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Background & purpose: With the introduction of more conformal techniques for breast cancer radiation therapy (RT), motion management is becoming increasingly important. We studied the breast-shape variability during RT after breast-conserving surgery (BCS). Materials & Methods: Planning computed tomography (CT) and follow-up cone-beam CT (CBCT) scans were available for 71 fractions of 17 patients undergoing RT after BCS. First, the CT and the CBCT scans were registered on bones. Subsequently, breast-contour data were generated. The CBCT contours were analyzed in 3D in terms of deviations (mean and standard deviation) relative to the contour of the CT scan for the upper medial, lower medial, upper lateral, and lower lateral breast quadrants, and the axilla. Results: Regional systematic and random standard deviations of the breast quadrants varied between 1.5 and 2.1 mm and 1.0–1.6 mm, respectively, and were larger for the axilla (3.0 mm). An absolute average shape change of ≥4.0 mm in at least one region was present in 21/71 fractions (30%), predominantly in breast volumes > 800 cc (p =

Background and purpose The aim of this study is to assess the toxicity and cosmetic outcome of preoperative accelerated partial breast irradiation (PAPBI) for breast cancer patients with low risk on local recurrence. Material and methods Women aged ⩾60years with an invasive, unifocal ⩽3cm on MRI, (non-lobular) adenocarcinoma of the breast and a negative sentinel node received PAPBI (40Gray in 10 fractions over 2weeks). Six weeks after radiotherapy a wide local excision was performed. Results 70 patients with a median follow-up of 23months (3–44months) were evaluated. The overall postoperative infection rate was 11%. At 1, 2 and 3years of follow-up respectively 89%, 98% and 100% of patients had no or mild induration-fibrosis. Fibrosis was only found in a small volume of the breast. The global cosmetic outcome was good to excellent in 77% at 6months to 100% at 3years. Two patients developed a local recurrence. Conclusion Our first results show limited fibrosis in a small volume and good to excellent cosmetic outcome. In selected patients, preoperative radiotherapy appears to be a good option for breast conserving therapy.

Background The delivery of radiotherapy (RT) involves the use of rather expensive resources and multi-disciplinary staff. As the number of cancer patients receiving RT increases, timely delivery becomes increasingly difficult due to the complexities related to, among others, variable patient inflow, complex patient routing, and the joint planning of multiple resources. Operations research (OR) methods have been successfully applied to solve many logistics problems through the development of advanced analytical models for improved decision making. This paper presents the state of the art in the application of OR methods for logistics optimization in RT, at various managerial levels. Methods A literature search was performed in six databases covering several disciplines, from the medical to the technical field. Papers included in the review were published in peer-reviewed journals from 2000 to 2015. Data extraction includes the subject of research, the OR methods used in the study, the extent of implementation according to a six-stage model and the (potential) impact of the results in practice. Results From the 33 papers included in the review, 18 addressed problems related to patient scheduling (of which 12 focus on scheduling patients on linear accelerators), 8 focus on strategic decision making, 5 on resource capacity planning, and 2 on patient prioritization. Although calculating promising results, none of the papers reported a full implementation of the model with at least a thorough pre-post performance evaluation, indicating that, apart from possible reporting bias, implementation rates of OR models in RT are probably low. Conclusions The literature on OR applications in RT covers a wide range of approaches from strategic capacity management to operational scheduling levels, and shows that considerable benefits in terms of both waiting times and resource utilization are likely to be achieved. Various fields can be further developed, for instance optimizing the coordination between the available capacity of different imaging devices or developing scheduling models that consider the RT chain of operations as a whole rather than the treatment machines alone. Electronic supplementary material The online version of this article (doi:10.1186/s12911-016-0390-4) contains supplementary material, which is available to authorized users.

Purpose To investigate the heart position variability in deep-inspiration breath-hold (DIBH) radiation therapy (RT) for breast cancer when 3D surface imaging would be used for monitoring the BH depth during treatment delivery. For this purpose, surface setup data were compared with heart setup data. Materials and methods Twenty patients treated with DIBH-RT after breast-conserving surgery were included. Retrospectively, heart registrations were performed for cone-beam computed tomography (CBCT) to planning CT. Further, breast-surface registrations were performed for a surface, captured concurrently with CBCT, to planning CT. The resulting setup errors were compared with linear regression analysis. Furthermore, geometric uncertainties of the heart (systematic [Σ] and random [σ]) were estimated relative to the surface registration. Based on these uncertainties planning organ at risk volume (PRV) margins for the heart were calculated: 1.3Σ − 0.5σ. Results Moderate correlation between surface and heart setup errors was found: R2 = 0.64, 0.37, 0.53 in left–right (LR), cranio-caudal (CC), and in anterior–posterior (AP) direction, respectively. When surface imaging would be used for monitoring, the geometric uncertainties of the heart (cm) are [Σ = 0.14, σ = 0.14]; [Σ = 0.66, σ = 0.38]; [Σ = 0.27, σ = 0.19] in LR; CC; AP. This results in PRV margins of 0.11; 0.67; 0.25 cm in LR; CC; AP. Conclusion When DIBH-RT after breast-conserving surgery is guided by the breast-surface position then PRV margins should be used to take into account the heart-position variability relative to the breast-surface.

