A Prospective Study of Machine Learning-Assisted Radiation Therapy Planning for Patients Receiving 54 Gy to the Brain.

PURPOSE: The capacity for machine learning (ML) to facilitate radiation therapy (RT) planning for primary brain tumors has not been described. We evaluated ML-assisted RT planning with regard to clinical acceptability, dosimetric outcomes, and planning efficiency for adults and children with primary brain tumors. METHODS AND MATERIALS: In this prospective study, children and adults receiving 54 Gy fractionated RT for a primary brain tumor were enrolled. For each patient, one ML-assisted RT plan was created and compared with 1 or 2 plans created using standard ("manual") planning procedures. Plans were evaluated by the treating oncologist, who was blinded to the method of plan creation. The primary endpoint was the proportion of ML plans that were clinically acceptable for treatment. Secondary endpoints included the frequency with which ML plans were selected as preferable for treatment, and dosimetric differences between ML and manual plans. RESULTS: A total of 116 manual plans and 61 ML plans were evaluated across 61 patients. Ninety-four percent of ML plans and 93% of manual plans were judged to be clinically acceptable (P = 1.0). Overall, the quality of ML plans was similar to manual plans. ML plans comprised 34.5% of all plans evaluated and were selected for treatment in 36.1% of cases (P = .82). Similar tumor target coverage was achieved between both planning methods. Normal brain (brain minus planning target volume) received an average of 1 Gy less mean dose with ML plans (compared with manual plans, P < .001). ML plans required an average of 45.8 minutes less time to create, compared with manual plans (P < .001). CONCLUSIONS: ML-assisted automated planning creates high-quality plans for patients with brain tumors, including children. Plans created with ML assistance delivered slightly less dose to normal brain tissues and can be designed in less time.

Paediatric radiation therapy without anaesthesia - Are the children moving?

PURPOSE: Children who require radiation therapy (RT) should ideally be treated awake, without anaesthesia, if possible. Audiovisual distraction is a known method to facilitate awake treatment, but its effectiveness at keeping children from moving during treatment is not known. The aim of this study was to evaluate intrafraction movement of children receiving RT while awake. METHODS: In this prospective study, we measured the intrafraction movement of children undergoing treatment with fractionated RT, using pre- and post-RT cone beam CT (CBCT) with image matching on bony anatomy. Study CBCTs were acquired at first fraction, weekly during RT, and at last fraction. The primary endpoint was the magnitude of vector change between the pre- and post-RT scans. Our hypothesis was that 90 % of CBCT acquisitions would have minimal movement, defined as <3 mm for head-and-neck (HN) treatments and <5 mm for non-HN treatments. RESULTS: A total of 65 children were enrolled and had evaluable data across 302 treatments with CBCT acquisitions. Median age was 11 years (range, 2-18; 1st and 3rd quartiles 7 and 14 years, respectively). Minimal movement was observed in 99.4 % of HN treatments and 97.2 % of non-HN treatments. The study hypothesis of >90 % of evaluations having minimal movement was met. Children who were age >11 years moved less at initial evaluation but tended to move more as a course of radiation progressed, as compared to children who were younger. CONCLUSION: Children receiving RT with audiovisual distraction while awake had small magnitudes of observed intrafraction movement, with minimal movement in >97 % of observed RT fractions. This study validates methods of anaesthesia avoidance using audiovisual distraction for selected children.

Late Cardiac Toxic Effects Associated With Treatment Protocols for Hodgkin Lymphoma in Children.

