Delineation Of Lumpectomy Cavity Research Articles

DE-MR simulation imaging for prone radiotherapy after breast-conserving surgery: assessing its application in lumpectomy cavity delineation based on deformable image registration

BackgroundThe application of delayed-enhancement magnetic resonance (DE-MR) simulation imaging in lumpectomy cavity (LC) delineation for prone radiotherapy in patients with an invisible seroma or a low seroma clarity score (SCS) after breast-conserving surgery (BCS) based on deformable image registration (DIR) was assessed.MethodsTwenty-six patients who were suitable for radiotherapy in prone positions after BCS were enrolled, and both computed tomography (CT) and DE-MR simulation scans were acquired. The LC delineated based on titanium surgical clips on CT images was denoted as LCCT. The LC delineated based on the signal of cavity boundaries on fat-suppressed T2-weighted imaging (T2WI) and multiphase delayed-enhancement T1-weighted imaging (DE-T1WI), which was performed at 2 min, 5 min and 10 min postinjection, were denoted as LCT2, LC2T1, LC5T1 and LC10T1, respectively. Afterwards, DIR was performed to compare the volumes and locations of the LCs with MIM software. The generalized conformity index (CIgen) of inter (intra) observer (Inter-CIgen and Intra-CIgen) was also used to explore the inter(intra) observer variation for LC delineation on each image modality.ResultsLCCT–LC10T1 provided the best conformal index (CI) and degree of inclusion (DI), increasing by 2.08% and 4.48% compared to LCCT–LCT2, 11.36% and 2.94% for LCCT–LC2T1, and 8.89% and 7.69% for LC5T1–LCCT, respectively. The center of mass (COM) of LCCT–LC10T1 decreased by 17.86%, 6.12% and 13.21% compared with that of LCCT–LCT2, LCCT–LC2T1 and LCCT–LC5T1, respectively. The agreement of LC delineation was strongest for 10th min DE-TIWI (coefficient of variation, COV = 2.30%, Inter-CIgen = 87.06%, Intra-CIgen = 92.64%).ConclusionFor patients with a low SCS (SCS ≤ 2) after BCS, it is feasible to contour the LC based on prone DE-MR simulation images. Furthermore, the LC derived from prone DE-T1WI at 10 min was found to be most similar to that derived from prone CT simulation scans using titanium surgical clips regardless of the volume and location of the LC. Inter (intra) variability was minimal for the delineation of the LC based on 10th min DE-TIWI.

Comparison of Magnetic Resonance Imaging and Computed Tomography–Based Volume Delineation of Lumpectomy Cavity Without Surgical Clips in Breast-Conserving Radiotherapy

First, to compare magnetic resonance (MR) imaging and computed tomography (CT) -based definition of lumpectomy cavity in patients without surgical clips. Second, to quantify consistency of MR and CT-based lumpectomy cavity delineation for breast-conserving radiotherapy. Between August 2018 and March 2019, twenty patients with T1-2N0M0 breast cancer at our institution were enrolled in this study. All the patients had been treated by breast-conserving surgery without implantation of surgical clips, and prepared to receive radiotherapy. MR and CT images were required in the same day for each patient. Three radiation oncologists independently assigned cavity visualization score (CVS), and delineated the lumpectomy cavity based on CT then on MR images with a 14-day interval for each patient. Interobserver variability was assessed by volumes, generalized conformity index (CIgen) and the distance between the centers of mass (dCOM). Differences in means were tested by the paired sample t-test or One-way analysis of variance, as appropriate. The median age of included patients was 48 years old (range, 33-73). Mean volumes of lumpectomy cavity derived from MR were 22%, 27% and 21% smaller than those based on CT images for each radiation oncologist. And mean CVS was 2.43±0.92 and 3.23±1.34 for CT and MR scans (P = 0.035). In addition, mean CIgen was significantly superior and dCOM was closer for MR when compared to CT (CIgen: 0.59 vs 0.52, P = 0.008; dCOM: 1.30 cm vs 1.39 cm, P = 0.095). In the subgroup with a CVS≥3, the mean dCOM was also obviously larger obtained from CT than those from the MR images (1.35 cm vs 1.19 cm, P = 0.048). A positive association was observed between CVS and CIgen for CT and MR, while CVS was negatively correlated with dCOM for MR images (both P <0.001). In the present study, when compared to CT, MR was able to improve the visualization of postoperative lumpectomy cavity changes. In addition, MR yielded a more precise definition of lumpectomy cavity and improved the consistency of lumpectomy cavity delineation in patients without the aid of surgical clips.