In recent years, accelerated partial breast irradiation (APBI) has been considered an alternative to whole breast irradiation for patients undergoing breast-conserving therapy. APBI delivers higher doses of radiation in fewer fractions to the post-lumpectomy tumor bed with a 1–2cm margin, targeting the area at the highest risk of local recurrence while sparing normal breast tissue. However, there are inherent challenges in defining accurate target volumes for APBI. Studies have shown that significant interobserver variation exists among radiation oncologists defining the lumpectomy cavity, which raises the question of how to improve the accuracy and consistency in the delineation of tumor bed volumes. The combination of standardized guidelines and surgical clips significantly improves an observer’s ability in delineation, and it is the standard in multiple ongoing external-beam APBI trials. However, questions about the accuracy of the clips to mark the lumpectomy cavity remain, as clips only define a few points at the margin of the cavity. This paper reviews the techniques that have been developed so far to improve target delineation in APBI delivered by conformal external beam radiation therapy, including the use of standardized guidelines, surgical clips or fiducial markers, pre-operative computed tomography imaging, and additional imaging modalities, including magnetic resonance imaging, ultrasound imaging, and positron emission tomography/computed tomography. Alternatives to post-operative APBI, future directions, and clinical recommendations were also discussed.

Purpose The purpose of this study was to investigate if FDG-PET and DWI identify the same or different targets for dose escalation in the GTV of HN cancer patients. Additionally, the dose coverage of DWI-targets in an FDG-PET-based dose painting plan was analyzed. Materials and methods Eighteen HN cancer patients underwent FDG-PET and DWI exams, which were converted to standardized uptake value (SUV)- and apparent diffusion coefficient (ADC)-maps. The correspondence between the two imaging modalities was determined on a voxel-level using Spearman's correlation coefficient ( ρ ). Dose painting plans were optimized based on the 50% isocontour of the maximum SUV ( SUV 50%max ). Dose coverage was analyzed in three different SUV- and three different ADC-targets using the mean dose and the near-minimum and near-maximum doses. Results The average maximum SUV was 13.9 and the mean ADC was 1.17·10 −3 mm 2 /s. The average ρ between SUV and ADC was −0.2 (range: −0.6 to 0.4). The ADC-targets were only partly overlapping the SUV 50%max -target and the dose parameters were significantly smaller in the ADC-targets compared to the SUV 50%max -target. Conclusions FDG-PET and DWI contain different information, resulting in different targets. Further information about failure patterns and dose relations can be obtained by adding DWI to currently ongoing dose painting trials.

Purpose To investigate the applicability of 3-dimensional (3D) surface imaging for image guidance in deep-inspiration breath-hold radiation therapy (DIBH-RT) for patients with left-sided breast cancer. For this purpose, setup data based on captured 3D surfaces was compared with setup data based on cone beam computed tomography (CBCT). Methods and Materials Twenty patients treated with DIBH-RT after breast-conserving surgery (BCS) were included. Before the start of treatment, each patient underwent a breath-hold CT scan for planning purposes. During treatment, dose delivery was preceded by setup verification using CBCT of the left breast. 3D surfaces were captured by a surface imaging system concurrently with the CBCT scan. Retrospectively, surface registrations were performed for CBCT to CT and for a captured 3D surface to CT. The resulting setup errors were compared with linear regression analysis. For the differences between setup errors, group mean, systematic error, random error, and 95% limits of agreement were calculated. Furthermore, receiver operating characteristic (ROC) analysis was performed. Results Good correlation between setup errors was found: R 2 =0.70, 0.90, 0.82 in left-right, craniocaudal, and anterior-posterior directions, respectively. Systematic errors were ≤0.17 cm in all directions. Random errors were ≤0.15 cm. The limits of agreement were −0.34-0.48, −0.42-0.39, and −0.52-0.23 cm in left-right, craniocaudal, and anterior-posterior directions, respectively. ROC analysis showed that a threshold between 0.4 and 0.8 cm corresponds to promising true positive rates (0.78-0.95) and false positive rates (0.12-0.28). Conclusions The results support the application of 3D surface imaging for image guidance in DIBH-RT after BCS.

Purpose To investigate the accuracy of surface imaging for monitoring intrafraction motion purposes in frameless stereotactic body radiotherapy (SBRT) of lung cancer by comparison with cone-beam computed tomography (CBCT). Materials and methods Thirty-six patients (18 males, 18 females) were included. During each fraction, three CBCT scans were acquired; CBCT1: before treatment, CBCT2: after correction for tumor misalignment, and CBCT3: after treatment. Intrafraction motion was derived by registering CBCT2 and CBCT3 to the mid-ventilation planning CT scan. Surfaces were captured concurrently with CBCT acquisitions. Retrospectively, for each set of surfaces, an average surface was created: Surface1, Surface2, and Surface3. Subsequently, Surface3 was registered to Surface2 to assess intrafraction motion. For the differences between CBCT- and surface-imaging-derived 3D intrafraction motions, group mean, systematic error, random error and limits of agreement (LOA) were calculated. Results Group mean, systematic and random errors were smaller for females than for males: 0.4 vs. 1.3, 1.3 vs. 3.1, and 1.7 vs. 3.3mm respectively. For female patients deviations between CBCT-tumor- and 3D-surface-imaging-derived intrafraction motions were between −3.3 and 4.3mm (95% LOA). For male patients these were substantially larger: −5.9–9.5mm. Conclusion Surface imaging is a promising technology for monitoring intrafraction motion purposes in SBRT for female patients.

