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The use of radiation therapy (RT) for pancreatic cancer continues to be controversial, despite recent technical advances. Improvements in systemic control have created an evolving role for RT and the need for improved local tumor control, but currently, no standardized approach exists. Advances in stereotactic body RT, motion management, real-time image guidance, and adaptive therapy have renewed hopes of improved outcomes in this devastating disease with one of the lowest survival rates. This case-based guide provides a practical framework for delivering stereotactic body RT for locally advanced pancreatic cancer. In conjunction with multidisciplinary care, an intradisciplinary approach should guide treatment of the high-risk cases outlined within these guidelines for prospective peer review and treatment safety discussions., Competing Interests: Disclosures Christopher H. Crane receives consulting fees from Trisalis and honoraria from Elekta and has stock options in Oncternal. Karyn A. Goodman serves on the advisory board of RenovoRx and leadership in the NCI GI Steering Committee. Percy Lee receives consulting fees from Varian, ViewRay, AstraZeneca, Genentech, Johnson & Johnson, RTOG Foundation, honoraria from Varian, ViewRay, AstraZeneca, and travel support from Radiosurgery Society; serves on the advisory board for Genentech, ViewRay, AstraZeneca, Roche, and leadership of Radiosurgery Society, ASTRO. Michael D. Chuong receives grants, consulting fees, honoraria, and travel support from ViewRay, and serves on the advisory board of ViewRay., (Copyright © 2024 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: External beam radiation therapy (EBRT) is a highly effective treatment in select patients with hepatocellular carcinoma (HCC). However, the Barcelona Clinic Liver Cancer system does not recommend the use of EBRT in HCC due to a lack of sufficient evidence and intends to perform an individual patient level meta-analysis of ablative EBRT in this population. However, there are many types of EBRT described in the literature with no formal definition of what constitutes "ablative." Thus, we convened a group of international experts to provide consensus on the parameters that define ablative EBRT in HCC., Methods and Materials: Fundamental parameters related to dose, fractionation, radiobiology, target identification, and delivery technique were identified by a steering committee to generate 7 Key Criteria (KC) that would define ablative EBRT for HCC. Using a modified Delphi (mDelphi) method, experts in the use of EBRT in the treatment of HCC were surveyed. Respondents were given 30 days to respond in round 1 of the mDelphi and 14 days to respond in round 2. A threshold of ≥70% was used to define consensus for answers to each KC., Results: Of 40 invitations extended, 35 (88%) returned responses. In the first round, 3 of 7 KC reached consensus. In the second round, 100% returned responses and consensus was reached in 3 of the remaining 4 KC. The distribution of answers for one KC, which queried the a/b ratio of HCC, was such that consensus was not achieved. Based on this analysis, ablative EBRT for HCC was defined as a BED10 ≥80 Gy with daily imaging and multiphasic contrast used for target delineation. Treatment breaks (eg, for adaptive EBRT) are allowed, but the total treatment time should be ≤6 weeks. Equivalent dose when treating with protons should use a conversion factor of 1.1, but there is no single conversion factor for carbon ions., Conclusions: Using a mDelphi method assessing expert opinion, we provide the first consensus definition of ablative EBRT for HCC. Empirical data are required to define the a/b of HCC., Competing Interests: Disclosures Ted K. Yanagihara reports grants or contracts from the Radiation Oncology Institute and Lineberger Comprehensive Cancer Center; serving as an expert independent reviewer for the North Carolina Medical Board; and serving as an American Board of Radiology Maintenance of Certification online longitudinal assessment senior reviewer. Andrew M. Moon reports grants or contracts from the American Association for the Study of Liver Diseases, the American College of Gastroenterology, and the National Institutes of Health; consulting feeds from Target RWE; and serving on the American Association for the Study of Liver Diseases Practice Guidelines Committee. Aisling Barry reports honoria from Eisai. Ferran Torres reports grants or contracts from the Hospital Clinic Barcelona (IDIBAPS); consulting fees from Universal DX; and participation in the data safety monitoring board/advisory board of the Hospital Clinic Barcelona with partial support from Bayer. Daniel T. Chang reports grants or contracts from RefleXion Medical, ViewRay, Inc, Varian Medical Systems; honoraria for presentation from Varian Medical Systems; support for attending meetings and travel from Varian Medical