Deep Inspiration Breath Hold Scans Research Articles

Minimizing normal tissue low dose bath for left breast Volumetric Modulated Arc Therapy (VMAT) using jaw offset.

With proper beam setup and optimization constraints in the treatment planning system, volumetric modulated arc therapy (VMAT) can improve target dose coverage and conformity while reducing doses to adjacent structures for whole breast radiation therapy. However, the low-dose bath effect on critical structures, especially the heart and the ipsilateral lung, remains a concern. In this study, we present a VMAT technique with the jaw offset VMAT (JO-VMAT) to reduce the leakage and scatter doses to critical structures for whole breast radiation therapy. The data of 10 left breast cancer patients were retrospectively used for this study. CT images were acquired on a CT scanner (GE, Discovery) with the deep-inspiration breath hold (DIBH) technique. The planning target volumes (PTVs) and the normal structures (the lungs, the heart, and the contralateral breast) were contoured on the DIBH scan. A 3D field-in-field plan (3D-FiF), a tangential VMAT (tVMAT) plan, and a JO-VMAT plan were created with the Eclipse treatment planning system. An arc treatment field with the x-jaw closed across the central axis creates a donut-shaped high-dose distribution and a cylinder-shaped low-dose volume along the central axis of gantry rotation. Applying this setup with proper multi-leaf collimator (MLC) modulation, the optimized plan potentially can provide sufficient target coverage and reduce unnecessary irradiation to critical structures. The JO-VMAT plans involve 5-6 tangential arcs (3 clockwise arcs and 2-3 counterclockwise arcs) with jaw offsets. The plans were optimized with objective functions specified to achieve PTV dose coverage and homogeneity; For organs at risk (OARs), objective functions were specified individually for each patient to accomplish the best achievable treatment plan. For tVMAT plans, optimization constraints were kept the same except that the jaw offset was removed from the initial beam setup. The dose volume histogram (DVH) parameters were generated for dosimetric evaluation of PTV and OARs. The D95% to the PTV was greater than the prescription dose of 42.56Gy for all the plans. With both VMAT techniques, the PTV conformity index (CI) was statistically improved from 0.62 (3D-FiF) to 0.83 for tVMAT and 0.84 for JO-VMAT plans. The difference in the homogeneity index (HI) was not significant. The Dmax to the heart was reduced from 12.15Gy for 3D-FiF to 8.26Gy for tVMAT and 7.20Gy for JO-VMAT plans. However, a low-dose bath effect was observed with tVMAT plans to all the critical structures including the lungs, the heart, and the contralateral breast. With JO-VMAT, the V5Gy and V2Gy of the heart were reduced by 32.7% and 15.4% compared to 3D-FiF plans. Significantly, the ipsilateral lung showed a reduction in mean dose (4.65-3.44Gy) and low dose parameters (23.4% reduction for V5Gy and 10.7% reduction for V2Gy) for JO-VMAT plans compared to the 3D-FiF plans. The V2Gy dose to the contralateral lung and breast was minimal with JO-VMAT techniques. A JO-VMAT technique was evaluated in this study and compared with 3D-FiF and tVMAT techniques. Our results showed that the JO-VMAT technique can achieve clinically comparable coverage and homogeneity and significantly improve dose conformity within PTV. Additionally, JO-VMAT eliminated the low-dose bath effect at all OARs evaluation metrics including the ipsilateral/contralateral lung, the heart, and the contralateral breast compared to 3D-FiF and tVMAT. This technique is feasible for the whole breast radiation therapy of left breast cancers.

A Prospective Study on the Use of Deep Inspiration Breath-Hold Technique in External Beam Radiotherapy for Breast Cancer

Background Breast cancer is the most common cancer and the leading cause of death in women. The deep inspiration breath-hold (DIBH) technique helps reduce the dose received by the heart and lungs in breast cancers during adjuvant radiotherapy (RT). We present the dosimetry of heart and lungs with DIBH technique, reproducibility, and ease of execution. Materials and Methods This is a prospective study among breast cancer patients planned for adjuvant RT following either breast conservation or mastectomy. Patients received adjuvant RT to a dose of 42.5 Gy/16 Fr to the chest wall/whole breast followed by a boost of 10 Gy/5 Fr for breast conservation surgery patients with either three-dimensional conformal RT or volumetric modulated arc therapy technique. The dosimetric parameters such as lung mean dose, heart mean dose, and V25 Gy were compared between DIBH and free-breathing (FB) scans. Data were analyzed using SPSS software, and p-value <0.05 was considered statistically significant. Results The study was conducted from September 2018 to August 2020, and 32 patients were included. The compliance to the DIBH technique was good. The dose received by ipsilateral lung V20 (17 vs. 25%) and mean dose (9 vs. 12 Gy) were significantly lower in DIBH compared with FB (p < 0.001). The V5 (31 vs. 15%), V25 (9 vs. 2%), and mean dose (7 vs. 3.3 Gy) to the heart were much higher in FB compared with DIBH (p < 0.001). Conclusion DIBH-based RT treatment delivery for breast cancer patients requiring adjuvant RT showed good compliance and offers a significant reduction in radiation dose to the heart and lung.

