Contralateral Breast Mean Dose Research Articles

Comparison of Early Outcomes of Stereotactic Accelerated Partial Breast Irradiation vs. Volumetric Modulated Arc Therapy-Based FAST-FORWARD Whole Breast Irradiation for Breast Cancer

Despite evidence supporting APBI from 8 published prospective randomized trials enrolling over 10,000 women, the uptake of APBI in clinical practice is surprisingly low. This is being exacerbated by a new, convenient, and safe shortened WBI schedule. Here, we report the dosimetric and early outcome analyses of the first >1000 patients treated at our institution since the first adoption of stereotactic APBI and the ultra-hypofractionated WBI regimen. From 2016 to 2022, 801 women with breast cancers in the suitable or cautionary categories according to the ASTRO APBI consensus panel guidelines, received 30 Gy in 5 fractions (92%) either using a robotic stereotactic radiation system (83%) or stereotactic volumetric-based arc therapy (VMAT, 17%). Between 2020 and 2022, 468 women, who were not candidates for APBI and not undergoing any regional irradiation received 26 Gy in 5 fractions using VMAT to the whole breast with the addition of cardiac sparing technique in left-sided breast cancer patients. Tumor bed boosts were delivered in 99% of FF-WBI patients. We evaluated dose-volume histogram parameters for target volumes and organs-at-risk and radiation-related toxicities during RT or within 6 months after the end of RT. Target volume coverage was acceptable in both groups, with mean 96% of the target volumes receiving 95% of the prescribed doses and 0 cm3 within target volumes exceeding 105% of the prescribed doses. S-APBI resulted in small, but statistically significant, reductions in the radiation dose delivered to the ipsilateral breast, contralateral breast, lungs, heart, and coronary artery compared with FF-WBI. Comparing WBI to APBI, the mean contralateral breast dose, ipsilateral lung V20 Gy, mean contralateral lung dose, and mean heart dose, were reduced by 89%, 78%, 73%, and 29%, respectively. With median follow-up periods of 32 months for s-APBI and 19 months for FF-WBI, acute toxicity was assessable in all patients. The risks of any grade acute toxicity were 21% for s-APBI and 25% for FF-WBI (p = .117). Among them, grade 2 rates were 1.3% in both groups and no severe toxicity has been reported. We found s-APBI and VMAT-based FF WBI were associated with favorable dosimetric and acute toxicity profiles. However, considering significantly less irradiated volume in the breast, lungs, and heart, APBI with advanced available technique options should be considered over any WBI-based approach for patients at low risk for local recurrence.

Prone Breast and Lymph Node Irradiation in 5 or 15 Fractions: A Randomized 2 × 2 Design Comparing Dosimetry, Acute Toxicity, and Set-Up Errors

PurposeProne whole breast irradiation results in lower dose to organs at risk compared with supine position, especially lung dose. However, the adoption of prone position for whole breast irradiation + lymph node irradiation remains limited and data on lymph node irradiation in 5 fractions are lacking. Although the study was ended prematurely for the primary endpoint (breast retraction at 2 years), we decided to report acute toxicity for prone and supine positions and 5 and 15 fractions. Additionally, dosimetry and set-up accuracy between prone and supine positions were evaluated. Methods and MaterialsA randomized open-label factorial 2 × 2 design was used for an acute toxicity comparison between prone and supine positions and 5 and 15 fractions. The primary endpoint of the trial was breast retraction 2 years after treatment. In total, 57 patients were evaluated. Dosimetry and set-up errors were compared between prone and supine positions. All patients were positioned on either our in -house developed prone crawl breast couch or a Posirest-2 (Civco). ResultsNo difference in acute toxicity between prone and supine positions was found, but 5 fractions did result in a lower risk of desquamation (15% vs 41%; P = .04). Prone positioning resulted in lower mean ipsilateral lung dose (2.89 vs 4.89 Gy; P < .001), mean thyroid dose (3.42 vs 6.61 Gy; P = .004), and mean contralateral breast dose (0.41 vs 0.54 Gy; P = .007). No significant difference in mean heart dose (0.90 vs 1.07 Gy; P = .22) was found. Set-up accuracy was similar between both positions. ConclusionsUnfortunately, the primary endpoint of the trial was not met due to premature closure of the trial. Acceleration in 5 fractions resulted in a lower risk of desquamation. Prone positioning did not influence acute toxicity or set-up accuracy, but did result in lower ipsilateral mean lung dose, thyroid dose, and contralateral breast dose.

Comparison of Deep Inspiration Breath Hold Versus Free Breathing in Radiotherapy for Left Sided Breast Cancer.