Systems; and participation on data safety monitoring board for the SMART trial for ViewRay. Chandan Guha reports grants or contracts from the NIH, Janssen and Celldex; consulting fees from Janssen; participation in the data safety monitoring board or advisory board of the Focused Ultrasound Foundation; and is a founder of BioConvergent Health. Morten Hoyer reports honoraria from Novo Nordisk. Lisa Kachnic reports receiving grants or contracts from Varian Medical Systems; serving as an editor for UpToDate; participation on the data safety monitoring committee for Beta Innovations; and is a board member of the Radiation Therapy Oncology Group. Eugene J. Koay reports funding from the Department of Defense and National Institutes of Health; grants or contracts from Philips Healthcare, GE Healthcare, Stand up to Cancer, Project Purple, Elekta, Department of Defense; royalties from Taylor and Francis, LLC; consulting fees from RenovoRx, AstraZeneca, Augmenix, and Kallisio; honoraria for lectures from Apollo Cancer hospitals in Chnnai India, Bayer Healthcare, Philips Healthcare, and Aptitude Health; a patent pending for 3-dimensional printed oral stents; serving on the scientific medical advisory board of the International Cholangiocarcinoma Research Network; and stock ownership of Quantum Aurea Capital. Joel Mases reports grants or contracts from Boston Scientific and royalties or licenses from Springer and UpToDate. Pablo Munoz-Schuffenegger reports grants or contracts from the National Fund for Scientific and Technological Development, National Commission for Scientific and Technological Research, Government of Chile; honoraria for lectures from Bayer and Roche Pharma AG; serving on an advisory board for AstraZeneca; and serving on the advanced radiation therapy committee, International Association for the Study of Lung Cancer. Dawn Owen reports payment from UpToDate and receipt of goods/services from AstraZeneca and Varian Medical Systems. Marta Scorsetti reports grants or contracts from Varian Medical Systems, Sofar, and IPSEN. Jenniefer Y. Wo reports grants or contracts from Genentech. Maria Reig reports grants or contracts from Bayer, Ipsen, and ISCII; serving as a consultant or on advisory boards and/or receiving travel support from Bayer, BMS, Roche, Ipsen, AstraZeneca, Eisai, Geneos Therapeutics, UniveralDx, MSD and Lilly; receiving lecture fees from Bayer, BMS, Gilead, AstraZeneca, ROCHE and Lilly; receiving support for attending meetings and/or travel from Bayer, BMS, Roche, Ipsen, AstraZeneca, Eisai, MSD, and Lilly; and serving as EASL representative in UEG. Laura A. Dawson reports serving as chair of ASTRO., (Copyright © 2023. Published by Elsevier Inc.)

Purpose: Although arterial phase enhancement is commonly used to evaluate treatment response for hepatocellular carcinoma, it may not accurately describe response for lesions treated with stereotactic body radiation therapy (SBRT). We aimed to describe the post-SBRT imaging findings to better inform the optimal timing of salvage therapy after SBRT., Methods and Materials: We retrospectively reviewed patients with hepatocellular carcinoma treated with SBRT from 2006 to 2021 at a single institution with available imaging showing lesions with characteristic arterial enhancement and portal venous washout. Patients were then stratified into 3 groups based on treatment: (1) concurrent SBRT and transarterial chemoembolization, (2) SBRT only, and (3) SBRT followed by early salvage therapy due to persistent enhancement. Overall survival was analyzed with the Kaplan-Meier method, and cumulative incidences were calculated with competing risk analysis., Results: We included 82 lesions in 73 patients. The median follow-up time was 22.3 months (range, 2.2-88.1 months). The median time to overall survival was 43.7 months (95% confidence interval, 28.1-57.6 months) and median progression-free survival was 10.5 months (95% confidence interval, 7.2-14.0 months). There were 10 (12.2%) lesions that experienced local progression and there was no difference in rates of local progression between the 3 groups (P = .32). In the SBRT-only group, the median time to resolution of arterial enhancement and washout was 5.3 months (range, 1.6-23.7 months). At 3, 6, 9, and 12 months, 82%, 41%, 13%, and 8% of lesions, respectively, continued to show arterial hyperenhancement., Conclusions: Tumors treated with SBRT may continue to exhibit persistence of arterial hyperenhancement. Without an increase in size of enhancement, continued surveillance may be appropriate for these patients., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Trimodality therapy per the German Rectal Trial has led to excellent locoregional outcomes for locally advanced rectal cancer. Recent efforts have shifted toward improving distant control and health-related quality of life in this disease. To this end, total neoadjuvant therapy has become an increasingly used