Simultaneous irradiation of the breast and regional lymph nodes in prone position using helical tomotherapy

Objective We investigated dosimetric advantages of using helical tomotherapy to simultaneously irradiate the breast and regional lymph nodes for patients positioned prone, and compared tomotherapy plan qualities for the prone position with those previously published for the supine position. Methods Tomotherapy plans for 11 patients (5 left breast, 6 right) simulated with the involved breast suspended downward were generated. Each target (ipsilateral breast and supraclavicular, axillary and internal mammary chain nodes) was to receive 45 Gy. Results For targets, V(40.5)≥99.9% and V(42.8)≥99.5% for all patients, where V(40.5) and V(42.8) denote the relative target volume receiving at least 40.5 and 42.8 Gy, respectively. The targets' maximum dose was, on average, approximately 49.5 Gy. The mean doses to the contralateral lung and heart were lower for right-breast cases (2.8 Gy lung, 2.7 Gy heart) than for left-breast cases (3.8 Gy lung, 8.7 Gy heart). Mean organ doses to the ipsilateral lung (9.3 Gy) and contralateral breast (2.3 Gy) from the prone breast tomotherapy plans were similar to those reported for conventional radiotherapy techniques. For the left breast with regional nodes, tomotherapy plans for prone-positioned patients yielded lower mean doses to the contralateral breast and heart than previously reported data for tomotherapy plans for supine-positioned patients. Conclusion Helical tomotherapy with prone breast positioning can simultaneously cover the breast and regional nodes with acceptable uniformity and can provide reduced mean dose to proximal organs at risk compared with tomotherapy with supine position. The similarity of plan quality to existing data for conventional breast radiotherapy indicates that this planning approach is appropriate, and that the risk of secondary tumour formation should not be significantly greater.     

Dosimetric comparison of conventional and forward-planned intensity-modulated techniques for comprehensive locoregional irradiation of post-mastectomy left breast cancers.

Three recently published randomized trials have shown a survival benefit to postoperative radiation therapy when the internal mammary chain (IMC), supraclavicular (SCV), and axillary lymphatics are treated. When treating the IMC, techniques that minimize dose to the heart and lungs may be utilized to prevent excess morbidity and mortality and achieve the survival benefit reported. The purpose of this study was to dosimetrically compare forward-planned intensity-modulated radiation therapy (fIMRT) with conventional techniques for comprehensive irradiation of the chest wall and regional lymphatics. For irradiation of the chest wall and IMC, 3 treatment plans, (1) fIMRT, (2) partially-wide tangent (PWT) fields, and (3) a photon-electron (PE) technique, were compared for 12 patients previously treated at our institution with fIMRT to the left chest wall and regional lymphatics. Additionally, the SCV and infraclavicular lymphatics were irradiated and 4 methods were compared: 2 with anterior fields only (dose prescribed to 3 and 5 cm [SC3cm, SC5cm]) and 2 with anterior and posterior fields (fIMRT, 3DCRT). Each patient was planned to receive 50 Gy in 25 fractions. Regions of interest (ROIs) created for each patient included chest wall (CW) planning target volume (PTV), IMC PTV, and SCV PTV. Additionally, the following organs at risk (OAR) volumes were created: contralateral breast, heart, and lungs. For each plan and ROI, target volume coverage (V(95-107)) and dose homogeneity (D(95-5)) were evaluated. Additionally, the mean OAR dose and normal tissue complication probability (NTCP) were computed. For irradiation of the CW, target volume coverage and dose homogeneity were improved for the fIMRT technique as compared to PE (p < 0.001, p = 0.023, respectively). Similar improvements were seen with respect to IMC PTV (p = 0.012, p = 0.064). These dosimetric parameters were also improved as compared to PWT, but not to the same extent (p = 0.011, p = 0.095 for CW PTV, and p = 0.164, p > 0.2 for IMC PTV). The PE technique resulted in the lowest heart V30, although this difference was not significant (p > 0.2). The NTCP values for excess cardiac mortality for fIMRT and PE were equivalent (1.9%) and lower than with PWT (2.8%, p > 0.2). The fIMRT technique was able to reduce heart dose and NTCP for each patient as compared to PWT. When comparing the anterior field techniques of treating SCV PTV, prescribing dose to 5 cm resulted in a improved V50 (p = 0.089). However, when compared to fIMRT, the SC3cm and SC5cm had inferior target volume coverage (p = 0.055, p = 0.014) and significantly greater dose heterogeneity (p = 0.031, p = 0.043). The addition of a posterior field increased the volume of lung receiving 40 and 50 Gy, but not significantly (p > 0.2). For complex breast treatments that irradiate the chest wall, IMC, and SCV, fIMRT resulted in improved dose homogeneity and target volume coverage as compared to conventional techniques. Furthermore, the dosimetric gains in target volume coverage with fIMRT came at no significant increase in dose to OAR. The fIMRT technique demonstrated the ability to maintain the advantage of each of the other 2 techniques: reducing the dose to OARs, as with PE, and providing superior target volume coverage, as with PWT.     

