A Dosimetric Analysis of IMRT and Multistatic Fields Techniques for Left Breast Radiotherapy

The purpose of this study was to analyze the dosimetric difference between intensity-modulated radiation therapy (IMRT) using 3 or 5 beams and multistatic field technique (MSF) in radiotherapy of the left breast. We made comparative analysis of two kinds of radiotherapy that can achieve improved dose homogeneity. First is a MSF that uses both major and small irradiation fields at the same time. The other is IMRT using 3 or 5 beams with an inverse planning system using multiple static multileaf collimators. We made treatment plans for 16 early left breast cancer patients who were randomly selected and had undergone breast conserving surgery and radiotherapy, and analyzed them in the dosimetric aspect. For the mean values of V₉₅ and dose homogeneity index, no statistically significant difference was observed among the three therapies. Extreme hot spots receiving >110% of prescribed dose were not found in any of the three methods. Using Tukey's test, IMRT showed a significantly larger increase in exposure dose to the ipsilateral lung and the heart than MSF in the low-dose area, but in the high-dose area, MSF showed a slight increase. To improve dose homogeneity, the application of MSF, which can be easily planned and applied more widely, is considered optimal as an alternative to IMRT for radiotherapy of early left breast cancer.     

Dosimetric Impact of Surgical Clips in Electron Beam Treatment of Breast Cancer

Titanium clips are commonly used to delineate the location of the tumor bed during breast cancer surgery. Electron beams are frequently used to boost radiation dose to the breast cavity. This research investigated the effect on such boost treatments as a result of metallic clip perturbation potentially exhibited through attenuation and scatter processes using measurements with Gafchromic film and treatment planning simulation with both generalized Gaussian pencil beam and electron Monte Carlo algorithms. Results showed that the potential effect of clip interference is unidentifiable from both algorithms. Dosimetry with Gafchromic external beam therapy film did detect dose perturbations caused by the titanium clips in proximal plane, 0.23 mm away, resulting in 3.0% backscatter and 2.4% attenuation at 6 MeV and 2.0% backscatter and 6.7% attenuation at 9 MeV. The noise contribution of the film scanner is estimated to be about 0.4% and nearly 2% uncertainty in film calibration. As a result, we conclude that the magnitude of dose perturbations from clip is negligible for clinical findings.     

影像检查对乳腺癌诊断价值的探讨

目的探讨多种影像检查手段在乳腺癌诊断中的价值。材料与方法回顾性研究１３４例手术治疗乳腺癌病人,比较超声影像、钼靶摄片及物理查体同病理检查结果的符合率。结果超声影像和钼靶摄片对乳腺癌诊断的敏感性分别为７０％（９８／１３４）和７３．１（３２／４６）,超声影像对腋窝淋巴结转移评价的符合率为５６％（４７／８４）,物理查体的符合率为３３．３％（２／８４）。结论超声影像和钼靶摄片对乳腺癌诊断的敏感性高于物理查体。超声影像和钼靶摄片均可用于乳腺癌普查和术前评价,超声影像对乳腺癌术前腋窝淋巴结检查具有较高价值。     

Postoperative Intensity Modulated Radiation Therapy in High Risk Prostate Cancer: A Dosimetric Comparison

The aim of this study was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal technique (3D-CRT), with respect to target coverage and irradiation of organs at risk for high dose postoperative radiotherapy (PORT) of the prostate fossa. 3D-CRT and IMRT treatment plans were compared with respect to dose to the rectum and bladder. The dosimetric comparison was carried out in 15 patients considering 2 different scenarios: (1) exclusive prostate fossa irradiation, and (2) pelvic node irradiation followed by a boost on the prostate fossa. In scenario (1), a 3D-CRT plan (box technique) and an IMRT plan were calculated and compared for each patient. In scenario (2), 3 treatment plans were calculated and compared for each patient: (a) 3D-CRT box technique for both pelvic (prophylactic nodal irradiation) and prostate fossa irradiation (3D-CRT only); (b) 3D-CRT box technique for pelvic irradiation followed by an IMRT boost to the prostatic fossa (hybrid 3D-CRT and IMRT); and (c) IMRT for both pelvic and prostate fossa irradiation (IMRT only). For exclusive prostate fossa irradiation, IMRT significantly reduced the dose to the rectum (lower Dmean, V50%, V75%, V90%, V100%, EUD, and NTCP) and the bladder (lower Dmean, V50%, V90%, EUD and NTCP). When prophylactic irradiation of the pelvis was also considered, plan C (IMRT only) performed better than plan B (hybrid 3D-CRT and IMRT) as respect to both rectum and bladder irradiation (reduction of Dmean, V50%, V75%, V90%, equivalent uniform dose [EUD], and normal tissue complication probability [NTCP]). Plan (b) (hybrid 3D-CRT and IMRT) performed better than plan (a) (3D-CRT only) with respect to dose to the rectum (lower Dmean, V75%, V90%, V100%, EUD, and NTCP) and the bladder (Dmean, EUD, and NTCP). Postoperative IMRT in prostate cancer significantly reduces rectum and bladder irradiation compared with 3D-CRT.     