It has been shown that seroma volumes decrease during breast conserving radiotherapy in a significant percentage of patients. We report on our experience with an adaptive radiation therapy (ART) strategy involving rescanning and replanning patients to take this reduction into account during a course of intensity-modulated radiation therapy with simultaneously integrated boost (IMRT-SIB).From April 2007 till December 2009, 1274 patients eligible for SIB treatment were enrolled into this protocol. Patients for which the time between the initial planning CT (CT(1)) and lumpectomy was less than 30 days and who had an initial seroma volume30 cm(3) were rescanned at day 10 of treatment (CT(2)) and replanned when significant changes were observed by the radiation oncologist. Patients received 28 fractions of 1.81 Gy to the breast and 2.30 Gy to the boost volume.Nine percent (n=113) of the 1274 patients enrolled met the criteria and were rescanned. Of this group, 77% (n=87) of treatment plans were adapted. Time between surgery and CT(1) (20 days versus 20 days for adapted and non-adapted plans, p=0.89) and time between CT(1) and CT(2) (21 days versus 22 days for adapted and non-adapted plans, p=0.43) revealed no procedural differences which might have biased our results. In the adapted plans, seroma decreased significantly from 60 to 27 cm(3) (p0.001), TBV from 70 to 45 cm(3) (p0.001) and PTV(boost) from 277 to 220 cm(3) (p0.001). The volume receiving more than 95% of the boost dose (V(95%(total-dose))) could be reduced by 19% (linear fit, R(2)=0.73) from on average 360 to 292 cm(3) (p0.001). Delay in treatment and the use of a prolonged treatment schedule with different fractionation for patients with seroma could thus be prevented.The adaptive radiation therapy IMRT-SIB procedure has proven to be efficient and effective, leading to a clinically significant reduction of the high dose volume. Seroma present in a subgroup of patients referred for breast radiation therapy does not hamper the introduction of highly conformal IMRT-SIB techniques.

This study aims to determine magnitude, causes and consequences of post-operative breast tumour target volume delineation variation among radiation oncologists in the presence of guidelines.Excision cavities, CTVs and PTVs of eight breast cancer patients were delineated on CT scans by 13 Dutch radiation oncologists (observers) from 12 Dutch institutes participating in the international Young Boost Trial. Delineated volumes and conformity indices were determined. CTV delineation variation (SD) was determined for anatomically relevant regions. Non-parametric statistics were performed to establish effects of observers, patient characteristics and regions on delineation variation.Even in the presence of delineation guidelines considerable delineation variation is present (0.24SD1.22 cm). Presence of clips or seroma reduced interobserver variation (0.24SD0.62 cm). Region-specific analysis showed distinct regions of higher variability per patient. This could not always be ascribed to anatomical features, suggesting interobserver variation is not solely due to lack of image quality.In this study, interobserver delineation variation in breast tumour target volume delineation is larger than, e.g. setup inaccuracies and results from limited reliable visual guidance as well as interpretation differences between observers, despite guidelines. Reduction of delineation variation is essential in view of current developments in planning techniques, particularly for External Partial Breast Irradiation.

The aim of this study was to develop a technique for axillary radiotherapy that minimizes the risk of radiation-induced damage to the surrounding normal tissue (i.e., arm, shoulder, lung, esophagus, and spinal cord) while keeping the risk of a nodal recurrence to a minimum. A planning study was performed in 20 breast cancer patients. The target volume of the axillary treatment encompassed the periclavicular and axillary lymph node areas. The 3-dimensional (3D) computed tomography (CT) information in this study was used to outline the lymph node areas and the organs at risk (i.e., the esophagus, spinal cord, brachial plexus, and lung). A conventional AP-PA technique (with a transmission plate placed in the AP beam) was evaluated. In addition, a new single-isocenter technique consisting of AP/PA fields using a gantry rotation of +/-20 degrees and a medial AP segment was developed. Both techniques were compared by evaluation of the calculated dose distributions and the dose-volume histograms of the target volume and surrounding organs at risk. The field borders and humeral shielding were redefined based on the 3D anatomical references. Adapting the humeral shielding reduced the irradiated volume by 19% and might contribute to a reduction of the incidence of arm edema and impairment of shoulder function. The maximum radiation dose in the esophagus and spinal cord was reduced by more than 50% using the single-isocenter technique. The difference between both techniques with respect to the mean doses in the target volume and lung, and the maximum dose in brachial plexus, was not statistically significant. Moreover, the single-isocenter technique allowed a fast and easy treatment preparation and reduced the execution time considerably (with approximately 10 minutes per fraction).

