During Deep Inspiration Breath-hold Research Articles

Correlation between maximum heart distance and thoracic diameter changes and diaphragmatic descent in left-sided breast cancer patients during deep inspiration breath-hold (DIBH).

Cardioprotection is valued in radiotherapy for patients with left-sided breast cancer. Deep inspiration breath-hold (DIBH) technique can achieve cardioprotection well. However, during DIBH, the extent to which the heart enters the radiation field is affected by the movement of the thorax and diaphragm. The aim of this study was to analyze the correlation between the maximum distance of the heart entering the field (maximum heart distance, MHD) and thoracic diameter changes and diaphragmatic descent in left-sided breast cancer patients during DIBH. Ninety-eight patients with left-sided breast cancer were included in this retrospective study. They performed simulation in Sentinel-guided DIBH, and two sets of CT images were collected under both free breathing (FB) and DIBH, and diaphragm positions, anteroposterior thoracic diameter (ATD), transverse thoracic diameter (TTD), gating window level (GWL), and MHD were measured, and the change (Δ) of each parameter in DIBH relative to that in FB were calculated. Pearson or Spearman test were used to analyze the correlation between ΔMHD and the changes in other parameters. For all patients with DIBH, the average of ΔMHD was -8.3 mm, and the average of ΔATD and ΔTTD were 11.0 and 8.6 mm, and the median of both left diaphragmatic descent (LDD) and right diaphragmatic descent (RDD) were 35.0 mm, and the median of GWL was 11.1 mm. The correlation coefficients between MHD decrease (ΔMHD) and LDD, RDD, and ΔTTD were -0.430 (p = 0.000), -0.592 (p = 0.000) and 0.208 (p = 0.040), respectively, but not significantly correlated with ΔATD or GWL. The MHD decrease showed a moderate correlation with diaphragmatic descent In Sentinel-guided DIBH for patients with left-sided breast cancer, while there was a weak or no correlation with thoracic diameter changes or GWL. Abdominal breathing can lower diaphragm more and may be more beneficial to the heart stay away from tangential field.

Can bronchoscopically implanted anchored electromagnetic transponders be used to monitor tumor position and lung inflation during deep inspiration breath-hold lung radiotherapy?

To evaluate the efficacy of using bronchoscopically implanted anchored electromagnetic transponders (EMTs) as surrogates for 1) tumor position and 2) repeatability of lung inflation during deep-inspiration breath-hold (DIBH) lung radiotherapy. Forty-one patients treated with either hypofractionated (HF) or conventional (CF) lung radiotherapy on an IRB-approved prospective protocol using coached DIBH were evaluated for this study. Three anchored EMTs were bronchoscopically implanted into small airways near or within the tumor. DIBH treatment was gated by tracking the EMT positions. Breath-hold cone-beam-CTs (CBCTs) were acquired prior to every HF treatment or weekly for CF patients. Retrospectively, rigid registrations between each CBCT and the breath-hold planning CT were performed to match to 1) spine, 2) EMTs and 3) tumor. Absolute differences in registration between EMTs and spine were analyzed to determine surrogacy of EMTs for lung inflation. Differences in registration between EMTs and the tumor were analyzed to determine surrogacy of EMTs for tumor position. The stability of the EMTs was evaluated by analyzing the difference between inter-EMT displacements recorded at treatment from that of the plan for the CF patients, as well as the geometric residual (GR) recorded at the time of treatment. A total of 219 CBCTs were analyzed. The average differences between EMT centroid and spine registration among all CBCTs were 0.45±0.42cm, 0.29±0.28cm, and 0.18±0.15cm in superior-inferior (SI), anterior-posterior (AP) and lateral directions, respectively. Only 59% of CBCTs had differences in registration<0.5cm for EMT centroid compared to spine, indicating that lung inflation is not reproducible from simulation to treatment. The average differences between EMT centroid and tumor registration among all CBCTs were 0.13±0.13cm, 0.14±0.13cm and 0.12±0.12cm in SI, AP and lateral directions, respectively. Ninety-five percent of CBCTs resulted ina <0.5cm change between EMT centroid and tumor registration, indicating that EMT positions correspond well with tumor position during treatments. Six out of the seven recorded CF patients had average differences in inter-EMT displacements ≤0.26cm and average GR ≤0.22cm, indicating that the EMTs are stable throughout treatment. Bronchoscopically implanted anchored EMTs are good surrogates for tumor position and are reliable for maintaining tumor position when tracked during DIBH treatment, as long as the tumor size and shape are stable. Large differences in registration between EMTs and spine for many treatments suggest that lung inflation achieved at simulation is often not reproduced.