approach in which most, if not all, chemotherapy is delivered before surgery to improve compliance and to address micrometastases early. To avoid surgical morbidity, a "watch-and-wait" approach, in which total mesorectal excision is deferred, has also been studied for patients who achieve a clinical complete response after chemoradiation. These 2 concurrent treatment trends have raised many points of uncertainty in what used to be a relatively straightforward neoadjuvant treatment paradigm. We discuss here our approach to neoadjuvant therapy for locally advanced rectal cancer, based on the data we currently have and through shared decision-making with patients to help them select the treatment that best aligns with their preferences and values., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

In the recent guideline statement from the American Society of Clinical Oncology, experts reviewed relevant literature and provided treatment recommendations for multimodality treatment approaches. The guidelines recommend either preoperative concurrent neoadjuvant chemoradiotherapy (CRT) or perioperative chemotherapy for locally advanced adenocarcinoma and either preoperative CRT followed by esophagectomy or definitive CRT for squamous cell carcinoma. Whether radiation can be omitted in patients with adenocarcinoma or whether surgery can be omitted in patients with squamous cell carcinoma is a subject of ongoing debate and clinical trials., (Copyright © 2021 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: This guideline reviews the evidence and provides recommendations for the indications and appropriate technique and dose of neoadjuvant radiation therapy (RT) in the treatment of localized rectal cancer., Methods: The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the use of RT in preoperative management of operable rectal cancer. These questions included the indications for neoadjuvant RT, identification of appropriate neoadjuvant regimens, indications for consideration of a nonoperative or local excision approach after chemoradiation, and appropriate treatment volumes and techniques. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength., Results: Neoadjuvant RT is recommended for patients with stage II-III rectal cancer, with either conventional fractionation with concurrent 5-FU or capecitabine or short-course RT. RT should be performed preoperatively rather than postoperatively. Omission of preoperative RT is conditionally recommended in selected patients with lower risk of locoregional recurrence. Addition of chemotherapy before or after chemoradiation or after short-course RT is conditionally recommended. Nonoperative management is conditionally recommended if a clinical complete response is achieved after neoadjuvant treatment in selected patients. Inclusion of the rectum and mesorectal, presacral, internal iliac, and obturator nodes in the clinical treatment volume is recommended. In addition, inclusion of external iliac nodes is conditionally recommended in patients with tumors invading an anterior organ or structure, and inclusion of inguinal and external iliac nodes is conditionally recommended in patients with tumors involving the anal canal., Conclusions: Based on currently published data, the American Society for Radiation Oncology task force has proposed evidence-based recommendations regarding the use of RT for rectal cancer. Future studies will look to further personalize treatment recommendations to optimize treatment outcomes and quality of life., (Copyright © 2020 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Background: Signet ring cell carcinoma (SRCC) of the ampulla of Vater is poorly understood, with approximately 22 reported cases. Our study sought to create a comprehensive review of cases in the United States., Methods: We used the Surveillance, Epidemiology, and End Results Program to collect all cases of ampullary adenocarcinoma diagnosed between 2010 and 2015., Results: The age-adjusted incidence rate of SRCC of the ampulla of Vater was 1.2 cases per 10,000,000 persons per year, with 50% more cases in males than females. We identified 3448 cases of adenocarcinoma of the ampulla of Vater, 81 of which were SRCC (2.3%). SRCC tended to present a later stage than other ampullary cancers, with median survival times of 17 vs. 25 months, (p = 0.07). Survival was significantly worse for SRCC when accounting for other clinical features (HR 1.46, p = 0.01). Factors portending worse prognosis in SRCC of the ampulla of Vater were advanced age, late stage and lack of surgical intervention., Conclusion: Our study represents the largest study of SRCC of the ampulla of Vater to date. SRCC has a poorer prognosis compared with other ampullary cancers. Optimal treatment regimen is the most important future area of study., (Copyright © 2020 International Hepato-Pancreato-Biliary Association Inc. Published by Elsevier Ltd. All rights reserved.)