Delayed Contrast Enhanced Magnetic Resonance Simulation Imaging in Prone Position for Radiotherapy After Breast Conserving Surgery: Assessing the Application in Lumpectomy Cavity Delineation Using Deformable Image Registration

Delayed Contrast Enhanced Magnetic Resonance Simulation Imaging in Prone Position for Radiotherapy After Breast Conserving Surgery: Assessing the Application in Lumpectomy Cavity Delineation Using Deformable Image Registration

Abstract OT2-04-04: Multi-institution phase II trial of intraoperative electron beam radiotherapy boost at the time of breast conserving surgery with oncoplastic reconstruction in women with early-stage breast cancer

Abstract Background: In women amenable to breast conserving therapy, lumpectomy followed by adjuvant whole breast irradiation (WBI) remains the standard of care. Randomized trials demonstrate that addition of a lumpectomy cavity boost significantly reduces the risk of ipsilateral breast tumor recurrences but also increases the risk of breast fibrosis. Contemporary randomized trials define the lumpectomy cavity boost volume as a 1.7 cm isometric expansion on the lumpectomy cavity as delineated on CT. However, identifying the lumpectomy cavity can be challenging, especially in women that receive adjuvant chemotherapy and in cases in which surgical clips are not present. Recently, the use of oncoplastic techniques in breast conserving surgery has increased. These techniques are used to prevent the poor cosmetic results that can occur when a large volume of breast tissue is resected. Women that undergo oncoplastic reconstruction represent especially difficult cases for lumpectomy cavity delineation. Retrospective series have evaluated the use of intraoperative electron radiotherapy (IOERT) as a boost prior to WBI in women receiving lumpectomy without oncoplastic reconstruction. In the largest series of IOERT boost prior to WBI the local control rate of this approach was &amp;gt;99%. Prospective data regarding IOERT boost in women undergoing oncoplastic reconstruction are limited. The advantages of this approach include direct visualization/irradiation of the tumor bed, sparing the skin of irradiation, and reducing the treatment time by ˜1 week. We hypothesize that IOERT boost followed by WBI will result in acceptably low rates of grade 3 fibrosis in women undergoing lumpectomy with oncoplastic reconstruction. Trial Design: This is a single-arm, prospective study to evaluate the safety, toxicity and efficacy of IOERT boost at the time of breast conserving surgery in women with early-stage breast cancer undergoing oncoplastic reconstruction. Eligible women will receive 1 dose of 8 Gy to the surgical bed after lumpectomy but prior to oncoplastic reconstruction. Women will then receive adjuvant WBI of 40 Gy in 15 fractions or 50 Gy in 25 fractions. Eligibility: Key criteria include age≥18 yo, clinically node-negative stage I/II, any breast cancer subtype. Specific Aims: To determine the rate of grade 3 breast fibrosis at 1 year. Additional aims include surgical complication rates, cosmesis, and local regional cancer control. Statistical Methods: Safety will be evaluated by the rate of surgical complications necessitating hospital readmission or return to the operating room within 30 days of surgery+IOERT. If ≥4 events in the first 10 patients, ≥7 events in the first 20 patients, or ≥9 events in the first 30 patients are seen, the study will be halted. We hypothesize that the grade 3 fibrosis rate in our study will be ≤5%. Assuming an actual rate of 4%, an unacceptable rate of 9%, and a drop-out rate of 10%, the expected sample size is 176. Sites: Ohio State University, Avera Medical Group, University of North Carolina-Chapel Hill Patient Accrual: Current accrual is 5/176. Contact Information: Jose Bazan (jose.bazan2@osumc.edu) Funding Source: Intraop Medical Citation Format: Bazan JG, Stephens J, Agnese D, Skoracki R, Arneson K, Reiland J, Gupta G, Gallagher K, McElroy S, Gupta N, White JR. Multi-institution phase II trial of intraoperative electron beam radiotherapy boost at the time of breast conserving surgery with oncoplastic reconstruction in women with early-stage breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr OT2-04-04.