To quantify the interfraction position variability of the excision cavity (EC) and to compare the rib and breast surface as surrogates for the cavity. Additionally, we sought to determine the required margin for on-line, off-line and no correction protocols in external beam radiotherapy. A total of 20 patients were studied who had been treated in the supine position for 28 daily fractions. Cone-beam computed tomography scans were regularly acquired according to a shrinking action level setup correction protocol based on bony anatomy registration of the ribs and sternum. The position of the excision area was retrospectively analyzed by gray value cone-beam computed tomography-to-computed tomography registration. Subsequently, three setup correction strategies (on-line, off-line, and no corrections) were applied, according to the rib and breast surface registrations, to estimate the residual setup errors (systematic [Sigma] and random [sigma]) of the excision area. The required margins were calculated using a margin recipe. The image quality of the cone-beam computed tomography scans was sufficient for localization of the EC. The margins required for the investigated setup correction protocols and the setup errors for the left-right, craniocaudal and anteroposterior directions were 8.3 mm (Sigma = 3.0, sigma = 2.6), 10.6 mm (Sigma = 3.8, sigma = 3.2), and 7.7 mm (Sigma = 2.7, sigma = 2.9) for the no correction strategy; 5.6 mm (Sigma = 2.0, Sigma = 1.8), 6.5 mm (Sigma = 2.3, sigma = 2.3), and 4.5 mm (Sigma = 1.5, sigma = 1.9) for the on-line rib strategy; and 5.1 mm (Sigma = 1.8, sigma = 1.7), 4.8 mm (Sigma = 1.7, sigma = 1.6), and 3.3 mm (Sigma = 1.1, sigma = 1.6) for the on-line surface strategy, respectively. Considerable geometric uncertainties in the position of the EC relative to the bony anatomy and breast surface have been observed. By using registration of the breast surface, instead of the rib, the uncertainties in the position of the EC area were reduced

Item does not contain fulltext The challenge of adequate target volume definition in external beam partial breast irradiation (PBI) could be overcome with preoperative irradiation, due to less inter-observer variation. We compared the target volume delineation for external beam PBI on preoperative versus postoperative CT scans of twenty-four breast cancer patients.

Due to the limitations of existing microdosimetry models, a new model called MICOR has been developed to analyze the spatial distribution of microscopic energy deposition for boron neutron capture therapy (BNCT). As in most existing models, the reactions independent of the incident neutron energy such as the boron and the nitrogen capture reactions can be considered. While other models do not include reactions that are dependent on the neutron energy such as the proton recoil reaction, the present model is designed so that the energy deposition resulting from these reactions is included. The model MICOR has been extended to enable the determination of the biological effects of BNCT, which cannot be done with the existing models. The present paper describes the determination of several microscopic quantities such as the number of hits, the energy deposition in the cell nucleus, and the distribution of lineal and specific energy deposition. The companion paper (Radiat. Res. 155, 000-000 2001) deals with the conversion of these microscopic quantities into biological effects. The model is used to analyze the results of a radiobiological experiment performed at the HB11 facility in the HFR in Petten. This analysis shows the value of the model in determining the dose depositions on a cellular scale and the importance of the extension to the energy deposition of the proton recoil.

Radiotherapy techniques have evolved rapidly over the last decade with the introduction of Intensity Modulated RadioTherapy (IMRT) in different forms. It is not clear which of the IMRT techniques is superior in the treatment of head and neck cancer patients in terms of coverage of the planning target volumes (PTVs), sparing the organs at risk (OARs), dose to the normal tissue, number of monitor units needed and delivery time.The present paper aims to compare Step and Shoot (SS) IMRT, Sliding Window (SW) IMRT, RapidArc (RA) planned with Eclipse, Elekta VMAT planned with SmartArc (SA) and helical TomoHD™ (HT)., info:eu-repo/semantics/published

Purpose: To evaluate the variability in heart position in deep-inspiration breath-hold (DIBH) radiotherapy for breast cancer when 3D surface imaging would be used for monitoring the depth of the breath hold during treatment. Materials and Methods: Ten patients who received DIBH radiotherapy after breast-conserving surgery (BCS) were included. Retrospectively, heart-based registrations were performed for cone-beam computed tomography (CBCT) to planning CT and breast surface registrations were performed for a 3D surface (two different regions of interest [ROIs]), captured concurrently with CBCT, to planning CT. The resulting setup errors were compared with linear regression analysis and receiver operating characteristic (ROC) analysis was performed to investigate the prediction quality of 3D surface imaging for 3D heart displacement. Further, the residual setup errors (systematic [Σ] and random [σ]) of the heart were estimated relative to the surface registrations. Results: When surface imaging [ROI left-side ;ROI both-sides ] would be used for monitoring, the residual errors of the heart position are in left-right: Σ=[0.36;0.12], σ=[0.16;0.14]; cranio-caudal: Σ=[0.54;0.54], σ=[0.28;0.31]; and in anteriorposterior: Σ=[0.18;0.14], σ=[0.20;0.19] cm. Correlations between setup errors were: R 2 = [0.23;0.73], [0.67;0.65], [0.65;0.73] in left-right, cranio-caudal, and anterior-posterior direction, respectively. ROC analysis resulted in an area under the ROC curve of [0.82;0.78]. Conclusion: The use of ROI both-sides provided promising results. However, considerable variability in the heart position, particularly in CC direction, is observed when 3D surface imaging would be used for guidance in DIBH radiotherapy after BCS. Planning organ at risk volume margins should be used to take into account the heart-position variability.