Appropriate margin for planning target volume for breast radiotherapy during deep inspiration breath-hold by variance component analysis

BackgroundThis study aimed to quantify errors by using a cine electronic portal imaging device (cine EPID) during deep inspiration breath-hold (DIBH) for left-sided breast cancer and to estimate the planning target volume (PTV) by variance component analysis.MethodsThis study included 25 consecutive left-sided breast cancer patients treated with whole-breast irradiation (WBI) using DIBH. Breath-holding was performed while monitoring abdominal anterior–posterior (AP) motion using the Real-time Position Management (RPM) system. Cine EPID was used to evaluate the chest wall displacements in patients. Cine EPID images of the patients (309,609 frames) were analyzed to detect the edges of the chest wall using a Canny filter. The errors that occurred during DIBH included differences between the chest wall position detected by digitally reconstructed radiographs and that of all cine EPID images. The inter-patient, inter-fraction, and intra-fractional standard deviations (SDs) in the DIBH were calculated, and the PTV margin was estimated by variance component analysis.ResultsThe median patient age was 55 (35–79) years, and the mean irradiation time was 20.4 ± 1.7 s. The abdominal AP motion was 1.36 ± 0.94 (0.14–5.28) mm. The overall mean of the errors was 0.30 mm (95% confidence interval: − 0.05–0.65). The inter-patient, inter-fraction, and intra-fractional SDs in the DIBH were 0.82 mm, 1.19 mm, and 1.63 mm, respectively, and the PTV margin was calculated as 3.59 mm.ConclusionsErrors during DIBH for breast radiotherapy were monitored using EPID images and appropriate PTV margins were estimated by variance component analysis.

PD-0177: Interfraction heart motion during Deep Inspiration Breath Hold (DIBH) radiotherapy measured by CBCT.

PD-0177: Interfraction heart motion during Deep Inspiration Breath Hold (DIBH) radiotherapy measured by CBCT.

The Feasibility of Implementing Deep Inspiration Breath-Hold for Pediatric Radiation Therapy

Radiation therapy delivery during deep inspiration breath-hold (DIBH) reduces the irradiation of the heart and lungs and is therefore recommended for adults with mediastinal lymphoma. However, no studies have addressed the use of DIBH in children. This pilot study investigates the feasibility of and compliance with DIBH in children. Children from the age of 5 years were recruited to a training session to assess their ability to perform DIBH. No children received radiation therapy. The children were placed in a potential radiation therapy position. The DIBH was voluntary and monitored using an optical surface system providing visual feedback. Children who performed 3 stable DIBHs of 20 seconds each and remained motionless were deemed DIBH compliant. Compliance, equipment suitability, and coaching were further assessed in a semistructured interview. We included 33 children (18 healthy and 15 hospitalized children with cancer) with a mean age of 8.5 years (range, 5-15). A total of 28 (85%) children were DIBH compliant. Twenty children were deemed immediately DIBH compliant, and 8 were deemed conditionally DIBH compliant, as DIBH compliance was presumed with custom-made immobilization and/or additional DIBH training. Mean age of the DIBH-compliant and the non-DIBH-compliant children was 8.9 years (range, 5-15) and 6 years (range, 5-9), respectively. Only 1 of 15 hospitalized children was not DIBH compliant and only 1 of all 33 children was unable to grasp the DIBH concept. The available DIBH equipment was suitable for children, and 94% reported that they were happy with training and performing DIBH. This pilot study demonstrated that children from the age of 5 years can potentially comply with the DIBH technique and perform stable and reproducible DIBHs suitable for radiation therapy. Custom-made immobilization and adequate training will potentially increase DIBH compliance. A prospective clinical trial (NCT03315546), investigating the dosimetric benefit of radiation therapy delivery in DIBH compared with free breathing with pediatric patients, has been initiated.

