Radiation Therapy Oncology Group Consensus Research Articles

Target volume coverage in clinically designed radiotherapy plan of post-mastectomy adjuvant radiotherapy of breast cancer patients in comparison with radiation therapy oncology group-based contoured plan: A dosimetric study.

Conventional field radiotherapy based on anatomical landmarks has been the traditional treatment for breast cancer. Having proven efficacy, it is still the current standard of treatment. The Radiation Therapy Oncology Group (RTOG) has published guidelines for contouring target volumes in postmastectomy patients. The impact of this guideline in the current clinical practice is less known; hence, we have analyzed dose-volume histograms (DVHs) for these plans and compared them with the proposed treatment plans to treat RTOG-defined targets. RTOG consensus definitions were used to contour the target volumes in 20 previously treated postmastectomy patients. The prescription was 42.4 Gy in 16 fractions. DVHs were generated from clinically designed plans that had actually been delivered to each patient. For comparing dose to target volumes, new plans were generated with the goal of covering 95% of volume to 90% of prescribed dose. In RTOG contoured Group, coverage improved for the supraclavicular (V90 = 83 vs. 94.9%, P < 0.05) and chest wall (V90 = 89.8 vs. 95.2%, P < 0.05). Axillary nodal coverage improved for Level-1(V90 = 80.35 vs. 96.40%, P < 0.05), Level-II (V90 = 85.93 vs. 97.09%, P < 0.05) and Level III (V90 = 86.67 vs. 98.6%, P < 0.05). The dose to the ipsilateral lung is increased (V20 = 23.87 vs. 28.73%, P < 0.05). Low dose to heart is increased in left-sided cases (V5 = 14.52 vs. 16.72%, P < 0.05) while same in right-sided cases. The study shows that radiotherapy using the RTOG consensus guidelines improves coverage to target volumes with a nonsignificant increase in normal organ dose compared to that based on anatomical landmarks.

Mapping of Local Recurrences After Radical Prostatectomy Using 68-Gallium–Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography: Implications for Postprostatectomy Radiation Therapy Clinical Target Volumes

Our objective is to describe the distribution of local recurrences after radical prostatectomy (RP) as delineated using 68-Gallium-prostate-specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) to identify areas where current consensus guideline clinical target volumes (CTVs) are insufficient or excessive and to identify predictors of recurrence location within the fossa. Retrospective review of databases from 2 tertiary referral centers was performed to identify patients who underwent 68Ga-PSMA PET/CT for biochemical recurrence after RP. Those with a component of local recurrence were included for further analysis. The epicenter of each recurrence was defined relative to reference points in 3 axes, categorized into 1 of 7 levels in the superior/inferior axis relative to the vesicourethral anastomosis, and recorded as within or outside the Faculty of Radiation Oncology Genito-urinary Group (FROGG) and Radiation Therapy Oncology Group consensus CTVs. Univariate and multivariate analysis was performed to identify predictors of recurrence location based on clinical and histopathologic variables. One thousand forty-nine 68Ga-PSMA PET/CT scans were reviewed. One hundred forty sites of local recurrence were identified on 132 scans. Relative to the vesicourethral anastomosis, 13 (9%), 31 (22%), 17 (12%), 24 (17%), 27 (19%), 20 (14%), and 8 (6%) recurrences occurred >5 mm inferior; within 5 mm above or below; and 6 to 15 mm, 16 to 25 mm, 26 to 35 mm, 36 to 45 mm, and >45 mm superiorly, respectively. Thirteen (9%) and 2 (1.4%) recurrences occurred beyond the FROGG and Radiation Therapy Oncology Group consensus CTVs, respectively, with all below the inferior CTV margin. In the largest study to date mapping local recurrences after RP in 3-dimensions, we provide several insights to inform future contouring guidelines; in particular, 9% of recurrences occurred inferior to the FROGG CTV.

Validating Modern Pelvic Nodal and Prostate Bed Contouring Guidelines for Post-Prostatectomy Salvage Radiation: A Secondary Analysis of the LOCATE Trial