Catheter-based delineation of lumpectomy cavity for accurate target definition in partial-breast irradiation with multicatheter interstitial brachytherapy.

PurposeIn partial-breast irradiation (PBI), accurate lumpectomy cavity (LC) delineation is critical. Seroma-based delineation (SBD) using computed tomography (CT) with clips remains uncertain, causing an expansion of the LC and planning target volume (PTV). In catheter-based delineation (CBD), the implanted catheters were used as reference markers for LC delineation in multicatheter interstitial brachytherapy (MIB).Material and methodsBetween October 2008 and October 2018, 513 patients who underwent MIB-PBI were examined. In CBD, anatomical relations of LC to catheters were recorded. In randomly selected 22 CBD cases, the LC volume and PTV were retrospectively recontoured on SBD, and the relationship between the contribution of CBD and cavity visuality was evaluated. The LC volume and PTV before and after the introduction of CBD were compared.ResultsThe mean LC volumes based on SBD and CBD were 19.1 cm3 and 14.1 cm3, respectively (p < 0.001). The mean PTVs based on SBD and CBD were 47.9 cm3 and 35.7 cm3, respectively (p < 0.0001). More reductions in the LC volume (5.1 cm3) (p < 0.05) and PTV (7.7 cm3) (p = 0.13) were observed in the poorly visible LC than in the visible LC. The LC volume and PTV before the introduction of CBD (n = 411) were compared with those after introduction (n = 102). Significant reductions were observed in the LC volume (5.9 cm3) (p < 0.0001) after the introduction of CBD; moreover, PTV tended to be reduced (3.9 cm3) (p = 0.17).ConclusionsCBD may help to establish the standardized procedure for MIB-PBI and prevent unnecessary radiation exposure to the normal breast tissue.

Abstract OT2-03-01: Multi-institution phase II trial of intraoperative electron beam radiotherapy boost at the time of breast conserving surgery with oncoplastic reconstruction in women with early-Stage breast cancer

Abstract Background: In women amenable to breast conserving therapy, lumpectomy followed by adjuvant whole breast irradiation (WBI) remains the standard of care. Randomized trials have demonstrated that the addition of a lumpectomy cavity boost significantly reduces the risk of ipsilateral breast tumor recurrences but also increases the risk of breast fibrosis. Contemporary randomized trials define the lumpectomy cavity boost volume as a 1.7 cm isometric expansion on the lumpectomy cavity as delineated on CT. However, identifying the lumpectomy cavity can be challenging, especially in women that receive adjuvant chemotherapy and in cases in which surgical clips are not present. Recently, the use of oncoplastic techniques in breast conserving surgery has increased. These techniques are used to prevent the poor cosmetic results that can occur when a large volume of breast tissue is resected. Women that undergo oncoplastic reconstruction represent especially difficult cases for lumpectomy cavity delineation. Retrospective series have evaluated the use of intraoperative electron radiotherapy (IOERT) as a boost prior to WBI in women receiving lumpectomy without oncoplastic reconstruction. In the largest series of IOERT boost prior to WBI the local control rate of this approach was &amp;gt;99%. Prospective data regarding IOERT boost in women undergoing oncoplastic reconstruction are limited. Advantages of this approach include direct visualization/irradiation of the tumor bed, sparing the skin of irradiation, and reducing the treatment time by ˜1 week. We hypothesize that IOERT boost followed by WBI will result in acceptably low rates of grade 3 fibrosis in women undergoing lumpectomy with oncoplastic reconstruction. Trial Design: This is a single-arm, prospective study to evaluate the safety, toxicity and efficacy of IOERT boost at the time of breast conserving surgery in women with early-stage breast cancer undergoing oncoplastic reconstruction. Eligible women will receive 1 dose of 8 Gy to the surgical bed after lumpectomy but prior to oncoplastic reconstruction. Women will then receive adjuvant WBI of 40 Gy in 15 fractions or 50 Gy in 25 fractions. Eligibility: Key inclusion criteria include age≥18 yo, clinically node-negative stage I/II, any breast cancer subtype. Specific Aims: Our primary aim is to determine the rate of grade 3 breast fibrosis at 1 year. Additional aims include surgical complication rates, cosmesis, and local regional cancer control. Statistical Methods: Safety will be evaluated by the rate of surgical complications necessitating hospital readmission or return to the operating room within 30 days of surgery+IOERT. If ≥4 events in the first 10 patients, ≥7 events in the first 20 patients, or ≥9 events in the first 30 patients are seen, the study will be halted. We hypothesize that the grade 3 fibrosis rate in our study will be ≤5%. Assuming an actual rate of 4%, an unacceptable rate of 9%, and a drop-out rate of 10%, the expected sample size is 176. Patient Accrual: Current accrual is 0 of 176. Contact Information: Soyhum McElroy (soyhun.mcelroy@osumc.edu) or Jose Bazan (jose.bazan2@osumc.edu) Funding Source: Intraop Medical Citation Format: Bazan JG, Stephens J, Terando A, Skoracki R, McElroy S, Sexton J, Gupta N, White J. Multi-institution phase II trial of intraoperative electron beam radiotherapy boost at the time of breast conserving surgery with oncoplastic reconstruction in women with early-Stage breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr OT2-03-01.