5. Analysis of correspondence between width of gating window and chest wall position during deep inspiration breath-hold (DIBH) for left-sided breast radiotherapy

Purpose Aim of our study is to verify the correspondence between gating window width and chest wall position by analysis of Respiration Waveform acquired by Varian RPM Respiratory Gating System during treatments of left-sided breast in DIBH. Methods Two CT series were obtained for each patient, in free breathing (FB) and DIBH using RPM. In DIBH the width of the gating window, i.e. the allowed chest wall motion, was identified for each patient considering 5 mm margins and stored on Reference Respiration Waveform to be used during treatment. Respiration Waveforms acquired during 211 treatments (9 patients) were compared with proper Reference, considering the minimum point before DIBH as common origin, both in time and chest wall motion. The difference between treatment chest wall position and reference chest wall position was evaluated as difference between median values of RPM block position stored during treatment and during CT scan (plateau in graphic, Fig. 1). Results The differences between median values of RPM block position stored during treatment and during CT scan ranged from −9.0 mm to 8.2 mm; the average value is 0.2 mm and the standard deviation is 3.3 mm. The frequency of the differences is reported in Table 1 . Conclusions Our analysis of Respiration Waveforms acquired during treatments shows good correspondence between the chosen gating window and the variability in chest wall position in DIBH, confirming that 5 mm margins around the Reference Position is advisable to limit significant misalignments between treatment fields and patient’s tissues.

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.

Can Bronchoscopically Implanted Anchored Transponders be Used As a Surrogate to Accurately Track Lung Tumors During Deep Inspiration Breath Hold Radiation Therapy?

Implanted EMTs provide a means to position and track, in real time, tumors during deep inspiration breath hold (DIBH) radiotherapy. However, during a course of RT, the local anatomy of a lung tumor can change, possibly reducing the geometric accuracy of the EMTs. We investigate whether correcting for such changes prior to each treatment is clinically feasible. 14 patients with lung tumors accrued to an IRB approved protocol were each implanted with 3 anchored EMTs placed in small airways (< 2mm) near or within the tumor. The EMT is investigational; the study was conducted under an IDE. Cone beam scans were acquired prior to every SBRT treatment, and once weekly for conventional fractionated patients. Dual registrations: tumor to tumor and EMT to EMT were done for each scan. Any discrepancy was used to correct the EMT tracking. Correction was verified using CBCT and EMT tracking. Retrospectively, 5 registrations of each DIBH CBCT with the planning scan were made; features registered were: the tumor, each EMT, and 3-4 vertebrae at tumor level. The displacement of each EMT with respect to the tumor was computed. From the CBCT scans, the mean and std. dev. of the distributions of the absolute differences of the change in each EMT position with respect to the tumor were (in mm) 1.0 ± 0.9 Left-Right, 1.0±1.1 Post-Ant, and 1.1±1.3 Sup-Inf. Individual EMT displacements of more than 2 and 3 mm with respect to the tumor occurred in 76% and 59% of 66 CBCT scans. The EMT centroid exhibited fewer large displacements, centroid displacements of more than 2 and 3 mm occurring in 30% and 15% of scans. Thus deformation of the EMT - tumor anatomy occurs. Examination of small lung features in the volume around the transponders showed no evidence of their migration. The variation in EMT position with respect to the tumor appears to arise from the dynamic nature of the tumor and lung tissue surrounding it. Tumor shrinkage in conventionally fractionated patients, occasional tumor associated atelectasis, and differences in the diaphragm shape during breath hold were all observed. In 3/14 patients, EMT tracking coordinates were altered immediately prior to treatment based on dual CBCT registrations. Anchored EMTs, combined with CBCT scans, can be used as part of a clinically robust procedure to accurately track a lung tumor throughout a course of DIBH RT.

