gastric lymphomas cardiac late effects are of most concern. The aim of this study was to assess if the dose to the heart could be reduced with deep inspiration breath-hold (DIBH) without compromising the dose to the target or increasing the risk of other late effects.

Methods and patients

Fifteen patients with gastric lymphoma were included. RT plans were made using DIBH and Free breathing (FB) scans. Clinical target volume (CTV) was the stomach plus 1 cm margin. The heart and surrounding organs at risk (OAR) were contoured. Two sets of plan comparisons were made, one with 1 cm CTV to planning target volume (PTV) margin in both DIBH and FB and one set with an additional 5 mm CTV to PTV margin in cranio-caudal direction with FB. Datasets were analysed with Wilcoxon signed rank test for non-parametric paired data.

Results

All patients tolerated the procedures and were treated with volumetric arc therapy technique in DIBH. Target coverage was kept equal between FB and DIBH, while a statistically significant reduction of the estimated does to the heart was seen with DIBH. Median mean heart dose was reduced from 7.1 Gy (5.7–12) to a median of 3.2 Gy (1.2–7.0) and heart V20 from a median of 54 (17–106) cm³ to 15. (0.0–78) cm³. The estimated mean doses to the liver, duodenum, pancreas and spinal cord were at the same level.

Conclusion

This clinical trial of RT with DIBH for gastric lymphomas showed that the heart dose could be reduced without compromising PTV coverage. The doses to abdominal OARs were similar with FB and DIBH.

Patient setup accuracy in DIBH radiotherapy of breast cancer with lymph node inclusion using surface tracking and image guidance

Studying setup accuracy in breast cancer patients with axillary lymph node inclusion in deep inspiration breath-hold (DIBH) after patient setup with surface-guided radiotherapy (SGRT) and image-guided radiotherapy (IGRT). Breast cancer patients (N = 51) were treated (50 Gy in 25 fractions) with axillary lymph nodes within the planning target volume (PTV). Patient setup was initiated with tattoos and lasers, and further adjusted with SGRT. The DIBH guidance was based on SGRT. Orthogonal and/or tangential imaging was analyzed for residual position errors of bony landmarks, the breath-hold level (BHL), the skin outline, and the heart; and setup margins were calculated for the PTV. The calculated PTV margins were 4.3 to 6.3 and 2.8 to 4.6 mm before and after orthogonal imaging, respectively. The residual errors of the heart were 3.6 ± 2.2 mm and 2.5 ± 2.4 mm before and 3.0 ± 2.5 and 2.9 ± 2.3 mm after orthogonal imaging in the combined anterior-posterior/lateral and the cranio-caudal directions, respectively, in tangential images. The humeral head did not benefit from daily IGRT, but SGRT guided it to the correct location. We presented a slightly complicated but highly accurate workflow for DIBH treatments. The residual position errors after both SGRT and IGRT were excellent compared to previous literature. With well-planned SGRT, IGRT brings only slight improvements to systematic accuracy. However, with the calculated PTV margins and the number of outliers, imaging cannot be omitted despite SGRT, unless the PTV margins are re-evaluated.

Evaluation of the voluntary deep inspiration breath-hold reproducibility in left-sided breast radiotherapy

PURPOSE

Voluntary deep inspiration breath hold (v-DIBH) reduces cardiac dose during left-sided breast irradiation. The purpose of this study is to evaluate the reproducibility and variability of breath-hold level (BHL) using breath-hold curves and lateral kV setup images together.

MATERIAL/METHOD

A retrospective analysis of 30 left breast cancer patients treated using the v-DIBH technique in our department is performed. The BHL difference is measured from breath hold curves and lateral (LAT) kilo-Voltage (kV) setup images. The planning CT image and the selected treatment fraction data are collected. If the changes in BHL relate to the displacement of various bones in the kV setup, images are assessed. Furthermore, the maximum heart distance inside the treatment field is compared from LAT MV portal images.

RESULTS

The median and mean values of the BHL are nearly identical in different fractions (good reproducibility). However, the mean BHL values between planning and all measured fractions are statistically different; 16.3 vs. 20.8 mm for the planning and measured fractions (p < 0.001), which indicates that the variability of BHL is significantly different.

CONCLUSION

While reproducibility testing shows good agreement for inter-fractional breath-hold level, the variability between planning and fractions is relatively poor.

The impact of modern radiotherapy on long-term cardiac sequelae in breast cancer survivor: a focus on deep inspiration breath-hold (DIBH) technique

INTRODUCTION

One of the most feared side effects of radiotherapy (RT) in the setting of breast cancer (BC) patients is cardiac toxicity. This side effect can jeopardize the quality of life (QoL) of long-term survivors. The impact of modern techniques of RT such as deep inspiration breath hold (DIBH) have dramatically changed this setting. We report and discuss the results of the literature overview of this paper.

