Treatment Of Left Breast Cancer Research Articles

A Comparative Study of Cardiac Toxicity Analysis in Hypo-Fractionated Vs Conventionalfractionated Adjuvant Radiotherapy in Post-Mastectomy Leftbreast Carcinoma

Background: Post-mastectomy adjuvant radiotherapy improves long-term survival by reducing the risk of loco-regional recurrence in breast cancer patients with high-risk features. Considering radiation therapy to the left sided chest wall heart is an important organ at risk. Hypo-fractionated radiotherapy is increasingly being used due to involvement of fewer treatment sessions and is almost radio-biologically equivalent to conventionally fractionated radiotherapy. Objective: This study was conducted to evaluate cardiac toxicities between hypo and conventionally fractionated radiotherapy. Methods: This quasi-experimental study was done at the National Institute of Cancer Research and Hospital, Mohakhali, Dhaka from January 2019 to December 2019, 60 patients were purposively assigned into two groups and each group included 30 patients. Arm A: received Conventional fractionated radiotherapy (50Gy/25 fractions over 5 weeks, at 2Gy/fraction). Arm B: received Hypo- fractionated radiotherapy (40.05 Gy in 15 fractions over 3 weeks at 2.67 Gy/fraction). Echocardiography (ECHO), Electrocardiography (ECG) was performed to find the cardiac toxicities. Results: The mean age of the patients in arm A was 50.03 ± 6.82 years and that of arm B was 48.08 ± 5.08 years. No significant statistical difference was found between the two groups regarding socio-demographic variables and clinical presentations. Most of the patients in both arms showed grade 0 cardiac toxicity (arm A: 70% and arm B: 80%) & few showed grade 1 cardiac toxicity (arm A: 20% and arm B: 13.3%) and three patients (10.0%) in arm A and two patients (6.66%) in arm B had shown grade 2 cardiac toxicities six months after treatment. However, this difference was statistically not significant (p >0.05). Before treatment, the ejection fraction (EF) of arm A and arm B were 63.3 ± 5.621 and 64.7± 4.991. Six months after treatment the EF of both arms decreased (arm A 60.2 ± 4.051 & arm B 60.9 ± 5.121) but the difference was statistically not significant (p >0.05). Conclusion: Hypo-fractionated radiotherapy in the adjuvant setting for the treatment of left breast cancer has no additional cardiac toxicity in comparison to conventionally fractionated radiotherapy while maintaining same efficacy. J Bangladesh Coll Phys Surg 2024; 42: 169-175

Atrial fibrillation in a patient with diffuse myocardial fibrosis and mitral annular disjunction

A case of atrial fibrillation and premature ventricular complexes (PVC) in a patient with mitral valve prolapse and mitral annular disjunction is described. Rhythm disturbances occurred after a new coronavirus infection. Also, the patient has a history of combined treatment of left breast cancer, which contributed to the appearance of myocardial fibrosis as an arrhythmogenic substrate. Due to the ineffectiveness of conservative antiarrhythmic therapy, a radiofrequency catheter procedure was performed, which proved unsuccessful. The purpose of the article is to present the possible causes of cardiac arrhythmias and the role of magnetic resonance imaging in the diagnosis of arrhythmogenic myocardial fibrosis and mitral annular disjunction.

Most Appropriate Radiation Therapy Techniques for The Breast Cancer Treatment: Dosimetric Analysis of Three Different Radiation Therapy Methods

Background: Radiation-induced cardiac events and pneumonitis are the major late radiotherapy side effects. Methods: We explored the differences in dose distribution between 3D CRT, IMRT and VMAT in 125 women with unilateral breast cancer. The various dose distribution to the tumor and OARs were studied for left and right sided irradiation. Results: Upon using 3D CRT breasts with lymph nodes, we observed a significant dose increase in the ipsilateral lung. Having irradiated only the right breast, there was a negligible Dmean difference to the adjacent lung between three methods, likewise for the myocardium in left breast cases. For right-sided cases 3D CRT showed the lowest doses in myocardium. Conclusion: Radiation oncologists should consider VMAT if conditions do not allow devising three plans with different methods. This in turn will reduce cardio and pneumotoxicity of left breast cancer treatment. In the treatment of right breast cancer, physicians should focus on 3D CRT.