Inaugural Experience with Real-time Gated Liver Proton SBRT and Treatment Plan Quality Improvement

DIBH SBRT is routinely used for liver proton therapy. While intra-fraction target motion is limited with DIBH, acquisition of DIBH CT simulations in triplicate, as is done at our institution, reveals that variation does exist between each DIBH scan. The related target position can also vary correspondingly. The most common setup uncertainty for robust proton SBRT liver plan used at our institution is 5 mm sup-inf (SI) and 3 mm radially. Real-time gated proton therapy (RGPT) has the potential to provide instantaneous feedback for intra-fraction target motion to maximize patient safety and inform optimal treatment planning. Our first RGPT liver SBRT with intra-fraction motion under deep inspiration breath hold (DIBH). The potential treatment plan quality improvement brought by RGPT is investigated. The following metrics were used in establishing our RGPT proton DIBH SBRT liver program: the iso center is always set at the fiducial mark; the beam orientation is selected to achieve both good plan quality and tracking performance; daily CBCTs are acquired and verified using fiducial maker position with kV images; robust uncertainty is determined by the gating tolerance; SBRT plan has three beams with uniform dose. Target motion was monitored throughout treatment. To evaluate dose sparing for surrounding OARs, a plan with tighter gating tolerance (3 mm SI and 2 mm radially) is optimized for dosimetric comparison. Statistical analyses were conducted using a programming environment. Each of the three proton beams were delivered using DIBH over a total of 120-140 seconds. The average beam on time were 61.4, 66.9 and 62.8 seconds. The intra-fraction motion showed that targets could move up to 3 mm within the same DIBH. The motion increased with time. The table details the mean, maximum, standard deviation, and estimated upper 95% of directional shifts for three beams. Based on these results, plan delivery efficiency was maintained even with tighter gating tolerance. The comparison plan with tight gating tolerance showed significantly less dose (-25%) to the stomach in coronal view. RGPT successfully tracked fiducial marker motion for DIBH SBRT liver treatment. Despite target drift during DIBH, the uncertainty of our DIBH SBRT procedure was sufficient to cover target motion throughout treatment. Based on the target drift value, a maximum of 25 seconds for breath hold time should be employed. Utilizing a tighter gating tolerance of 3 mm SI and 2 mm radially has the potential to maintain target coverage while significantly reducing OAR dose. Aggregated RGPT-derived data may provide optimal treatment planning parameters such as variable uncertainty based on target location.

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

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. 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 1cm margin. The heart and surrounding organs at risk (OAR) were contoured. Two sets of plan comparisons were made, one with 1cm CTV to planning target volume (PTV) margin in both DIBH and FB and one set with an additional 5mm CTV to PTV margin in cranio-caudal direction with FB. Datasets were analysed with Wilcoxon signed rank test for non-parametric paired data. 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 7.1Gy (5.7-12) to a median of 3.2Gy (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. 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.

Dosimetric comparison of normal breathing and deep inspiration breath hold technique for synchronous bilateral breast cancer using 6MV flattened beam and flattening filter free beam.

BackgroundThe present study was to investigate the usefulness of deep inspiration breath hold (DIBH) in bilateral breast patients using 6MV flattened beam (FB) and flattening filter free beam (FFFB).Materials and methodsTwenty bilateral breast cancer patients were simulated, using left breast patients treated with DIBH technique. CT scans were performed in the normal breathing (NB) and DIBH method. Three-dimensional conformal radiotherapy (3DCRT) and volumetric arc therapy (VMAT) plans were generated.ResultsIn our study the best organ at risk (OAR) sparing is achieved in the 3DCRT DIBH plan with adequate PTV coverage (V95 ≥ 47.5 Gy) as compared to 6MV FB and FFFB VMAT DIBH plans. The DIBH scan plan reduces the heart mean dose significantly at the rate of 49% in 3DCRT (p = 0.00) and 22% in VMAT (p = 0.010). Similarly, the DIBH scan plan produces lesser common lung mean dose of 18% in 3DCRT (p = 0.011) and 8% in VMAT (0.007) as compared to the NB scan. The conformity index is much better in VMAT FB (1.04 ± 0.04 vs. 1.04 ± 0.05), p =1.00 and VMAT FFFB (1.04 ± 0.05 vs. 1 ± 0.24, p = 0.345) plans as compared to 3DCRT (1.63 ± 0.2 vs. 1.47 ± 0.28, p = 0.002). The homogeneity index of all the plans is less than 0.15. The global dmax is more in VMAT FFFB DIBH plan (113.7%). The maximum MU noted in the NB scan plan (478 vs. 477MU, 1366 vs. 1299 MU and 1853 vs. 1788 MU for 3DCRT, VMAT FB and VMAT FFFB technique as compared to DIBH scan.ConclusionWe recommend that the use of DIBH techniques for bilateral breast cancer patients significantly reduces the radiation doses to OARs in both 3DCRT and VMAT plans.

Abstract P3-19-02: Should deep inspiration breath hold scans be standardly acquired for right-sided breast/chestwall and regional nodal irradiation?