MATERIALS AND METHODS

Literature references were obtained with a PubMed query, hand searching, and clinicaltrials.gov.

RESULTS

We reported and discussed the toxicity of RT and the improvements due to the modern techniques in the setting of BC patients.

CONCLUSIONS

BC patients often have a long life expectancy, thus the RT should aim at limiting toxicities and at the same time maintaining the same high cure rates. Further studies are needed to evaluate the risk-benefit ratio to identify patients at higher risk and to tailor the treatment choices.

No changes in myocardial perfusion following radiation therapy of left-sided breast cancer: A positron emission tomography study

BACKGROUND

Adjuvant radiation therapy (RT) for breast cancer has improved overall survival. However, incidental exposure of the heart has been linked to development of radiation-induced heart disease. The aim of this study was, in a cohort of asymptomatic post-irradiation breast cancer patients, to investigate changes in myocardial blood flow (MBF) and presence of perfusion defects in myocardial perfusion positron-emission-tomography (PET) in the irradiated myocardium.

METHODS AND RESULTS

Twenty patients treated with RT for left-sided breast cancer underwent 13N-ammonia myocardial perfusion PET 7(± 2) years after breath adapted RT to a total dose of 48 Gy given in 24 fractions. No differences in rest or stress MBF were noted between the irradiated and non-irradiated myocardium (1.29 (± 0.29) vs 1.33 (± 0.29) mL/g/min, ns; 2.74 (± 0.59) vs 2.78 (± 0.66) mL/g/min, ns, respectively). One patient demonstrated a myocardial perfusion defect localized in the irradiated anterior wall myocardium.

CONCLUSION

Although limited by a small sample size, early signs of cardiac injury detected by NH3 myocardial perfusion PET was at least not frequent in our cohort of patients treated with a modern RT technique for left-sided breast cancer, even 7 years after treatment. The findings however, may not rule out subsequent development of myocardial injury.

Variability of Breast Surface Positioning Using an Active Breathing Coordinator for a Deep Inspiration Breath Hold Technique

Purpose

The Elekta Active Breathing Coordinator^TM (ABC) is used to control breathing and guide deep inspiration breath hold (DIBH). It has been shown to be accurate in lung cancers, but limited analysis has been performed on the spatial accuracy and reproducibility of the breast surface. The use of optical surface-image guidance for patient positioning has grown in popularity and is an alternative solution for breast DIBH. This study aims to evaluate the breast surface variability of an ABC-guided DIBH by using a three-dimensional (3D) surface imaging system to record surface position.

Methods

Ten participants were placed in the treatment position, and breathing baselines and inhalation volume threshold baselines were monitored and recorded using the ABC. Over 60 minutes, the breathing patterns were recorded by the ABC and CatalystHD^TM (C-RAD, Uppsala, Sweden). For each breath hold, the valve of the ABC closed at the baseline inhalation threshold and a 3D surface image was acquired. For each point on the baseline breast surface, a 3D vector was calculated to the subsequent breath hold surface as well as a root mean square (RMS) vector magnitude for the entire surface.

Results

The average and standard deviation for the RMS difference between the baseline and subsequent evaluated images were 7.12 ± 2.70 mm.

Conclusion

This study shows that while the ABC-guided inhalation volume is kept constant, a non-negligible variability of the breast surface position exists. Special considerations should be used in clinical situations, where the positioning of the surface is considered more important than inhalation volume.

The dosimetric benefit of in-advance respiratory training for deep inspiration breath holding is realized during daily treatment in left breast radiotherapy: A comparative retrospective study of serial surface motion tracking

Introduction

A novel approach of in‐advancepreparatory respiratory training and practice for deep inspiration breath holding (DIBH) has been shown to further reduce cardiac dose in breast cancer radiotherapy patients, enabled by deeper (extended) DIBH. Here we investigated the consistency and stability of such training‐induced extended DIBH after training completion and throughout the daily radiotherapy course.

Methods

Daily chestwall motion from real‐time surface tracking transponder data was analysed in 67 left breast radiotherapy patients treated in DIBH. Twenty‐seven received preparatory DIBH training/practice (_prepTrn) 1–2 weeks prior to CT simulation, resulting in an extended DIBH (_extDIBH) and reduced cardiac dose at simulation. Forty had only conventional immediate pre‐procedure DIBH instruction without _prepTrn and without extended DIBH (non‐Trn group). Day‐to‐day variability in chestwall excursion pattern during radiotherapy was compared among the groups.

Results

The average of daily maximum chestwall excursions was overall similar, 2.5 ± 0.6 mm for _prepTrn/_extDIBH vs. 2.9 ± 0.8 mm for non‐Trn patients (P = 0.24). Chestwall excursions beyond the 3‐mm tolerance threshold were less common in the _prepTrn/_extDIBH group (18.8% vs. 37.5% of all fractions within the respective groups, P = 0.038). Among patients with cardiopulmonary disease those with _prepTrn/_extDIBH had fewer chestwall excursions beyond 3 mm (9.4% vs. 46.7%, P = 0.023) and smaller average maximum excursions than non‐Trn patients (2.4 ± 0.3 vs. 3.0 ± 0.6 mm, P = 0.047, respectively).