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

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. AnSGRT-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. Atotal of 24patients, 12treated with atangential technique and 12with alocoregional technique, were evaluated for atotal 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. Lateral cumulative distributions of SGRT shifts for both locoregional and tangential samples were consistent with anull 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. 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.

Dosimetric advantages of volumetric modulated arc therapy (VMAT) with deep inspiration breath hold (DIBH) technique in Halcyon Linac for left breast cancer treatment.

To evaluate the dosimetric advantages of incorporating the deep inspiration breath hold (DIBH) technique into left breast cancer volumetric modulated arc therapy (VMAT) treatment under Halcyon Linac and to investigate the correlation between mean heart dose (MHD) and distance from the heart to target volumes in left breast cancer VMAT treatment. Fifteen Post-lumpectomy, left-sided breast patients treated between January 2017 and October 2020 were selected. Two plans were generated for each patient using Eclipse treatment planning system (TPS) with the prescription of 50.4 Gy to planning target volume (PTV) breast and 58.8 Gy to PTV boost in 28 fractions. For each patient, DIBH and free breathing (FB) VMAT treatment plans under Halcyon Linac were generated. Dosimetric parameters, monitor unit and beam-on time of both DIBH and FB groups were compared. Three-dimensional distances from heart surface to each target volume were measured on computed tomography images using the TPS contouring tool and their correlation with MHD was evaluated by Pearson's correlation coefficient (r). Comparable target coverage was shown in both groups. Mean dose to heart, left anterior descending artery, and left ventricle in Halcyon-DIBH-VMAT group were significantly reduced by 0.49 Gy, 1.19 Gy, and 0.57 Gy, respectively, compared to Halcyon-FB-VMAT (p < 0.001). A significant lung dose reduction was also achieved in Halcyon-DIBH-VMAT group. There was also a strong negative correlation between MHD and distance from heart surface to PTV boost in both FB and DIBH group (r = -0.741, p < 0.001), but not observed for distance from heart surface to PTV breast. Incorporating DIBH into left breast cancer VMAT treatment under Halcyon Linac demonstrated significant cardiac and lung dose reduction. It was also demonstrated that MHD had a strong negative correlation with distance from heart surface to PTV boost but relatively independent of distance from heart surface to PTV breast. Recognizing the distance from the heart surface to PTV boost as the main factor in affecting MHD could potentially facilitate clinical treatment planning workflow and decision.

A comparative study evaluating the dose volume parameters in 3D conformal radiation of left sided whole breast irradiation including regional lymphnodes - a need of resource constrained countries.

BackgroundThe purpose of this study was to compare four 3D conformal radiation techniques in treatment of left breast cancer patients.Materials and methodsRadiation was planned for 20 patients to the left breast and regional lymph nodes using four techniques: partially wide tangents, photon-photon mix, photon-electron mix and 30/70 photon-electron mix. All plans were evaluated for internal mammary nodes (IMN) coverage, hotspot and normal tissue constraints.ResultThe 85% of planning target volume (PTV) coverage was lesser for upper IMN than the lower IMN (below the lower border of the clavicular head) for all four techniques. The lower IMN coverage was better for partially wide tangent (80.46%) and photon-photon mix (88.88%). The lowest value of hotspot was seen in the partially wide tangent technique (112.69% ± 1.92). Hotspot is unacceptably high in both photon-electron mix and 30/70 photon-electron mix (> 120%). Left lung mean dose for all techniques on a pair-wise comparison showed no statistical difference. Left lung V20 values for partially wide tangent was 37.56% ± 8.17 and for photon-photon mix it was 40.49% ± 3.36. The mean heart dose with partially wide tangent was 9.43 ± 3.15 Gy and with photon-photon mix it was 10.10 ± 2.70 Gy. The mean heart dose for photon-electron mix was 7.56 ± 1.95 Gy and for 30/70 photon-electron mix it was 7.98 ± 2.16 Gy.ConclusionNo single technique satisfies all the criteria. The decision should be made on a case-by-case basis, considering the anatomy of the patient, availability of electron facilities and setup accuracy and reproducibility.