<h3>Purpose/Objective(s)</h3> We used the patterns of recurrence on ¹⁸F-fluciclovine PET/CT in post-prostatectomy patients enrolled in the LOCATE trial to evaluate how well the most recent NRG Oncology and Groupe Francophone de Radiothérapie Urologique (GFRU) contouring recommendations encompassed all sites of recurrence in the prostate fossa and pelvic nodes in comparison to former Radiation Therapy Oncology Group (RTOG) recommendations. <h3>Materials/Methods</h3> Patients with biochemically recurrent prostate cancer after radical prostatectomy with a positive finding within the prostate fossa or pelvic nodes on ¹⁸F-fluciclovine PET/CTs were identified from the LOCATE patient population. Areas of gross disease were delineated. Prostate fossa contours were delineated using both the 2010 RTOG consensus guidelines, as well as the recently published 2020 GFRU consensus guidelines. Pelvic nodes were contoured with both the 2009 RTOG consensus guidelines and the 2020 NRG consensus guidelines. The performance of the contouring guidelines was assessed by determining what proportion of gross recurrent lesions were encompassed completely or marginally. <h3>Results</h3> Of the 213 patients within the LOCATE trial, a total of 45 patients were eligible for analysis with positive ¹⁸F-fluciclovine PET findings. Of the 30 total prostate fossa recurrences, the 2010 RTOG contour covered 20 (67%), and missed or marginally covered 10 (33%). The 2020 GFRU contour covered 27 (90%) recurrences, and missed or marginally covered 3 (10%). Of the 43 total nodal recurrences, the 2009 RTOG pelvic nodal contour covered 29 nodes (67%), and missed or marginally covered 14 (32%). The 2020 NRG pelvic nodal contour covered 43 nodes (100%), with no misses or marginal coverage. <h3>Conclusion</h3> This secondary analysis of the LOCATE trial exemplifies the improved coverage of the latest prostate fossa contouring recommendations from the GFRU. Similarly, it also validates the updated 2020 NRG pelvic nodal contouring guidelines by demonstrating improved coverage of recurrent disease in this patient population.

Validating Modern NRG Oncology Pelvic Nodal and Groupe Francophone de Radiothérapie Urologique Prostate Bed Contouring Guidelines for Post-Prostatectomy Salvage Radiation: A Secondary Analysis of the LOCATE Trial

We used the patterns of recurrence on 18F-fluciclovine positron emission tomography (PET)-computed tomography (CT) in patients enrolled in the LOCATE trial after prostatectomy to evaluate how well the most recent NRG Oncology and Groupe Francophone de Radiothérapie Urologique (GFRU) contouring recommendations encompassed all sites of recurrence in the prostate fossa and pelvic nodes in comparison to former Radiation Therapy Oncology Group (RTOG) recommendations. Patients with biochemically recurrent prostate cancer after radical prostatectomy with a positive finding within the prostate fossa or pelvic nodes on 18F-fluciclovine PET/CTs were identified from the LOCATE patient population. Areas of gross disease were delineated. Prostate fossa contours were delineated using both the 2010 RTOG consensus guidelines and the recently published 2020 GFRU consensus guidelines. Pelvic nodes were contoured with both the 2009 RTOG consensus guidelines and the 2020 NRG consensus guidelines. The performance of the contouring guidelines was assessed by determining what proportion of gross recurrent lesions were encompassed completely or marginally. Of the 213 patients within the LOCATE trial, 45 patients were eligible for analysis with positive 18F-fluciclovine PET findings. Of the 30 total prostate fossa recurrences, the 2010 RTOG contour covered 20 (67%) and missed or marginally covered 10 (33%). The 2020 GFRU contour covered 27 recurrences (90%), and missed or marginally covered 3 (10%). Of the 43 total nodal recurrences, the 2009 RTOG pelvic nodal contour covered 29 nodes (67%), and missed or marginally covered 14 (32%). The 2020 NRG pelvic nodal contour covered 43 nodes (100%), with no misses or marginal coverage. This secondary analysis of the LOCATE trial exemplifies the improved coverage of the latest prostate fossa contouring recommendations from the GFRU. Similarly, it also validates the updated 2020 NRG pelvic nodal contouring guidelines by demonstrating improved coverage of recurrent disease in this patient population.

NRG Oncology Updated International Consensus Atlas on Pelvic Lymph Node Volumes for Intact and Postoperative Prostate Cancer