ObjectivesModern breast cancer techniques, such as the deep inspiration breath-hold (DIBH) technique has been applied for left-sided breast cancer. Whether the DIBH regimen is the optimal solution for left-sided breast cancer remains unclear. This meta-analysis aims to elucidate the differences of DIBH and free-breathing (FB) for patients receiving radiotherapy for left-sided breast cancer and provide a practical reference for clinical practice.MethodsRelevant research available on PubMed, Embase, Cochrane Library, and the Web of Science published before November 30, 2021 was independently and systematically examined by two investigators. Data were extracted from eligible studies for assessing their qualities and calculating the standardized mean difference (SMD) and 95% confidence intervals (CIs) using Review Manager software 5.4 (RevMan 5.4).ResultsForty-one studies with a total of 3599 left-sided breast cancer patients were included in the meta-analysis. Compared with FB, DIBH reduced heart dose (D mean, D max, V30, V10, V5), left anterior descending branch (LAD) dose (D mean, D max), ipsilateral lung dose (D mean, V20, V10, V5), and heart volume significantly. Lung volume increased greatly, and a statistically significant difference. For contralateral breast mean dose, DIBH has no obvious advantage over FB. The funnel plot suggested this study has no significant publication bias.ConclusionsAlthough DIBH has no obvious advantage over FB in contralateral breast mean dose, it can significantly reduce heart dose, LAD dose, ipsilateral lung dose, and heart volume. Conversely, it can remarkably increase the ipsilateral lung volume. This study suggests that soon DIBH could be more widely utilized in clinical practice because of its excellent dosimetric performance.

Retrospective dosimetric comparison of VMAT versus t-IMRT for patients with carbon dioxide tissue expanders undergoing left sided PMRT using the recent ESTRO-ACROP target volume delineation

Introduction: The Aeroform tissue expander device (ATED) is a novel alternative system for patients who have had mastectomy for breast cancer (BC) and require adjuvant radiation therapy (RT), and investigations are required when used during RT. We aim to compare RT dosimetry outcomes using volumetric modulated arc therapy (VMAT) versus tangential intensity-modulated radiation therapy (t-IMRT) techniques when planning post-mastectomy RT (PMRT), using the recent European Society for Radiation Oncology – Advisory Committee on Radiation Oncology Practice (ESTRO-ACROP) target volume delineation consensus guideline.1 Methods: Five patients with left-sided BC undergoing PMRT with ATED in-situ were identified. Retrospectively, their CT-simulation scans were utilised to delineate the chest wall (CW) and nodal target volumes. A dose of 50.4Gy in 28 fractions was prescribed and four plans generated. Dosimetry for all target volumes and organs at risk were extracted, with paired means compared. Results: When comparing VMAT with t-IMRT techniques, there was no statistically significant difference in the PTV50.4 D95% or D2% coverage. Within t-IMRT plans, excluding internal mammary nodes (IMN) leads to higher D95% coverage. The heart mean dose and V25 were significantly lower with VMAT than t-IMRT. There was no significant difference to the heart dose whether IMN was included or not. The ipsilateral lung V20 was significantly lower with VMAT than t-IMRT, but not the V5. Within t-IMRT plans, excluding IMN leads to lower ipsilateral lung V20. The t-IMRT plans had lower contralateral lung V5, and even lower when IMN was not included. The contralateral breast mean dose was not significantly different between VMAT and t-IMRT. Within t-IMRT plans, the right breast mean dose was lower if IMN was excluded. Conclusion: We have not shown a clear advantage of VMAT over t-IMRT techniques when prescribing PMRT for left-sided BC patients with ATED in-situ.

Breast Stereotactic Body Radiation Therapy (SBRT) Reduces Organ at Risk Exposure, Treatment Time and Duration in Partial Breast Irradiation

<h3>Purpose/Objective(s)</h3> Interest has rapidly grown in past years in reducing the duration and volume of adjuvant radiation therapy for women with early-stage breast cancer. One such technique that accomplishes both is breast SBRT. We undertook an IRB-approved prospective clinical trial of 30 Gy/5fx SBRT to study local recurrence outcomes and skin toxicity in women who were suitable for partial breast irradiation (PBI) according to ASTRO guidelines. Here we report the plan quality, organ-at-risk dosimetry, and treatment efficiency for the treated patients. <h3>Materials/Methods</h3> We accrued 20 women to the trial, with 19 treatments available for analysis at time of submission. 16 were treated in prone, and 3 in the supine position. Women had bioabsorbable fiducial markers placed at time of surgery, which we used for cavity delineation, patient alignment, and intrafraction triggered imaging. We added a 1cm CTV and 0.3cm PTV expansion to the cavity. Plans were delivered in five consecutive days. In addition to trial outcomes, we catalogued plan quality according to conformity (RTOG), R50 (V50%/V100%), OAR exposure, as well as treatment delivery time. Plans were delivered with 7-13 co-planar IMRT fields (median MUs/fx = 2189) with 10MV FFF beams on an Edge linear accelerator. <h3>Results</h3> Median lumpectomy cavity size was 7.2 ± 3.6 cc. Median PTV size was 78.3 ± 25.7 cc. Conformity (RTOG_median = 1.04 ± 0.03) and gradient (R50_median = 3.1 ± 0.4) of all plans were excellent. Heart dose was low for left and right-sided plans (103.4 ± 52.9 & 59.14 ± 21.7) was cGY respectively. Mean ipsilateral breast dose was 750 ± 257 cGY, mean contralateral breast dose was 142 ± 74 cGY. Median beam & total treatment times 4.5 ± 2.4 and 12.7 ± 10.2 min per fraction. <h3>Conclusion</h3> Breast SBRT is an exceptional and convenient means of adjuvantly treating lumpectomy cavities with partial breast irradiation that spares OARs including non-at-risk ipsilateral breast tissue and allows patients to finish their treatment courses within one week with little to no additional time on the treatment table. Bioabsorbable fiducial markers facilitated lumpectomy cavity delineability and were also useful for patient positioning and intrafraction motion monitoring. Future work will assess the viability of condensing treatment to a single fraction to further reduce treatment burden on patients.