Dosimetric comparison of supine versus prone radiotherapy techniques in patients with breast cancer

Early-stage breast cancer patients survive longer so a radiotherapy technique which can reduce late toxicity is important. In this study, we made a dosimetric comparison of supine and prone breast irradiation techniques in patients with left breast cancer. Ten patients scheduled for whole-breast radiotherapy after lumpectomy were included in this study. The patients underwent computed tomography scans in both supine and prone positions on a breast board. The breast was contoured as per standard guidelines. Treatment planning was done for both the positions. A dose of 40 Gy/15#/3 weeks was prescribed. Mean dose to the heart and left lung was calculated for each patient in the supine and prone positions. Dose-volume histograms were generated and compared between the two sets. Paired t test was applied to test the significance of difference between the mean doses received by the heart and left lung for the two techniques. The difference was considered statistically significant if p value was < 0.05. The heart and left lung were better spared in the prone position compared to supine. Mean heart dose in the supine and prone positions was 4.5558 Gy and 2.063 Gy (p = 0.02), respectively. Mean lung dose in the supine and prone positions was 6.5797 Gy and 0.8491 Gy (p = 0.001), respectively. Rotational setup error was noted in 3 and 1 patient in the prone position and supine position, respectively. The prone position for the radiotherapy treatment of left breast cancer was dosimetrically better than the supine position in terms of mean dose to the heart and left lung.

Impact of acuros XB algorithm in deep-inspiration breath-hold (DIBH) respiratory techniques used for the treatment of left breast cancer.

To investigate the impact of Acuros XB (AXB) algorithm in the deep-inspiration breath-hold (DIBH) technique used for treatment of left sided breast cancer. AXB may estimate better lung toxicities and treatment outcome in DIBH. Treatment plans were computed using the field-in-field technique for a 6 MV beam in two respiratory phases - free breathing (FB) and DIBH. The AXB-calculations were performed under identical beam setup and the same numbers of monitor units as used for AAA-calculation. Mean Hounsfield units (HU), mass density (g/cc) and relative electron density were -782.1 ± 24.8 and -883.5 ± 24.9; 0.196 ± 0.025 and 0.083 ± 0.032; 0.218 ± 0.025 and 0.117 ± 0.025 for the lung in the FB and DIBH respiratory phase, respectively. For a similar target coverage (p > 0.05) in the DIBH respiratory phase between the AXB and AAA algorithm, there was a slight increase in organ at risk (OAR) dose for AXB in comparison to AAA, except for mean dose to the ipsilateral lung. AAA predicts higher mean dose to the ipsilateral lung and lesser V20Gy for the ipsilateral and common lung in comparison to AXB. The differences in mean dose to the ipsilateral lung were 0.87 ± 2.66 % (p > 0.05) in FB, and 1.01 ± 1.07% (p < 0.05) in DIBH, in V20Gy the differences were 1.76 ± 0.83% and 1.71 ± 0.82% in FB (p < 0.05), 3.34 ± 1.15 % and 3.24 ± 1.17 % in DIBH (p < 0.05), for the ipsilateral and common lung, respectively. For a similar target volume coverage, there were important differences between the AXB and AAA algorithm for low-density inhomogeneity medium present in the DIBH respiratory phase for left sided breast cancer patients. DIBH treatment in conjunction with AXB may result in better estimation of lung toxicities and treatment outcome.