In 2009, the Radiation Therapy Oncology Group (RTOG) genitourinary members published a consensus atlas for contouring prostate pelvic nodal clinical target volumes (CTVs). Data have emerged further informing nodal recurrence patterns. The objective of this study is to provide an updated prostate pelvic nodal consensus atlas. A literature review was performed abstracting data on nodal recurrence patterns. Data were presented to a panel of international experts, including radiation oncologists, radiologists, and urologists. After data review, participants contoured nodal CTVs on 3 cases: postoperative, intact node positive, and intact node negative. Radiation oncologist contours were analyzed qualitatively using count maps, which provided a visual assessment of controversial regions, and quantitatively analyzed using Sorensen-Dice similarity coefficients and Hausdorff distances compared with the 2009 RTOG atlas. Diagnostic radiologists generated a reference table outlining considerations for determining clinical node positivity. Eighteen radiation oncologists' contours (54 CTVs) were included. Two urologists' volumes were examined in a separate analysis. The mean CTV for the postoperative case was 302 cm3, intact node positive case was 409 cm3, and intact node negative case was 342 cm3. Compared with the original RTOG consensus, the mean Sorensen-Dice similarity coefficient for the postoperative case was 0.63 (standard deviation [SD] 0.13), the intact node positive case was 0.68 (SD 0.13), and the intact node negative case was 0.66 (SD 0.18). The mean Hausdorff distance (in cm) for the postoperative case was 0.24 (SD 0.13), the intact node positive case was 0.23 (SD 0.09), and intact node negative case was 0.33 (SD 0.24). Four regions of CTV controversy were identified, and consensus for each of these areas was reached. Discordance with the 2009 RTOG consensus atlas was seen in a group of experienced NRG Oncology and international genitourinary radiation oncologists. To address areas of variability and account for new data, an updated NRG Oncology consensus contour atlas was developed.

Patterns of Failure After Adjuvant Stereotactic Body Radiation Therapy for Pancreatic Cancer With Close or Positive Margins

PurposeThere is no consensus on treatment volumes for adjuvant stereotactic body radiation therapy (SBRT) for pancreatic cancer. Herein, we report patterns of failure after pancreatic SBRT for close/positive margins, which may inform target volume design. Methods and MaterialsAn institutional review board-approved retrospective review of patients with pancreatic adenocarcinoma treated with adjuvant SBRT for close/positive margins from 2009 to 2018 was conducted. Patterns of failure were defined as local (LF) within the tumor bed, regional (RF) within lymph nodes or anastomoses, or distant (DF). The cumulative incidence of locoregional failure was calculated using the cumulative incidence function accounting for the competing risk of death. LFs were mapped to the planning target volume (PTV) and classified as in-field (completely within the PTV), marginal (partially within the PTV), or out-of-field (completely outside the PTV). The location of LFs was compared with the Radiation Therapy Oncology Group 0848 contouring atlas to determine whether standard postoperative radiation therapy volumes would have included the LF. ResultsSeventy-six patients were treated with adjuvant SBRT for close (51.3%) or positive (48.7%) margins. Most (81.6%) received 36 Gy in 3 fractions, with a median PTV volume of 17.8 cc (interquartile range, 12.1-25.6). With a median follow-up of 17.0 months (interquartile range, 7.3-28.4), crude rates of first isolated LF, isolated RF, and DF +/– LF or RF were 9.2%, 6.6%, and 56.6%, respectively. Two-year cumulative incidences of LF, RF, locoregional failure, and DF were 34.9%, 30.8%, 49.2%, and 60.4%, respectively. Of 28 reviewable LFs, 21.4% were in-field while the remainder were completely outside (60.7%) or partially outside (17.9%) the PTV. Most LFs (92.9%) would have been encompassed by the Radiation Therapy Oncology Group consensus target volumes. ConclusionsAfter adjuvant pancreatic SBRT for close/positive margins, the majority of LFs were outside the PTV but within contemporary target volumes for conventional radiation therapy.

Definition of Internal Mammary Node Target Volume Based on the Position of the Internal Mammary Sentinel Lymph Nodes Presented on SPECT/CT Fusion Images.