Abstract Background: Adjuvant regional nodal irradiation (RNI) after breast conserving surgery or mastectomy is supported by clinical trials for patients with node-positive breast cancer. RNI results in increased radiation dose to organs-at-risk (OARs) such as the heart and lungs. While regular acquisition of both free breathing (FB) and deep inspiration breath hold (DIBH) scans has been widely adopted for left-sided breast cancers (LBCs) as a cardiac-sparing technique, DIBH scans are not routinely acquired for right-sided breast cancers (RBCs). Therefore, when OAR constraints cannot be met with 3D conformal radiation therapy (3DCRT) planning on the FB scan, the only option is intensity modulated radiation therapy (IMRT), with its inherent increased cost, resource utilization, and requirement for insurance authorization. Given these challenges, we have regularly acquired FB and DIBH scans for right-sided RNI since 2018. We hypothesized that acquisition of DIBH scans would result in a reduced need for IMRT and reduced dose to OARs. Methods: We retrospectively identified patients who were treated with right-sided RNI who had both FB and DIBH scans. All patients had target volumes (breast or chest wall and regional lymph nodes [undissected axillary, supraclavicular, and internal mammary nodes]) prospectively contoured on the FBCT scan based upon the RTOG Breast Atlas. This initiated a treatment planning algorithm that began with creating a FB 3DCRT plan and changed to DIBH 3DCRT then FB IMRT when OAR constraints could not be met while maintaining acceptable planning target volume (PTV) coverage. For patients who did not have contours available on the DIBH scan, the treating physician retrospectively completed the PTV contours. For each patient, three total plans were created for comparison using our institutional target coverage and OAR metrics: FB 3DCRT, FB IMRT, and DIBH 3DCRT. We compared PTV coverage and doses to multiple OARs including the contralateral breast, esophagus, heart, lungs (left, right, total lung dose), and liver. PTV coverage and OAR doses were evaluated by a one-way ANOVA followed by Bonferroni comparison. A p < 0.05 was considered statistically significant.Results: We identified 38 patients in whom FB and DIBH scans were acquired. Only 32% (N=12) were treated with the standard FB 3DCRT. Of the remaining 26 patients 73% (N=19) were treated DIBH 3DCRT, and only 27% (N=7) were treated with FB IMRT, resulting in a FB IMRT rate of 18% overall. Without DIBH scans, 68% (N=19) would have advanced to FB IMRT. Dosimetric comparison across these 38 patients (N=114 plans) demonstrated that DIBH 3DCRT had at least equivalent OAR metrics as compared to FB 3DCRT, with significant improvement in max heart dose (9.6 Gy vs. 14.9 Gy; p = 0.034), right lung V20 (32.1% vs 37.8%; p < 0.01), mean total lung dose (8.9 Gy vs. 10.5 Gy; p < 0.01), and mean liver dose (1.8 Gy vs. 4.0 Gy; p < 0.01). FB IMRT plans resulting in significantly lower right lung V20 (26.3% FB IMRT vs. 37.8% FB 3DCRT vs. 32.1% DIBH 3DCRT), but resulted in higher dose to the heart and contralateral breast: mean heart dose (2.2 Gy FB IMRT vs. 1.0 Gy FB 3DCRT vs. 0.9 Gy DIBH 3DCRT; p < 0.01), maximum heart dose (16.4 Gy FB IMRT vs. 14.9 Gy FB 3DCRT vs. 9.6 Gy DIBH 3DCRT; p < 0.01) and contralateral breast D5% (5.0 Gy FB IMRT vs. 2.9 Gy FB 3DCRT vs. 3.0 Gy DIBH 3DCRT; p < 0.01).Conclusions: We found that acquiring DIBH scans for RBC patients receiving RNI reduced the need for FB IMRT from 68% to 18%. As compared to FB 3DCRT, DIBH 3DCRT resulted in in equivalent target coverage with significantly lower lung and liver doses. FB IMRT is useful to keep the right lung V20 within acceptable limits at the expense of higher dose to other OARs. Our data support the routine acquisition of DIBH scans in RBC patients undergoing RNI in order to decrease the proportion of patients that require FB IMRT. Citation Format: Sachin R Jhawar, Kylee Lindsey, Karla Kuhn, Kayla Tedrick, Ian Zoller, William Taylor, Eric Cochran, Erin Healy, Sasha Beyer, Julia White, Jose G Bazan. Should deep inspiration breath hold scans be standardly acquired for right-sided breast/chestwall and regional nodal irradiation? [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-19-02.

Estimating the second primary cancer risk due to proton therapy compared to hybrid IMRT for left sided breast cancer

Background and purpose Proton therapy has been proposed as a technique to improve the long-term quality of life of breast cancer patients. This is due to its ability to reduce the dose to healthy tissue compared to conventional X-ray therapy. The aim of this study was to investigate the risk of secondary carcinogenesis due to proton therapy compared to hybrid IMRT for breast treatments. Material and methods In this study, the Pinnacle treatment planning system was used to simulate treatment plans for 15 female left-sided whole breast cancer patients with deep inspiration breath hold scans. Two treatment plans were generated for each patient: hybrid intensity modulated radiotherapy (h-IMRT) and intensity modulated proton therapy (IMPT). Using the dose-volume histograms (DVHs) from these plans, the mean lifetime attributed risk (LAR) for both lungs and the contralateral breast were evaluated using the BEIR VII and Schneider full risk models. Results The results from both risk models show lower LAR estimates for the IMPT treatment plan compared to the h-IMRT treatment plan. This result was observed for all organs of interest and was consistent amongst the two separate risk models. For both treatment plans, the organs from most to least at risk were: ipsilateral lung, contralateral breast, and contralateral lung. In all cases, the risk estimated via the BEIR VII model was higher that the Schneider full risk model. Conclusion The use of proton therapy for breast treatments leads to reduced risk estimates for secondary carcinogenesis. Therefore, proton therapy shows promise in improving the long term treatment outcome of breast patients.