Importance: Contemporary North American trials for children with Hodgkin lymphoma (HL) have decreased radiation therapy (RT) use and increased pharmacologic cardioprotection but also increased the cumulative doxorubicin dose, making overall treatment consequences for late cardiac toxic effects uncertain. Objective: To estimate the risk of cardiac toxic effects associated with treatments used in modern pediatric HL clinical trials. Design, Setting, and Participants: For this cohort study, Fine and Gray models were fitted using survivors in the Childhood Cancer Survivor Study who were diagnosed with HL between January 1, 1970, and December 31, 1999, and were followed for a median of 23.5 (range, 5.0-46.3) years. These models were applied to the exposures in the study population to estimate the 30-year cumulative incidence of cardiac disease. The study population comprised patients with intermediate-risk or high-risk HL treated in 4 consecutive Children's Oncology Group clinical trials from September 2002 to October 2022: AHOD0031, AHOD0831, AHOD1331, and S1826. Data analysis was performed from April 2020 to February 2023. Exposures: All patients received chemotherapy including doxorubicin, and some patients received mediastinal RT, dexrazoxane, or mediastinal RT and dexrazoxane. Main Outcomes and Measures: Estimated 30-year cumulative incidence of grade 3 to 5 cardiac disease. Results: The study cohort comprised 2563 patients, with a median age at diagnosis of 15 (range, 1-22) years. More than half of the patients were male (1357 [52.9%]). All 2563 patients received doxorubicin, 1362 patients (53.1%) received mediastinal RT, and 307 patients (12.0%) received dexrazoxane. Radiation therapy use and the median mean heart dose among patients receiving RT decreased, whereas the planned cumulative dose of doxorubicin and use of dexrazoxane cardioprotection increased. For patients treated at age 15 years, the estimated 30-year cumulative incidence of severe or fatal cardiac disease was 9.6% (95% CI, 4.2%-16.4%) in the AHOD0031 standard treatment group (enrolled 2002-2009), 8.6% (95% CI, 3.8%-14.9%) in the AHOD0831 trial (enrolled 2009-2012), 8.2% (95% CI, 3.6%-14.3%) in the AHOD1331 trial (enrolled 2015-2019), and 6.2% (95% CI, 2.7%-10.9%) in the S1826 trial (enrolled 2019-2022), whereas the expected rate in an untreated population was 5.0% (95% CI, 2.1%-9.3%). Despite the estimated reduction in late cardiac morbidity, the frequency of recommended echocardiographic screening among survivors will increase based on current guidelines. Conclusions and Relevance: In this cohort study of sequential HL trials, reductions in the proportion of children receiving mediastinal RT and increases in dexrazoxane use were estimated to offset the increased doxorubicin dose and produce a net reduction in late cardiac disease. Further studies on dexrazoxane are warranted to confirm whether its role in reducing cardiac toxic effects is maintained long term. These findings suggest that survivorship follow-up guidelines should be refined to align with the risks associated with treatment.

Proton Therapy Mediates Dose Reductions to Brain Structures Associated With Cognition in Children With Medulloblastoma.

PURPOSE: Emerging evidence suggests proton radiation therapy may offer cognitive sparing advantages over photon radiation therapy, yet dosimetry has not been compared previously. The purpose of this study was to examine dosimetric correlates of cognitive outcomes in children with medulloblastoma treated with proton versus photon radiation therapy. METHODS AND MATERIALS: In this retrospective, bi-institutional study, dosimetric and cognitive data from 75 patients (39 photon and 36 proton) were analyzed. Doses to brain structures were compared between treatment modalities. Linear mixed-effects models were used to create models of global IQ and cognitive domain scores. RESULTS: The mean dose and dose to 40% of the brain (D40) were 2.7 and 4.1 Gy less among proton-treated patients compared with photon-treated patients (P = .03 and .007, respectively). Mean doses to the left and right hippocampi were 11.2 Gy lower among proton-treated patients (P < .001 for both). Mean doses to the left and right temporal lobes were 6.9 and 7.1 Gy lower with proton treatment, respectively (P < .001 for both). Models of cognition found statistically significant associations between higher mean brain dose and reduced verbal comprehension, increased right temporal lobe D40 with reduced perceptual reasoning, and greater left temporal mean dose with reduced working memory. Higher brain D40 was associated with reduced processing speed and global IQ scores. CONCLUSIONS: Proton therapy reduces doses to normal brain structures compared with photon treatment. This leads to reduced cognitive decline after radiation therapy across multiple intellectual endpoints. Proton therapy should be offered to children receiving radiation for medulloblastoma.