Conclusion

Similar stability of daily DIBH among patients with and without preparatory training/practice suggests that the training‐induced extended DIBH and cardiac dose reductions were effectively sustained throughout the radiotherapy course. Training further reduced beyond‐tolerance chestwall excursions, particularly in patients with cardiopulmonary disease.

Cardiac dose reduction using deep inspiratory breath hold (DIBH) in radiation treatment of left sided breast cancer patients with breast conservation surgery and modified radical mastectomy

PURPOSE

Deep inspiration breath hold (DIBH) reduces heart and pulmonary doses during left-sided breast radiation therapy (RT); however, there is limited information whether the reduction in doses is similar in patients with modified radical MRM (MRM) and breast conservation surgery (BCS). The primary objective was to determine whether DIBH offers greater dosimetric reduction in cardiac doses in patients with MRM as compared to BCS with secondary objectives of documenting time consumed in counseling, simulation and planning such techniques.

METHODS

Thirty patients with diagnosis of left sided breast cancer underwent CT simulation both free breathing (FB) and DIBH. Patients were grouped into two cohorts: MRM (n = 20) and BCS (n = 10). 3D-conformal plans were developed and FB was compared to DIBH for entire group (n = 30) and each cohort using Wilcoxon signed-rank tests for continuous variables and McNemar's test for discrete variables. The percent relative reduction conferred by DIBH in mean heart (D_mean heart) and left anterior descending artery dose (LAD_mean and LAD_max), heart V25,V10, V2 and ipsilateral D_meanLung,V20, V12 were compared between the two cohorts using Wilcox rank-sum testing. A two-tailed p-value ≤ 0.05 was considered statistically significant. Time consumed during FB and DIBH from patient counseling to planning was documented.

RESULTS

Patients undergoing BCS had comparable boost target coverage on DIBH and FB. For the overall group (n = 30), DIBH reduced D_mean heart and LAD dose, V25, V10 and V2 doses for the heart and Ipsilateral D_meanLung, V20, V12 which was statistically significant. For individual cohorts DIBH did not significantly reduce the lung (Ipsilateral D_meanLung, V20, V12) and LAD (LAD_mean and LAD_max) doses for BCS while significant reduction in all cardiopulmonary doses was seen in MRM cohort. Despite significant reductions with DIBH in MRM, ipsilateral lung constraint of V12 < 15% was less commonly achieved in MRM (n = 11, 55%) requiring nodal radiation as compared to BCS (n = 3, 30%). Percent reduction in all cardiac and pulmonary dosimetric parameters with DIBH was similar in the MRM cohort as compared to BCS cohort. In total 73.1 ± 2.6 min was required for FB as compared to 108.1 ± 4.1 min in DIBH.

CONCLUSION

DIBH led to significant reduction of cardiac doses in both MRM and BCS. Reduction of lung and LAD doses were significant in MRM cohort. All cardiac constraints were met with DIBH in both cohorts, lung constraints were less frequently met in MRM cohort requiring nodal radiation.

Proton pencil beam scanning reduces secondary cancer risk in breast cancer patients with internal mammary chain involvement compared to photon radiotherapy

Purpose

Proton pencil beam scanning (PBS) represents an interesting option for the treatment of breast cancer (BC) patients with nodal involvement. Here we compare tangential 3D-CRT and VMAT to PBS proton therapy (PT) in terms of secondary cancer risk (SCR) for the lungs and for contralateral breast.

Methods

Five BC patients including supraclavicular (SVC) nodes in the target (Group 1) and five including SVC plus internal-mammary-nodes (IMNs, Group 2) were considered. The Group 1 patients were planned by PT versus tangential 3D-CRT in free-breathing (FB). The Group 2 patients were planned by PT versus VMAT considering both FB and deep-inspiration breath hold (DIBH) irradiation. The prescription dose to the target volume was 50 Gy (2 Gy/fraction). A constant RBE = 1.1 was assumed for PT. The SCR was evaluated with the excess absolute risk (EAR) formalism, considering also the age dependence. A cumulative EAR was finally computed.

Results

According to the linear, linear-exponential and linear-plateau dose response model, the cumulative EAR for Group 1 patients after PT was equal to 45 ± 10, 17 ± 3 and 15 ± 3, respectively. The corresponding relative increase for tangential 3D-CRT was equal to a factor 2.1 ± 0.5, 2.1 ± 0.4 and 2.3 ± 0.4. Group 2 patients showed a cumulative EAR after PT in FB equal to 65 ± 3, 21 ± 1 and 20 ± 1, according to the different models; the relative risk obtained with VMAT increased by a factor 3.5 ± 0.2, 5.2 ± 0.3 and 5.1 ± 0.3. Similar values emerge from DIBH plans. Contrary to photon radiotherapy, PT appears to be not sensitive to the age dependence due to the very low delivered dose.