Early Experiences of Deep Inspiration Breath Hold Technique in Stereotactic Body Radiotherapy for Localized Lung Tumor

Organ motion management in stereotactic body radiotherapy (SBRT) for localized lung tumor is key for a successful treatment delivery. We would like to describe our limited clinical experiences of deep inspiration breath hold (DIBH) technique in stereotactic body radiotherapy for localized lung tumor and compare the dosimetric results with free breathing (FB) technique. Five patients with Tumor Staging T1 – T2 N0 M0 (Size < 5.0 cm) with peripheral lesion were treated with DIBH-SBRT were included in this study. All the five patients under went CT simulation using DIBH and 4D-CT for FB techniques. Plans were created using two to three coplanar modulated partial arcs using 10MV flattening filter free (FFF) bream with a dose rate of 2400 MU/min in both FB and DIBH CT data sets using True Beam Linear accelerator. Same dose constraints for the target and the critical structures for a particular patient were used during the plan optimization process in DIBH and FB datasets. All the patients received 50 Gy in 5 fractions (BED10 100 Gy10) for all the patients using DIBH CT dataset on the other hand FB data set plans were only used for dosimetric comparisons. Daily gated DIBH cone-beam CT were performed for all the patients during treatment delivery. For standardization, all the plans were normalized at target mean of the planning target volume (PTV). Doses to the critical structures and targets were recorded from the dose volume histogram for evaluation. The overall survival (OS) and local control (LC) and toxicity assessment were documented during the follow-up. In spite of our small sample size, there is a strong evidence that DIBH-SBRT plans were far superior to the FB-SBRT plans. The mean age of all the patients is 65.2 years (range 55 to 78 years) with a mean follow-up of 24.2 months (range 10 to 32 months). Out of five patients, four patients are still alive with complete remission of disease and one patient died after 10 months due to septicemia during blood transfusion. No grade 3 acute and late toxicity were documented during treatment and follow-up. The mean right and left lung volumes were inflated by 1.55 and 1.60 times in DIBH scans compared to the FB scans. The mean internal target volume (ITV) increased in the FB datasets by 1.45 times compared to the DIBH data sets. The mean dose followed by standard deviation (x̄ ± sx̄) of ipsilateral lung for DIBH-SBRT and FB-SBRT plans were 7.48 ± 3.57 (Gy) and 10.23 ± 4.58 (Gy) respectively, with a mean reduction of 36.84% in DIBH-SBRT plans. Ipsilateral lung was reduced to 36.84% in DIBH plans compared to FB plans. Significant dose reduction in ipsilateral lung due to the lung inflation and target volume reduction due to motion restriction in DIBH-SBRT plans were observed compare to FB-SBRT. DIBH-SBRT plans demonstrate superior dose reduction to the normal tissues and other critical structures. DIBH-SBRT provides us simpler and safer organ motion management in the treatment of localized lung tumor.

Decreased heart dose with deep inspiration breath hold for the treatment of gastric lymphoma with IMRT

We hypothesized that deep inspiration breath-hold (DIBH) and computed-tomography image-guided radiotherapy (CT-IGRT) may be beneficial to decrease dose to organs at risk (OARs), when treating the stomach with radiotherapy for lymphoma. We compared dosimetric parameters of OARs from plans generated using free-breathing (FB) versus DIBH for 10 patients with non-Hodgkin lymphoma involving the stomach treated with involved site radiotherapy. All patients had 4DCT and DIBH scans. Planning was performed with intensity modulated radiotherapy (IMRT) to 30.6 Gy in 17 fractions. Differences in target volume and dosimetric parameters were assessed using a paired two-sided t-test. All heart and left ventricle parameters including mean dose, V30, V20, V10, and V5 were statistically significantly lower with DIBH. For IMRT-FB plans the average mean heart dose was 4.9 Gy compared to 2.6 Gy for the IMRT-DIBH group (p < 0.001). There was a statistically significant decrease in right kidney dose with DIBH. For lymphoma patients treated to the stomach with IMRT, DIBH provides superior OAR sparing compared to FB-based planning, most notably reducing dose to the heart and left ventricle. This strategy could be considered when treating other gastric malignancies.

Deep Inspiration Breath Hold Technique for Right Breast Irradiation with Supraclavicular and Internal Mammary Lymph Nodes