Recent advances in breast cancer radiotherapy: Evolution or revolution,or how to decrease cardiac toxicity?

Radiation therapy has a major role in the management of breast cancers. However, there is no consensus on how to irradiate and on volume definitions, and there are strong differences in strategies according to different centers and physicians. New treatment protocols and techniques have been used with the principal purpose of decreasing lung and heart toxicity and adapting radiation treatment to patients' anatomy. There is evidence that indicates internal mammary chain radiotherapy should be used carefully and that high quality techniques should be used for decreasing the dose delivered to the heart. This review of the literature presents the state of the art on breast cancer radiotherapy, with special focus on the indications, techniques, and potential toxicity.     

Invers geplante intensitätsmodulierte Strahlenbehandlung bei einer Patientin mit rechtsseitigem Mammakarzinom und Trichterbrust

BACKGROUND: A 44-year old woman with breast cancer was transferred to our institution for irradiation. Due to a pronounced funnel chest no satisfying dose distribution was obtained by conventional techniques. Thus an intensity-modulated radiotherapy (IMRT) based on inverse optimisation was carried out. IMRT was compared to conventional techniques regarding dose distribution and feasibility. PATIENT AND METHODS: Tumor site was in the right middle lower quadrant. Target volume included the right breast and the parasternal lymph nodes. Target dose was 50.4 Gy. Based on inverse optimisation irradiation was carried out in "step-and-shoot"-technique with twelve intensity modulated beams with six intensity steps. Additionally, treatment plans were calculated using conventional techniques (technique A with two tangential wedged 6-MV photon beams, technique B with additional oblique 15-MeV electron portal). We analysed conformality and homogeneity of target volume and dose distribution within normal tissue. RESULTS: Dose conformality was substantially improved by IMRT. Dose homogeneity was slightly decreased compared to technique A. Lung volume irradiated with a dose higher than 20 Gy was reduced from 56.8% with technique A and 40.1% with technique B, respectively to 22.1% with IMRT. Treatment was tolerated well by the patient without relevant side effects. Mean treatment time was 19.5 min. CONCLUSION: The inversely planned IMRT using multiple beam directions is suitable for breast irradiation following breast conserving surgery. In the present case of a woman with funnel chest lung dose was substantially reduced without reduction of target dose. In which was the complex treatment technique leads to a clinically detectable advantage is examined at present, in the context of a study.     