Geometrical uncertainty of heart position in deep-inspiration breath-hold radiotherapy of left-sided breast cancer patients

Background: This study aimed to determine the geometrical uncertainty of the position of the heart with daily cone beam computed tomography (CBCT) during deep-inspiration breath-hold (DIBH) treatment of the left breast.Material and methods: A visually guided optical respiratory monitoring system was used in DIBH treatment of 15 breast cancer patients. Heart position was determined in relation to the planning target volume (PTV) in 225 fractions in which daily low-dose CBCT images were compared with planning CT images. In addition, the position of the left lung apex and diaphragm was measured to evaluate the success of the DIBH.Results: The median shift of the heart was 1 mm to the left, 1 mm superiorly and 0 mm in the anterior–posterior (AP) direction during the treatment course when compared to the PTV position in planning CT. Based on these movements, an AP margin of 4 mm, a lateral (LR) margin of 3 mm, and a superior–inferior (SI) margin of 5 mm should be added to the heart contour to ensure avoiding the heart when planning treatment. The distance between the left lung apex and diaphragm, applied as a surrogate for lung volume, was 2mm (median) smaller during the CBCT acquisitions than during the planning CT acquisition. The correlation coefficient between the surrogate of lung volume and the distance between the heart and PTV was r = .46 in the AP, r = .72 in the LR and r = .79 in the SI directions.Conclusion: Residual variation was observed in the position of the heart in comparison to PTV, even with a visually guided DIBH technique. These geometrical uncertainties should be taken into account when planning radiotherapy treatment. The success of DIBH may make a major contribution to the variation of the heart position during treatment.

39. Dose computation for lung stereotactic radiotherapy during deep inspiration breath-hold: A comparison between AAA and Geant4

Introduction Limits of Radiotherapy Treatment Planning System (TPS) when computing dose in moderate density media are known. Previous studies were published using Monte Carlo methods [1] . When treating lung cancer during Deep Inspiration Breath Hold (DIBH), lung density can decrease up to 0.12 g cm−3. The goal of this study is to assess performances of a TPS (Eclipse AAA) and of a MC model under these particular conditions: small fields and very low densities. Films measurements in heterogeneous phantoms are compared to both computation systems. Material and methods MC computation and model of the TrueBeam Linac head (Varian, Palo Alto, CA) are achieved using GATE/Geant4. Geometrical dimensions as well as the space phase files are furnished by Varian [2] . Jaws, mylar and baseplate are modeled and validated for the following energies: X6, X10, X6FFF and X10FFF. For this validation, MC computation are compared with Semiflex (PTW) ion chamber measurements in a water tank for a large range of field sizes (3 × 3 to 20 × 20 cm2). Percentage depth dose (PDD) and lateral dose profiles at different depths obtained by measurement and computation are compared (Gamma Index method). Two different qualities of cork (densities of 0.24 and 0.12 g cm3 are used to build two heterogeneous water/lung phantoms. These densities correspond to the lung densities during free breathing and DIBH respectively. Phantoms are composed of 20 × 20 cm2 slabs: PMMA (3 cm) + cork (7 cm) + PMMA (15 cm). See Fig. 1. Dose is measured at several depths using EBT3 gafchromic films (Ashland). Field sizes were 3 × 3 and 8 × 8 cm2 for X6FFF and X10FFF photon fields. These phantoms are implemented both in Eclipse (AAA) and MC. Download : Download high-res image (121KB) Download : Download full-size image Results TrueBeam MC model and measurements are in good agreement for all field sizes in both water and heterogeneous phantoms. More than 99% of PDD and lateral profiles passed the gamma index test (2% 2 mm). In lung heterogeneity, differences are observed between AAA and measurement results. These differences were higher for small field and very low density. As an example, for a 3 × 3 cm2 field at density 0.12 g cm−3, dose at a depth of 7 cm was 56.61%, 56.25%, and 67.54% for measure, MC and AAA respectively. Conclusion For very low densities, AAA shows its limits when MC is in good agreement with measurements. This MC model will allow us to assess our TPS results in complex cases like lung patients treated by Stereotactic Radiotherapy during DIBH.