To reduce the volume of the ipsilateral lung included in the radiation fields for right breast cancer patients receiving radiation to the breast/chest wall and to the supraclavicular and internal mammary lymph nodes (LN). Based on available literature, it is accepted practice to keep the ipsilateral mean lung dose (MLD) below 15 Gy and the V20 to 20% and when internal mammary LN are included to 30% in order to minimize the risk of radiation pneumonitis. Deep inspiration breath hold (DIBH) increases the lung volume and might help in reducing the ipsilateral lung doses when irradiating the nodes. Nine right breast cancer patients were CT simulated twice, first while free breathing (FB) and then simulated using DIBH technique. All nine patients were contoured on both CT scans for the right and left lungs, heart, breast PTV, tumor bed and tumor bed PTV (for patients suitable to receive simultaneous integrated boost), supraclavicular and internal mammary lymph nodes, according to the ESTRO contouring atlas. 3D plans were created for both FB and DIBH scans. We attempted to keep the ipsilateral lung V20 and the MLD as low as possible without compromising breast and node coverage. For all patients the coverage of the breast PTV was kept identical. The MLD was 15.4±3.2 Gy and 11.3±2.8 Gy for the FB and the DIBH plans, respectively. The V20 for the ipsilateral lung was 30%±7 for the FB plans and 20.9%±6.7 for the DIBH plans. For five patients the ipsilateral lung V20 values for the FB plans were above 30% of the ipsilateral lung volume, which is higher than we accept clinically. With DIBH technique we were able to keep the values below 30%. For those patients who had a V20 value of less than 30%, DIBH still reduced this value from an average of 23.9%±2.6 to 15.8%±3.4 of the ipsilateral lung volume. For patients receiving radiotherapy to the right breast with supraclavicular and internal mammary lymph nodes an additional simulation using the DIBH technique should be considered, so as to spare as much dose as possible to the ipsilateral lung.

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

AbstractBackground: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.

Comparison of Techniques for Involved-Site Radiation Therapy in Patients With Lower Mediastinal Lymphoma

PurposePatients with lower mediastinal lymphoma (LML) benefit dosimetrically from proton therapy (PT) compared with intensity modulated radiation therapy (IMRT). The added dosimetric benefit of deep-inspiration breath-hold (DIBH) is unknown; therefore, we evaluated IMRT versus PT and free-breathing (FB) versus DIBH among patients with LML. Methods and MaterialsTwenty-one patients with LML underwent 4-dimensional computed tomography and 3 sequential DIBH scans at simulation. Involved-site radiation therapy target volumes and organ-at-risk contours were developed for both DIBH and FB scans. FB-IMRT, DIBH-IMRT, FB-PT, and DIBH-PT plans were generated for each patient for comparison. ResultsThe median difference in lung volume between the DIBH and FB scans was 1275 mL; the average difference in clinical target volume was 5.7 mL. DIBH-IMRT produced a lower mean lung dose (10.8 vs 11.9 Gy; P < .001) than FB-IMRT, with no difference in mean heart dose (MHD; 16.1 vs 15.0 Gy; P = .992). Both PT plans produced a significantly lower mean dose to the lung, heart, left ventricle, esophagus, and nontarget body than DIBH-IMRT. DIBH-PT reduced the median MHD by 4.2 Gy (P < .0001); left ventricle dose by 5.1 Gy (P < .0001); and lung V5 by 26% (P < .0001) versus DIBH-IMRT. The 2 PT plans were comparable, with DIBH-PT reducing mean lung dose (7.0 vs 7.7 Gy; P = .063) and with no difference in MHD (10.3 vs 9.5 Gy; P = .992). ConclusionsAmong patients with LML, DIBH (IMRT or PT) improved lung dosimetry over FB but had little influence on MHD. PT (DIBH and FB) significantly reduced lung, heart, esophagus, and nontarget body dose compared with DIBH IMRT, potentially reducing the risk of late complications.

Comparison of butterfly volumetric modulated arc therapy to full arc with or without deep inspiration breath hold for the treatment of mediastinal lymphoma

PurposeRadiotherapy is an effective treatment for mediastinal lymphoma but induces late effects including cardiac toxicity and secondary breast and lung cancer. Therefore reducing the dose to these organs is vital. We compared full arc volumetric modulated arc therapy (F-VMAT) against limited angle ‘Butterfly’ VMAT (B-VMAT) on free breathing (FB) and deep inspiration breath-hold (DIBH) computed tomography scans. The aim was to assess the benefits of B-VMAT over F-VMAT and to establish if the addition of DIBH results is a cumulative benefit. Materials and methodsF-VMAT and B-VMAT plans were calculated for 20 consecutive patients (15 females) with mediastinal lymphoma on both FB and DIBH scans. The planning target volume V95% was kept comparable between all plans while reducing organ doses as much as possible. ResultsB-VMAT significantly reduced low lung doses (V5–10), while F-VMAT was better for higher lung doses (V20–30). DIBH further improved lung doses for both types of plans. DIBH B-VMAT produced the lowest mean lung dose. With FB, heart doses were slightly higher for B-VMAT but the maximum difference was small (0.8% for V20) and only statistically significant for V10-20. The mean heart dose increased by only 0.1 Gy. The addition of DIBH however significantly reduced heart doses. While DIBH F-VMAT had the lowest heart doses, the difference was small compared with DIBH B-VMAT. B-VMAT significantly reduced breast V4 while DIBH reduced the V10. ConclusionB-VMAT and DIBH are both effective in reducing organ doses and the dosimetric benefit is additive for some parameters and complementary for others.