Improvement of consistency in delineating breast lumpectomy cavity using surgical clips

BackgroundDelineation of lumpectomy cavity for whole breast radiation therapy after breast conserving surgery can be challenging because of poor visualization of the cavity. The use of surgical clips on lumpectomy cavity walls has been suggested as an effective and low-cost method to improve the accuracy and consistency of lumpectomy cavity delineation. Materials and methodsTwenty-three eligible female breast cancer patients who were treated with lumpectomy and adjuvant radiation therapy were recruited for this study. During breast conserving surgery, four surgical clips were placed on the superior, inferior, lateral, and medial walls of the lumpectomy cavity. Patients were imaged prior and during radiation treatment. Software was developed to anonymize the image sets and digitally remove the clips from the computed tomography images. Three radiation oncologists contoured the lumpectomy cavity volume, with and without presence of clips. Contoured image sets were analyzed with regard to cavity volume, dimensions, and concordance index. Statistical analysis was performed using a paired t-test. ResultsThe presence of clips significantly increased the average lumpectomy cavity volumes from 23.50 cc to 26.42 cc (P < 0.0001). The presence of clips also significantly increased the mean craniocaudal, anteroposterior, and mediolateral dimensions by 6.8, 2.3, and 2.9 mm, respectively (all P < 0.01). In addition, the presence of surgical clips improved the consistency in delineation in CC dimension by significantly decreasing the standard deviation (P < 0.006). ConclusionsThe presence of surgical clips improves the accuracy of lumpectomy cavity delineation. However, consistency is only improved in CC dimension.

Change of target volume and its dosimetric impact during the course of accelerated partial breast irradiation using intraoperative multicatheter interstitial brachytherapy after open cavity surgery