Conclusions

PBS PT is associated to significant SCR reduction in BC patients compared to photon radiotherapy. The benefits are maximized for young patients with both SVC and IMNs involvement. When combined with the improved sparing of the heart, this might contribute to the establishment of effective patient-selection criteria for proton BC treatments.

The benefits evaluation of abdominal deep inspiration breath hold based on knowledge-based radiotherapy treatment planning for left-sided breast cancer

Purpose

To study the impact of abdominal deep inspiration breath hold (DIBH) technique on knowledge‐based radiotherapy treatment planning for left‐sided breast cancer to guide the application of DIBH technology.

Materials and methods

Two kernel density estimation (KDE) models were developed based on 40 left‐sided breast cancer patients with two CT acquisitions of free breathing (FB‐CT) and DIBH (DIBH‐CT). Each KDE model was used to predict dose volume histograms (DVHs) based on DIBH‐CT and FB‐CT for another 10 new patients similar to our training datasets. The predicted DVHs were taken as a substitute for dose constraints and objective functions in the Eclipse treatment planning system, with the same requirements for the planning target volume (PTV). The mean doses to the heart, the left anterior descending coronary artery (LADCA) and the ipsilateral lung were evaluated and compared using the T‐test among clinical plans, KDE predictions, and KDE plans.

Results

Our study demonstrated that the KDE model can generate deliverable simulations equivalent to clinically applicable plans. The T‐test was applied to test the consistency hypothesis on another ten left‐sided breast cancer patients. In cases of the same breathing status, there was no statistically significant difference between the predicted and the clinical plans for all clinically relevant DVH indices (P > 0.05), and all predicted DVHs can be transferred into deliverable plans. For DIBH‐CT images, significant differences were observed between FB model predictions and clinical plans (P < 0.05). DIBH model prediction cannot be optimized to a deliverable plan based on FB‐CT, with a counsel of perfection.

Conclusion

KDE models can predict DVHs well for the same breathing conditions but degrade with different breathing conditions. The benefits of DIBH for a given patient can be evaluated with a quick comparison of prediction results of the two models before treatment planning.

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.

Three-dimensional versus four-dimensional dose calculation for breast intensity-modulated radiation therapy

OBJECTIVE

To analyze the effect of intra- and interfractional motion during breast intensity modulated radiation therapy (IMRT) by calculating dose distribution based on four-dimensional computed tomography (4DCT).

METHODS

20 patients diagnosed with left breast cancer were enrolled. Three-dimensional CT (3DCT) along with 10 phases of 4DCT were collected for each patient, with target volumes independently delineated on both 3DCT and all phases of 4DCT. IMRT plans were generated based on 3DCT (43.2 Gy in 16 fractions). The plan parameters for each segment were split into phases based on time duration estimates for each respiratory phase, with phase-specific dose distributions calculated and summated (4D-calculated dose). The procedure is repeated for 16 fractionations by randomly allocating starting phase using random-number generation to simulate interfractional discrepancy caused by different starting phase. Comparisons of plan quality between the original and 4D-calculated doses were analyzed.

RESULTS

There was a significant distortion in 4D-calculated dose induced by respiratory motion in terms of conformity and homogeneity index compared to those of the original 3D plan. Mean doses of the heart and the ipsilateral lung were significantly higher in the 4D-calculated doses compared to those of the original 3D plan (0.34 Gy, p = 0.010 and 0.59 Gy, p < 0.001), respectively). The mean internal mammary lymph node (IMN) dose was significantly greater in the 4D-calculated plan, compared to the original 3D plan (1.42 Gy, p < 0.001).

CONCLUSIONS

IMN doses should be optimized during the dose-calculation for the free-breathing left breast IMRT.

ADVANCES IN KNOWLEDGE

The interplay effect between respiratory motion and multileaf collimator modulation caused discrepancies in dose distribution, particularly in IMN.

Evaluation of an in-house self-held respiration monitoring device for deep inspiration breath hold techniques for radiotherapy of patients with cancer of the left breast

Background:

An in-house self-held respiration monitoring device (SHRMD) was developed for providing deep inspiration breath hold (DIBH) radiotherapy. The use of SHRMD is evaluated in terms of reproducibility, stability and heart dose reduction.

Methods and materials:

Sixteen patients receiving radiotherapy of left breast cancer were planned for treatment with both a free breathing (FB) scan and a DIBH scan. Both FB and DIBH plans were generated for comparison of the heart, left anterior descending (LAD) artery and lung dose. All patients received their treatments with DIBH using SHRMD. Megavoltage cine images were acquired during treatments for evaluating the reproducibility and stability of treatment position using SHRMD.