Half Beam Technique in Patient with Left Breast Cancer and Evaluate its Dosimetry Parameters from Dosevolume Histograms

Using of 3DCRT for the treatment of left breast cancer by a single isocenter with half beam in the junctionof tangential and supraclavicular fields is an important method. The purpose was to evaluate the outcome ofRadiation Treatment Plans (RTP) that includes planning target volume (PTV) dose, conformity index (CI),homogeneity index (HI), organs at risk (OAR), and compared with tolerance doses of left-sided whole breastirradiation by half beam technique. Thirteen patients with left breast cancer who had received radiotherapyby using 6, 10, and 18 MV photons. The clinical target volume [CTV] was contoured as a target volume, andleft lung, right lung, heart, and spinal cord tissues as OAR planning technique was analyzed at Zhianawacancer center (ZCC), Sulaimany-KR-Iraq. There was No risk for 12 patients CI (&lt;1), accept patient No.(6) CI&gt;1. the PTV was under coverage (4060±32.116 cGy), was close to 4005 Gy volume. The left lung,and right lung mean dose was (33.923, 1018.231cGy &lt; tolerance mean Dose (4000 cGy), and for Lt lungDose V20 &lt; 30 cGy. Heart Dose V35 (2.354) &lt;20Gy, and Heart mean Dose (cGy)Dose was (358.308 cGy)&lt; tolerance mean Dose (2600 cGy). Cord Max dose was (682.692cGy) &lt; 2000. the Dose mean value ofesophagus was (29,077)cGy was &lt;3400 (Esophagus Tolerance mean dose (cGy). The application of leftbreast cancer provides significant advantages especially in PTV and OAR dosages.

Assessment of deep inspiration breath hold technique setup reproducibility using mega voltage imaging for left breast cancer radiation therapy–integrated network study

We evaluated daily setup reproducibility of deep inspiration breath hold (DIBH) using mega voltage (MV) imaging for left breast cancer radiation therapy. Analysis of 109 left breast cancer patients across UPMC Hillman Cancer Center network treated using DIBH technique with daily MV imaging was done. Patient characteristics, MV imaging procedure used and inter-fraction directional shifts were collected. For the statistical analyses, we separated all patients into 2 groups in each of the following 3 categories; (1) obese (BMI ≥ 30) vs nonobese, (2) mastectomy vs lumpectomy, (3) internal mammary node (IMN) treatment vs no IMN treatment. The group mean inter-fraction directional shifts were as following: (1) 0.7 mm (superior), 0.8 mm (inferior); (2) 0.65 mm (left), 0.64 mm (right); (3) 0.89 mm (anterior), 0.83 mm (posterior). Also, any directional shift ≥ 2 mm, ≥ 3 mm, ≥ 4 mm, ≥ 5 mm, ≥ 10 mm was found to be 52.9%, 37.6%, 30.9%, 21.9%, 3.7% of total fractions, respectively. In the stratified analysis, obese patients had larger directional shifts (p < 0.05) and highly associated with number of fractions for ≥ 5 mm in any directional shift compared to nonobese patients (29% vs 17%; p = 0.04). DIBH setup for left breast cancer treatment at our large cancer center network was reproducible with any mean directional shifts less than 1.0 mm using MV imaging. Daily imaging would be more beneficial for obese patients compared to nonobese patients.

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.

Dosimetric analysis of tangent-based volumetric modulated arc therapy with deep inspiration breath-hold technique for left breast cancer patients

BackgroundTangent-based intensity modulated radiation therapy (TIMRT) is a common adjuvant radiotherapy strategy for breast cancer patients. This study compared the dosimetric characteristics of tangent-based volumetric modulated arc therapy (TVMAT) and TIMRT for left breast cancer patients during deep inspiration breath-hold (DIBH) and free breathing (FB) techniques.MethodsFourteen patients with left breast cancer after breast-conserving surgery were included. The first arc started at 331.8–353.6 degrees and stopped at 281.8–315.0 degrees. The third arc started at 123.2–149.1 degrees and stopped at 88.0–96.0 degrees. The second and fourth arcs were reverse arcs of first and third arcs. DIBH-TIMRT inversing plans were generated using opposing tangential fields. Wilcoxon signed rank test and Spearman correlation were used to examine the significance of dose difference.ResultsCompared with FB-TVMAT, the mean heart dose of DIBH-TVMAT plans was reduced from 7.9 Gy to 3.2 Gy (p < 0.001). The average left lung volume receiving 30 Gy or more (V30Gy) was reduced from 12.9 to 5.7% (p < 0.001). DIBH-TVAMT plans resulted in a lower mean dose to the contralateral breast and lung (2 Gy and 0.7 Gy vs 3.4 Gy and 1.5 Gy, respectively) as compared to FB-TVMAT plans. Compared with DIBH-TIMRT, the average left lung V30Gy of DIBH-TVMAT plans was reduced from 8.5 to 5.7% (p = 0.031). As for low-dose areas, exposure of the left lung, right breast, heart and right lung volume with 10 Gy or more was not significantly different between the IMRT- and VMAT-plans.ConclusionsDIBH-TVMAT for left breast cancer treatment retains treatment plan quality similar to the DIBH-IMRT technique without compromising dose restrictions to the heart, right breast and right lung. DIBH-TVMAT increased left lung protection but still had higher V5Gy to right breast and substantially higher V5Gy to heart. For left breast cancer patients receiving treatment with the DIBH technique, DIBH-TVMAT provides better treatment quality and is a safe and feasible treatment strategy.