Purpose: Our purpose was to report the outcome of stereotactic ablative radiation therapy (SABR) to the primary tumor for patients with metastatic pancreatic cancer., Methods and Materials: We examined the records of patients with metastatic pancreatic cancer treated with SABR to the primary tumor between 2002 and 2018. Toxicities were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events Version 4.03. Pain intensity pre- and post-SABR was scored according to the Stanford Pain Scale as reported by the patient. Time-to-events were calculated from the date of end of SABR delivery., Results: In total, 27 patients were identified that met the inclusion criteria. Seventeen (63%) patients received single fraction SABR with a median dose of 25 Gy (range, 12.5-25), and 10 (37%) patients were treated in 5 fractions with a median dose of 33 Gy (range, 25-40). Before the start of SABR, 17 (63%) patients reported having abdominal pain, with a median intensity of 5 in the 0 to 10 pain scale (range, 1-9), 11 (41%) of them needing continuous opioid use. The median follow-up was 6 months (range, 0-18). Median overall survival was 7 months (95% confidence interval, 3-10), with a cumulative incidence of local failures at 1 year of 25% (95% confidence interval, 10-44). After SABR, there was a significant reduction in the mean intensity of pain (P = .01), and a 46% relative reduction in continuous opioid use. Only 2 patients (7%) presented a grade 3 toxicity that could be attributed to treatment., Conclusions: In this small series, SABR was a safe and effective option for the local palliation of metastatic pancreatic cancer, with measurable improvements in abdominal pain and the need for opioids., (Copyright © 2020 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: Nonrandomized data exploring pancreas stereotactic body radiation therapy (SBRT) has demonstrated excellent local control rates and low toxicity. Before commencing a randomized trial investigating pancreas SBRT, standardization of prescription dose, dose constraints, simulation technique, and clinical target volume delineation are required., Methods and Materials: Specialists in radiation oncology, medical oncology, hepatobiliary surgery, and gastroenterology attended 2 consecutive Australasian Gastrointestinal Trials Group workshops in 2017 and 2018. Sample cases were discussed during workshop contact with specifically invited international speakers highly experienced in pancreas SBRT. Furthermore, sample cases were contoured and planned between workshop contact to finalize dose constraints and clinical target volume delineation., Results: Over 2 separate workshops, consensus was reached on dose and simulation technique. The working group recommended a dose prescription of 40 Gy in 5 fractions. Treatment delivery during end-expiratory breath hold with triple-phase contrast enhanced computed tomography was recommended. In addition, dose constraints, stepwise contouring guidelines, and an anatomic atlas for pancreatic SBRT were developed., Conclusions: Pancreas SBRT is emerging as a promising treatment modality requiring prospective evaluation in randomized studies. This work attempts to standardize dose, simulation technique, and volume delineation to support the delivery of high quality SBRT in a multicenter study., (Copyright © 2019 American Society for Radiation Oncology. All rights reserved.)

Purpose: Germline variants in double-strand DNA damage repair (dsDDR) genes (e.g., BRCA1/2) predispose to pancreatic adenocarcinoma (PDAC) and may predict sensitivity to platinum-based chemotherapy and poly(ADP) ribose polymerase (PARP) inhibitors. We sought to determine the prevalence and significance of germline cancer susceptibility gene variants in PDAC with paired somatic and survival analyses., Methods: Using a customized next-generation sequencing panel, germline/somatic DNA was analyzed from 289 patients with resected PDAC ascertained without preselection for high-risk features (e.g., young age, personal/family history). All identified variants were assessed for pathogenicity. Outcomes were analyzed using multivariable-adjusted Cox proportional hazards regression., Results: We found that 28/289 (9.7%; 95% confidence interval [CI] 6.5-13.7%) patients carried pathogenic/likely pathogenic germline variants, including 21 (7.3%) dsDDR gene variants (3 BRCA1, 4 BRCA2, 14 other dsDDR genes [ATM, BRIP1, CHEK2, NBN, PALB2, RAD50, RAD51C]), 3 Lynch syndrome, and 4 other genes (APC p.I1307K, CDKN2A, TP53). Somatic sequencing and immunohistochemistry identified second hits in the tumor in 12/27 (44.4%) patients with germline variants (1 failed sequencing). Compared with noncarriers, patients with germline dsDDR gene variants had superior overall survival (hazard ratio [HR] 0.54; 95% CI 0.30-0.99; P = 0.05)., Conclusion: Nearly 10% of PDAC patients harbor germline variants, although the majority lack somatic second hits, the therapeutic significance of which warrants further study.