PurposeTo investigate the change of clinical target volume (CTV) and its dosimetric impact during the course of accelerated partial breast irradiation (APBI) using intraoperative multicatheter interstitial brachytherapy after open cavity surgery. Methods and MaterialsTwenty-two patients of APBI with intraoperative placement of catheters underwent computed tomography scans for the treatment planning before the first (CT1) and the last (CT2) treatment fraction. Delineation of lumpectomy cavity and CTV was done consistently on both CT data sets by one of the coauthors. Optimum plan (PCT1) was made on CT1. PCT1 was manually reproduced in CT2 which yielded plan PCT2. Plans were compared using coverage index (CI), dose homogeneity index (DHI), external volume index (EI), overdose volume index (OI) and conformal index (COIN). ResultsThe mean ± SD volume of lumpectomy cavity and CTV was 78.5 ± 40.7 cm3, 156.4 ± 69.0 cm3 for PCT1, and 84.7 ± 50.1 cm3 (p = 0.11), 165.7 ± 82.8 cm3 (p = 0.15) for PCT2, respectively. CTV volume increase by ≥ 10% was observed in 9 cases however decrease of ≥10% was observed in 5 cases. Mean (SD) of absolute pairwise difference in CTV volume was found to be 13.2 (6.7) %. For cases with increase in CTV volume, significant (p < 0.05) decrease of 8.4%, 12.2%, and 5.5% was observed in CI, EI, and COIN of CTV respectively. However for cases with shrinkage of CTV, significant (p = 0.004) increase of 45% in EI was observed, whereas COIN reduced significantly (p = 0.001) by 13.5%. Overall 22 cases showed significant decrease of 5.8% and 8.1% in mean CI and COIN, respectively. ConclusionsThe change of CTV during the course of APBI using intraoperative multicatheter interstitial brachytherapy after open cavity surgery was found patient specific and showed a significant impact on coverage and conformity.

Interobserver variations of target volume delineation and its impact on irradiated volume in accelerated partial breast irradiation with intraoperative interstitial breast implant.

PurposeTo investigate the interobserver variations in delineation of lumpectomy cavity (LC) and clinical target volume (CTV), and its impact on irradiated volume in accelerated partial breast irradiation using intraoperative multicatheter brachytherapy.Material and methodsDelineation of LC and CTV was done by five radiation oncologists on planning computed tomography (CT) scans of 20 patients with intraoperative interstitial breast implant. Cavity visualization index (CVI), four-point index ranging from (0 = poor) to (3 = excellent) was created and assigned by observers for each patient. In total, 200 contours for all observers and 100 treatment plans were evaluated. Spatial concordance (conformity index, CIcommon, and CIgen), average shift in the center of mass (COM), and ratio of maximum and minimum volumes (Vmax/Vmin) of LC and CTV were quantified among all observers and statistically analyzed. Variation in active dwell positions (0.5 cm step) for each catheter, total reference air kerma (TRAK), volume enclosed by prescription isodose (V100%) among observers and its spatial concordance were analyzed.ResultsThe mean ± SD CIcommon of LC and CTV was 0.54 ± 0.09, and 0.58 ± 0.08, respectively. Conformity index tends to increase, shift in COM and Vmax/Vmin decrease significantly (p < 0.05), as CVI increased. Out of total 309 catheters, 29.8% catheters had no change, 29.8% and 17.5% catheters had variations of 1 and 2 dwell positions (0.5 cm and 1 cm), respectively. 9.3% catheters shown variations ≥ 10 dwell positions (5 cm). The mean ± SD CIcommon of V100% was 0.75 ± 0.11. The mean observed Vmax/Vmin of prescription isodose and TRAK was 1.18 (range, 1.03 to 1.56) and 1.11 (range, 1.03 to 1.35), respectively.ConclusionsInterobserver variability in delineation of target volume was found to be significantly related to CVI. Smaller variability was observed with excellent visualization of LC. Interobserver variations showed dosimetric impact on irradiation of breast tissue volume with prescription dose.

Magnetic Resonance Imaging for Breast Lumpectomy Cavity Delineation: Computed Tomography Comparison and Sequence Variation

Magnetic Resonance Imaging for Breast Lumpectomy Cavity Delineation: Computed Tomography Comparison and Sequence Variation

Inter observer variation in delineating lumpectomy cavity and CTV for patients undergoing APBI using intra-operative implants and its impact on implant dosimetry