Set-up Reproducibility for Deep Inspiration Breath Hold for Left Sided Breast Cancer Treatment Using Daily Mega Voltage Imaging-Integrated Network Study

Deep inspiration breath hold (DIBH) technique has been effective to reduce cardiac dose for left sided breast cancer treatment. However there are limited data on the setup reproducibility with DIBH technique. Herein we report the daily setup reproducibility and variation of DIBH using daily mega voltage (MV) imaging based on a large network of data. In total, 109 left breast cancer patients from 10 hospital sites across the UPMC Hillman Cancer Center network were treated using DIBH technique with daily MV imaging from May 2016 to July 2017. All patients had visual coaching via iPod device as well as voice coaching for DIBH for CT simulation and treatment. The same procedure and technique for DIBH CT simulation and treatment planning have been shared between physicists and physicians across the network. For each patient, BMI, age, surgery type (lumpectomy or mastectomy), regional and internal mammary nodes (IMN) involvement, MV imaging procedure used, number of total portal images and inter-fraction directional shifts were collected. For the statistical analyses, we separated all patients into two groups in each of the following three categories; 1) obese (BMI ≥ 30) vs. non- obese, 2) surgery type: mastectomy vs. lumpectomy, 3) internal mammary node (IMN) treatment vs. no IMN treatment. A total of 1833 treatments and 2818 MV portal images were analyzed. Minimum mean distance from heart to the tangential field edge was 2.5 mm (ranges 0-12 mm). The group mean inter-fraction directional shifts were as following: 1) 0.7 mm (superior; SD = 2.26), 0.8 mm (inferior; SD = 2.21), 2) 0.65 mm (left; SD =1.60), 0.64 mm (right; SD = 1.62), 3) 0.89 mm (anterior; SD = 1.96), 0.83 mm (posterior; SD=2.03). However between hospitals, there was found a difference in mean inter-fraction directional shift (p < 0.001). Any inter-fraction directional shift for ≥ 2mm, ≥ 3mm, ≥ 4mm, ≥ 5mm, ≥ 10mm was found to be 52.9 %, 37.6 %, 30.9 %, 21.9 %, 3.7 % of total fractions, respectively. In the stratified analysis, obese patients had larger directional shifts (p < 0.05) and highly associated with number of fractions for ≥ 5mm in any directional shift compared to non-obese patients (29 % vs. 17 %; p =0.04). To the best of our knowledge, this is the first and the largest study that reports the daily setup reproducibility and variation using MV images and patient’s visual feedback. DIBH setup for left breast cancer treatment at our large cancer center network was reproducible with any mean directional shifts less than 1.0 mm, although there was some inter-fraction variation between hospital sites. Consideration of daily imaging for obese patients should be taken to ensure the benefit of DIBH for that population. Also, if the distance of heart to the edge of the tangential treatment field is relatively close, it would be more beneficial to have daily imaging because 53 % of patients still had ≥ 2 mm shift.