Compared to static beam Intensity-Modulated Radiation Therapy (IMRT), the main advantage of Volumetric Modulated Arc Therapy (VMAT) is a shortened delivery time, which leads to improved patient comfort and possibly smaller intra-fraction movements. This study aims at a treatment planner-independent comparison of radiotherapy treatment planning of IMRT and VMAT for head-and-neck cancer performed by several institutes and based on the same CT- and contouring data., info:eu-repo/semantics/published

Purpose To quantify set-up uncertainties during voluntary deep inspiration breath hold (DIBH) radiotherapy using 3D-surface imaging in patients with left sided breast cancer. Material and methods Nineteen patients were included. Cone-beam CT-scan (CBCT) was used for online set-up correction while patients were instructed to perform a voluntary DIBH. The reproducibility of the DIBH during treatment was monitored with 2D-fluoroscopy and portal imaging. Simultaneously, a surface imaging system was used to capture 3D-surfaces throughout CBCT acquisition and delivery of treatment beams. Retrospectively, all captured surfaces were registered to the planning-CT surface. Interfraction, intra-fraction and intra-beam set-up variability were quantified in left–right, cranio–caudal and anterior–posterior direction. Results Inter-fraction systematic ( Σ ) and random ( σ ) translational errors (1SD) before and after set-up correction were between 0.20–0.50cm and 0.09–0.22cm, respectively, whereas rotational Σ and σ errors were between 0.08 and 1.56°. The intra-fraction Σ and σ errors were ⩽0.14cm and ⩽0.47°. The intra-beam SD variability was ⩽0.08cm and ⩽0.28° in all directions. Conclusion Quantification of 3D set-up variability in DIBH RT showed that patients are able to perform a very stable and reproducible DIBH within a treatment fraction. However, relatively large inter-fraction variability requires online image guided set-up corrections.

Purpose To quantify the inter-fraction shape variation of the CTV in rectal-cancer patients treated with 5×5 (SCRT) and 25×2Gy (LCRT) and derive PTV margins. Methods and materials Thirty-three SCRT with daily repeat CT scans and 30 LCRT patients with daily scans during the first week followed by weekly scans were included. The CTV was delineated on all scans and local shape variation was calculated with respect to the planning CT. Margin estimation was done using the local shape variation to assure 95% minimum dose for at least 90% of patients. Results Using 482 CT scans, systematic and random CTV shape variation was heterogeneous, ranging from 0.2cm close to bony structures up to 1.0cm SD at the upper-anterior CTV region. A significant reduction in rectal volume during LCRT resulted in an average 0.5cm posterior shift of the upper-anterior CTV. Required margins ranged from 0.7cm close to bony structures up to 3.1 and 2.3cm in the upper-anterior region for SCRT and LCRT, respectively. Conclusions Heterogeneous shape variation demands anisotropic PTV margins. Required margins were substantially larger in the anterior direction compared to current clinical margins. These larger margins were, however, based on strict delineated CTVs, resulting in smaller PTVs compared to current practice.

Purpose: Accurate dose delivery in deep-inspiration breath-hold (DIBH) radiotherapy for patients with breast cancer relies on precise treatment setup and monitoring of the depth of the breath hold. This study entailed performance evaluation of a 3D surface imaging system for image guidance in DIBH radiotherapy by comparison with cone-beam computed tomography (CBCT). Materials and Methods: Fifteen patients, treated with DIBH radiotherapy after breast-conserving surgery, were included. The performance of surface imaging was compared to the use of CBCT for setup verification. Retrospectively, breast surface registrations were performed for CBCT to planning CT as well as for a 3D surface, captured concurrently with CBCT, to planning CT. The resulting setup errors were compared with linear regression analysis. For the differences between setup errors, group mean, systematic and random errors were calculated. Furthermore, a residual error after registration (RRE) was assessed for both systems by investigating the root-mean-square distance between the planning CT surface and registered CBCT/captured surface. Results: Good correlation between setup errors was found: R 2 =0.82, 0.86, 0.82 in left-right, cranio-caudal and anteriorposterior direction, respectively. Systematic and random errors were ≤0.16cm and ≤0.13cm in all directions, respectively. RRE values for surface imaging and CBCT were on average 0.18 versus 0.19cm with a standard deviation of 0.10 and 0.09cm, respectively. Wilcoxon-signed-ranks testing showed that CBCT registrations resulted in higher RRE values than surface imaging registrations (p=0.003). Conclusion: This performance evaluation study shows very promising results