Purpose: This study aims to determine how the albumin-bilirubin (ALBI) score compares with the Child-Pugh (CP) score for assessing liver function following stereotactic body radiation therapy (SBRT)., Methods and Materials: In total, 60 patients, 40 with hepatocellular carcinoma (HCC) and 20 with cholangiocarcinoma (CCA), were treated with SBRT. Liver function panels were obtained before and at 1, 3, 6, and 12 months after SBRT. Laboratory values were censored after locoregional recurrence, further liver-directed therapies, or liver transplant., Results: A significant decline in hepatic function occurred after SBRT for HCC patients only (P = .001 by ALBI score; P < .0001 by CP score). By converting radiation doses to biologically equivalent doses by using a standard linear quadratic model using α/β of 10, the strongest dosimetric predictor of liver function decline for HCC was the volume of normal liver irradiated by a dose of 40 Gy when assessing liver function by the ALBI score (P = .07), and the volume of normal liver irradiated by a dose of 20 Gy by using the CP score (P= .0009). For CCA patients, the volume of normal liver irradiated by a dose of 40 Gy remained the strongest dosimetric predictor when using the ALBI score (P = .002), but no dosimetric predictor was significant using the CP score. Hepatic function decline correlated with worse overall survival for HCC (by ALBI, P = .0005; by CP, P < .0001) and for CCA (by ALBI, P = NS; by CP, P = .008)., Conclusions: ALBI score was similarly able to predict hepatic function decline compared with CP score, and both systems correlated with survival., (Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: Evaluation of local tumor progression (LP) has typically been defined by contrast-enhanced computed tomography (CT) imaging after stereotactic body radiation therapy (SBRT) for locally advanced pancreatic cancer (PDAC). The purpose of this study is to determine the benefit of adding 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging to CT for LP assessment of PDAC after SBRT., Methods and Materials: We retrospectively reviewed pretreatment, follow-up images, and outcomes of all patients treated with definitive SBRT for unresectable PDAC between December 2002 and December 2015 at our institution. For each patient, we independently analyzed LP both by CT and by FDG-PET criteria, using the Response Evaluation Criteria In Solid Tumors version 1.1 and the FDG-PET Response Evaluation Criteria In Solid Tumors version 1.0, respectively., Results: Among 206 patients treated with definitive SBRT for unresectable PDAC, we identified 30 with LP on follow-up. Four did not undergo follow-up FDG-PET. Median time to LP after SBRT was 7.5 months (range, 2-25 months). Of the 26 patients with LP who had follow-up FDG-PET, 21 were diagnosed by FDG-PET (80.7%), 14 by CT (53.8%), and 9 by both FDG-PET and CT (34.6%). Use of CT alone revealed only 53.8% of cases of LP detected when FDG-PET and CT were combined. The cumulative incidence of LP, based on competing risk of death, at 1 and 2 years after SBRT was 9.6% and 16.7% by CT and 11% and 29.1% by FDG-PET, respectively., Conclusion: FDG-PET increases the chance of detecting LP of unresectable PDAC after SBRT and can have an important impact on reported outcomes. We recommend obtaining FDG-PET to assess treatment response when evaluating efficacy of SBRT and taking its use into account when comparing clinical data., (Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: We previously reported clinical outcomes and physician-reported toxicity of gemcitabine and hypofractionated stereotactic body radiation therapy (SBRT) in locally advanced pancreatic cancer (LAPC). Here we prospectively investigate the impact of gemcitabine and SBRT on patient-reported quality of life (QoL)., Methods and Materials: Forty-nine LAPC patients received 33 Gy SBRT (6.6 Gy daily fractions) upfront or after ≤3 doses of gemcitabine (1000 mg/m 2 ) followed by gemcitabine until progression. European Organization for Research and Treatment of Cancer QoL core cancer (QLQ-C30) and pancreatic cancer-specific (European Organization for Research and Treatment of Cancer QLQ-PAN26) questionnaires were administered to patients pre-SBRT