Introduction 3D conformal brachytherapy utilized limited source positions in catheters and thus may impact dosimetry for inter observer variation in target delineation. Purpose To investigate the inter observer variations in lumpectomy cavity (LC) and clinical target volume (CTV) delineation and their dosimetric impact. Material and methods Delineation of LC and CTV was done by five radiation oncologists on 20 patients of interstitial breast implant. Cavity visualization index (CVI), four point scale ranging from (0-excellent) to (3-poor) was developed for open cavity technique and assigned for each patient. Total 200 contours for all five observers and 100 geometrical optimized plans were made. Spatial concordance (CI), average shift in the center of mass (COM) and SD of structure volume were quantified among all observers and statistically analyzed. Variation in source dwell positions for each tube and volume encompassing prescription isodose (Vmax/Vmin) among observers was estimated. Results The mean ± SD CI of LC and CTV was 0.54 ± 0.08 and 0.58 ± 0.08. Mean assigned CVI was 0.85 ± 0.81. CI tends to decrease and shift in COM increase significantly ( p Conclusion Significant correlation of CVI was observed with CI and COM shift. Inter observer variations have shown the impact on the source positions along catheters and thus have dosimetric impact on irradiation of breast tissue with prescription isodose.

Evaluating a Role for Oncotype Dx Breast Cancer Assay in the Management of Ductal Carcinoma In Situ

lumpectomy and adjuvant radiation at the Nova Scotia Cancer Center from July 2010 to December 2011. During breast conserving surgery, four surgical clips were placed on superior, inferior, lateral and medial walls of the lumpectomy cavity. Patients were imaged twice, first with CT for treatment planning and again between fractions 11 and 13 of the adjuvant radiation. To assess the effect of the clips on delineating using the same image data, in-house software was developed to digitally remove the clips from CT images using texture synthesis algorithm. Four radiation oncologists specializing in breast cancer treatment contoured the lumpectomy cavity volume, first with the clips digitally removed, and then several weeks later with the clips restored. Contours from three of the four participating radiation oncologists were included in the analysis, based on adherence to contouring guidelines. Contoured image sets were analyzed with regard to cavity volume, dimensions and concordance index. Statistical analysis was performed using a paired ttest. Results: The presence of clips significantly increased lumpectomy cavity volumes to 26.42 cc from 23.50 cc without clips (p < 0.0001). The presence of clips significantly increased the mean craniocaudal (CC), anteroposterior (AP) and lateral dimension by 7 mm, 2.3 mm, and 3 mm (all p < 0.01). Surgical clips improved consistency in delineation among observers in the craniocaudal dimension (p Z 0.005). Anteroposterior and lateral standard deviations were not affected significantly. There was also no significant difference in average concordance index with the presence of the surgical clips. Conclusions: The presence of surgical clips improves consistency of lumpectomy cavity delineation among radiation oncologists and also influences average delineated cavity volume and dimensions. Author Disclosure: S. Atrchian: None. P. Sadeghi: None. W. Cwajna: None. L. Helyer: None. D. Rheaume: None. M. Nolan: None. R. Rutledge: None. V. Calverley: None. S. Bennett: None. J. Robar: None.

Analysis of influential factors for variability in delineation of lumpectomy cavity based on 4DCT in end-exhalation phase

Objective To investigate the effects of computed tomography (CT) slice thickness,lumpectomy cavity (LC) volume,cavity visualization score (CVS),and number of metal clips on the interobserver and intraobserver variability in the delineation of LC after breast-conserving surgery based on four-dimensional (4D) CT.Methods Thirty-five patients who had underwent breast-conserving surgery and had at least 5 metal clips placed in the LCs underwent 4DCT scans.For each patient,LC was delineated on the CT images in the T50 (end-exhalation) phase.The patients were stratified according to LC volume,CVS,CT slice thickness,and number of metal clips.Among different patient groups,interobserver and intraobserver variability in LC (Ai and Aintra) and the dice similarity coefficients (DSCs) between LCs (DSCinter and DSCintra) were evaluated and compared.Results LC volume,CVS,number of metal clips,and 4DCT slice thickness were not significantly correlated with △intra and DSCintra (P =0.628,0.842,0.080).There were no significant differences in △inter and DSCinter between the patient groups with 4DCT slice thickness of 2,3,and 5 mm (P =0.211 and 0.727),and there was no correlation between 4DCT slice thickness and Ainter and DSCinter (P =0.414,0.594).LC volume was negatively correlated with Ai (P =0.024);compared with those with LC volumes smaller than the mean value,the patients with LC volumes not smaller than the mean value had a significantly higher DSCinter (P =0.025) and a significantly lower Ainter(P =0.009).The patient group with a CVS of 3-5 had a significantly higher DSCinter than that with a CVS of 1-2(P =0.004),and CVS was positively correlated with DSCinter(P =0.007).There were no significant differences in Ainter and DSCinter between the patient groups with 7-9 and 5-6 metal clips (P =0.159,0.825).Conclusions For the breast cancer patients who have at least 5 metal clips placed at the boundary of LC after breast-conserving surgery,LC volume and CVS are still the main influential factors for variability in LC delineation.More metal clips in addition to 5-6 ones are not helpful for LC delineation. Key words: Breast conserving radiotherapy; Lumpectomy cavity delineation; Tomography, Xray computed,slice thickness; Surgical clip number; Cavity visualization score