Radiotherapy of Internal Mammary Lymph Nodes in Breast Cancer Principle Considerations on the Basis of Dosimetric Data

BACKGROUND: Radiotherapy of internal mammary lymph nodes (IMN) in breast cancer is discussed controversially due to its potential toxicity and debatable efficacy. Aim of the present study was to assess the cardiac and lung dose in 3-D planned radiotherapy and to discuss these results with regard to arguments pro and contra IMN irradiation. PATIENTS AND METHODS: 32 patients underwent 3-D planning (Helax TMS) for irradiation of breast and IMN in three different techniques either using separate IMN fields (A, B) or a wide tangent (C). For each technique the respective doses to the heart (including the base of the aorta and the ostium of the coronary arteries) and lung were analyzed in dose volume histograms. RESULTS: The mean dose to the heart (left side irradiation) was 6.4 Gy (A), 8.1 Gy (B) and 3.8 Gy (C). The mean dose to the lung was 11.7 Gy (A), 15.4 Gy (B) and 10.2 Gy (C). The 10-Gy isodose comprised 19.5% (A), 32.9% (B) and 5.6% (C) of the heart (left breast). The respective values for the 20-Gy isodose were 7.8, 11.5 and 4.4%. The irradiated volumes of the lung were 37.7% (A), 52.7% (B) and 20% (C) in the 10-Gy isodose. The 20-Gy isodose comprised 16.7% (A), 28.3% (B) and 17.8% (C). CONCLUSION: Whether radiotherapy of the IMN may improve treatment results in breast cancer is currently unresolved. However, the present data indicate that relevant cardiovascular side effects are unlikely to occur. Thus, the indication should be considered on the basis of individual risk factors.     

Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes

The purpose of this study was to determine the optimum beam number and orientation for inverse-planned, dynamic intensity-modulated radiation therapy (IMRT) for treatment of left-sided breast cancer and internal mammary nodes (IMNs) to improve target coverage while reducing cardiac and ipsilateral lung irradiation. Computed tomography (CT) data was used from 5 patients with left-sided breast cancer in whom the heart was close to the chest wall. The planning target volume (PTV) was the full breast plus ipsilateral IMNs. Two geometric beam arrangements were investigated, 240° and 190° sector angles, and the number of beams was increased from 7 to 9 to 11. Dose comparison metrics included: PTV homogeneity and conformity indices (HI, CI), heart V30, left lung V20, and mean doses to surrounding structures. To assess clinical application, the IMRT plans with 11 beams equally spaced in a 190° sector angle were compared to conventional plans. Treatment times were modeled. The 190° IMRT plans improved PTV HI and CI and reduced mean dose to the heart, lungs, contralateral breast, and total healthy tissue (all p < 0.05) compared to a 240° sector angle. The 11-beam plan significantly improved PTV HI and CI, heart V30, left lung V20, and healthy tissue V5 compared to a 7-beam plan (all p < 0.05). The 11-beam plan reduced heart V30 and left lung V20 (p < 0.05) without compromising PTV coverage, compared to a 9-beam plan. Compared to a conventional plan, the IMRT class solution significantly improved PTV HI and CI (both p < 0.01), heart V30 (p = 0.01), and marginally reduced left lung V20 (p = 0.07) but increased contralateral breast and lung mean dose (p < 0.001) and healthy tissue V5 (p < 0.001). An 11-beam 190° sector angle IMRT technique as a class solution is clinically feasible.     

Evaluation of irradiation techniques in breast carcinoma using dose-volume histograms. Comparison of the heart and lung exposure

For irradiation of the internal mammary lymph nodes (IMN), together with irradiation of the breast the commonly used treatment techniques are of three types: 1. two tangential opposed fields, 2. three field plans with a separate "straight on" IMN-field, or 3. with a separate "angled" IMN-field. To determine lung and heart volumes and doses for these techniques, dose-volume-histograms in 30 patients were analyzed. The optimum dose distribution was achieved with the "angled" field technique and an appropriate combination of electrons and 60Co gamma radiation for the IMN-field. (The beam mixture used was 40% 60Co beam and 60% electron beam.) The least possible dose to the lung was obtained with the "straight-on" field technique and the least possible dose to the heart with the separate "angled" IMN-field technique.     