Purpose: Mapping the distribution of internal mammary sentinel lymph nodes (IM-SLNs) presented on single photon emission computed tomography in conjunction with computed tomography (SPECT/CT) images to explore the value of IM-SLN to guide tailored clinical target volume (CTV) delineation of postoperative prophylactic IMNI.Materials and methods: Ninety-seven patients who underwent preoperative lymphoscintigraphy by SPECT/CT and had imaging of IM-SLN were selected in this study. The imaging IM-SLNs on SPECT/CT of eligible patients were projected onto corresponding anatomical positions of a representative axial CT image. The IMN CTVs were delineated on the representative axial CT images according to the Radiation Therapy Oncology Group (RTOG) and Danish Breast Cancer Cooperative Group (DBCG) guideline, and defined as CTVRTOG and CTVDBCG. The location of the IM-SLNs was compared with the RTOG and DBCG guidelines of IMN target volume delineations, respectively. The intercostal space distribution of IM-SLNs was recorded. The distances from the CTVRTOG and CTVDBCG to the IM-SLNs were measured, respectively.Results: The total number of imaging IM-SLNs was 136. IM-SLNs were mostly found in the first intercostal space (40.4%), with 30.2, 24.3, 4.4, and 0.7% of IM-SLNs in the second, third, fourth, and fifth intercostal space, respectively. The average distance from the edge of the CTVRTOG and the edge of CTVDBCG to the central points of the IM-SLNs was 4.10 mm (SD, 3.3 mm) and 1.60 mm (SD, 2.6 mm), respectively (t = 16.640, P = 0.000). The average distance from the edge of CTVRTOG and the edge of CTVDBCG to the lateral border IM-SLN was 6.40 mm (SD, 3.5 mm) and 3.34 mm (SD, 3.3 mm), respectively (t = 19.815, P = 0.000). Only 18.4% of IM-SLN central points were included in the CTVRTOG, and 60.3% of IM-SLN central points were included in the CTVDBCG. When covering 90 and 100% of the IM-SLN center points, the CTVRTOG needs to expand 8 and 15 mm, respectively, and the CTVDBCG needs to expand 5 and 13 mm, respectively.Conclusion: Neither the RTOG nor DBCG consensus guideline about the delineation of IMN CTV was sufficient to cover 90% of IM-SLNs. For 90% coverage of IM-SLN central points, CTVRTOG needed to be expanded by 8 mm, and CTVDBCG needed to be expanded by 5 mm.

&lt;p&gt;Postmastectomy radiotherapy using three different techniques: a retrospective evaluation of the incidental dose distribution in the internal mammary nodes&lt;/p&gt;

ObjectiveTo evaluate the incidental coverage dose to the internal mammary nodes (IMN) in patients treated with postmastectomy radiotherapy (PMRT) and its relationship with the treatment plan.Patients and methodsWe retrospectively analyzed 138 patients undergoing PMRT and divided them into three groups: three-dimensional conformal radiotherapy (3D-CRT), field-in-field forward intensity-modulated radiotherapy (F-IMRT), and inverse intensity-modulated radiotherapy (I-IMRT). The IMN were contoured according to the Radiation Therapy Oncology Group consensus and not included in the planning target volume. We analyzed incidental IMN dose coverage and its relationship with the lung and heart.ResultsThe mean dose (Dmean) to the IMN was 32.85 Gy for all patients, and the dose delivered to the IMN showed no differences in 3D-CRT, F-IMRT, and I-IMRT (33.80, 29.65, and 32.95 Gy, respectively). In addition, 10.42%, 2.04%, and 9.76% of patients achieved ≥45 Gy with 3D-CRT, F-IMRT, and I-IMRT, respectively. No differences were evident among the three treatment plans regarding IMN dose in the first three intercostal spaces (ICS1–3). The Dmean, V20, V30, V40, and V50 of ICS2 and ICS3 were superior to those of ICS1 for all three plans. For 3D-CRT, a moderate positive correlation was evident between the Dmean to the IMN and the Dmean to the heart. For F-IMRT and I-IMRT, positive correlations were evident between the Dmean of the IMN and the Dmean and V20 of the lung.ConclusionThe mean incidental dose to the IMN for IMRT (F-IMRT and I-IMRT) and 3D-CRT after modified radical mastectomy was insufficient to treat subclinical disease. A substantial dose was delivered to the IMN in some patients. Higher incidental doses to the IMN were associated with a higher heart mean dose for 3D-CRT and a higher dose to the lung for IMRT. Future prospective studies should further explore subgroups that do not require IMN irradiation.

Impact of Staging 68Ga-PSMA-11 PET Scans on Radiation Treatment Plansin Patients With Prostate Cancer

ObjectiveTo evaluate the impact of staging 68Ga-PSMA-11 PET imaging on radiotherapy (RT) dose and volumes in patients with prostate cancer. MethodsForty-five patients (89% high or very high risk by NCCN criteria) who underwent 68Ga-PSMA-11 PET imaging prior to definitive treatment for prostate cancer between December 2015 and December 2016 were included. Locations of 68Ga-PSMA-11-avid lesions were compared to Radiation Therapy Oncology Group consensus pelvic nodal volumes (clinical target volume [CTV]); coverage of lesions outside the consensus CTV was considered a major change, while dose-escalation to lesions within the consensus CTV was considered a minor change. ResultsAll patients had 68Ga-PSMA-11 PET uptake in the prostate. Twenty-five patients (56%) had N1/M1a disease on 68Ga-PSMA-11 PET scan, of whom 21 (47%) were previously N0. Six patients (13%) had bone metastases on 68Ga-PSMA-11 PET scan, of whom 4 had prior negative bone scans. Eight patients (18%) had lymph node metastases outside the consensus CTV. Twelve patients (27%) received a RT boost to nodes within the consensus CTV. Six patients (13%) had limited bone metastases treated with focal RT. Overall PSMA PET imaging resulted in major and/or minor changes to RT plans in 24 patients (53%). Conclusion68Ga-PSMA-11 PET imaging resulted in RT changes in 53% of patients. Prospective investigation is needed to evaluate the clinical benefit of RT changes based on staging 68Ga-PSMA-11 PET imaging.