MRI- Versus CT-Based Volume Delineation of Lumpectomy Cavity in Supine Position in Breast-Conserving Therapy: An Exploratory Study

To examine magnetic resonance imaging (MRI) and computed tomography (CT) for lumpectomy cavity (LC) volume delineation in supine radiotherapy treatment position and to assess the interobserver variability. A total of 15 breast cancer patients underwent a planning CT and directly afterward MRI in supine radiotherapy treatment position. Then, 4 observers (2 radiation oncologists and 2 radiologists) delineated the LC on the CT and MRI scans and assessed the cavity visualization score (CVS). The CVS, LC volume, conformity index (CI), mean shift of the center of mass (COM), with the standard deviation, were quantified for both CT and MRI. The CVS showed that MRI and CT provide about equal optimal visibility of the LC. If the CVS was high, magnetic resonance imaging provided more detail of the interfaces of the LC seroma with the unaffected GBT. MRI also pictured in more detail the interfaces of axillary seromas (if present) with their surroundings and their relationship to the LC. Three observers delineated smaller, and one observer larger, LC volumes comparing the MRI- and CT-derived delineations. The mean ± standard deviation CI was 32% ± 25% for MRI and 52% ± 21% for CT. The mean ± standard deviation COM shift was 11 ± 10 mm (range 1-36) for MRI and 4 ± 3 mm (range 1-10) for CT. MRI does not add additional information to CT in cases in which the CVS is assessed as low. The conformity (CI) is lower for MRI than for CT, especially at a low CVS owing to greater COM shifts for MRI, probably caused by inadequate visibility of the surgical clips on magnetic resonance (MR) images. The COM shifts seriously dictate a decline in the CI more than the variability of the LC volumes does. In cases in which MRI provides additional information, MRI must be combined with the CT/surgical clip data.

3D-conformal accelerated partial breast irradiation treatment planning: the value of surgical clips in the delineation of the lumpectomy cavity.

BackgroundAccurate localisation of the lumpectomy cavity (LC) volume is one of the most critical points in 3D-conformal Partial breast irradiation (3D-APBI) treatment planning because the irradiated volume is restricted to a small breast volume. Here, we studied the role of the placement of surgical clips at the 4 cardinal points of the lumpectomy cavity in target delineation.MethodsForty CT-based 3D-APBI plans were retrieved on which a total of 4 radiation oncologists, two trainee and two experienced physicians, outlined the lumpectomy cavity. The inter-observer variability of LC contouring was assessed when the CTV was defined as the delineation that encompassed both surgical clips and remodelled breast tissue.ResultsThe conformity index of tumour bed delineation was significantly improved by the placement of surgical clips within the LC (median at 0.65). Furthermore, a better conformity index of LC was observed according to the experience of the physicians (median CI = 0.55 for trainee physicians vs 0.65 for experienced physicians).ConclusionsThe placement of surgical clips improved the accuracy of lumpectomy cavity delineation in 3D-APBI. However, a learning curve is needed to improve the conformity index of the lumpectomy cavity.