Left-sided breast cancer irradiation using rotational and fixed-field radiotherapy

The 3-dimensional conformal radiotherapy (3DCRT) technique is the standard for breast cancer radiotherapy. During treatment planning, not only the coverage of the planning target volume (PTV) but also the minimization of the dose to critical structures, such as the lung, heart, and contralateral breast tissue, need to be considered. Because of the complexity and variations of patient anatomy, more advanced radiotherapy techniques are sometimes desired to better meet the planning goals. In this study, we evaluated external-beam radiation treatment techniques for left breast cancer using various delivery platforms: fixed-field including TomoDirect (TD), static intensity-modulated radiotherapy (sIMRT), and rotational radiotherapy including Elekta volumetric-modulated arc therapy (VMAT) and tomotherapy helical (TH). A total of 10 patients with left-sided breast cancer who did or did not have positive lymph nodes and were previously treated with 3DCRT/sIMRT to the entire breast were selected, their treatment was planned with Monaco VMAT, TD, and TH. Dosimetric parameters including PTV coverage, organ-at-risk (OAR) sparing, dose-volume histograms, and target minimum/maximum/mean doses were evaluated. It is found that for plans providing comparable PTV coverage, the Elekta VMAT plans were generally more inhomogeneous than the TH and TD plans. For the cases with regional node involvement, the average mean doses administered to the heart were 9.2 (± 5.2) and 8.8 (± 3.0) Gy in the VMAT and TH plans compared with 11.9 (± 6.4) and 11.8 (± 9.2) Gy for the 3DCRT and TD plans, respectively, with slightly higher doses given to the contralateral lung or breast or both. On average, the total monitor units for VMAT plans are 11.6% of those TH plans. Our studies have shown that VMAT and TH plans offer certain dosimetric advantages over fixed-field IMRT plans for advanced breast cancer requiring regional nodal treatment. However, for early-stage breast cancer fixed-field radiotherapy is potentially more beneficial in terms of OAR sparing.     

Comparison of Wedge versus Segmented Techniques in Whole Breast Irradiation

PURPOSE: To compare two irradiation techniques for whole breast irradiation: tangential wedged beams (WT) versus "open" fields (without wedges) with forward planned segments (ST). PATIENTS AND METHODS: For 20 patients two comparative 3-D plans were defined using Pinnacle P3D and analyzed with respect to dose, dose homogeneity in the target volume, and scattered dose to organs at risk. The plans of six patients were reproduced in an Alderson phantom. Measurements were performed in the planning target volume (PTV), contralateral breast, lungs, heart, thyroid gland and in mid-pelvis. RESULTS: Dose distribution in the PTV was nearly identical for WT and ST with the exception of D(1). Scattered doses were significantly smaller for ST. In the contralateral breast the doses per 2-Gy fraction were 7.3 cGy +/- 2.1 cGy (WT), and 4.7 cGy +/- 1.9 cGy (ST; p < 0.01). Similar doses were measured for lung and heart. In mid pelvis the largest difference was observed (WT: 1.0 cGy +/- 0.2 cGy, ST: 0.2 cGy +/- 0.1 cGy; p < 0.01). CONCLUSION: Partial volume segments can replace wedges for improved dose coverage and homogeneity in the PTV. The ST causes significantly less scattered dose to extra-target organs. This may have implications for long-term risks after exposure to low radiation doses.     

Treatment techniques for 3D conformal radiation to breast and chest wall including the internal mammary chain.