Comparison of Various Radiation Therapy Techniques in Breast Cancer Where Target Volume Includes Mammaria Interna Region

In breast cancer radiotherapy, the internal mammary lymphatic chain is treated in the target volume in a group of patients with high-risk criteria. Because of the variability of the anatomic region and structures in the irradiation field, there are a number of different techniques in breast radiotherapy. While irradiating the target volume, we also consider minimizing the dose to critical structures such as heart, lung, and contralateral breast tissue. In this study, we evaluated the dose distribution of different radiotherapy techniques in patients with left-sided breast cancer who had breast-conserving surgery. A three-dimensional computerized planning system (3DCPS) was used for each patient to compare wide-field, oblique photon-electron, and perpendicular photon-electron techniques in terms of dose homogeneities in the target volume; the doses received by the contralateral breast, heart, and lung; and the coverage of the internal mammary chain. Data from 3DCPS were controlled by the Rando-phantom and thermoluminescence dosimetry. Critical structures were irradiated with acceptable dose percentages in addition to the internal mammary chain with both wide-field and photon-electron techniques. We detected more frequent hot spots in the oblique photon-electron technique than in the other techniques, and this situation necessitated changing the junctions. The wide-field technique was easy to perform and exposed less radiation dose to the heart than photon-electron techniques. In conclusion, we suggest the use of the wide-field technique in breast irradiation when the internal mammary area is in the target volume.     

IORT with Electrons as Boost Strategy during Breast Conserving Therapy in Limited Stage Breast Cancer: Results of an ISIORT Pooled Analysis

Strahlentherapie und Onkologie -     

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.     

乳腺癌的MRI成像技术及其诊断价值

目的:探讨乳腺癌的MRI特征表现,分析各种MR成像技术的临床应用价值和存在的不足.方法:38例乳腺癌患者术前均经MRI平扫、DWI、动态增强及1H-MRS检查,回顾性分析乳腺癌的MRI表现,并分析各种乳腺MR成像技术的应用价值及存在的不足.结果:在平扫T1WI、压脂T2WI乳腺癌多表现为等或低信号;DWI中b=0时病灶呈明显高信号,随b值增加病灶信号强度依次降低;以形状不规则、毛刺征、环形强化、早期增强率≥70%和Ⅱ型或Ⅲ型曲线作为诊断乳腺癌标准,其敏感度分别为65%、67.5%、80%、95%和95%;1H-MRS显示乳腺癌出现明显升高的Cho峰,Cho/Cr升高,基于Cho峰的出现诊断乳腺癌的敏感度为77.5%.结论:乳腺癌MRI病灶形态学、动态增强特点具有特征性,DW和1H-MRS检查具有重要的辅助诊断价值,但是部分良、恶性病灶的表现存在部分重叠,对乳腺导管原位癌的诊断MRI无明显优势.     