Purpose: To determine the use of surgical clips as a surrogate for localization of the excision cavity and to quantify the stability of the clips' positions during the course of external beam radiotherapy for breast cancer patients, using cone beam computed tomography (CBCT) scans.Methods and Materials: Twenty-one breast cancer patients with surgical clips placed in the breast excision cavity were treated in a supine position with 28 daily fractions. CBCT scans were regularly acquired for a setup correction protocol. Retrospectively, the CBCT scans were registered to the planning CT scans, using gray-value registration of the excision cavity region and chamfer matching of the clips. Subsequently, residual setup errors (systematic [Sigma] and random [sigma]) of the excision cavity were estimated relative to the clips' registration. Finally, the stability of the clips' positions were quantified as the movement of each separate clip according to the center of gravity of the excision cavity.Results: When clips were used for online setup corrections, the residual errors of the excision cavity were Sigma(left-right) = 1.2, sigma(left-right) = 1.0; Sigma(cranial-caudal) = 1.3, sigma(cranial-caudal) = 1.2; and Sigma(anterior-posterior) = 0.7, sigma(anterior-posterior) = 0.9 mm. Furthermore, the average distance (over all patients) between the clips and centers of gravity of the excision cavities was 18.8 mm (on the planning CT) and was reduced to 17.4 mm (measured on the last CBCT scan).Conclusion: Clips move in the direction of the center of gravity of the excision cavity, on average, 1.4 mm. The clips are good surrogates for locating the excision cavity and providing small residual errors. (c) 2011 Elsevier Inc.

Purpose The aim of this study was to report on the development of a standardized target and organ-at-risk naming convention for use in radiation therapy and to present the nomenclature for structure naming for interinstitutional data sharing, clinical trial repositories, integrated multi-institutional collaborative databases, and quality control centers. This taxonomy should also enable improved plan benchmarking between clinical institutions and vendors and facilitation of automated treatment plan quality control. Materials and Methods The Advanced Technology Consortium, Washington University in St. Louis, Radiation Therapy Oncology Group, Dutch Radiation Oncology Society, and the Clinical Trials RT QA Harmonization Group collaborated in creating this new naming convention. The International Commission on Radiation Units and Measurements guidelines have been used to create standardized nomenclature for target volumes (clinical target volume, internal target volume, planning target volume, etc.), organs at risk, and planning organ-at-risk volumes in radiation therapy. The nomenclature also includes rules for specifying laterality and margins for various structures. The naming rules distinguish tumor and nodal planning target volumes, with correspondence to their respective tumor/nodal clinical target volumes. It also provides rules for basic structure naming, as well as an option for more detailed names. Names of nonstandard structures used mainly for plan optimization or evaluation (rings, islands of dose avoidance, islands where additional dose is needed [dose painting]) are identified separately. Results In addition to its use in 16 ongoing Radiation Therapy Oncology Group advanced technology clinical trial protocols and several new European Organization for Research and Treatment of Cancer protocols, a pilot version of this naming convention has been evaluated using patient data sets with varying treatment sites. All structures in these data sets were satisfactorily identified using this nomenclature. Conclusions Use of standardized naming conventions is important to facilitate comparison of dosimetry across patient datasets. The guidelines presented here will facilitate international acceptance across a wide range of efforts, including groups organizing clinical trials, Radiation Oncology Institute, Dutch Radiation Oncology Society, Integrating the Healthcare Enterprise, Radiation Oncology domain (IHE-RO), and Digital Imaging and Communication in Medicine (DICOM).

Purpose Three boost radiotherapy (RT) techniques were compared to evaluate the dosimetric effect of seroma reduction during RT after breast-conserving surgery (BCS). Materials and methods Twenty-one patients who developed seroma after BCS were included. Each patient underwent three CT scans: one week before RT (CT −1 ), in the third (CT 3 ) and fifth (CT 5 ) week of RT. For each patient, three plans were generated. (1) SEQ: whole breast irradiation planned on CT −1, sequential boost planned on CT 5 , (2) SIB: simultaneous integrated boost planned on CT −1 , (3) SIB adaptive radiation therapy (SIB-ART): planned on CT −1 and re-planned on CT 3 . Irradiated volumes, mean lung (MLD) and maximum heart dose (HD max ) were projected and compared on CT 5 . Results On average 62% seroma reduction during RT was observed. Volumes receiving ⩾107% of prescribed whole breast dose were significantly smaller with SIB-ART compared to SEQ and SIB. The undesired volume receiving ⩾95% of prescribed total dose was also significantly smaller with SIB-ART. For SEQ, SIB-ART and SIB, respectively, small but significant differences were found in MLD (4.2 vs. 4.6 vs. 4.7Gy) and in HD max for patients with left-sided breast cancer (39.9 vs. 35.8 vs. 36.9Gy). Conclusions This study demonstrates a dosimetric advantage for patients with seroma when simultaneous integrated boost is used with re-planning halfway through treatment.