Breast, chest wall, and regional nodal irradiation have been associated with an improved outcome in high-risk breast cancer patients. Complex treatment planning is often utilized to ensure complete coverage of the target volume while minimizing the dose to surrounding normal tissues. The 2 techniques evaluated in this report are the partially wide tangent fields (PWTFs) and the 4-field photon/electron combination (the modified "Kuske Technique"). These 2 techniques were evaluated in 10 consecutive breast cancer patients. All patients had computerized tomographic (CT) scans for 3D planning supine on a breast board. The breast was defined clinically by the physician and confirmed radiographically with radiopaque bebes. The resulting dose-volume histograms (DVHs) of normal and target tissues were then compared. The deep tangent field with blocks resulted in optimal coverage of the target and the upper internal mammary chain (IMC) while sparing of critical and nontarget tissues. The wide tangent technique required less treatment planning and delivery time. We compared the 2 techniques and their resultant DVHs and feasibility in a busy clinic.     

Breast cancer and funnel chest

Background and purpose

Preserving lung, heart, and the contralateral breast from toxicity is a technical challenge in women with funnel chest, who require breast irradiation. The purpose of this study was to determine whether helical tomotherapy (HT) offers an advantage compared to three-dimensional (3D) conformal radiotherapy (CRT) for patients with pectus excavatum with regard to its shape.

Patients and methods

Ten breast cancer patients with pectus excavatum were graded into a low or high deformation group using different indices, measured and calculated by using the planning CT. A planning comparison was performed, creating plans for CRT and HT. Target uniformity, target conformity, and exposure to the organs at risk (OARs) were compared.

Results

The uniformity and conformity of the target dose distribution and the median/average dose of the planning target volume (PTV) was inferior in CRT compared to HT in both deformation groups. By using tomotherapy, the volume of the lungs, the contralateral breast, and the heart, which received high dose exposure, could be significantly reduced. Tomotherapy plans led to a significantly higher low dose exposure to the lungs and contralateral breast.

Conclusion

This is the first study which evaluates a group of 10?breast cancer patients with funnel chest. Better uniformity and conformity combined with a significant reduction of high dose exposure to the OARs can be reached using tomotherapy. However, tomotherapy plans have a significantly larger volume of low dose to the lungs and contralateral breast. Therefore, the stochastic risk should be considered after low dose exposure in women with low deformation.     

Inverse-planned, dynamic, multi-beam, intensity-modulated radiation therapy (IMRT): A promising technique when target volume is the left breast and internal mammary lymph nodes

The purpose of this study was to determine the optimum beam number and orientation for inverse-planned, dynamic intensity-modulated radiation therapy (IMRT) for treatment of left-sided breast cancer and internal mammary nodes (IMNs) to improve target coverage while reducing cardiac and ipsilateral lung irradiation. Computed tomography (CT) data was used from 5 patients with left-sided breast cancer in whom the heart was close to the chest wall. The planning target volume (PTV) was the full breast plus ipsilateral IMNs. Two geometric beam arrangements were investigated, 240° and 190° sector angles, and the number of beams was increased from 7 to 9 to 11. Dose comparison metrics included: PTV homogeneity and conformity indices (HI, CI), heart V30, left lung V20, and mean doses to surrounding structures. To assess clinical application, the IMRT plans with 11 beams equally spaced in a 190° sector angle were compared to conventional plans. Treatment times were modeled. The 190° IMRT plans improved PTV HI and CI and reduced mean dose to the heart, lungs, contralateral breast, and total healthy tissue (all p < 0.05) compared to a 240° sector angle. The 11-beam plan significantly improved PTV HI and CI, heart V30, left lung V20, and healthy tissue V5 compared to a 7-beam plan (all p < 0.05). The 11-beam plan reduced heart V30 and left lung V20 (p < 0.05) without compromising PTV coverage, compared to a 9-beam plan. Compared to a conventional plan, the IMRT class solution significantly improved PTV HI and CI (both p < 0.01), heart V30 (p = 0.01), and marginally reduced left lung V20 (p = 0.07) but increased contralateral breast and lung mean dose (p < 0.001) and healthy tissue V5 (p < 0.001). An 11-beam 190° sector angle IMRT technique as a class solution is clinically feasible.     