Dosimetric comparison of deep inspiration breath hold and free breathing technique in stereotactic body radiotherapy for localized lung tumor using Flattening Filter Free beam

Abstract Aim: To compare the dosimetric advantage of stereotactic body radiotherapy (SBRT) for localized lung tumor between deep inspiration breath hold technique and free breathing technique. Materials and methods: We retrospectively included ten previously treated lung tumor patients in this dosimetric study. All the ten patients underwent CT simulation using 4D-CT free breathing (FB) and deep inspiration breath hold (DIBH) techniques. Plans were created using three coplanar full modulated arc using 6 MV flattening filter free (FFF) bream with a dose rate of 1400 MU/min. Same dose constraints for the target and the critical structures for a particular patient were used during the plan optimization process in DIBH and FB datasets. We intend to deliver 50 Gy in 5 fractions for all the patients. For standardization, all the plans were normalized at target mean of the planning target volume (PTV). Doses to the critical structures and targets were recorded from the dose volume histogram for evaluation. Results: The mean right and left lung volumes were inflated by 1.55 and 1.60 times in DIBH scans compared to the FB scans. The mean internal target volume (ITV) increased in the FB datasets by 1.45 times compared to the DIBH data sets. The mean dose followed by standard deviation (x̄ ± σx̄) of ipsilateral lung for DIBH-SBRT and FB-SBRT plans were 7.48 ± 3.57 (Gy) and 10.23 ± 4.58 (Gy) respectively, with a mean reduction of 36.84% in DIBH-SBRT plans. Ipsilateral lung were reduced to 36.84% in DIBH plans compared to FB plans. Conclusion: Significant dose reduction in ipsilateral lung due to the lung inflation and target motion restriction in DIBH-SBRT plans were observed compare to FB-SBRT. DIBH-SBRT plans demonstrate superior dose reduction to the normal tissues and other critical structures.

Comparison of cardiac and lung doses for breast cancer patients with free breathing and deep inspiration breath hold technique in 3 dimensional conformal radiotherapy - a dosimetric study

Abstract Purpose: To investigate the cardio-pulmonary doses between Deep Inspiration Breath Hold (DIBH) and Free Breathing (FB) technique in left sided breast irradiation. Materials &amp; Methods: DIBH CT and FB CT were acquired for 10 left sided breast patients who underwent whole breast irradiation with or without nodal irradiation. Three fields single isocenter technique were used for patients with node positive patients along with two tangential conformal fields whereas only two tangential fields were used in node negative patients. All the critical structures like lungs, heart, esophagus, thyroid, etc., were delineated in both DIBH and FB scan. Both DIBH and FB scans were fused with the Dicom origin as they were acquired with the same Dicom coordinates. Plans were created in the DIBH scan for a dose range between 50 Gy in 25 fractions. Critical structures doses were recorded from the Dose Volume Histogram for both the DIBH and FB data set for evaluation. Results: The average mean heart dose in DIBH vs FB was 13.18 Gy vs 6.97 Gy, (p = 0.0063) significantly with DIBH as compared to FB technique. The relative reduction in average mean heart dose was 47.12%. The relative V5 reduced by 14.70% (i.e. 34.42% vs 19.72%, p = 0.0080), V10 reduced by 13.83% (i.e. 27.79 % vs 13.96%, p = 0.0073). V20 reduced by 13.19% (i.e. 24.54 % vs 11.35%, p = 0.0069), V30 reduced by 12.38% (i.e. 22.27 % vs 9.89 %, p = 0.0073) significantly with DIBH as compared to FB. The average mean left lung dose reduced marginally by 1.43 Gy (13.73 Gy vs 12.30 Gy, p = 0.4599) but insignificantly with DIBH as compared to FB. Other left lung parameters (V5, V10, V20 and V30) shows marginal decreases in DIBH plans compare to FB plans. Conclusion: DIBH shows a substantial reduction of cardiac doses but slight and insignificant reduction of pulmonary doses as compared with FB technique. Using the simple DIBH technique, we can effectively reduce the cardiac morbidity and at the same time radiation induced lung pneumonitis is unlikely to increase.

Deep inspiration breath hold level variability and deformation in locoregional breast irradiation

PurposeThe purpose of this study was to evaluate the dosimetric effect of breath hold level variability and deformation on breast, chest wall, internal mammary chain (IMC) nodes, and heart. Methods and materialsLeft-sided post-lumpectomy (n = 12) and postmastectomy (n = 3) patients underwent deep inspiration breath hold (DIBH) and exhale breath hold (EBH) computed tomography (CT) scans. Forward-planned locoregional breast plans were created on the DIBH scan. Two effects were modeled assuming no setup uncertainties: residual motion within the gating window and systematically shallow breath hold levels (BHLs). Real-time position management (RPM) was used to monitor BHL at simulation and during treatment. The RPM data were scaled to simulate BHL variation within symmetric gating window widths of ±1, 3, 5, and 7 mm; the dosimetric impact of this motion was simulated in the treatment planning system. Systematically “shallow” BHL errors were modeled using deformable image registration to map the patient trajectory from DIBH to EBH (n = 12). The deformable vector fields were scaled to produce synthetic CT scans modeling patient position during breath holds 1, 3, 5, and 7 mm shallower than simulator BHL. The original treatment plans were applied to the synthetic CTs and dose was recalculated. ResultsAcceptable plan quality was maintained for most patients with motion within gating windows up to ±7 mm. Patients with shallow median BHLs experienced loss of coverage at simulated gating windows ±5 mm or larger. At systematic 3 mm shallow BHL error, 4/12 patients had clinical target volume IMC V80% < 99%; this increased to 11/12 patients at 5 mm. Change in heart dose from systematic BHL errors was negligible. ConclusionsMotion within gating windows has minimal dosimetric impact for most BHL variability; however, loss of IMC coverage can occur even for small gating windows when BHLs are systematically shallow. This can be mitigated by restricting lower BHL tolerances or accounting for known uncertainties in planning.