Results:

Compared with FB plans, the maximum dose to the heart by DIBH technique with SHRMD was reduced by 29·9 ± 15·6%; and the maximum dose of the LAD artery was reduced by 41·6 ± 18·3%. The inter-fractional overall mean error was 0·01 cm and the intra-fractional overall mean error was 0·04 cm.

Conclusion:

This study demonstrated the potential benefits of using the SHRMD for DIBH to reduce the heart and LAD dose. The patients were able to perform stable and reproducible DIBHs.

Selection of patients with left breast cancer for IMRT with deep inspiration breath-hold technique

The deep inspiration breath-hold (DIBH) technique has been utilized to reduce the cardiac dose in left-sided breast cancer (BC) patients undergoing radiotherapy. Further investigation of the parameters for selecting which patients will benefit most from DIBH is essential. We performed dosimetric comparisons for 21 patients with left-sided BC who had both computed tomography (CT)-based free-breathing (FB) and DIBH plans. The doses to the heart and left anterior descending artery (LAD) and any reduction due to the DIBH technique were analysed. Based on CTFB plans, dosimetric analysis revealed that the irradiation doses to the heart and LAD were significantly correlated with the target volume, the ipsilateral lung volume (ILV) and the total lung volume (TLV). When patients had an ILV ≥ 950 cm3 or a TLV ≥ 2200 cm3, the irradiation doses to the heart and LAD were significantly decreased. Furthermore, the reduction in the mean heart dose (MHD) was correlated to the difference in lung volume between FB and DIBH. The difference in ILV between DIBH and FB of 1.8 indicated that the patients obtained more benefit from the DIBH technique. The data suggest that lung volume (ILV and TLV) measured on a CT-simulation scan and the difference between FB and DIBH could be utilized to help select patients for DIBH.

A Novel Device for Deep-Inspiration Breath Hold (DIBH): Results from a Single-Institution Phase 2 Clinical Trial for Patients with Left-Sided Breast Cancer

PURPOSE

To validate a novel device developed at our institution for deep inspiration breath hold (DIBH) within a phase 2 clinical trial for left-sided breast cancer and to evaluate the dosimetric benefits of its use.

METHODS AND MATERIALS

The device uses an external mechanical reference for guiding the patient to the desired breath level and gives acoustic and visual feedback to the patient and the radiation therapists, respectively. A phase 2 clinical trial was performed for its validation. The thoracic amplitude was used as a surrogate of the inspiration level. The stability, repeatability, reproducibility, and reliability of DIBH using the device were analyzed. The dosimetric parameters of the heart, the left anterior descending coronary artery, the ipsilateral lung, the contralateral breast, and the target coverage using free breathing and DIBH were compared.

RESULTS

Thirty-eight patients were included in the analysis. The maximum population value of stability and repeatability were 1.7 mm and 3.3 mm, respectively. The reproducibility mean value was 1.7 mm, and population systematic and random errors were 0.3 mm and 0.9 mm, respectively. The reliability was 98.9%. Statistically significant dose reductions were found for the heart, the left anterior descending coronary artery, and the ipsilateral lung dosimetric parameters in DIBH, without losing dose coverage to the planning target volumes.

CONCLUSIONS

The validation of the device within the phase 2 clinical trial demonstrates that it offers reliable, stable, repeatable, and reproducible breast cancer treatments in DIBH with its dosimetric benefits.

A Prospective Trial to Compare Deep Inspiratory Breath Hold With Prone Breast Irradiation

PURPOSE

To compare heart and lung doses for adjuvant whole breast irradiation (WBI) between radiation plans generated supine with deep inspiratory breath hold (S-DIBH) and prone with free-breathing (P-FB) and examine the effect of breast volume (BV) on dosimetric parameters.

METHODS AND MATERIALS

Patients with left breast ductal carcinoma in situ or invasive cancer receiving adjuvant WBI were enrolled on a single-institutional prospective protocol. Patients were simulated S-DIBH and P-FB; plans were generated using both scans. Wilcoxon signed-rank and rank-sum tests were used to compare intrapatient differences between plans for the entire cohort and within BV groups defined by tertiles.

RESULTS

Forty patients were enrolled. Thirty-four patients are included in the analysis owing to patient withdrawal or inability to hold breath. With WBI dose of 4005 to 4256 cGy, mean heart dose (MHD) was 80 cGy in S-DIBH and 77 cGy in P-FB (P = .08). Mean ipsilateral lung dose (MLD) was 453 cGy in S-DIBH and 45 cGy in P-FB (P < .0001). Mean and max left anterior descending artery doses were 251 cGy and 551 cGy in S-DIBH, respectively (P = .1), and 324 cGy and 993 cGy in P-FB, respectively (P = .3). Hot spot and separation were 109% and 22 cm in S-DIBH, respectively, and 107% and 16 cm in P-FB, respectively (P < .0001). For patients with smallest BV, S-DIBH improved MHD and left anterior descending artery doses; for those with largest BV, P-FB improved cardiac dosimetry. With increasing BV, there was an increasing advantage of P-FB for MHD (P = .05), and max (P = .03) and mean (P = .02) left anterior descending artery doses, and the reduction in MLD, hot spot, and separation with P-FB increased (P < .05).