Modern Rotational Radiation Techniques with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Optimal Sparing of the Lung and Heart in Left-Breast Cancer Radiotherapy Plus Regional Nodal Irradiation: A Comparative Dosimetric Analysis.

Simple SummaryFor advanced left-breast cancer patients, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. Modern arc RT techniques, volumetric-modulated arc therapy (VMAT), or helical tomotherapy (HT), can minimize normal organ exposure without compromising disease control. The aim of this study is to identify which arc technique is optimal for patients receiving left-breast RT with RNI, and to explore distinct RNI volumes with or without IMN. A total of 108 eligible patients were enrolled (70 VMAT, 38 HT). VMAT reduced the mean dose and low-dose exposure to the heart, ipsilateral lung, whole lung, contralateral breast, and esophagus compared with HT. The advantage of VMAT for normal organ sparing was distinct when performing RNI with IMN irradiation. To limit normal organ exposure and reduce potential toxicities, VMAT is the optimal technique for patients with left-breast cancer who are undergoing RT with RNI.Background: For advanced breast cancer with lymph node involvement, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. However, an extensive RT volume is associated with normal organ exposure, which increases the toxicity and affects patient outcomes. Modern arc RT techniques can improve normal organ sparing compared with conventional techniques. The aim of this study was to explore the optimal technique for left-breast RT with RNI. Methods: We retrospectively reviewed patients receiving RT with RNI for left-breast cancer. We used modern arc RT techniques with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT) with a novel block technique, and compared differences in dosimetry parameters between the two groups. Subgroup analysis of RNI with or without internal mammary node (IMN) volume was also performed. Results: A total of 108 eligible patients were enrolled between 2017 and 2020, of whom 70 received VMAT and 38 received HT. The median RT dose was 55 Gy. No significant differences were found regarding the surgery, RT dose, number of fractions, target volume, and RNI volume between the VMAT and HT groups. VMAT reduced the heart mean dose more than HT (3.82 vs. 5.13 Gy, p < 0.001), as well as the cardiac parameters of V5–V20, whole-lung mean dose, lung parameters of V5–V20, and contralateral-breast and esophagus mean dose. In the subgroup analysis of RNI with IMNs, the advantage of VMAT persisted in protecting the heart, lung, contralateral breast, and esophagus. HT was beneficial for lowering the thyroid mean dose. For RNI without IMN, VMAT improved the low-dose exposure of the heart and lung, but HT was similar to VMAT in terms of heart, whole-lung, and contralateral-breast mean dose. Conclusions: For patients with left-breast cancer receiving adjuvant RT with RNI, VMAT reduced the exposure dose to the heart, lung, contralateral breast, and esophagus compared with HT. VMAT was superior to HT in terms of normal organ sparing in the patients who underwent RNI with IMN irradiation. Considering the reduction in normal organ exposure and potential toxicity, VMAT is the optimal technique for patients receiving RNI when deep inspiration breath-hold is not available.

Dosimetric Comparison of Whole Breast Radiotherapy Using Field-in-Field and Volumetric Modulated Arc Therapy Techniques in Left-Sided Breast Cancer Patients.

IntroductionThe radiotherapy of left-sided breast cancers is challenging because of neighboring critical organs, posing an increased risk of complications. Various radiation delivery techniques have been used to deliver the desired dose of radiation to the target area while keeping the doses to nearby structures within constraints.The main aim of this study is to quantify doses delivered to the organs at risk (OARs) including heart, left lung, spinal cord, and contralateral breast, and to the planning target volume (PTV) using Field-in-Field (FIF) and Volumetric Modulated Arc Therapy (VMAT).Patients and methodsA retrospective review of 15 left-sided breast cancer patients was done. All the patients underwent breast-conserving surgery and adjuvant radiation. For every patient, two different radiation treatment plans were formulated and compared for the PTV coverage and doses to OARs, including heart, ipsilateral lung, spinal cord, and contralateral breast.The radiation treatment techniques utilized for this purpose were FIF and VMAT. The homogeneity index (HI), and conformity index (CI) required for the treatment planning were also calculated. Data was analyzed using Statistical Package for the Social Sciences (IBM Corp., Armonk, USA). An Independent T-test was used for statistical analysis.ResultsThe mean age was 41 years and the majority of them were stage II. Total nine patients were given 4005centi Gray (cGy) in 15 fractions (fr) followed by 10Gy boost, hence receiving a total dose of 5005cGy in 20fr. While remaining six patients were given a total dose 4005cGy in 15fr without any boost.All patients were hypofractionated and the dose was delivered at a rate of 267cGy per fr. The FIF technique utilized in breast cancer radiation significantly reduced the mean doses to OARs: mean heart dose (3.81cGy), ipsilateral lung dose (V16- 15cGy), mean contralateral breast dose (0.03cGy), and maximum spinal cord dose (0.18cGy); as compared to VMAT technique which delivered comparatively higher doses: mean heart dose (8.85cGy), ipsilateral lung dose (V16- 19.82cGy), mean contralateral breast dose (4.59cGy), and maximum spinal cord dose (7.14cGy).There was a significant mean difference between doses of OARs and all p-values were statistically significant (p<0.005). Moreover, the FIF technique also improves the dose distribution of PTV in terms of dose homogeneity. However, the conformity index is more enhanced with VMAT as opposed to FIF.ConclusionThe FIF technique is more advantageous than the VMAT planning technique because it provides better dose distribution in terms of PTV coverage and significantly lower doses to OARs in radiotherapy to left-sided breast cancer.