Variability of clinical target volume delineation for rectal cancer patients planned for neoadjuvant radiotherapy with the aid of the platform Anatom-e

ObjectiveDelineation of treatment volumes is a major source of uncertainties in radiotherapy (RT). This is also true for rectal cancer patients undergoing neoadjuvant RT, with a potential impact on treatment quality. We investigated the role of the digital platform Anatom-e (Anatom-e Information Sytems Ltd., Houston, Texas) in increasing the compliance to follow a specific treatment protocol in a multicentric setting. Materials and methodsTwo clinical cases of locally advanced rectal cancer were chosen. Participants were instructed to follow the 2009 Radiation Therapy Oncology Group consensus atlas and asked to manually segment clinical target volumes (CTVs), for both patient 1 and 2, on day 1 with and without the use of Anatom-e. After one week (day 2), the same radiation oncologist contoured again, with and without Anatom-e, the same CT series. Intraobserver (Intra-OV) and interobserver (Inter-OV) variability were evaluated with the Dice similarity coefficient (DSC), the Hausdorff distance (HD) and mean distance to agreement (MDA). ResultsFor clinical case 1, no significant difference was found for Intra-OV and Inter-OV. For clinical case 2, no significant difference was found for Intra-OV but a statistically significant difference was found for Inter-OV in DSC when using or not the platform. Mean DCS was 0.65 (SD: ±0.64; range: 0.58–0.79) for day 1 vs reference volume without Anatom-e and 0.72 (SD: ±0.39; range: 0.67–0.77) (p = 0.03) with it. Mean MDA was lower with Anatom-e (3.61; SD: ±1.33; range: 2.85–4.78) than without (4.14; SD: ±2.97; range: 2.18–5.21), with no statistical significance (p = 0.21) The use of Anatom-e decreased the SD from 2.97 to 1.33. Mean HD was lower with Anatom-e (26.06; SD: ±2.05; range: 24.08–32.62), with no statistical significance (p = 0.14) compared to that without (31.39; SD: ±1.31; range: 26.14–48.72). ConclusionsThe use of Anatom-e decreased the Inter-OV in the CTV delineation process for locally advanced rectal cancer with complex disease presentation planned for neoadjuvant RT. This system may be potentially helpful in increasing the compliance to follow shared guidelines and protocols.

68Ga-PSMA-11 PET/CT Mapping of Prostate Cancer Biochemical Recurrence After Radical Prostatectomy in 270 Patients with a PSA Level of Less Than 1.0 ng/mL: Impact on Salvage Radiotherapy Planning.

Target volume delineations for prostate cancer (PCa) salvage radiotherapy (SRT) after radical prostatectomy are usually drawn in the absence of visibly recurrent disease. 68Ga-labeled prostate-specific membrane antigen (PSMA-11) PET/CT detects recurrent PCa with sensitivity superior to standard-of-care imaging at serum prostate-specific antigen (PSA) values low enough to affect target volume delineations for routine SRT. Our objective was to map the recurrence pattern of PCa early biochemical recurrence (BCR) after radical prostatectomy with 68Ga-PSMA-11 PET/CT in patients with serum PSA levels of less than 1 ng/mL, determine how often consensus clinical target volumes (CTVs) based on the Radiation Therapy Oncology Group (RTOG) guidelines cover 68Ga-PSMA-11 PET/CT-defined disease, and assess the potential impact of 68Ga-PSMA-11 PET/CT on SRT. Methods: This was a post hoc analysis of an intention-to-treat population of 270 patients who underwent 68Ga-PSMA-11 PET/CT at 4 institutions for BCR after prostatectomy without prior radiotherapy at a PSA level of less than 1 ng/mL. RTOG consensus CTVs that included both the prostate bed and the pelvic lymph nodes were contoured on the CT dataset of the PET/CT image by a radiation oncologist masked to the PET component. 68Ga-PSMA-11 PET/CT images were analyzed by a nuclear medicine physician. 68Ga-PSMA-11-positive lesions not covered by planning volumes based on the consensus CTVs were considered to have a potential major impact on treatment planning. Results: The median PSA level at the time of 68Ga-PSMA-11 PET/CT was 0.48 ng/mL (range, 0.03-1 ng/mL). One hundred thirty-two of 270 patients (49%) had a positive 68Ga-PSMA-11 PET/CT result. Fifty-two of 270 (19%) had at least one PSMA-11-positive lesion not covered by the consensus CTVs. Thirty-three of 270 (12%) had extrapelvic PSMA-11-positive lesions, and 19 of 270 (7%) had PSMA-11-positive lesions within the pelvis but not covered by the consensus CTVs. The 2 most common 68Ga-PSMA-11-positive lesion locations outside the consensus CTVs were bone (23/52, 44%) and perirectal lymph nodes (16/52, 31%). Conclusion: Post hoc analysis of 68Ga-PSMA-11 PET/CT implied a major impact on SRT planning in 52 of 270 patients (19%) with PCa early BCR (PSA < 1.0 ng/mL). This finding justifies a randomized imaging trial of SRT with or without 68Ga-PSMA-11 PET/CT investigating its potential benefit on clinical outcome.