CONCLUSIONS

MHD did not differ between P-FB and S-DIBH, whereas MLD was significantly lower with P-FB. Analysis according to breast volume revealed improved cardiac dosimetry with S-DIBH for women with smallest BV and improved cardiac dosimetry with P-FB for women with larger BV, thereby providing a dosimetric rationale for using breast size to help determine the optimal positioning for WBI.

Radiation effect on late cardiopulmonary toxicity: An analysis comparing supine DIBH versus prone techniques for breast treatment

Two commonly used whole breast irradiation (WBI) techniques, deep inspiration breath hold (DIBH) and prone positioning, are compared with regard to dosimetry and estimated late cardiac morbidity and secondary lung cancer mortality using published models. Forty patients with left-sided DCIS or breast cancer who underwent lumpectomy and required adjuvant WBI were enrolled on a prospective trial comparing supine DIBH (S-DIBH) with prone free breathing (P-FB) planning. Patients underwent CT simulation in both positions; two plans were generated for each patient. Comparative dosimetry was available for 34 patients. Mean cardiac and lung doses were calculated. Risk of death from ischemic heart disease (IHD), risk of at least one acute coronary event (ACE), and lung cancer mortality were estimated from published data. Difference between S-DIBH and P-FB plans was compared using paired two-tailed t test. Estimated mean risk of death from IHD by age 80 was 0.1% (range 0.0%-0.2%) for both plans (P = 1.0). Mean risk of at least one ACE was 0.3% (range 0.1%-0.6%) for both plans (P = .6). Mean lung cancer mortality risk was 1.4% (range 0.5%-15.4%) for S-DIBH and 1.0% (range 0.4%-9.8%) for P-FB (P = .008). Excess lung cancer mortality due to radiation was 0.5% (range 0.1%-6.0%) with S-DIBH and 0.0% (range 0.0%-0.4%) with P-FB (P = .008). Both S-DIBH and P-FB provide excellent cardiac sparing. Prone positioning results in lower lung dose than S-DIBH and leads to an absolute decrease of 0.5% in excess lung cancer mortality for patients receiving WBI.

Liver dose reduction by deep inspiration breath hold technique in right-sided breast irradiation

Purpose

Deep inspiration breath hold (DIBH) is a well-established technique that enables efficient cardiac sparing in patients with left-sided breast cancer. The aim of the current study was to determine if DIBH is effective for reducing radiation exposure of of liver and other organs at risk in right breast radiotherapy (RT).

Materials and Methods

Twenty patients with right-sided breast cancer were enrolled in this study. Three-dimensional conformal RT plans were generated for each patient, with two different computed tomography scans of free breathing (FB) and DIBH. Nodes were contoured according to the Radiation Therapy Oncology Group contouring guidelines. Dose-volume histograms for the target volume coverage and organs at risk were evaluated and analyzed.

Results

DIBH plans showed significant reduction in mean liver dose (5.59 ± 2.07 Gy vs. 2.54 ± 1.40 Gy; p = 0.0003), V_20Gy (148.38 ± 73.05 vs. 64.19 ± 51.07 mL; p = 0.0003) and V_10Gy (195.34 ± 93.57 vs. 89.81 ± 57.28 mL; p = 0.0003) volumes compared with FB plans. Right lung doses were also significantly reduced in DIBH plans. Heart and left lung doses showed small but statistically significant improvement with application of the DIBH technique.

Conclusion

We report that the use of DIBH for right-sided breast cancer significantly reduces the radiation doses to the liver, lungs, and heart.

Cardio-Oncology: Vascular and Metabolic Perspectives: A Scientific Statement From the American Heart Association

Cardio-oncology has organically developed as a new discipline within cardiovascular medicine as a result of the cardiac and vascular adverse sequelae of the major advances in cancer treatment. Patients with cancer and cancer survivors are at increased risk of vascular disease for a number of reasons. First, many new cancer therapies, including several targeted therapies, are associated with vascular and metabolic complications. Second, cancer itself serves as a risk factor for vascular disease, especially by increasing the risk for thromboembolic events. Finally, recent data suggest that common modifiable and genetic risk factors predispose to both malignancies and cardiovascular disease. Vascular complications in patients with cancer represent a new challenge for the clinician and a new frontier for research and investigation. Indeed, vascular sequelae of novel targeted therapies may provide insights into vascular signaling in humans. Clinically, emerging challenges are best addressed by a multidisciplinary approach in which cardiovascular medicine specialists and vascular biologists work closely with oncologists in the care of patients with cancer and cancer survivors. This novel approach realizes the goal of providing superior care through the creation of cardio-oncology consultative services and the training of a new generation of cardiovascular specialists with a broad understanding of cancer treatments.