Monte-Carlo dose computation in radiotherapy for lung at very low density

Introduction In radiotherapy, some limits of clinical algorithms have been reported in low-density media. When patients are treated during Deep Inspiration Breath-Hold (DIBH), lung density can fall to 0.12 g cm -3 . Dose calculation with this density must be validated, in particular for Stereotactic (SBRT) treatment. Purpose We propose to evaluate the performance of Eclipse AAA algorithm (Varian) for SBRT lung treatment (including DIBH) with a Monte-Carlo model based on Geant4 (GATE). GATE, AAA, and measurements are compared for several phantoms including lung heterogeneity. Materials and methods A model of the Varian TrueBeam head was modelled using GATE. Validation was achieved by comparison with measurements in a homogeneous water tank for several static fields (3 × 3 to 20 × 20 cm 2 ) and four beam modes. Subsequently, two phantoms containing layers of water-equivalent material and cork, corresponding to lung during DIBH and free-breathing (0.12 and 0.24 g cm -3 ) were implemented. Percentage depth dose (PDD) measured by Gafchromic films were compared to AAA and GATE. Results GATE model showed a good agreement with experimental results in homogeneous and heterogeneous phantoms. In lung heterogeneity, differences were observed between AAA and measurements. These differences are higher for small fields and lower densities. As an example, for 3 × 3 field size inside a 0.12 g cm -3 heterogeneity, relative dose was 56,6%, 56,2%, and 67,5% for measurement, GATE, and AAA respectively. Conclusions In very low densities, AAA quickly showed its limits while GATE was validated. This will allow us to perform calculations for non measurable cases, for example patients treated by SBRT during DIBH.

A.154 - Analysis of setup uncertainties and choice of width of gating window for left-sided breast treatment during deep inspiration breath-hold (DIBH)

A.154 - Analysis of setup uncertainties and choice of width of gating window for left-sided breast treatment during deep inspiration breath-hold (DIBH)

Deep inspiration breath hold with electromagnetic confirmation of chest wall position for adjuvant therapy of left-sided breast cancer: Technique and accuracy

PurposeWith most patients now living long after their breast cancer diagnosis, minimizing long-term side effects of breast cancer treatment, such as reducing late cardiac and pulmonary side effects of radiation therapy (RT), is particularly important. It is now possible to use an electromagnetic tracking system to allow real-time tracking of chest wall (CW) position during the delivery of RT. Here, we report our experience using electromagnetic surface transponders as an added measure of CW position during deep inspiration breath hold (DIBH). Methods and materialsWe conducted a single-institution institutional review board–approved retrospective review of 15 female left-sided breast cancer patients treated between July 2012 and June 2013 with conventional whole breast radiation. We compared daily port films with treatment planning digitally reconstructed radiographs to establish daily setup accuracy, then used Calypso tracings to compare the position of the CW during the daily port film with the position of the CW during that day’s treatment to determine the reproducibility of the breath hold position. Finally, we created competing treatment plans not using DIBH and used a paired t test to compare mean heart (MH) and left anterior descending (LAD) coronary artery dose between the 2 techniques. ResultsMean total error (inter- and intrafraction) was dominated by interfraction error and was greatest in the longitudinal direction with a mean of 2.13 mm and 2 standard deviations of 8.2 mm. DIBH significantly reduced MH and LAD dose versus free breathing plans (MH, 1.26 Gy vs 2.84 Gy, P ≤ .001; LAD, 5.49 Gy vs 18.15 Gy, P ≤ .001). ConclusionsThis study demonstrates that DIBH with electromagnetic confirmation of CW position is feasible, and allows potential improvement in the accurate delivery of adjuvant RT therapy for breast cancer.

Quantification of the Correlation Between Surface Tracking Signal and Internal Body Structure Position During Deep Inspiration Breath Hold (DIBH) Based on Single-Acquisition CBCT

Quantification of the Correlation Between Surface Tracking Signal and Internal Body Structure Position During Deep Inspiration Breath Hold (DIBH) Based on Single-Acquisition CBCT

Radiation during deep inspiration allows loco-regional treatment of left breast and axillary-, supraclavicular- and internal mammary lymph nodes without compromising target coverage or dose restrictions to organs at risk