Conventional and conformal technique of external beam radiotherapy in locally advanced cervical cancer: Dose distribution, tumor response, and side effects

The objective of this study was to compare conventional and conformal techniques of external beam radiotherapy (EBRT) in terms of the dose distribution, tumor response, and side effects in the treatment of locally advanced cervical cancer patients. A retrospective cohort study was conducted on cervical cancer patients who underwent EBRT before brachytherapy in the Radiotherapy Department of Cipto Mangunkusumo Hospital. The prescribed dose distribution, tumor response, and acute side effects of EBRT using conventional and conformal techniques were investigated. In total, 51 patients who underwent EBRT using conventional techniques (25 cases using Cobalt-60 and 26 cases using a linear accelerator (LINAC)) and 29 patients who underwent EBRT using conformal techniques were included in the study. The distribution of the prescribed dose in the target had an impact on the patient’s final response to EBRT. The complete response rate of patients to conformal techniques was significantly greater (58%) than that of patients to conventional techniques (42%). No severe acute local side effects were seen in any of the patients (Radiation Therapy Oncology Group (RTOG) grades 3–4). The distribution of the dose and volume to the gastrointestinal tract affected the proportion of mild acute side effects (RTOG grades 1–2). The urinary bladder was significantly greater using conventional techniques (Cobalt-60/LINAC) than using conformal techniques at 72% and 78% compared to 28% and 22%, respectively. The use of conformal techniques in pelvic radiation therapy is suggested in radiotherapy centers with CT simulators and 3D Radiotherapy Treatment Planning Systems (RTPSs) to decrease some uncertainties in radiotherapy planning. The use of AP/PA pelvic radiation techniques with Cobalt-60 should be limited in body thicknesses equal to or less than 18 cm. When using conformal techniques, delineation should be applied in the small bowel, as it is considered a critical organ according to RTOG consensus guidelines.

Delineation of Internal Mammary Nodal Target Volumes in Breast Cancer Radiation Therapy

The optimal clinical target volume for internal mammary (IM) node irradiation is uncertain in an era of increasingly conformal volume-based treatment planning for breast cancer. We mapped the location of gross internal mammary lymph node (IMN) metastases to identify areas at highest risk of harboring occult disease. Patients with axial imaging of IMN disease were identified from a breast cancer registry. The IMN location was transferred onto the corresponding anatomic position on representative axial computed tomography images of a patient in the treatment position and compared with consensus group guidelines of IMN target delineation. The IMN location in 67 patients with 130 IMN metastases was mapped. The location was in the first 3 intercostal spaces in 102 of 130 nodal metastases (78%), whereas 18 of 130 IMNs (14%) were located caudal to the third intercostal space and 10 of 130 IMNs (8%) were located cranial to the first intercostal space. Of the 102 nodal metastases within the first 3 intercostal spaces, 54 (53%) were located within the Radiation Therapy Oncology Group consensus volume. Relative to the IM vessels, 19 nodal metastases (19%) were located medially with a mean distance of 2.2mm (SD, 2.9mm) whereas 29 (28%) were located laterally with a mean distance of 3.6mm (SD, 2.5mm). Ninety percent of lymph nodes within the first 3 intercostal spaces would have been encompassed within a 4-mm medial and lateral expansion on the IM vessels. In women with indications for elective IMN irradiation, a 4-mm medial and lateral expansion on the IM vessels may be appropriate. In women with known IMN involvement, cranial extension to the confluence of the IM vein with the brachiocephalic vein with or without caudal extension to the fourth or fifth interspace may be considered provided that normal tissue constraints are met.