Comparison of FDG-PET/CT and CT for Delineation of Lumpectomy Cavity for Partial Breast Irradiation

The success of partial breast irradiation critically depends on proper target localization. We examined the use of fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) for improved lumpectomy cavity (LC) delineation and treatment planning. Twelve breast cancer patients underwent FDG-PET/CT on a GE Discovery scanner with a median time from surgery to PET/CT of 49 days. The LC was contoured on the CT scan by a radiation oncologist and, together with a nuclear medicine physician, on the PET/CT scan. The volumes were calculated and compared in each patient. Treatment planning target volumes (PTVs) were calculated by expanding the margin 2 cm beyond the LC, maintaining a 5-mm margin from the skin and chest wall, and the treatment plans were evaluated. In addition, a study with a patient-like phantom was conducted to evaluate the effect that the window/level settings might have on contouring. The margin of the LC was well visualized on all FDG-PET images. The phantom results indicated that the difference between the known volume and the FDG-PET-delineated volume was <10%, regardless of the window/level settings. The PET/CT volumes were larger than the CT volumes in all cases (median volume ratio, 1.68; range, 1.24-2.45; p = 0.004). The PET/CT-based PTVs were also larger than the CT-based PTV (median volume ratio, 1.16; range, 1.08-1.64; p = 0.006). In 9 of 12 patients, a CT-based treatment plan did not provide adequate coverage of the PET/CT-based PTV (99% of the PTV received <95% of the prescribed dose), resulting in substantial cold spots in some plans. In these cases, treatment plans were generated which were specifically designed to cover the larger PET/CT-based PTV. Although these plans showed an increased dose to the normal tissues, the increases were modest: the non-target breast volume receiving > or =50 Gy, lung volume receiving > or =30 Gy, and heart volume receiving > or =5 Gy increased by 5.7%, 0.8%, and 0.2%, respectively. The normal tissue dose-volume objectives were still met with these plans. The results of our study have shown that FDG-PET/CT can be used to define the LC volume. The increased FDG uptake was likely a result of postoperative inflammation in the LC. The targets defined using PET/CT were significantly larger than those defined with CT alone. Our results have shown that treatment plans can be generated to cover these larger PET/CT target volumes with only a modest increase in irradiated tissue volume compared with CT-determined PTVs.

Variability Among Breast Radiation Oncologists in Delineation of the Postsurgical Lumpectomy Cavity

Partial breast irradiation (PBI) is becoming more widely used. Accurate determination of the surgical lumpectomy cavity volume is more critical with PBI than with whole breast radiation therapy. We examined the interobserver variability in delineation of the lumpectomy cavity among four academic radiation oncologists who specialize in the treatment of breast cancer. Thirty-four lumpectomy cavities in 33 consecutive patients were evaluated. Each physician contoured the cavity and a 1.5-cm margin was added to define the planning target volume (PTV). A cavity visualization score (CVS) was assigned (1-5). To eliminate bias, the physician of record was eliminated from the analysis in all cases. Three measures of variability of the PTV were developed: average shift of the center of mass (COM), average percent overlap between the PTV of two physicians (PVO), and standard deviation of the PTV. Of variables examined, pathologic resection volume was significantly correlated with CVS, with larger volumes more easily visualized. Shift of the COM decreased and PVO increased significantly as CVS increased. For CVS 4 and 5 cases, the average COM shift was 3 mm and 2 mm, respectively, and PVO was 77% and 87%, respectively. In multiple linear regression, pathologic diameter >4 cm and CVS > or =3 were significantly associated with smaller COM shift. When CVS was omitted from analysis, PVO was significantly larger with pathologic diameter > or =5 cm, days to planning <36, and older age. Even among radiation oncologists who specialize in breast radiotherapy, there can be substantial differences in delineation of the postsurgical radiotherapy target volume. Large treatment margins may be prudent if the cavity is not clearly defined.

2030: Comparison of PET/CT and CT for Delineation of Lumpectomy Cavity for Partial Breast Irradiation

2030: Comparison of PET/CT and CT for Delineation of Lumpectomy Cavity for Partial Breast Irradiation