Purpose To demonstrate the potential of volumetric-modulated arc therapy (VMAT) compared with intensity-modulated radiotherapy (IMRT) techniques with a limited number of segments for stereotactic body radiotherapy (SBRT) for early-stage lung cancer. Methods and Materials For a random selection of 27 patients eligible for SBRT, coplanar and noncoplanar IMRT and coplanar VMAT (using SmartArc) treatment plans were generated in Pinnacle 3 and compared. In addition, film measurements were performed using an anthropomorphic phantom to evaluate the skin dose for the different treatment techniques. Results Using VMAT, the delivery times could be reduced to an average of 6.6 min compared with 23.7 min with noncoplanar IMRT. The mean dose to the healthy lung was 4.1 Gy for VMAT and noncoplanar IMRT and 4.2 Gy for coplanar IMRT. The volume of healthy lung receiving >5 Gy and >20 Gy was 18.0% and 5.4% for VMAT, 18.5% and 5.0% for noncoplanar IMRT, and 19.4% and 5.7% for coplanar IMRT, respectively. The dose conformity at 100% and 50% of the prescribed dose of 54 Gy was 1.13 and 5.17 for VMAT, 1.11 and 4.80 for noncoplanar IMRT and 1.12 and 5.31 for coplanar IMRT, respectively. The measured skin doses were comparable for VMAT and noncoplanar IMRT and slightly greater for coplanar IMRT. Conclusions Coplanar VMAT for SBRT for early-stage lung cancer achieved plan quality and skin dose levels comparable to those using noncoplanar IMRT and slightly better than those with coplanar IMRT. In addition, the delivery time could be reduced by ≤70% with VMAT.

Purpose The purpose of the present study was to quantify the robustness of the dose distributions from three whole-breast radiotherapy (RT) techniques involving different levels of intensity modulation against whole patient setup inaccuracies and breast shape changes. Methods and Materials For 19 patients (one computed tomography scan and five cone beam computed tomography scans each), three treatment plans were made (wedge, simple intensity-modulated RT [IMRT], and full IMRT). For each treatment plan, four dose distributions were calculated. The first dose distribution was the original plan. The other three included the effects of patient setup errors (rigid displacement of the bony anatomy) or breast errors ( e.g., rotations and shape changes of the breast with respect to the bony anatomy), or both, and were obtained through deformable image registration and dose accumulation. Subsequently, the effects of the plan type and error sources on target volume coverage, mean lung dose, and excess dose were determined. Results Systematic errors of 1–2 mm and random errors of 2–3 mm (standard deviation) were observed for both patient- and breast-related errors. Planning techniques involving glancing fields (wedge and simple IMRT) were primarily affected by patient errors (∼6% loss of coverage near the dorsal field edge and ∼2% near the skin). In contrast, plan deterioration due to breast errors was primarily observed in planning techniques without glancing fields (full IMRT, ∼2% loss of coverage near the dorsal field edge and ∼4% near the skin). Conclusion The influences of patient and breast errors on the dose distributions are comparable in magnitude for whole breast RT plans, including glancing open fields, rendering simple IMRT the preferred technique. Dose distributions from planning techniques without glancing open fields were more seriously affected by shape changes of the breast, demanding specific attention in partial breast planning techniques.

To evaluate the feasibility, cardiac dose reduction, and the influence of the setup error on the delivered dose for fluoroscopy-guided deep inspiration breath hold (DIBH) irradiation using a cone-beam CT for irradiation of left-sided breast cancer patients.Nineteen patients treated according to the DIBH protocol were evaluated regarding dose to the ipsilateral breast (or thoracic wall), heart, (left ventricle [LV] and left anterior descending artery [LAD]), and lung. The DIBH treatment plan was compared to the free-breathing (FB) treatment planning and to the dose data in which setup error was taken into account (i.e., actual delivered dose).The largest setup variability was observed in the direction perpendicular to the RT field (μ = -0.8 mm, Σ = 2.9 mm, σ = 2.0 mm). The mean (D(mean)) and maximum (D(max)) doses of the DIBH treatment plan was significantly lower compared with the FB treatment plan for the heart (34% and 25%, p0.001), LV (71% and 28%, p0.001), and LAD (52% and 39.8%, p0.001). For some patients, large differences were observed between the heart D(max) according to the DIBH treatment plan and the actual delivered dose (up to 71%), although D(max) was always smaller than the planned FB dose (mean group reduction = 29%, p0.001).The image-guided DIBH treatment protocol is a feasible irradiation method with small setup variability that significantly reduces the dose to the heart, LV, and LAD.

Purpose To determine whether cone-beam CT (CBCT) is effective in monitoring seroma reduction during breast irradiation when compared with conventional CT. Patients and Methods This study included 19 women with Stage T1-2 breast cancer treated with breast-conserving therapy. Each patient underwent two to four CT and multiple CBCT scans (mean, 8; range, 7–13 scans) at various time intervals during radiotherapy. Seroma were contoured by two observers on all scans and checked by one radiation oncologist. Seroma clarity was determined according to The British Columbia Cancer Agency Seroma Clarity Score scale, and conformity index (CI) of the two observers was evaluated. Correlations in seroma contours and seroma characteristics between CBCT and CT, as well as interobserver variation, were examined. Results The mean differences in seroma volume between CT and CBCT (3%, p = 0.3) and between the two observers (6%, p = 0.2) were not statistically significant. Seroma clarity correlated significantly with CI for both CT and CBCT ( p = 0.02 and p = 0.001, respectively), indicating the higher the seroma clarity score, the greater the CI between the observers. With seroma clarity 3 or higher for CT and CBCT, a high level of observer concordance was shown (all CI of these scans were ≥50%). Conclusion Volume discrepancy between CBCT and CT and between the two observers was not statistically significant. Seroma clarity influenced observers' ability to contour on CT or CBCT equally. Therefore, CBCT is a good clinical surrogate for CT in monitoring seroma reduction during breast radiotherapy, especially for patients with seroma clarity score 3 or higher.