Effects of Preparatory Coaching and Home Practice for Deep Inspiration Breath Hold on Cardiac Dose for Left Breast Radiation Therapy

AIMS

Deep inspiration breath hold (DIBH) reduces cardiac radiation exposure by creating cardiac-chest wall separation in breast cancer radiotherapy. DIBH requires sustaining chest wall expansion for up to 40 s and involves complex co-ordination of thoraco-abdominal muscles, which may not be intuitive to patients. We investigated the effect of in-advance preparatory DIBH coaching and home practice on cardiac doses.

MATERIALS AND METHODS

Successive patients from 1 February 2015 to 31 December 2016 with left-sided breast cancer who underwent tangential field radiotherapy utilising the DIBH technique were included. The study cohort consisted of patients treated by a physician who routinely provided DIBH coaching and home practice instructions at least 5 days before simulation. The control group included non-coached patients under another physician's care. Minimum, maximum and mean cardiac doses and V5, V10 and V30 from DIBH and free breathing simulation computed tomography scans were obtained from the planning system. DIBH and free breathing cardiac doses and volume exposures were compared between the coached and non-coached groups using the two-sample t-test, Fisher's exact test and the Mann-Whitney U-test.

RESULTS

Twenty-seven coached and 42 non-coached patients were identified. The DIBH maximum cardiac dose was lower in coached patients at 13.1 Gy compared with 19.4 Gy without coaching (P = 0.004). The percentage cardiac volume exposure in DIBH was lower in coached patients; the DIBH V10 was 0.5% without coaching and 0.1% with coaching (P = 0.005). There was also a trend towards lower DIBH V5 in the coached group compared with the non-coached group (1.2% versus 1.9%, P = 0.071). No significant differences in patient cardiopulmonary comorbidity factors that might influence cardiac doses were found between the groups.

CONCLUSIONS

Our results suggest that cardiac dose sparing can potentially be further improved with a 5 day regimen of preparatory DIBH coaching and in-advance home practice before simulation. These hypothesis-generating findings should be confirmed in a larger study.

Heart-sparing radiotherapy techniques in breast cancer patients: a recommendation of the breast cancer expert panel of the German society of radiation oncology (DEGRO)

PURPOSE

The aim of this review was to analyze the respective efficacy of various heart-sparing radiotherapy techniques.

MATERIAL AND METHODS

Heart-sparing can be performed in three different ways in breast cancer radiotherapy: by seeking to keep the heart out of treated volumes (i.e. by prone position or specific breathing techniques such as deep inspiration breath-hold [DIBH] and/or gating), by solely irradiating a small volume around the lumpectomy cavity (partial breast irradiation, PBI), or by using modern radiation techniques like intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) or protons. This overview presents the available data on these three approaches.

RESULTS

Studies on prone position are heterogeneous and most trials only refer to patients with large breasts; therefore, no definitive conclusion can be drawn for clinical routine. Nonetheless, there seems to be a trend toward better sparing of the left anterior descending artery in supine position even for these selected patients. The data on the use of DIBH for heart-sparing in breast cancer patients is consistent and the benefit compared to free-breathing is supported by several studies. In comparison with whole breast irradiation (WBI), PBI has an advantage in reducing the heart dose. Of note, DIBH and PBI with multicatheter brachytherapy are similar with regard to the dose reduction to heart structures. WBI by IMRT/VMAT techniques without DIBH is not an effective strategy for heart-sparing in breast cancer patients with "standard" anatomy. A combination of DIBH and IMRT may be used for internal mammary radiotherapy.

CONCLUSION

Based on the available findings, the DEGRO breast cancer expert panel recommends the use of DIBH as the best heart-sparing technique. Nonetheless, depending on the treatment volume and localization, other techniques may be employed or combined with DIBH when appropriate.

Deep inspiration breath-hold for left-sided breast irradiation: Analysis of dose-mass histograms and the impact of lung expansion

Background

The aim of this study was to compare dose-volume histogram (DVH) with dose-mass histogram (DMH) parameters for treatment of left-sided breast cancer in deep inspiration breath-hold (DIBH) and free breathing (FB). Additionally, lung expansion and anatomical factors were analyzed and correlated to dose differences.

Methods

For 31 patients 3D conformal radiation therapy plans were retrospectively calculated on FB and DIBH CTs in the treatment planning system. The calculated doses, structures and CT data were transferred into MATLAB and DVHs and DMHs were calculated. Mean doses (Dmean), volumes and masses receiving certain doses (Vx, Mx) were determined for the left lung and the heart. Additionally, expansion of the left lung was evaluated using deformable image registration. Differences in DVH and DMH dose parameters between FB and DIBH were statistically analyzed and correlated to lung expansion and anatomical factors.