Delineation of Supraclavicular Target Volumes in Breast Cancer Radiation Therapy

To map the location of gross supraclavicular metastases in patients with breast cancer, in order to determine areas at highest risk of harboring subclinical disease. Patients with axial imaging of gross supraclavicular disease were identified from an institutional breast cancer registry. Locations of the metastatic lymph nodes were transferred onto representative axial computed tomography images of the supraclavicular region and compared with the Radiation Therapy Oncology Group (RTOG) breast cancer atlas for radiation therapy planning. Sixty-two patients with 161 supraclavicular nodal metastases were eligible for study inclusion. At the time of diagnosis, 117 nodal metastases were present in 44 patients. Forty-four nodal metastases in 18 patients were detected at disease recurrence, 4 of whom had received prior radiation to the supraclavicular fossa. Of the 161 nodal metastases, 95 (59%) were within the RTOG consensus volume, 4 nodal metastases (2%) in 3 patients were marginally within the volume, and 62 nodal metastases (39%) in 30 patients were outside the volume. Supraclavicular disease outside the RTOG consensus volume was located in 3 regions: at the level of the cricoid and thyroid cartilage (superior to the RTOG volume), in the posterolateral supraclavicular fossa (posterolateral to the RTOG volume), and in the lateral low supraclavicular fossa (lateral to the RTOG volume). Only women with multiple supraclavicular metastases had nodal disease that extended superiorly to the level of the thyroid cartilage. For women with risk of harboring subclinical supraclavicular disease warranting the addition of supraclavicular radiation, coverage of the posterior triangle and the lateral low supraclavicular region should be considered. For women with known supraclavicular disease, extension of neck coverage superior to the cricoid cartilage may be warranted.

Adoption of Radiation Therapy Oncology Group consensus guidelines for post-prostatectomy radiation therapy in an academic tertiary care center

Objective This study aimed to define the impact of Radiation Therapy Oncology Group (RTOG) guidelines for clinical target volume (CTV) delineation for post-prostatectomy external beam radiation therapy (EBRT) on radiation dosimetry and toxicity.

The Impact of Radiation Therapy Oncology Group Consensus Clinical Target Volume Guidelines on Outcomes in Patients Undergoing Post prostatectomy Radiation Therapy

The Impact of Radiation Therapy Oncology Group Consensus Clinical Target Volume Guidelines on Outcomes in Patients Undergoing Post prostatectomy Radiation Therapy

Statistical Modeling Approach to Quantitative Analysis of Interobserver Variability in Breast Contouring

To develop a new approach for interobserver variability analysis. Eight radiation oncologists specializing in breast cancer radiation therapy delineated a patient's left breast "from scratch" and from a template that was generated using deformable image registration. Three of the radiation oncologists had previously received training in Radiation Therapy Oncology Group consensus contouring for breast cancer atlas. The simultaneous truth and performance level estimation algorithm was applied to the 8 contours delineated "from scratch" to produce a group consensus contour. Individual Jaccard scores were fitted to a beta distribution model. We also applied this analysis to 2 or more patients, which were contoured by 9 breast radiation oncologists from 8 institutions. The beta distribution model had a mean of 86.2%, standard deviation (SD) of ±5.9%, a skewness of -0.7, and excess kurtosis of 0.55, exemplifying broad interobserver variability. The 3 RTOG-trained physicians had higher agreement scores than average, indicating that their contours were close to the group consensus contour. One physician had high sensitivity but lower specificity than the others, which implies that this physician tended to contour a structure larger than those of the others. Two other physicians had low sensitivity but specificity similar to the others, which implies that they tended to contour a structure smaller than the others. With this information, they could adjust their contouring practice to be more consistent with others if desired. When contouring from the template, the beta distribution model had a mean of 92.3%, SD±3.4%, skewness of -0.79, and excess kurtosis of 0.83, which indicated a much better consistency among individual contours. Similar results were obtained for the analysis of 2 additional patients. The proposed statistical approach was able to measure interobserver variability quantitatively and to identify individuals who tended to contour differently from the others. The information could be useful as feedback to improve contouring consistency.