Radiotherapy to the Left Breast with 3DCRT, IMRT or VMAT: International Medical Center Experience

Radiation therapy after conservative breast surgery is an integral part of the treatment of early breast cancer. The aim of radiotherapy is to achieve the best coverage of the Planning Target Volume (PTV), while reducing the dose to the Organs at Risk (OAR). Such goals are not always achievable with the conformal three dimensions plans (3DCRT). Recently, radiation oncologist uses Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) for irradiating the breast. In this study, we compared 3DCRT, IMRT and VMAT for left breast cancer patients in terms of PTV coverage, OAR. We also revised the different dose distribution in 1) different breast volume categories, 2) nodal irradiation versus breast only, and 3) boost versus no boost. Results: The routinely reported dose constrains for the ipsilateral lung and for the heart were not significantly different on comparing the three techniques. While for the contralateral lung, the difference in mean dose was in favor of 3DCRT. In large breast volume, 3DCRT provided a lower Max dose to the contralateral lung and the lowest mean dose to the contralateral breast when compared to IMRT p . In case of no nodal irradiation, the contralateral breast mean dose was lower in 3DCRT in comparison to IMRT and VMAT p : The three techniques (3DCRT, IMRT, and VMAT) can meet the clinical dosimetry demands of radiotherapy for left breast cancer after conservative surgery, as long as the routinely OARs only (heart and ipsilateral lung) are reported. Our study showed that 3CDRT can provide a lower dose to the contralateral organs (breast and lung), specially, in case of large breast volumes, no nodal irradiation and when a boost is given.

Usefulness of EZFluence software for radiotherapy planning of breast cancer treatment

This study compared the EZFluence planning technique for irradiation of the breast with commonly used Field-in-Field (FiF) technique by analyzing the dose uniformity, the dose to the lung, heart, and other organs at risk, the total Monitor Unit (MU), and the time spent for planning. Two different 3-dimensional conformal dose plans were created for 20 breast cancer patients. Six patients were treated to a dose of 5000 cGy in 25 fractions and 14 were treated to a dose of 4256 cGy in 16 fractions. Average breast volume was 800 cc (range 128 to 1892 cc). For the FiF technique, the planner manually created between 2 to 4 subfields per gantry angle and sequentially blocked the 115% and 110% isodose line until a homogenous dose distribution was achieved. For the EZFluence technique, the planner implemented the EZFluence script that created an optimal fluence pattern, which was then imported into Eclipse where dose was calculated. Both techniques were optimized to make sure 95% of the breast planning target volume (PTV) received at least 95% of the prescribed dose. Compared to FiF technique, the plans produced by using EZFluence technique, showed the MU increased by 36.9% (p = 0.0002), whereas the planning time decreased significantly by 84.6% (p = 0.00001). The mean heart dose and the relative volume of the heart receiving ≥ 30 Gy (V30) were similar for both techniques. The mean lung dose and the relative volume of lung receiving ≥ 20 Gy (V20) were also comparable between 2 techniques. The contralateral breast mean dose and its relative volume receiving ≥ 3 Gy (V3) and ≥10 Gy (V10) were equally spared and avoided. EZFluence planning technique yielded a 4.6% (p = 0.04) reduction in PTV receiving 105% of the prescribed dose (V105) for the large breast with separation > 22 cm and PTV volume > 650 cc. The EZFluence planning technique yielded the overall comparable or improved dosimetry while significantly reducing planning time.

Left Anterior Descending Coronary Artery Dose-Sparing Effects of Volumetric Modulated Arc Therapy in Patients Ineligible for Deep-Inspiration Breath-Hold in Left Breast Radiation Therapy

Deep-inspiration breath-hold (DIBH) is a widely used and highly efficient technique of adjuvant left breast radiotherapy (RT), associated with lower radiation exposure to the left anterior descending artery (LAD). This technique involves patient training and coaching and high level of compliance is required. Hence, DIBH cannot be performed in some patients with left-sided breast cancer and free-breathing (FB) tangential RT is usually used. Volumetric modulated arc therapy (VMAT) can achieve highly conformal dose distributions and reduces treatment time. The aim of our study was to evaluate whether the patients who are ineligible for DIBH will benefit from free-breathing volumetric modulated arc therapy (FB-VMAT). Twenty patients with left-sided breast cancer underwent computed tomography simulation and images were obtained in both FB and DIBH. Ten patients were ineligible for DIBH and in this group FB-VMAT plans were generated. In FB and DIBH plans 42.72 Gy in 16 fractions was prescribed to breast tissue with 10.0 Gy boost in 4 fractions to the tumor bed. In FB-VMAT group simultaneous integrated boost planning was performed and 54.0 Gy in 20 fractions was prescribed. Treatment plans (DIBH, FB and FB-VMAT) were compared using various parameters, including mean heart dose, mean and maximal LAD dose, mean ipsilateral lung dose, percentage of ipsilateral lung receiving 20 Gy (Lung V20), mean contralateral lung dose and mean contralateral breast dose. Statistical analysis was performed using one-way ANOVA and with post-hoc Tukey test. Mean heart dose was significantly lower in DIBH plans (1.96 Gy, p<0.001) compared to FB (7.05 Gy) and FB-VMAT plans (6.99 Gy). Mean LAD doses for DIBH, FB and FB-VMAT plans were 10.61 Gy, 35.71 Gy and 20.15 Gy (p < 0.001) and maximal LAD doses were 33.64 Gy, 45.59 Gy and 35.20 Gy (p<0.001), respectively. Mean ipsilateral lung dose was significantly higher in FB-VMAT plans (11.32 Gy, p=0.006) compared to FB (7.72 Gy) and DIBH (8.49 Gy) plans while no significant difference was noted for Lung V20 (15.74 Gy, 15.42 Gy and 14.91 Gy, respectively; p=0.956). Mean contralateral lung dose was significantly higher in FB-VMAT plans (3.31 Gy, p<0.001) compared to FB (0.31 Gy) and DIBH (0.28 Gy) plans. Mean contralateral breast dose was also significantly higher in FB-VMAT plans (2.65 Gy, p<0.001) compared to FB (0.47 Gy) and DIBH (0.43 Gy) plans. Compared to the FB plans, the FB-VMAT plans allowed significant dose sparing in LAD in terms of both mean and maximal dose. However, mean heart dose reduction was achieved only in DIBH plans. In addition, VMAT-FB plans resulted in significantly higher mean doses for both ipsi- and contralateral lung and contralateral breast which may be attributed to a higher whole-body exposure to leakage radiation described in this technique. This trade-off should be considered before implementation of VMAT-FB treatment planning in patients ineligible for DIBH.