三阴性乳腺癌与非三阴性乳腺癌的钼靶与超声比较

目的：比较三阴性乳腺癌（TNBC）与非三阴性乳腺癌（NTNBC）的钼靶X线及超声特征,提高TNBC的影像诊断水平。资料与方法根据免疫组化检测结果,将387例乳腺癌患者分成TNBC组54例和NTNBC组333例,回顾性分析两组患者的钼靶X线图像、超声声像图及临床病理资料。结果 TNBC组肿瘤组织学分级高,浸润性导管癌Ⅲ级明显多于NTNBC组（χ2=47.009, P<0.001）;腋窝淋巴结转移率高于NTNBC组（χ2=4.658, P<0.05）。乳腺钼靶X线显示,TNBC组主要表现为肿块（37例,69.8%）,钙化少见（10例,18.9%）,肿块多呈圆形或椭圆形（28例,62.2%）,边缘清晰（16例,35.6%）,毛刺征少见（5例,11.1%）;NTNBC组多表现为肿块伴钙化（138例,42.1%）,形态多不规则（119例,46.5%）,毛刺征多见（77例,30.1%）,两组在肿块、钙化、形态及边缘方面差异有统计学意义（χ2=24.618、19.889、32.605、21.102, P<0.001）。超声显示,TNBC组主要表现为肿块（52例,96.3%）,钙化少见（5例,9.3%）,肿块多呈圆形或椭圆形（27例,51.9%）,边缘清晰（25例,48.1%）,毛刺征少见（3例,5.8%）,肿块后方回声衰减少见（5例,9.6%）;NTNBC组多表现为肿块（318例,96.1%）,钙化多见（135例,40.8%）,形态多不规则（243例,76.4%）,毛刺征多见（76例,23.9%）,肿块后方回声衰减者多见（78例,24.5%）,两组在肿块钙化、形态、边缘、肿块后方回声方面差异有统计学意义（χ2=19.006、18.339, P<0.001;χ2=16.170、8.429, P<0.05）。结论在钼靶X线和超声中,TNBC主要表现为边缘清晰的圆形或椭圆形肿块,肿块后方回声衰减少见,更倾向于良性肿瘤的影像学特点;NTNBC主要表现为形态不规则的毛刺边缘肿块,钙化多见,上述影像学特征有助于TNBC的早期诊断。     

Dosimetric Parameters in Partial Breast Irradiation Through Brachytherapy

The objective of this work is to evaluate biological models and dose homogeneity in a new partial breast irradiation method, the MammoSite RTS. The study is based on 11 patients who received the therapy. For each patient, we determined the dose volume distribution delivered to the breast. Based on these data, we estimate some important biological parameters. Eleven patients with early-stage, invasive, ductal breast cancer were treated using MammoSite RTS brachytherapy, which delivers radiation through a balloon placed in the lumpectomy bed. The radiation was provided by an Iridium-192 source, and 340 cGy were delivered per fraction twice daily. We calculated some commonly used dosimetric parameters, and evaluated the biological parameters tumor control probability (TCP) and normal tissue complication probability (NTCP). We also looked for correlations among these parameters. The average equivalent uniform dose (EUD), NTCP, and TCP were 43.66 Gy, 47.95%, and 91.78%, respectively. The coefficient of variation (CV) among the patients was very low for all 3 parameters. Two dose homogeneity indices (DHI and the S-index) are strongly correlated (r = −0.815). The area under the dose-volume histogram (DVH) and the treatment volume (TXV) also showed a strong correlation (r = 0.995, p < 0.0001). A simplified logit Poisson–EUD model is suitable for determining NTCP and TCP. Other factors such as the area under the DVH and dose homogeneity indices are also useful in planning radiotherapy treatments for early breast cancer.     

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.     

Dosimetric effects of saline- versus water-filled balloon applicators for IORT using the model S700 electronic brachytherapy source

PurposeThe Xoft Axxent Electronic Brachytherapy System (Xoft, Inc., San Jose, CA) is a viable option for intraoperative radiation therapy (IORT) treatment of early-stage breast cancer. The low-energy (50-kVp) X-ray source simplifies shielding and increases relative biological effectiveness but increases dose distribution sensitivity to medium composition. Treatment planning systems typically assume homogenous water for brachytherapy dose calculations, including precalculated atlas plans for Xoft IORT. However, Xoft recommends saline for balloon applicator filling. This study investigates dosimetric differences due to increased effective atomic number (Z_eff) for saline (Z_eff = 7.56) versus water (Z_eff = 7.42).MethodsBalloon applicator diameters range from 3 to 6 cm. Monte Carlo N-Particle software is used to calculate dose at the surface (D_s) of and 1 cm away (D_1cm) from the water-/saline-filled balloon applicator using a single dwell at the applicator center as a simple estimation of the dosimetry and multiple dwells simulating the clinical dose distributions for the atlas plans.ResultsSingle-dwell plans show a 4.4–6.1% decrease in D_s for the 3- to 6-cm diameter applicators due to the saline. Multidwell plans show similar results: 4.9% and 6.4% D_s decrease, for 4-cm and 6-cm diameter applicators, respectively. For the single-dwell plans, D_1cm decreases 3.6–5.2% for the 3- to 6-cm diameter applicators. For the multidwell plans, D_1cm decreases 3.3% and 5.3% for the 4-cm and 6-cm applicators, respectively.ConclusionsThe dosimetric effect introduced by saline versus water filling for Xoft balloon applicator–based IORT treatments is ∼5%. Users should be aware of this in the context of both treatment planning and patient outcome studies.     