乳腺癌保乳术后全乳加瘤床补量照射不同治疗计划的比较

目的 探讨乳腺癌保乳术后全乳加瘤床照射不同治疗计划靶区剂量适形度、靶区剂量分布均匀性及肺脏、心脏和对侧乳腺受照剂量体积的差异。方法 选择术腔各边界放置银夹且无腋窝淋巴结转移的12 例左侧乳腺癌保乳术后患者, 每例患者分别制定常规放疗(CRT)、无挡肺子野调强放疗(IMRT-F)、挡肺子野调强(IMRT-F-L) 和瘤床同步整合补量调强放疗(SIB-IMRT) 计划。比较不同治疗计划全乳靶区和瘤床靶区的剂量适形度和剂量分布均匀性, 对比不同治疗计划肺脏、心脏和对侧乳腺受照剂量体积。结果 各计划中V_{处方剂量- PTV}1 V_PTV1、V_PTV1 处方剂量 V_PTV2、V_{处方剂量-PTV2 V- 处方剂量、VPTV2-处方剂量 VPTV2组间差异均有统计学意义;CRT 计划中患侧肺V20显著高于不同方式的IMRT 计划, 但不同方式的IMRT 计划之间V20差异无统计学意义;CRT 计划中心脏受照剂量显著高于IMRT 和SIB-I MRT 计划。CRT 计划中对侧乳腺最大照射剂量 Dmax和平均剂量Dmean明显高于不同实现方式的IMRT计划, 但不同实现方式的IMRT 计划中 Dmax和Dmean差异无统计学意义。结论 IMRT-F、IMRT-F-L、SIB-I MRT 计划均显著优于 CRT 计划, 而不同方式I MRT 计划间除个别参数外差异无统计学意义。}     

Chest wall radiotherapy with volumetric modulated arcs and the potential role of flattening filter free photon beams

Purpose

The goal of the work was to assess the role of RapidArc treatments in chest wall irradiation after mastectomy and determine the potential benefit of flattening filter free beams.

Methods and material

Planning CT scans of 10?women requiring post-mastectomy chest wall radiotherapy were included in the study. A dose of 50?Gy in 2?Gy fractions was prescribed. Organs at risk (OARs) delineated were heart, lungs, contralateral breast, and spinal cord. Dose–volume metrics were defined to quantify the quality of concurrent treatment plans assessing target coverage and sparing of OARs. Plans were designed for conformal 3D therapy (3DCRT) or for RapidArc with double partial arcs (RA). RapidArc plans were optimized for both conventional beams as well as for unflattened beams (RAF). The goal for this planning effort was to cover 100% of the planning target volume (PTV) with ≥?90% of the prescribed dose and to minimize the volume inside the PTV receiving >?105% of the dose. The mean ipsilateral lung dose was required to be lower than 15?Gy and V_20?Gy?Results All techniques met planning objectives for PTV and for lung (3DCRT marginally failed for V_20?Gy). RA plans showed superiority compared to 3DCRT in the medium to high dose region for the ipsilateral lung. Heart irradiation was minimized by RAF plans with ~4.5?Gy and ~15?Gy reduction in maximum dose compared to RA and 3DCRT, respectively. RAF resulted in superior plans compared to RA with respect to contralateral breast and lung with a reduction of ~1.7?Gy and 1.0?Gy in the respective mean doses.

Conclusion

RapidArc treatment resulted in acceptable plan quality with superior ipsilateral tissue sparing compared to traditional techniques. Flattening filter free beams, recently made available for clinical use, might provide further healthy tissue sparing, particularly in contralateral organs, suggesting their applicability for large and complex targets.     