Minimum breast distance largely explains individual variability in doses to contralateral breast from breast-cancer radiotherapy

PurposeTo provide personalized estimates of doses to contralateral breast (CB) from breast-cancer radiotherapy. MethodsWhole-breast irradiations using 3D conformal, intensity-modulated and hybrid techniques with 50.4 Gy prescribed dose were planned for 128 breast-cancer patients. From their CT images, 17 anatomic measures were assessed and tested by model fitting as predictors for CB dose–volume characteristics. ResultsMulti-field intensity-modulated radiotherapy (IMRT) yielded mean CB doses of 0.8–7.1 Gy, with no correlation to the studied anatomic parameters. Tangential whole-breast irradiation led to much lower mean CB doses, 0.2–1.6 Gy. About 60% of this inter-patient variability was explained by individual variations in a single anatomic measure, the minimum breast distance (MBD), defined as the CB distance from the tangent to the treated breast. Per 1 cm increase in MBD, the mean CB dose decreased by 10–15%. As an alternative to MBD, dose estimates could be based on the breast-to-breast distance, which is highly correlated with MBD. ConclusionThe results enable personalized assessment of CB doses from tangential whole-breast irradiation, based only on parameters assessable from CT data. This may help support clinical decision-making processes as well as analyse retrospective studies on CB risks.

Short tangential arcs in VMAT based breast and chest wall radiotherapy lead to conformity of the breast dose with lesser cardiac and lung doses: a prospective study of breast conservation and mastectomy patients.

Volumetric modulated arc therapy (VMAT) is modern rotational intensity modulated therapy used for treatment of several sites. The study aimed to analyze partial tangential arc VMAT treatment planning and delivery, including analyzing the cardiac and contralateral breast doses resulting from this technique. A total of 153 consecutively treated breast cancer (conservation as well as mastectomy) patients were taken for this dosimetric study. All patients were planned using partial arc VMAT in the Monaco treatment planning system using two partial arc beams. All patients were divided into seven different categories: (1) all the patients in the study, (2) left sided whole breast and chest wall patients, (3) left Chest wall patients, (4) left whole breast patients, (5) right sided whole breast and chest wall patients, (6) right chest wall patients, and (7) right whole breast patients. We evaluated each treatment plan for PTV coverage and doses to OARs. SPSS version 16.0 software was used for statistical analysis. There were 91 left sided and 62 right sided breast cancer patients in the overall analysis. The percentage of PTV volume receiving 95% of the prescription dose (PTV V95%, mean ± SD) varied in the range of 91.2 ± 5.2-94.8 ± 2.1% with mean dose of 92.4 ± 5.2% for all cases. The (mean ± SD) cardiac dose for all the patients was 289 ± 23cGy. The (mean ± SD) cardiac doses were higher for left sided patients (424 ± 33.8cGy) as compared to right sided patients (123.9 ± 80cGy) (p < 0.001). Cardiac mean doses were higher with arc angles >30° versus 30° (324.5 ± 247.1 vs. 234.4 ± 188.4cGy) (p = 0.001). Similarly contralateral breast mean dose was higher with arc angles >30° versus 30° (126 ± 115 vs. 88.6 ± 76.1cGy) (p = 0.001). However cardiac V20, V30 and V40Gy did not exhibit any statistical difference between the two groups (p = 0.26, 0.057 and 0.054 respectively). This is the first large study of its kind that assesses the dosimetric outcome of tangential partial arc VMAT treatments in a large group of mastectomy and breast conservation patients. Our study demonstrates the efficacy of this technique in dose coverage of PTV as well as in minimizing dose to OARs. Further, based on our results, we conclude that the arc length for the bi-tangential arcs should be 30° since it helps to achieve the most optimal balance between target coverage and acceptable OAR doses.