乳腺癌动态增强MRI与X线摄影的对比分析

目的:通过对乳腺癌动态增强MRI表现与X线摄影的对比分析,评价两者对乳腺癌的诊断价值。材料和方法:回顾性分析了50例乳腺癌的动态增强MRI与X线摄影,MRI分别采用自旋回波(FSE)序列加预饱和脂肪抑制技术(SPIR)、减影技术及快速三维动态增强扫描。X线摄影采用常规方法摄片。结果:乳腺MRI在显示肿块形态、边缘、内部结构、与周围组织关系、乳内淋巴结方面优于X线摄影;X线摄影在显示钙化方面占绝对优势,检出乳腺癌的敏感性分别为:MRI93%(47/50),X线摄影82%(41/50),两者比较差异有显著性(P<0.01);两种方法结合检查的敏感性为98%(49/50)。结论:NRI、X线摄影各有优势和限度,检查乳腺癌敏感性MRI较X线摄影高,而当两种方法联合应用时,可减少乳腺癌的漏诊率,从而提高病变诊断的准确性。     

Dosimetric Effects of Setup Uncertainties on Breast Treatment Delivery

This study aimed to assess the dosimetric impact of setup errors during the delivery of radiotherapy to the breast, and use this information to make recommendations on intervention tolerances for portal imaging of breast treatments. Translational and rotational setup errors were simulated for 10 recent breast patients using an Oncentra MasterPlan treatment planning system. The effect of these errors on the breast and tumor bed target volumes receiving 95% and 107% of the prescribed dose were assessed. For the majority of patients, shifts of up to 10 mm or a 4° patient rotation about the cranio-caudal axis had no significant effect on the dose distribution. Changes in dosimetry were more likely if the reference plan contained large hot or cold spots. For a typical patient, it is estimated that a shift of 5 mm in any one direction, or a 2° patient rotation would not cause more than a 5% change in the target volume receiving between 95% and 107% of the prescribed dose. If combinations of errors occur, greater dosimetric changes would be expected. It is concluded that individual patient shifts of up to 5 mm or rotations about the cranio-caudal axis of 2° or less are unlikely to affect dose-volume histogram parameters by an amount judged as clinically significant. Setup errors exceeding these values may cause large dosimetric changes for some patients, particularly those with larger hot or cold regions in the dose distribution, and intervention is therefore recommended.     

Comparison of Contrast-Enhanced Mammography With Conventional Digital Mammography in Breast Cancer Screening: A Pilot Study

PurposeTo perform a pilot evaluation of contrast-enhanced mammography (CEM) for screening to determine whether it can improve accuracy and reader confidence in diagnosis.Methods and MaterialsThis institutional review board–approved reader study was comprised of 64 de-identified CEM cases acquired from December 1, 2014, to June 7, 2016, including 48 negative, 5 biopsy-proven benign, and 11 biopsy-proven malignancies. Negative cases were followed for at least 2 years without evidence of cancer. Ten breast imagers of varying experience first rated the low-energy (LE) mammogram and then the CEM examination using BI-RADS categories and a 5-point Likert scale for confidence in diagnosis.ResultsThere were 635 out a total possible 640 complete reader interpretations included in this analysis. The remaining five incomplete interpretations were excluded. Median sensitivity and specificity improved with the addition of CEM (sensitivity: 0.86 [95% confidence interval {CI}: 0.74-0.95] versus 1 [95% CI: 0.83-1.00], specificity: 0.85 [95% CI: 0.64-0.94] versus 0.88 [95% CI: 0.80-0.92]). Individual receiver operating characteristic curves showed significant improvement with CEM (mean area under the curve increase = 0.056 [95% CI: 0.015-0.097], P = .002). The addition of CEM significantly improved average confidence in 5 of 10 readers when compared with LE (P < .0001) and improved pooled confidence across all tissue density categories, except the almost entirely fatty category. There was a trend toward improved confidence with increasing tissue density with CEM. Degree of background parenchymal enhancement did not affect readers’ level of improvement in confidence when interpreting CEM.SummaryCEM improved reader performance and confidence compared with viewing only LE, suggesting a role for CEM in breast cancer screening for which larger trials are warranted.