and at 4 to 6 weeks (first follow-up [1FUP]) and 4 months (2FUP) post-SBRT. Changes in QoL scores were deemed clinically relevant if median changes were at least 5 points in magnitude., Results: Forty-three (88%) patients completed pre-SBRT questionnaires. Of these, 88% and 51% completed questionnaires at 1FUP and 2FUP, respectively. There was no change in global QoL from pre-SBRT to 1FUP (P = .17) or 2FUP (P > .99). Statistical and clinical improvements in pancreatic pain (P = .001) and body image (P = .007) were observed from pre-SBRT to 1FUP. Patients with 1FUP and 2FUP questionnaires reported statistically and clinically improved body image (P = .016) by 4 months. Although pancreatic pain initially demonstrated statistical and clinical improvement (P = .020), scores returned to enrollment levels by 2FUP (P = .486). A statistical and clinical decline in role functioning (P = .002) was observed in patients at 2FUP., Conclusions: Global QoL scores are not reduced with gemcitabine and SBRT. In this exploratory analysis, patients experience clinically relevant short-term improvements in pancreatic cancer-specific symptoms. Previously demonstrated acceptable clinical outcomes combined with these favorable QoL data indicate that SBRT can be easily integrated with other systemic therapies and may be a potential standard of care option in patients with LAPC., (Copyright © 2016 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Objectives: The goal of the current study is to investigate the role of adjuvant radiation therapy (adjuvant RT) in minor salivary gland tumors (mSGT) using an established national database., Methods: The Surveillance, Epidemiology, and End Results (SEER) database was used to identify patients treated with or without adjuvant RT for mSGT from 1988 to 2008. Regression analyses were performed to identify factors associated with improved overall survival (OS)., Results: Most tumors were located within the oral cavity (75%) followed by nasal cavity/paranasal sinuses (15%). Multivariate Cox analysis showed that adjuvant RT was associated with better OS compared to surgery alone. Using logistic regression analysis, we provide a novel web based tool for predicting survival impact of adjuvant RT in patients with mSGT., Conclusions: Adjuvant RT is associated with improved survival in patients with mSGT and adverse clinicopathologic factors such as advanced T/N category, adenoid cystic histology, high grade, and nasopharynx location., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: To identify various dosimetric parameters of bone marrow cavity that correlate with acute hematologic toxicity (HT) in patients with anal squamous cell carcinoma treated with definitive chemoradiation therapy (CRT)., Methods and Materials: We analyzed 32 patients receiving CRT. The whole pelvic bone marrow (PBM) and the lumbosacral spine (LSS) subregion were contoured for each patient. Marrow cavities were contoured using the Hounsfield units (HUs) of 100, 150, 200, and 250 as maximum density threshold levels. The volume of each region receiving at least 5, 10, 15, 20, 30, and 40 Gy was calculated. The endpoint was grade ≥3 HT (HT3+). Normal-tissue complication probability (NTCP) was evaluated with the Lyman-Kutcher-Burman (LKB) model. Maximal likelihood estimate was used to compare the parameter set. Logistic regression was used to test associations between HT and both dosimetric and clinical parameters., Results: Ten patients (31%) experienced HT3+. While dose to both LSS and PBM significantly predicted for HT3+, LSS was superior to PBM by logistic regression and LKB modeling. Constrained optimization of the LKB model for HT3+ yielded the parameters m = 0.21, n = 1, and TD50 = 32 Gy for LSS. The NTCP fits were better with the whole bone than with marrow cavity using any HU threshold. Mean LSS doses of 21 Gy and 23.5 Gy result in a 5% and 10% risk of HT3+, respectively. Mean dose and low-dose radiation parameters (V5, V10, V15, V20) of whole bone or bone cavities of LSS were correlated most significantly with HT3+., Conclusions: For predicting the risk of HT3+, whole-bone contours were superior to marrow cavity and LSS was superior to PBM by LKB modeling. The results confirm PBM and LSS as