Dosimetric evaluation of right coronary artery in radiotherapy for breast cancer

Comparison with control groups of untreated patients suggests that right-breast-cancer patients who receive radiotherapy have a higher rate of heart disease. Dose constraint for heart has been established to minimize radiotherapy-induced cardiotoxicity during left breast cancer treatment. Additionally, it is suggested to minimize the dosage on left anterior descending (LAD) artery. Right coronary artery (RCA), is the second largest artery, after left main coronary artery, supplying the heart. A dose evaluation study is not present for RCA; the proximal part of which is included in the irradiation field during breast cancer treatment of right breast. To investigate the presence of a correlation, doses resulting from right and left breast radiotherapy on proximal RCA (pRCA), LAD, and heart are evaluated in this study. Forty breast cancer patients who went under breast-conserving surgery are the subject of this study. Four groups were established; right breast, right breast and internal mammary (IM), left breast and left breast, and IM. pRCA, LAD, and heart volumes were contoured for each group on the planning tomographies. Resultant doses of tangential fields planning on these volumes were compared using dose-volume histograms. Mean and maximum doses of pRCA were statistically compared between groups. The highest mean and maximum point doses (192 to 284 cGy) were found in the right breast + IM group (p < 0.05). The mean and maximum doses only in the right breast and left breast + IM group did not differ statistically. However, the mean and maximum pRCA doses in these 2 groups were higher than only the left breast group (p < 0.05). pRCA receives high doses during radiotherapy of right and left breast especially if IM is included. This may predispose to coronary artery disease.

Model-basedcardiacdoseestimation in radiationtreatment of leftbreastcancer.

To develop a mathematical model for cardiac dose estimation for patients who have been treated for left-sided breast cancer without CT data. After obtaining institutionalreview board approvals, 147 patients with left-sided breast cancer were selected that were treated supine with opposed tangents. The heart blocks from the tangential fields were removed and dose calculations were performed with 6 MV beams using an advanced algorithm. This study was performed with CT data with DRR to represent a radiographic simulator image of yesteryear treatments. The beam'seye-view images showing delineated breast, lung and heart were created to represent views on radiograph. The maximum heart distance (MHD) was recorded and irradiated heart area (AREA) was computed by combination of triangles and rectangles. Based on accurate 3D dose calculation, mean dose (Dmean) and V10 to V50 of heart were analyzed with respect to MHD and AREA for dosimetric parameters using linear and quadratic fit. The treatment parameters calculated by MHD and segments using 2D radiographs were within 2% of the actual dosimetric parameters computed from the 3D planning system. The MHD and AREA vs Dmean, V10, V20, V30 and V50 showed very good correlation with linear model (R2 >0.91); however the correlation was significantly better with quadratic model (R2 >0.92). The analysis of the dosimetric error with our linear and quadratic model is remarkable within <3% error for most cases. The proposed mathematical model for the cardiac dose estimation is accurate within ±3% using a radiograph without CT data. This provides avenues for patient pooling in future studies related to radiation dose and cardiac toxicity. These results will help in estimating cardiac dose analysis accurately from previous studies as well as in centers still using 2D planning. The evidence of cardiac risk following radiotherapy continues to be one of the important considerations for the management of left-sided breast cancer patients. One of the problem in the estimation of dose-risk effects is the reconstruction of heart dose for pre-CT treatments. In this study, a simple mathematical model is presented that could estimate cardiac dose within ±3% in left breast cancer treatment from 2D radiograph where CT data do not exist.

SU‐F‐T‐525: Monitordeep‐Inspiratory Breathhold with a Laser Sensor for Radiation Therapy of Left Breast Cancer

Purpose:Radiation therapy (RT) of left sided breast cancers with deep‐inspiratory breathhold (DIBH) can reduce the dose to heart. The purpose of this study is to develop and test a new laser‐based tool to improve ease of RT delivery using DIBH.Methods:A laser sensor together with breathing monitor device (Anzai Inc., Japan) was used to record the surface breathing motion of phantom/volunteers. The device projects a laser beam to the chestwall and the reflected light creates a focal spot on a light detecting element. The position change of the focal spot correlates with the patient's breathing motion and is measured through the change of current in the light detecting element. The signal is amplified and displayed on a computer screen, which is used to trigger radiation gating. The laser sensor can be easily mounted to the simulation/treatment couch with a fixing plate and a magnet base, and has a sensitivity range of 10 to 40 cm from the patient. The correlation of breathing signals detected by laser sensor and visionRT is also investigated.Results:It is found that the measured breathing signal from the laser sensor is stable and reproducible and has no noticeable delay. It correlates well with the VisionRT surface imaging system. The DIBH reference level does not change with movement of the couch because the laser sensor and couch move together.Conclusion:The Anzai laser sensor provides a cost‐effective way to improve beam gating with DIBH for treating left breast cancer. It can be used alone or together with VisionRT to determine the correct DIBH level during the radiation treatment of left breast cancer with DIBH.