Purpose: To quantify the differences in setup errors measured with the cone-beam computed tomography (CBCT) and electronic portal image devices (EPID) in breast cancer patients.Methods and Materials: Repeat CBCT scan were acquired for routine offline setup verification in 20 breast cancer patients. During the CBCT imaging fractions, EPID images of the treatment beams were recorded. Registrations of the bony anatomy for CBCT to planning CT and EPID to digitally reconstructed-radiographs (DRRs) were compared. In addition, similar measurements of an anthropomorphic thorax phantom were acquired. Bland-Altman and linear regression analysis were performed for clinical and phantom registrations. Systematic and random setup errors were quantified for CBCT and EPID-driven correction protocols in the EPID coordinate system (U, V), with V parallel to the cranial-caudal axis and U perpendicular to V and the central beam axis.Results: Bland-Altman analysis of clinical EPID and CBCT registrations yielded 4 to 6-mm limits of agreement, indicating that both methods were not compatible. The EPID-based setup errors were smaller than the CBCT-based setup errors. Phantom measurements showed that CBCT accurately measures setup error whereas EPID underestimates setup errors in the cranial caudal direction. In the clinical measurements, the residual bony anatomy setup errors after offline CBCT-based corrections were Sigma(U) = 1.4 mm, Sigma(V) = 1.7 mm, and sigma(U) = 2.6 mm, sigma(V) = 3.1 mm. Residual setup errors of EPID driven corrections corrected for underestimation were estimated at Sigma(U) = 2.2mm, Sigma(V) = 3.3 mm, and sigma(U) = 2.9 mm, sigma(V) = 2.9 mm.Conclusion: EPID registration underestimated the actual bony anatomy setup error in breast cancer patients by 20% to 50%. Using CBCT decreased setup uncertainties significantly. (C) 2010 Elsevier Inc.

Background and purpose To design a clinically reliable and efficient step-and-shoot IMRT delivery technique for the treatment of breast cancer using direct aperture optimization (DAO). Using DAO, segments are created and optimized within the same optimization process. Patients and methods The DAO technique implemented in the Pinnacle treatment planning system, which is called direct machine parameter optimization (DMPO), was used to generate IMRT plans for twelve breast cancer patients. The prescribed dose was 50Gy. Two DMPO plans were generated. The first approach uses DMPO only; the second technique combines DMPO with two predefined segments (DMPO segm ), having shapes identical to the conventional tangential fields. The weight of these predefined segments is optimized simultaneously with DMPO. The DMPO plans were compared with normal two-step (TS) IMRT, creating segments after optimizing the intensity. Results Dose homogeneity within the target volume was 4.8±0.6, 4.3±0.5 and 3.8±0.5Gy for the TS, DMPO and DMPO segm plans, respectively. Comparing the IMRT plans with an idealized dose distribution obtained using only beamlet optimization, the degradation of the dose distribution was less for the DMPO plans compared with the two-step IMRT approach. Furthermore, this degradation was similar for all patients, while for the two-step IMRT approach it was patient specific. Conclusions An efficient step-and-shoot IMRT solution was developed for the treatment of breast cancer using DMPO combined with two predefined segments.

A model has been developed to obtain a better understanding of the effects of boron neutron capture therapy (BNCT) on a cellular scale. This model, the microdosimetry model MICOR, has been developed to include all reactions important for BNCT. To make the model more powerful in the translation from energy deposition to biological effect, it has been designed to be capable of calculating the effectiveness function. Based on this function, the model can calculate surviving fractions, RBE values and boron concentration distributions. MICOR has been used to analyze an extensive set of biological experiments performed at the HB11 beam in Petten. For V79 Chinese hamster cells, the effectiveness function is determined and used to generate surviving fractions. These fractions are compared with measured surviving fractions, which results in a good agreement between the measured and calculated surviving fractions (within the uncertainties of the measurements).

Purpose To investigate bowel exposure using prone, supine, or two different belly boards for rectal cancer intensity modulated RT plans using a full bladder protocol. Methods and materials For 11 volunteers four MR scans were acquired, on a flat table in prone, supine, and on two different belly boards (IT-V Medizintechnik GmbH® (BB1) and CIVCO® (BB2)), using a full bladder protocol. On each scan a 25 × 2 Gy IMRT plan was calculated. Results BB2 led to an average bowel area volume reduction of 20–30% at any dose level compared to prone. BB1 showed a smaller dose reduction effect, while no differences between prone and supine were found. Differences between BB2 and prone, supine or BB1 were significant up to a level of respectively, 45, 35, and 30 Gy. The reducing effect varied among individuals, except for the 50 Gy region, where no effect was found. An increase in bladder volume of 100 cc led to a significant bowel area V15 reduction of 16% independent of scan type. Conclusions In the low and intermediate dose region a belly board still attributes to a significant bowel dose reduction when using IMRT and a full bladder protocol. A larger bladder volume resulted in a significant decreased bowel area dose.