Cardiac dose-sparing effects of deep-inspiration breath-hold in left breast irradiation

Background

Given the reduction in death from breast cancer, as well as improvements in overall survival, adjuvant radiotherapy is considered the standard treatment for breast cancer. However, left-sided breast irradiation was associated with an increased rate of fatal cardiovascular events due to incidental irradiation of the heart. Recently, considerable efforts have been made to minimize cardiac toxicity of left-sided breast irradiation by new treatment methods such as deep-inspiration breath-hold (DIBH) and new radiation techniques, particularly intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). The primary aim of this study was to evaluate the effect of DIBH irradiation on cardiac dose compared with free-breathing (FB) irradiation, while the secondary objective was to compare the advantages of IMRT versus VMAT plans in both the FB and the DIBH position for left-sided breast cancer.

Methods

In all, 25 consecutive left-sided breast cancer patients underwent CT simulation in the FB and DIBH position. Five patients were excluded with no cardiac displacement following DIBH-CT simulation. The other 20 patients were irradiated in the DIBH position using respiratory gating. Four different treatment plans were generated for each patient, an IMRT and a VMAT plan in the DIBH and in the FB position, respectively. The following parameters were used for plan comparison: dose to the heart, left anterior descending coronary artery (mean dose, maximum dose, D25% and D45%), ipsilateral, contralateral lung (mean dose, D20%, D30%) and contralateral breast (mean dose). The percentage in dose reduction for organs at risk achieved by DIBH for both IMRT and VMAT plans was calculated and compared for each patient by each treatment plan.

Results

DIBH irradiation significantly reduced mean dose to the heart and left anterior descending coronary artery (LADCA) using both IMRT (heart –20%; p = 0.0002, LADCA –9%; p = 0.001) and VMAT (heart –23%; p = 0.00003, LADCA –16%; p = 0.01) techniques as compared with FB radiation. There were no significant changes in left lung dose by IMRT; however, with VMAT planning, mean dose to the left lung was reduced by –4% (p = 0.0004). In addition, DIBH significantly increased the mean dose to the contralateral breast with IMRT (+14%, p = 0.002) and significantly reduced the dose to the contralateral breast with VMAT planning (–9%, p = 0.003) compared with the FB position. Additionally, in comparison with VMAT, the IMRT technique reduced mean heart dose both in the FB and the DIBH-position by –30% (p = 0.0004) and –26% (p = 0.002), respectively. Furthermore, IMRT increased the mean dose to the left lung in both the FB and the DIBH position (+5%, p = 0.003, p = 0.006), respectively. There were no significant changes in dose to the right lung and contralateral breast either in the FB or DIBH position between IMRT and VMAT techniques.

Conclusion

Left-sided breast irradiation is best performed in the DIBH position, since a considerable dose sparing to the heart and LADCA can be achieved by using either IMRT or VMAT techniques. A significant additional decrease in heart and LADCA dose by IMRT in both FB and DIBH irradiation was seen compared with VMAT.

     

A novel technique for post-mastectomy breast irradiation utilising non-coplanar intensity-modulated radiation therapy