MA 09.09 Isotoxic Dose-Escalated Radiotherapy (RT) in Non-Small Cell Lung Cancer (NSCLC) with Deep Inspiration Breath Hold (DIBH)

With interest in the use of isotoxic dose-escalated RT in treatment of inoperable NSCLC, this study investigated the impact of DIBH using the Active Breathing Coordinator™ (ABC- Elekta, Stockholm, Sweden) device on isotoxic dose escalation potential. Following informed consent, a four-dimensional (4D) planning CT scan and a DIBH scan using the ABC device were acquired in patients sequentially in the same session. A motion-encompassing target volume on the 4D scan and a motion-managed target volume on the DIBH scan were created. The RayStation radiotherapy treatment planning system (research version 5.99.0.16) was used to generate two corresponding volumetric modulated arc therapy (VMAT) plans for each patient, following the guidelines of the isotoxic IMRT trial (NCT01836692). The target dose was escalated up to a maximum of 79.2 Gy in 44 twice daily fractions and plans optimized to minimize dose to normal tissues. Potential to escalate target dose and differences in dose-volume metrics between the plans were compared using the Wilcoxon signed-rank test. 21 patients were included. The mean total lung volume was significantly higher with DIBH compared to 4D scans with an increase of 44.7 % ± 17.4 % (mean ± standard deviation), p <0.001). In 20/21 patients, the maximum target dose of 79.2 Gy was achievable in both plans, however in one patient 61.2 Gy was achieved with 4D compared to 75.6 Gy with DIBH planning. In the 20 patients achieving equivalent target dose-escalation, the mean lung dose was 17.0 Gy (± 0.3Gy ) with 4D versus 14.6 Gy (± 0.3 Gy) with DIBH (p <0.001). There was a significant mean reduction in heart dose between the DIBH compared to 4D plans of 0.3 Gy (± 0.2 Gy, p<0.001) and significant reductions in heart D100 %, D66 % and D33 %(p <0.01). Mediastinal envelope and oesophageal doses were similar using both techniques. The use of DIBH compared to 4D planning aids lung and cardiac sparing in isotoxic dose escalated RT and for a small number of patients may allow an increase in target dose. Particularly given the interaction between lung and cardiac toxicity in locally advanced NSCLC treated with radical RT, use of DIBH for treatment may lead to a reduction in toxicity compared to a 4D approach. In acknowledgement of the use of a mid-ventilation technique in some institutions, comparison with this method is planned.

Non-coplanar Butterfly VMAT and Deep Inspiration Breath Hold for Mediastinal Lymphoma: Do We Need Both?

Reducing doses to organs at risk (OAR) is an important goal when treating mediastinal lymphoma in young individuals. Volumetric modulated arc therapy (VMAT) improves target coverage & heart sparing but at the expense of low-dose bath to lungs and breasts. Butterfly VMAT (B-VMAT) uses non-co-planar partial arc VMAT, limiting doses to lungs and breasts, but heart sparing may be reduced. In addition, deep inspiration breath hold (DIBH) has been shown to reduce lung and heart doses. The aim of this planning study was to assess the dosimetric benefit of B-VMAT compared to full arc VMAT and also to investigate any added benefit of adding DIBH to either technique. Forty plans for 13 consecutive patients (age: 22-59, 6 females) with mediastinal lymphoma were compared. A free-breathing (FB) scan was acquired for all patients. Two VMAT plans were produced: two full arcs and B-VMAT. The B-VMAT used double 600 partial anterior & posterior arcs and 2 craniocaudal 60° anterior arcs. Seven of these patients also had a DIBH scan and additional VMAT and B-VMAT plans were produced. Plans were optimized to achieve comparable planning target volume (PTV) coverage. Dose to lungs, heart, spinal cord, esophagus, and female breasts were reduced as much as possible. Mean PTV coverage and doses to OARs were compared and differences were tested for statistical significance with Wilcoxon signed-rank test. Results are shown in Table 1. For the FB plans, the Mean Lung Dose (MLD) decreased by 11% and lung V5 reduced by 26% when using B-VMAT. V20 did however increase by 13%. No significant difference was seen in the heart dose between the two techniques. Breast V4 was significantly reduced by 62%. DIBH had more effect on reducing MLD than B-VMAT and the combination of the two techniques was additive. The DIBH B-VMAT plans showed significant reduction in both high and low dose to the lung when compared with FB plans, as well as a significant reduction in mean and high dose to the heart and breast V4. B-VMAT reduces low-dose bath to lungs and female breast with minimal effect on heart sparing and a small increase in lung V20. The benefits of DIBH and B-VMAT are additive and result in maximum sparing of lungs, heart and breasts.Tabled 1Abstract 132; Table 1 *Superscript indicates techniques with which a comparison provides a statistically significant differenceAll patients (13)FB + DIBH cohort (7)*VMATB-VMATP value1:VMAT & FB2:BVMAT & FB3:VMAT & DIBH4:BVMAT & DIBHPTV V95% (%)97.897.90.38298.298.098.198.1MLD (Gy)7.66.80.0056.92,3,46.21,3,44.91,2,44.41,2,3Lung V20 (%)12.714.40.04612.22,3,413.41,3,46.11,2,47.71,2,3Lung V5 (%)43.331.90.00138.42,428.51,431.8421.31,2,3Heart mean dose (Gy)5.65.90.0554.03,44.23,42.81,23.01,2Heart V30 (%)5.65.20.2353.53,43.33,41.61,21.91,2Heart V15 (%)15.115.70.1249.8310.536.51,2,47.13Breast V10 (%)3.33.54.34.43.32.7Breast V4 (%)20.07.718.68.419.26.9 Open table in a new tab