Dosimetric study of three-dimensional conformal radiotherapy, electronic compensator technique, intensity-modulated radiation therapy and volumetric-modulated arc therapy in whole breast irradiation

AbstractBackgroundWhole breast irradiation is an essential treatment after breast-conserving surgery (BCS). However, there are some adverse effects from inhomogeneity and dose to adjacent normal tissues.ObjectiveAim of this study was to compare dosimetry among standard technique, three-dimensional conformal radiotherapy (3D-CRT), and advanced techniques, electronic compensator (ECOMP), inverse intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT).MethodsWhole breast irradiation treatment plans of patients who had underwent BCS and whole breast irradiation were re-planned with all four techniques. Clinical target volume was contoured according to the Radiation Therapy Oncology Group atlas for breast only in patients who had negative node or ductal carcinoma in situ and breast with chest wall for patients with positive node. Planning target volume was non-uniformly expanded. Dose prescription was 50 Gy in 25 fractions with 6 MV photon energy.ResultsIn total, 25 patients underwent whole breast irradiation with computed tomography simulation from November 2013 to November 2014 were included. Six patients with positive nodes were re-planned for breast with chest wall irradiation and 19 patients with negative nodes were re-planned for breast only irradiation. Primary outcome, radical dose homogeneity index (HI) of 3D-CRT, ECOMP, IMRT and VMAT were 0·865, 0·889, 0·890 and 0·866, respectively. ECOMP and IMRT showed significant higher HI than 3D-CRT (p-value&lt;0·001). Secondary outcome, conformity index (CI) of advanced technique were significantly better than 3D-CRT. Lung V20, mean ipsilateral lung dose (MILD), mean heart dose (MHD), heart V25, heart V30 of advanced techniques were also lower than 3D-CRT. ECOMP had better mean lung dose (MLD), mean contralateral lung dose (MCLD) and mean contralateral breast dose (MCBD) when compared with 3D-CRT. Monitor units of advanced techniques were significantly higher than 3D-CRT.ConclusionsHI of ECOMP and IMRT were significantly higher than 3D-CRT technique. All advanced techniques showed statistically better in CI. Lung V20, MILD, heart V25 and heart V30 of advanced techniques were lower than 3D-CRT. However, only ECOMP showed decreased MLD, MHD, MCLD and MCBD when compared with 3D-CRT.

Dosimetric study of 3-dimensional conformal radiotherapy, electronic compensator technique, intensity modulated radiation therapy, and volumetric arc therapy in whole-breast irradiation.

44 Background: Whole breast irradiation is an essential treatment after breast conserving surgery (BCS). Adverse effects are from inhomogeneity of PTV and excessive dose to normal tissues. Aim of this study is to compare dosimetry among standard technique, three-dimensional Conformal Radiotherapy (3D-CRT) and advanced techniques, Electronic Compensator (ECOMP), Intensity Modulated Radiation Therapy (IMRT) and Volumetric Arc Therapy (VMAT). Methods: Images from CT simulation of patients who underwent BCS were replanned. Clinical Target Volume (CTV) was contoured followed RTOG atlas as breast only and breast with chest wall respectively. Planning Target Volume (PTV) was expanded 0.7 cm from CTV. Each patient was replanned with all four techniques. Dose prescription was 50 Gy in 25 fractions. Results: Twenty five patients underwent CT simulation from November 2013 to November 2014 were included. Six patients with node positive were planned for breast with chest wall irradiation and 19 patients with node negative were planned for breast only irradiation. Primary outcome, homogeneity index (HI) of 3D-CRT, ECOMP, IMRT and VMAT were 0.865, 0.889, 0.890 and 0.866 respectively which ECOMP and IMRT were significant higher than 3D-CRT (p values &lt; 0.001). Secondary outcome, conformity index (CI), Mean heart dose (MHD), heart V25, heart V30, mean lung dose (MLD), mean ipsilaterallung dose (MILD), mean contralateral lung dose (MCLD) and mean contralateral breast dose (MCBD) of advanced techniques were significant better than 3D-CRT technique. Conclusions: HI of ECOMP and IMRT were statistically significant higher compared with 3D-CRT technique. Advanced techniques showed statistically significant superior in CI dose to heart, lungs and contralateral breast.

Early Toxicity in Patients Treated With Postoperative Proton Therapy for Locally Advanced Breast Cancer

To report dosimetry and early toxicity data in breast cancer patients treated with postoperative proton radiation therapy. From March 2013 to April 2014, 30 patients with nonmetastatic breast cancer and no history of prior radiation were treated with proton therapy at a single proton center. Patient characteristics and dosimetry were obtained through chart review. Patients were seen weekly while on treatment, at 1 month after radiation therapy completion, and at 3- to 6-month intervals thereafter. Toxicity was scored using Common Terminology Criteria for Adverse Events version 4.0. Frequencies of toxicities were tabulated. Median dose delivered was 50.4 Gy (relative biological equivalent [RBE]) in 5 weeks. Target volumes included the breast/chest wall and regional lymph nodes including the internal mammary lymph nodes (in 93%). No patients required a treatment break. Among patients with >3 months of follow-up (n=28), grade 2 dermatitis occurred in 20 patients (71.4%), with 8 (28.6%) experiencing moist desquamation. Grade 2 esophagitis occurred in 8 patients (28.6%). Grade 3 reconstructive complications occurred in 1 patient. The median planning target volume V95 was 96.43% (range, 79.39%-99.60%). The median mean heart dose was 0.88 Gy (RBE) [range, 0.01-3.20 Gy (RBE)] for all patients, and 1.00 Gy (RBE) among patients with left-sided tumors. The median V20 of the ipsilateral lung was 16.50% (range, 6.1%-30.3%). The median contralateral lung V5 was 0.34% (range, 0%-5.30%). The median maximal point dose to the esophagus was 45.65 Gy (RBE) [range, 0-65.4 Gy (RBE)]. The median contralateral breast mean dose was 0.29 Gy (RBE) [range, 0.03-3.50 Gy (RBE)]. Postoperative proton therapy is well tolerated, with acceptable rates of skin toxicity. Proton therapy favorably spares normal tissue without compromising target coverage. Further follow-up is necessary to assess for clinical outcomes and cardiopulmonary toxicities.

Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

IntroductionCorrect target positioning is crucial for accurate dose delivery in breast radiotherapy resulting in utilisation of daily imaging. However, the radiation dose from daily imaging is associated with increased probability of secondary induced cancer. The aim of this study was to quantify doses associated with three imaging modalities and investigate the correlation of dose and varying breast size in breast radiotherapy.MethodsPlanning computed tomography (CT) data sets of 30 breast cancer patients were utilised to simulate the dose received by various organs from a megavoltage computed tomography (MV-CT), megavoltage electronic portal image (MV-EPI) and megavoltage cone-beam computed tomography (MV-CBCT). The mean dose to organs adjacent to the target volume (contralateral breast, lungs, spinal cord and heart) were analysed. Pearson correlation analysis was performed to determine the relationship between imaging dose and primary breast volume and the lifetime attributable risk (LAR) of induced secondary cancer was calculated for the contralateral breast.ResultsThe highest contralateral breast mean dose was from the MV-CBCT (1.79 Gy), followed by MV-EPI (0.22 Gy) and MV-CT (0.11 Gy). A similar trend was found for all organs at risk (OAR) analysed. The primary breast volume inversely correlated with the contralateral breast dose for all three imaging modalities. As the primary breast volume increases, the likelihood of a patient developing a radiation-induced secondary cancer to the contralateral breast decreases. MV-CBCT showed a stronger relationship between breast size and LAR of developing a radiation-induced contralateral breast cancer in comparison with the MV-CT and MV-EPI.ConclusionsFor breast patients, imaging dose to OAR depends on imaging modality and treated breast size. When considering the use of imaging during breast radiotherapy, the patient's breast size and contralateral breast dose should be taken into account.

Comparative dosimetric analysis of IMRT and VMAT (RapidArc) in brain, head and neck, breast and prostate malignancies

Purpose: Intensity modulated radiotherapy (IMRT) in the recent past has established itself as a gold standard for organs at risk (OAR) sparing, target coverage and dose conformity. With the advent of a rotational treatment technology such as volumetric modulated arc therapy (VMAT), an inter-comparison is warranted to address the advantages and disadvantages of each technique. Methods: Twenty patients were selected retrospectively from our patient database. Sites included were brain, head and neck, chest wall, and prostate, with five patients for each site. For all the selected patients, both the IMRT and VMAT treatment plans were generated. Plan comparison was done in terms of OAR dose, dose homogeneity index (HI), dose conformity index (CI), target coverage, low isodose volumes, monitor units (MUs), and treatment time. Results: The VMAT showed better sparing of “parotids minus planning target volume (PTV)”, spinal cord and head of femur as compared to the IMRT. The lung V 40 for VMAT was lower, whereas the lung V 10 , contralateral lung mean dose, contralateral breast mean dose and mean body dose were lower with IMRT for chest wall cases. Both the VMAT and IMRT achieved comparable HI except for the brain site, where IMRT scored over VMAT. The CI achieved by the IMRT and VMAT were similar except for chest wall cases, whereas the VMAT achieved better dose conformity. The target coverage was comparable with both the plans. The VMAT clearly scored over IMRT in terms of average MUs (486 versus 812 respectively) and average treatment time (2.54 minutes versus 5.54 minutes) per treatment session. Conclusion: The VMAT (RapidArc) has a potential to generate treatment plans for various anatomical sites which are comparable with the corresponding IMRT plans in terms of OAR sparing and plan quality parameters. The VMAT significantly reduces treatment time as compared to the IMRT, thus VMAT can increase the throughput of a busy radiotherapy department.

Left-Sided Breast Cancer Locoregional Radiation Therapy With Deep Inspiration Breath Hold (DIBH): Does Volumetric Modulated Arc Therapy (VMAT) Reduce the Cardiac Dose Further When Compared to Tangential Intensity Modulated Radiation Therapy (T-IMRT)?