Results

DIBH reduced Dmean (DVH) and relative V20 (V20 [%]) of the left lung in all patients, on average by − 19 ± 9% (mean ± standard deviation) and − 24 ± 10%. Dmean (DMH) and M20 [%] were also significantly reduced (− 12 ± 11%, − 16 ± 13%), however 4 patients had higher DMH values in DIBH than in FB. Linear regression showed good correlations between DVH and DMH parameters, e.g. a dosimetric benefit smaller than 8.4% for Dmean (DVH) in DIBH indicated more irradiated lung mass in DIBH than in FB. The mean expansion of the left lung between FB and DIBH was 1.5 ± 2.4 mm (left), 16.0 ± 4.0 mm (anterior) and 12.2 ± 4.6 mm (caudal). No significant correlations were found between expansions and differences in Dmean for the left lung. The heart dose in DIBH was reduced in all patients by 53% (Dmean) and this dosimetric benefit correlated to lung expansion in anterior.

Conclusions

Treatment of left-sided breast cancer in DIBH reduced dose to the heart and in most cases the lung dose, relative irradiated lung volume and lung mass. A mass related dosimetric benefit in DIBH can be achieved as long as the volume related benefit is about ≥8–9%. The lung expansion (breathing pattern) showed no impact on lung dose, but on heart dose. A stronger chest breathing (anterior expansion) for DIBH seems to be more beneficial than abdominal breathing.

A seven-year experience of using moderate deep inspiration breath-hold for patients with early-stage breast cancer and dosimetric comparison

We present our seven-year experience of using moderate deep inspiration breath-hold (mDIBH) with an active breathing control (ABC) device for patients with early-stage breast cancer and dosimetric comparison to evaluate the benefit of mDIBH on the heart, lung, and liver.We retrospectively reviewed all patients with newly diagnosed breast cancer and having clinical stage Tis, I, or II disease treated between November 2010 and October 2017. Among the 369 patients included in this study, 107 patients were treated with mDIBH and 262 patients were treated with free breathing (FB). Dosimetric analysis was performed to compare dose distribution in the heart, lung, and liver between the two treatment groups. The chi-square test was used to compare the distribution of stage and tumor site between the two groups. The independent samples t-test was used to compare the remaining parameters between the two groups.For all 369 patients, there was a significantly lower ipsilateral lung V5 (relative volume receiving ≧5 Gy), ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose in the mDIBH group. For 184 patients with a left-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, and mean heart dose were observed in the mDIBH group. For 185 patients with a right-sided breast tumor, significantly lower ipsilateral lung V5, ipsilateral lung V10, ipsilateral lung V20, mean ipsilateral lung dose, whole lung V5, whole lung V10, whole lung V20, mean whole lung dose, heart V10, heart V30, heart V40, mean heart dose, liver V30, and mean liver dose were observed in the mDIBH group.For early-stage breast cancer patients, mDIBH reduces not only the heart dose but also the lung and liver doses. The routine integration of mDIBH using an ABC device may decrease radiation-induced toxicity in the heart, lung, and liver.

Does deep inspiration breath hold reduce plan complexity? Multicentric experience of left breast cancer radiotherapy with volumetric modulated arc therapy

PURPOSE

Volumetric modulated arc therapy (VMAT) for left breast treatments allows heart sparing without compromising PTV coverage. However, this technique may require highly complex plans. Deep Inspiration Breath Hold (DIBH) procedure increases the heart-to-breast distance, facilitating the dose sparing of the heart. The aim of the present work was to investigate if the cardiac-sparing benefits of the DIBH technique were achieved with lower plan modulation and complexity than Free Breathing (FB) treatments.

METHODS AND MATERIALS

Ten left side breast cases were considered by two centers with different treatment planning systems (TPS) and Linacs. VMAT plans were elaborated in FB and DIBH according to the same protocol. Plan complexity was evaluated by scoring several complexity indices. A new global score index accounting for both plan quality and dosimetric parameters was defined. Pre-treatment QA was performed for all VMAT plans using EPID and Epiqa software.

RESULTS

DIBH-VMAT plans were associated with significant PTV coverage improvement and mean heart dose reduction (p < 0.003), increasing the resulting global score index. All the evaluated complexity indices showed lower plan complexity for DIBH plans than FB ones, but only in few cases the results were statistically significant. All plans passed the gamma analysis with the selected criteria.

CONCLUSIONS

The DIBH technique is superior to the FB technique when the heart needs further sparing, allowing a reduction of the doses to OARs with a slightly lower degree of plan complexity and without compromising plan deliverability. These benefits were achieved regardless of the technological scenarios adopted.