Postmastectomy Radiation Therapy Technique and Cardiopulmonary Sparing: A Dosimetric Comparative Analysis Between Photons and Protons With and Without Deep Inspiration Breath Hold

Post-mastectomy radiation therapy (PMRT) can be challenging in patients with left-sided disease due to significant risk of cardiopulmonary toxicity. Prior dosimetric studies have suggested greater cardiopulmonary sparing with protons over tangential photons for left-sided PMRT. However, modern techniques, such as deep inspiration breath hold (DIBH), can help spare the heart. This analysis compares photon and proton delivery with and without DIBH. Ten women with left breast cancer referred for PMRT on a prospective clinical trial underwent free breathing (FB) and DIBH CT simulation. Target volumes and cardiopulmonary organs-at-risk were delineated with assistance of the RTOG atlas by a single physician. Structures were contoured on the FB scan and transferred to the DIBH scan using MimVista deformable registration and modified. A partially wide tangent (PWTF) during DIBH (photon-BH), passively scattered proton during FB (scatter-FB), pencil-beam scanning (PBS) proton during FB (PBS-FB), and PBS proton during DIBH (PBS-BH) plan was completed for each patient. Each plan was designed to achieve 95% prescription dose coverage of 95% of all target volumes while maximally sparing the heart and lung. ANOVA or Kruskal-Wallis test was used to measure a difference in target volume coverage, chest wall homogeneity index (HI), and cardiopulmonary avoidance among the four plans. For each metric with a significant interaction (P < 0.05), pairwise t-test and Wilcoxon test with Bonferroni correction was used to compare individual plans. All techniques resulted in similar target coverage, though protons improved chest wall HI and cardiopulmonary sparing (omnibus P < 0.0001 for each metric). Heart/lung metrics for photon-BH, scatter-FB, PBS-FB, and PBS-BH, respectively, were as follows: mean heart dose (2.09, 0.39, 0.98, 0.71 Gy(RBE)), mean left ventricle dose (3.72, 0.08, 0.19, 0.21 Gy(RBE)), V20 left ventricle (2.73, 0.03, 0, 0%), maximum LAD artery dose (46.14, 8.28, 4.58, 4.63 Gy(RBE)), mean lung dose (13.30, 5.74, 7.63, 7.49 Gy(RBE)), V20 lung (26.04, 12.04, 15.18, 14.43 %). Pairwise testing confirmed an improvement in each metric with all proton plans compared to photon-BH; however, there were no differences in HI or cardiopulmonary sparing between passively scattered and PBS protons, regardless of addition of DIBH. For left-sided PMRT, passively scattered or PBS protons with or without DIBH improves homogeneity and cardiopulmonary sparing without compromise in target coverage compared to PWTF photons with DIBH. Furthermore, the addition of DIBH to proton therapy did not provide a significant dosimetric benefit.

SU‐F‐J‐123: CT‐Based Determination of DIBH Variability and Its Dosimetric Impact On Post‐Mastectomy Plus Regional Nodal Radiation Therapy

Purpose:Breast cancer radiotherapy delivered using voluntary deep inspiration breath‐hold (DIBH) requires reproducible breath holds, particularly when matching supraclavicular fields to tangential fields. We studied the impact of variation in DIBHs on CTV and OAR dose metrics by comparing the dose distribution computed on two DIBH CT scans taken at the time of simulation.Methods:Ten patients receiving 50Gy in 25 fractions to the left chestwall and regional lymph nodes were studied. Two simulation CT scans were taken during separate DIBHs along with a free‐breathing (FB) scan. The treatment was planned using one DIBH CT. The dose was recomputed on the other two scans using adaptive planning (Pinnacle 9.10) in which the scans are registered using a cross‐correlation algorithm. The chestwall, lymph nodes and OARs were contoured on the scans following the RTOG consensus guidelines. The overall translational and rotational variation between the DIBH scans was used to estimate positional variation between breath‐holds. Dose metrics between plans were compared using paired t‐tests (p &lt; 0.05) and means and standard deviations were reported.Results:The registration parameters were sub‐millimeter and sub‐degree. Although DIBH significantly reduced mean heart dose by 2.4Gy compared to FB (p &lt; 0.01), no significant changes in dose were observed for targets or OARs between the two DIBH scans. Nodal coverage as assessed by V90% was 90%±8% and 89%±8% for supraclavicular and 99%±2% and 97%±22% for IM nodes. Though a significant decrease (10.5%±12.4%) in lung volume in the second DIBH CT was observed, the lung V20Gy was unchanged (14±2% and 14±3%) between the two DIBH scans.Conclusion:While the lung volume often varied between DIBHs, the CTV and OAR dose metrics were largely unchanged. This indicates that manual DIBH has the potential to provide consistent dose delivery to the chestwall and regional nodes targets when using matched fields.