Left-sided breast cancer radiation therapy has been associated with an increased risk of major coronary events. There is evidence demonstrating that the increase is proportional to mean heart dose. DIBH has been shown to decrease the heart dose compared with free breathing for left breast radiation therapy. T-IMRT with DIBH is routinely used in our center for adjuvant loco-regional left breast radiation therapy. This study aims to investigate the potential benefit of utilizing VMAT to reduce heart dose. We compared VMAT to T-IMRT in the treatment of left breast and regional nodes using DIBH. Radiation therapy for 10 patients previously treated with DIBH technique for left-sided breast cancer was replanned with T-IMRT and VMAT using DIBH. A dose of 50 Gy/25# was prescribed to cover the left breast and supraclavicular, axillary and internal mammary nodes. T-IMRT plans were generated using inverse-planned tangentially orientated fields to cover the breast, axillary and internal mammary nodes, and 2 to 4 photon fields to cover the supraclavicular nodes. VMAT treatment plans were generated using 2-3 partial arcs, with an average arc angle of 190 degrees. Plans were optimized to cover at least 95% of PTV by 95% of prescribed dose, while maximally sparing organs at risk (OAR). Dosimetric comparisons were made between the two techniques using the paired t-test. The mean D95 was 47.6 and 48.0 Gy, the mean maximum point dose was 55.2 and 55.8 Gy, and the mean number of monitor units was 533 and 565 for T-IMRT and VMAT respectively. Compared to T-IMRT, VMAT resulted in a significant reduction in volumes receiving moderate to high doses with heart V25 (6.7 vs 2.8 %, p = 0.004), heart V45 (1.5 vs 0.04 %, p = 0.039), lung V20 (18.1 vs 15.2 %, p = 0.003) and lung V30 (16.2 vs 8.5%, p < 0.001). VMAT led to a significant reduction in left anterior descending coronary artery maximum (46.7 vs 35.6 Gy, p = 0.001) and mean dose (27.3 vs 20.1 Gy, p = 0.007). However, VMAT resulted in a trend towards a higher heart mean dose (5.1 vs 6.9 Gy, p = 0.06) and significantly higher heart V5 (16.3 vs 44.7 %, p = 0.002), lung V5 (27.0 vs 60.5 %, p < 0.001), lung mean dose (9.2 vs 10.7 Gy, p = 0.002) and contralateral breast mean dose (1.4 vs 5.1 Gy, p < 0.001). T-IMRT-DIBH should remain one of the standard treatment techniques for loco-regional radiation therapy of left breast cancer. VMAT-DIBH should be adopted into routine practice with caution, given the significant low dose bath to the heart, lung, and contralateral breast resulting in a significantly higher mean lung and contralateral breast dose, and a trend towards higher mean heart dose.

Volumetric modulated arc therapy and breath-hold in image-guided locoregional left-sided breast irradiation

PurposeTo investigate the effects of using volumetric modulated arc therapy (VMAT) and/or voluntary moderate deep inspiration breath-hold (vmDIBH) in the radiation therapy (RT) of left-sided breast cancer including the regional lymph nodes. Materials and methodsFor 13 patients, four treatment combinations were compared; 3D-conformal RT (i.e., forward IMRT) in free-breathing 3D-CRT(FB), 3D-CRT(vmDIBH), 2 partial arcs VMAT(FB), and VMAT(vmDIBH). Prescribed dose was 42.56Gy in 16 fractions. For 10 additional patients, 3D-CRT and VMAT in vmDIBH only were also compared. ResultsDose conformity, PTV coverage, ipsilateral and total lung doses were significantly better for VMAT plans compared to 3D-CRT. Mean heart dose (Dmean,heart) reduction in 3D-CRT(vmDIBH) was between 0.9 and 8.6Gy, depending on initial Dmean,heart (in 3D-CRT(FB) plans). VMAT(vmDIBH) reduced the Dmean,heart further when Dmean,heart was still >3.2Gy in 3D-CRT(vmDIBH). Mean contralateral breast dose was higher for VMAT plans (2.7Gy) compared to 3DCRT plans (0.7Gy). ConclusionsVMAT and 3D-CRT(vmDIBH) significantly reduced heart dose for patients treated with locoregional RT of left-sided breast cancer. When Dmean,heart exceeded 3.2Gy in 3D-CRT(vmDIBH) plans, VMAT(vmDIBH) resulted in a cumulative heart dose reduction. VMAT also provided better target coverage and reduced ipsilateral lung dose, at the expense of a small increase in the dose to the contralateral breast.

Quantification of Contralateral Breast Dose and Risk Estimate of Radiation-Induced Contralateral Breast Cancer Among Young Women Using Tangential Fields and Different Modes of Breathing

Whole breast irradiation with deep-inspiration breath-hold (DIBH) technique among left-sided breast cancer patients significantly reduces cardiac irradiation; however, a potential disadvantage is increased incidental irradiation of the contralateral breast. Contralateral breast dose (CBD) was calculated by comparing 400 treatment plans of 200 left-sided breast cancer patients whose tangential fields had been planned on gated and nongated CT data sets. Various anatomic and field parameters were analyzed for their impact on CBD. For a subgroup of patients (aged ≤45 years) second cancer risk in the contralateral breast (CB) was modeled by applying the linear quadratic model, compound models, and compound models considering dose-volume information (DVH). The mean CBD was significantly higher in DIBH with 0.69 Gy compared with 0.65 Gy in normal breathing (P=.01). The greatest impact on CBD was due to a shift of the inner field margin toward the CB in DIBH (mean 0.4 cm; range, 0-2), followed by field size in magnitude. Calculation with different risk models for CBC revealed values of excess relative risk/Gy ranging from 0.48-0.65 vs 0.46-0.61 for DIBH vs normal breathing, respectively. Contralateral breast dose, although within a low dose range, was mildly but significantly increased in 200 treatment plans generated under gated conditions, predominately due to a shift in the medial field margin. Risk modeling for CBC among women aged ≤45 years also pointed to a higher risk when comparing DIBH with normal breathing. This risk, however, was substantially lower in the model considering DVH information. We think that clinical decisions should not be affected by this small increase in CBD with DIBH because DIBH is effective in reducing the dose to the heart in all patients.