Background and purpose. Loco-regional radiotherapy of left-sided breast cancer represents a treatment planning challenge when the internal mammary chain (IMC) lymph nodes are included in the target volume. This treatment planning study evaluates the reduction in cardiopulmonary doses when radiation is given during deep inspiration breath-hold (DIBH). This was achieved without compromising dose coverage to the planning target volume (PTV). Patients and methods. Seventeen patients with early breast cancer, referred for adjuvant radiotherapy, were included. For each patient two computed tomography (CT)-scans were acquired; the first during free breathing (FB) and the second during DIBH. The scans were monitored by the Varian RPMTM respiratory gating system. Audio-visual guidance was used. The treatment planning of the two CT studies was performed focusing on good coverage (V95% > 98%) of the PTV. Doses to the heart, left anterior descending (LAD) coronary artery, lungs and contralateral breast were assessed. Results. With equal PTV coverage, average mean heart dose was reduced from 6.2 Gy to 3.1 Gy in DIBH plans as compared to FB. Average volume receiving 25 Gy or more (V25Gy) was reduced from 6.7% to 1.2%, and the number of patients with V25Gy > 5% was reduced from 8 to 1 utilizing DIBH. The average mean dose to the LAD coronary artery was reduced from 25.0 Gy to 10.9 Gy. The average ipsilateral lung volume receiving 20 Gy or more (V20Gy) was reduced from 44.5% to 32.7% with DIBH. In 11 of the DIBH plans V20Gy was lower than 35%, in accordance with national guidelines, while none of the FB plans fulfilled this recommendation. Conclusion. Respiratory gated radiotherapy during DIBH is a suitable technique for loco-regional breast irradiation even when IMC lymph nodes are included in the PTV. Cardiopulmonary doses are considerably decreased for all dose levels without compromising the dose coverage to PTV.

Cardiac Motion During Deep-Inspiration Breath-Hold: Implications for Breast Cancer Radiotherapy

Many patients with left-sided breast cancer receive adjuvant radiotherapy during deep-inspiration breath hold (DIBH) to minimize radiation exposure to the heart. We measured the displacement of the left anterior descending artery (LAD) and heart owing to cardiac motion during DIBH, relative to the standard tangential fields for left breast cancer radiotherapy. A total of 20 patients who had undergone computed tomography-based coronary angiography with retrospective electrocardiographic gating were randomly selected for the present study. The patients underwent scanning during DIBH to control the influence of respiration on cardiac motion. Standard medial and lateral tangential fields were placed, and the LADs were contoured on the systolic- and diastolic-phase computed tomography data sets by the clinicians. Displacement of the LAD during cardiac contractions was calculated in three directions: toward the posterior edge of the treatment fields, left-right, and anteroposterior. Displacement of the entire heart was measured on the maximal and minimal intensity projection computed tomography images. The mean displacement of the LAD from cardiac contraction without the influence of respiration for 20 patients was 2.3 mm (range, 0.7-3.8) toward the posterior edge of the treatment fields, 2.6 mm (range, 1.0-6.8) in the left-right direction, and 2.3 mm (range, 0.6-6.5) in the anteroposterior direction. At least 30% of the LAD volume was displaced >5 mm in any direction in 2 patients (10%), and <10% of the LAD volume was displaced >5 mm in 10 patients (50%). The extent of displacement of the heart periphery during cardiac motion was negligible near the treatment fields. Displacement of the heart periphery near the treatment fields was negligible during DIBH; however, displacement of the LAD from cardiac contraction varied substantially between and within patients. We recommend maintaining ≥ 5 mm of distance between the LAD and the field edge for patients undergoing breast cancer radiotherapy during DIBH.

Wide Tangential Fields Including the Internal Mammary Lymph Nodes in Patients with Left-Sided Breast Cancer

To evaluate the impact of wide-tangent fields including the internal mammary chain during deep inspiration breath-hold (DIBH) radiotherapy in patients with left-sided breast cancer on cardiac exposure. Eleven patients with left-sided breast cancer were irradiated postoperatively and underwent CT scans during free breathing and DIBH. For scientific interest only, treatment plans were calculated consisting of wide tangents including the ipsilateral mammary lymph nodes using both, the free breathing and respiratory-controlled CT scan. The resulting dose-volume histograms were compared for irradiated volumes and doses to organs at risk. The mean patient age was 51 years (range: 37-65 years). Radiotherapy using wide tangents with DIBH as compared to free breathing led to a significantly lower cardiac exposure. Mean irradiated heart volumes (> or = 20 Gy) were 14 cm(3) (range: 0-51.3 cm(3)) versus 35 cm(3) (range: 2.1-78.7 cm(3); p = 0.01). For eight patients, DIBH reduced irradiated relative lung volume, while in three patients, the lung volume slightly increased. Radiation exposure of organs at risk can significantly be reduced for breast cancer patients using the DIBH technique. If radiotherapy of the internal mammary lymph nodes is considered necessary, DIBH may be the preferable technique.