The aim of this study was to investigate if non-coplanar intensity-modulated radiation therapy (IMRT) in the post-mastectomy setting can reduce the dose to normal structures and improve target coverage. We compared this IMRT technique with a standard partial wide tangential (PWT) plan and a five-field (5F) photon-electron plan. 10 patients who underwent left-sided mastectomy were planned to 50.4 Gy using either (1) PWT to cover the internal mammary (IM) nodes and supraclavicular fields, (2) 5F comprising standard tangents, supraclavicular fields and an electron field for the IM nodes or (3) IMRT. The planning target volume (PTV) included the left chest wall, supraclavicular, axillary and IM lymph nodes. No beams were directed at the right lung, right breast or heart. Mean dose–volume histograms were constructed by combining the dose–volume histogram data from all 10 patients. The mean PTV to receive 95% of the dose (V95%) was improved with the IMRT plan to 94.2% from 91.4% (p = 0.04) with the PWT plan and from 87.7% (p = 0.012) with the 5F plan. The mean V110% of the PTV was improved to 3.6% for the IMRT plan from 16.8% (p = 0.038) for the PWT plan and from 51.8% (p = 0.001) for the 5F plan. The mean fraction volume receiving 30 Gy (v30Gy) of the heart was improved with the IMRT plan to 2.3% from 7.5% (p = 0.01) for the PWT plan and 4.9% (p = 0.02) for the 5F plan. In conclusion, non-coplanar IMRT results in improved coverage of the PTV and a lower heart dose when compared with a 5F or PWT plan.Several prospective studies have shown the benefit of post-mastectomy radiation in reducing locoregional recurrences and increasing overall survival [1–3]. These trials included comprehensive radiation to the chest wall and regional nodes including the internal mammary, axillary and supraclavicular regions.Comprehensive post-mastectomy radiation is technically difficult given the complexity of the target volume and its close proximity to critical structures including the heart, lung, brachial plexus and contralateral breast [4, 5]. Several studies have examined different three-dimensional (3D) radiation techniques comparing target coverage and dose to the neighbouring critical structures [6–12]. To date, there is no gold standard for the delivery of post-mastectomy radiation that adequately covers the regional nodes while avoiding the underlying critical structures. Each technique described in the literature is optimised and chosen to account for the individual patient''s unique anatomy.Recently, intensity-modulated radiation therapy (IMRT) has been evaluated in the left-sided post-mastectomy setting in technical feasibility studies [13]. These studies show that IMRT improves dose homogeneity and significantly spares the heart and left lung [13–16]. Most published studies to date, however, have utilised coplanar IMRT beams directed from all around the patient. The primary drawback of this technique is increased dose to the contralateral normal lung and breast because beams pass through these structures [13–16].We present a novel beam arrangement for the delivery of IMRT to the regional lymphatics and chest wall in patients who have undergone a left-sided mastectomy. The beams are arranged in an ipsilateral, non-coplanar manner to effectively spare the right lung and breast from receiving any direct radiation dose. This approach is compared with a partially wide tangential (PWT) and five-field (5F) arrangement.     

Postmastectomy radiotherapy for left-sided breast cancer patients: Comparison of advanced techniques

Postmastectomy radiotherapy (PMRT) has been shown to improve the overall survival for invasive breast cancer patients, and many advanced radiotherapy technologies were adopted for PMRT. The purpose of our study is to compare various advanced PMRT techniques including fixed-beam intensity-modulated radiotherapy (IMRT), non-coplanar volumetric modulated arc therapy (NC-VMAT), multiple arc VMAT (MA-VMAT), and tomotherapy (TOMO). Results of standard VMAT and mixed beam therapy that were published by our group previously were also included in the plan comparisons. Treatment plans were produced for nine PMRT patients previously treated in our clinic. The plans were evaluated based on planning target volume (PTV) coverage, dose homogeneity index (DHI), conformity index (CI), dose to organs at risk (OARs), normal tissue complication probability (NTCP) of pneumonitis, lifetime attributable risk (LAR) of second cancers, and risk of coronary events (RCE). All techniques produced clinically acceptable PMRT plans. Overall, fixed-beam IMRT delivered the lowest mean dose to contralateral breast (1.56 ± 0.4 Gy) and exhibited lowest LAR (0.6 ± 0.2%) of secondary contralateral breast cancer; NC-VMAT delivered the lowest mean dose to lungs (7.5 ± 0.8 Gy), exhibited lowest LAR (5.4 ± 2.8%) of secondary lung cancer and lowest NTCP (2.1 ± 0.4%) of pneumonitis; mixed beam therapy delivered the lowest mean dose to heart (7.1 ± 1.3 Gy) and exhibited lowest RCE (8.6 ± 7.1%); TOMO plans provided the most optimal target coverage while delivering higher dose to OARs than other techniques. Both NC-VMAT and MA-VMAT exhibited lower values of all OARs evaluation metrics compare to standard VMAT. Fixed-beam IMRT, NC-VMAT, and mixed beam therapy could be the optimal radiation technique for certain breast cancer patients after mastectomy.