parallel organs when predicting hematologic toxicity. Recommended dose constraints to the LSS are V10 ≤80%. An LSS mean dose of 23.5 Gy is associated with a 10% risk of HT., (Copyright © 2014 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: Metal artifacts can degrade computed tomographic (CT) simulation imaging and impair accurate delineation of tumors for radiation treatment planning purposes. We investigated a Digital Imaging and Communications in Medicine-based metal artifact reduction technique in tonsillar cancer delineation., Methods and Materials: Eight patients with significant artifact and tonsil cancer were evaluated. Each patient had a positron emission tomography (PET)-CT and a contrast-enhanced CT obtained at the same setting during radiotherapy simulation. The CTs were corrected for artifact using the metal deletion technique (MDT). Two radiation oncologists independently delineated primary gross tumor volumes (GTVs) for each patient on native (CTnonMDT), metal corrected (CTMDT), and reference standard (CTPET/nonMDT) imaging, 1 week apart. Mixed effects models were used to determine if differences among GTVs were statistically significant. Two diagnostic radiologists and 2 radiation oncologists independently qualitatively evaluated CTs for each patient. Ratings were on an ordinal scale from -3 to +3, denoting that CTMDT was markedly, moderately, or slightly worse or better than CTnonMDT. Scores were compared with a Wilcoxon signed-rank test., Results: The GTVPET/nonMDT were significantly smaller than GTVnonMDT (P = .004) and trended to be smaller than GTVMDT (P = .084). The GTVnonMDT and GTVMDT were not significantly different (P = .93). There was no significant difference in the extent to which GTVnonMDT or GTVMDT encompassed GTVPET/nonMDT (P = .33). In the subjective assessment of image quality, CTMDT did not significantly outperform CTnonMDT. In the majority of cases, the observer rated the CTMDT equivalent to (53%) or slightly superior (41%) to the corresponding CTnonMDT., Conclusions: The MTD modified images did not produce GTVMDT that more closely reproduced GTVPET/nonMDT than did GTVnonMDT. Moreover, the MTD modified images were not judged to be significantly superior when compared to the uncorrected images in terms of subjective ability to visualize the tonsilar tumors. This study failed to demonstrate value of the adjunctive use of a CT corrected for artifacts in the tumor delineation process. Artifacts do make tumor delineation challenging, and further investigation of other body sites is warranted., (Copyright © 2012 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate rectal motion and estimate an appropriate target volume for preoperative radiotherapy (RT) for rectal cancer., Methods: Between January 2006 and December 2009, 17 rectal cancer patients undergoing preoperative RT underwent 39 cone-beam computed tomographic scans (CBCTs). CBCTs were fused to treatment planning CT scans by bony anatomy. The rectum and bladder were contoured on each scan. Margins of 2, 5, 10, and 15 mm were added to the rectum, and the volume and percent rectum on CBCT outside each of these margins were determined. The clinical target volume (CTV) was examined to determine the necessary margin beyond the posterior bladder edge to ensure coverage of the mesorectum at all time points., Results: Median percentage rectum on CBCT outside the planning rectum was 7.77% (range, 0.19%-42.91%). Two patients had 1 or more CBCT with 1% or greater rectum outside a 1.5 cm margin. Five patients had 1 or more CBCT with 1% or greater rectum outside a 1.0 cm margin. A CTV extending 1 cm into the posterior bladder edge (CTV1.0) was adequate at all time points for 79% of evaluable patients, and a CTV with a 1.5 cm anterior margin was adequate for 93% of patients. For 2 patients, the rectum extended outside the CTV1.0 on CBCT., Conclusions: With a limited number of CBCT scans, we found that the rectum tended to remain within 1.5 cm of the initial location on treatment planning CT. However, an anterior margin of 1.5 cm beyond the posterior bladder edge provides better coverage of the mesorectum than 1 cm for the initial CTV., (Copyright © 2011 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)