Effect of RTOG breast/chest wall guidelines on dose‐volume histogram parameters*

Treatment planning for breast cancer has been traditionally based on clinical landmarks. The Radiation Therapy Oncology Group (RTOG) published consensus guidelines on contouring target volumes (TV) for the breast/chest wall and draining lymphatics. The effect of these guidelines on dosimetric parameters in surrounding organs at risk (OAR) and TVs is unknown. Fourteen patients treated with clinically derived plans from 2007‐2011 (Group I) and fourteen patients treated with target volume‐based plans from 2011‐2012 were selected for comparison (Group II). Treatment plans were constructed based on clinical landmarks (Group I) or TVs (Group II) to a median dose of 50.4 Gy to the breast/chest wall, axilla (Ax), supraclavicular (SCV), and internal mammary (IMN) lymph nodes. The RTOG TVs were then contoured in Group I patients by a single investigator blinded to the dose distributions. Dose‐volume histograms (DVH) were computed for the RTOG TVs and OARs in both groups, and DVH parameters were compared. In Group II, coverage improved for the SCV (V90=78.0% versus 93.6%, p=0.02) and intact breast (V95=95.6% versus 99.3%, p=0.007). The dose to the cord, the lung (V20Gy and V30Gy), and contralateral breast (V5Gy) were the same. Finally, the low dose to the heart and lung was decreased in Group II (heart V5Gy=48.7% versus 27.3%, p=0.02, heart V10Gy=33.5% vs. 17.5%, p=0.01, and ipsilateral lung V5Gy=84.5% vs. 69.3%, p=0.001). Overall, our study supports that treatment planning using the RTOG consensus guidelines can improve coverage to certain target volumes compared to treatments based solely on clinical landmarks. Additionally, treatment planning using these target volumes does not increase dose to the contralateral breast, cord, heart, or lungs. Longer follow‐up is needed to determine if using these target volumes will affect clinical outcomes.PACS number: 87.55.dk

Upper abdominal normal organ contouring guidelines and atlas: A Radiation Therapy Oncology Group consensus

PurposeTo standardize upper abdominal normal organ contouring guidelines for Radiation Therapy Oncology Group (RTOG) trials. Methods and MaterialsTwelve expert radiation oncologists contoured the liver, esophagus, gastroesophageal junction (GEJ), stomach, duodenum, and common bile duct (CBD), and reviewed and edited 33 additional normal organ and blood vessel contours on an anonymized patient computed tomography (CT) dataset. Contours were overlaid and compared for agreement using MATLAB (MathWorks, Natick, MA). S95 contours, defined as the binomial distribution to generate 95% group consensus contours, and normal organ contouring definitions were generated and reviewed by the panel. ResultsThere was excellent consistency and agreement of the liver, duodenal, and stomach contours, with substantial consistency for the esophagus contour, and moderate consistency for the GEJ and CBD contours using a Kappa statistic. Consensus definitions, detailed normal organ contouring recommendations and high-resolution images were developed. ConclusionsConsensus contouring guidelines and a CT image atlas should improve contouring uniformity in radiation oncology clinical planning and RTOG trials.

Pelvic Normal Tissue Contouring Guidelines for Radiation Therapy: A Radiation Therapy Oncology Group Consensus Panel Atlas

To define a male and female pelvic normal tissue contouring atlas for Radiation Therapy Oncology Group (RTOG) trials. One male pelvis computed tomography (CT) data set and one female pelvis CT data set were shared via the Image-Guided Therapy QA Center. A total of 16 radiation oncologists participated. The following organs at risk were contoured in both CT sets: anus, anorectum, rectum (gastrointestinal and genitourinary definitions), bowel NOS (not otherwise specified), small bowel, large bowel, and proximal femurs. The following were contoured in the male set only: bladder, prostate, seminal vesicles, and penile bulb. The following were contoured in the female set only: uterus, cervix, and ovaries. A computer program used the binomial distribution to generate 95% group consensus contours. These contours and definitions were then reviewed by the group and modified. The panel achieved consensus definitions for pelvic normal tissue contouring in RTOG trials with these standardized names: Rectum, AnoRectum, SmallBowel, Colon, BowelBag, Bladder, UteroCervix, Adnexa_R, Adnexa_L, Prostate, SeminalVesc, PenileBulb, Femur_R, and Femur_L. Two additional normal structures whose purpose is to serve as targets in anal and rectal cancer were defined: AnoRectumSig and Mesorectum. Detailed target volume contouring guidelines and images are discussed. Consensus guidelines for pelvic normal tissue contouring were reached and are available as a CT image atlas on the RTOG Web site. This will allow uniformity in defining normal tissues for clinical trials delivering pelvic radiation and will facilitate future normal tissue complication research.