Two Sub-obstructive Left Atrium Myxomasinduce Cardiac Failure after Breast Cancer Treatment

Atrial myxoma is a rare condition. Cardiac failure after left breast cancer treatment is not usually attributed to such pathology. We describe the case of a 69 year-old female who presented two sub-obstructive left atrium myxomas one year after the end of left breast cancer treatment. Acute cardiac failure, without history of prior cardiovascular disease, could have resolved from the combination of various factors involving myxomas and complications of radiotherapy and chemotherapy. The absence of atrial images on the computerised tomography and ultrasonography performed before cancer treatment question the accuracy of diagnosis imaging as well as the actual rate of growth of cardiac myxoma.

Right Parasternal Cardiac Surgery after Radical Treatment of Left Breast Cancer

A 74-year-old woman required surgical treatment of severe aortic valve stenosis and two-vessel coronary artery disease consisted of a significant stenosis of the left anterior descending branch and right coronary ostium. She had previously undergone radical mastectomy and radiation therapy for left breast cancer. Severe dermal sclerosis and subcutaneous tissue defect at the chest midline, which would cause poor wound healing because of insufficient blood flow, precluded conventional median sternotomy and a left mini-thoracotomy. Therefore, we selected a hybrid treatment approach using a combination of surgery and percutaneous coronary intervention. We performed aortic valve replacement and coronary bypass grafting to the right coronary artery using a right parasternal approach followed by percutaneous coronary intervention of the left anterior descending artery on postoperative day 13. Wound healing was quite satisfactory

Introduction of moderate deep inspiration breath hold for radiation therapy of left breast: Initial experience of a regional cancer center

PurposePractical aspects of introducing moderate deep inspiration breath hold (mDIBH) for treatment of left breast cancer in a regional cancer program in terms of workflow and treatment delivery requirements are described. Differences in heart and lung doses between free breathing (FB) and mDIBH plans are presented as well as heart position reproducibility and resulting dosimetric impact using cone beam computed tomography (CBCT). Methods and materialsA mDIBH process was established. Therapists observed duration and quantity of breath holds required for setup, imaging, and beam delivery during treatment. Treatment plans were generated on the FB and mDIBH CT datasets allowing comparison of heart and lung dose–volume data for 50 patients. Five consecutive CBCT images were used to measure the distance between the heart and chest wall for 5 patients. Estimates of dose to the translated heart were then made with the treatment planning system. ResultsWhen compared with FB delivery, mDIBH treatment time for tangents and boosts increased by 5 minutes, while 3- or 4-field techniques increased by 10 minutes. Differences in heart dose D10 cc, mean, V30 and V10 were statistically significant between the FB and mDIBH tangents and 3- or 4-field treatment plans. Statistically significant differences in V20, V10, V5, and mean lung doses were observed for 3- and 4-field FB and mDIBH plans. Differences between lung V5 dose metrics for FB and mDIBH 2-field plans were statistically significant. Interfraction mean translations in heart position coronally ranged from −6.2 to 2.6 mm and resulted in non-negligible increases in the heart dose. ConclusionsModerate deep inspiration breath hold has been successfully implemented in our regional cancer center for treatment of left breast cancer and is now a standard practice. This change in practice from FB to mDIBH treatment has not impacted our ability to meet provincial guidelines for patient throughput.

Implementing In-Room Visual Guidance Using a Digital Projector for Breath-Hold Treatment of Left Breast Cancer

Implementing In-Room Visual Guidance Using a Digital Projector for Breath-Hold Treatment of Left Breast Cancer