A User's Guide and Summary of Pediatric Normal Tissue Effects in the Clinic (PENTEC): Radiation Dose-Volume Response for Adverse Effects After Childhood Cancer Therapy and Future Directions.

Pediatric Normal Tissue Effects in the Clinic (PENTEC) is an international multidisciplinary effort that aims to summarize normal-tissue toxicity risks based on published dose-volume data from studies of children and adolescents treated with radiation therapy (RT) for cancer. With recognition that children are uniquely vulnerable to treatment-related toxic effects, our mission and challenge was to assemble our group of physicians (radiation and pediatric oncologists, subspecialists), physicists with clinical and modeling expertise, epidemiologists, and other scientists to develop evidence-based radiation dosimetric guidelines, as affected by developmental status and other factors (eg, other cancer therapies and host factors). These quantitative toxicity risk estimates could serve to inform RT planning and thereby improve outcomes. Tandem goals included the description of relevant medical physics issues specific to pediatric RT and the proposal of dose-volume outcome reporting standards to inform future studies. We created 19 organ-specific task forces and methodology to unravel the wealth of data from heterogeneous published studies. This report provides a high-level summary of PENTEC's genesis, methods, key findings, and associated concepts that affected our work and an explanation of how our findings may be interpreted and applied in the clinic. We acknowledge our predecessors in these efforts, and we pay homage to the children whose lives informed us and to future generations who we hope will benefit from this additional step in our path forward.

Comparative effectiveness of salvage chemotherapy regimens and chimeric antigen T-cell receptor therapies in relapsed and refractory diffuse large B cell lymphoma: a network meta-analysis of clinical trials.

The optimal salvage chemotherapy regimen (SC) for relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) prior to autologous stem cell transplant remains unclear. Moreover, although chimeric antigen receptor T cell (CAR-T) therapies were recently approved for primary refractory DLBCL, head-to-head comparisons are lacking. We searched MEDLINE, EMBASE and CENTRAL to July 2022, for randomized trials that enrolled adult patients with R/R DLBCL and performed network meta-analyses (NMA) to assess the efficacy of SC and CAR-T therapies. NMA of SC (6 trials, 7 regimens, n = 1831) indicated that rituximab with gemcitabine, dexamethasone, cisplatin (R-GDP) improved OS and PFS over compared regimens. NMA of 3 CAR-T trials (n = 865) indicated that both axi-cel and liso-cel improved PFS over standard of care, with no difference in OS. Our results indicate that R-GDP may be preferred for R/R DLBCL over other SC compared. Longer follow-up is required for ongoing comparative survival analysis as data from CAR-T trials matures.

Prognostic value of chest x-ray- and CT-defined large mediastinal adenopathy in high-risk pediatric Hodgkin lymphoma: A report from the Children's Oncology Group Study AHOD0831.

PURPOSE/OBJECTIVE: We compared the prognostic value of chest radiograph (CXR)- and computed tomography (CT)-derived definition of large mediastinal adenopathy (LMA) in pediatric Hodgkin lymphoma (HL). MATERIALS/METHODS: Total 143 patients treated for stage IIIB/IVB HL on COG AHOD0831 were included in this study. Six definitions of LMA were investigated: (i) mediastinal mass ratio on CXR (MRCXR ) > 1/3; (ii) mediastinal mass ratio on CT (MRCT ) > 1/3; (iii) mediastinal mass volume on CT (MVCT ) > 200 mL; (iv) normalized mediastinal mass volume (MVCT /thoracic diameter [TD]) > 1 mL/mm; (v) mediastinal mass diameter on CT (MDCT ) > 10 cm; and (vi) normalized mediastinal mass diameter (MDCT /TD) > 1/3. RESULTS: Median age at diagnosis was 15.8 years (range: 5.2-21.3 years). In patients with a slow early response (SER) to chemotherapy, MVCT  > 200 mL, MDCT  > 10 cm, and MDCT /TD > 1/3 were associated with worse relapse-free survival (RFS) on MVA, while MRCXR  > 1/3, MRCT  > 1/3, and MVCT /TD > 1 mL/mm trended toward worse RFS; MDCT /TD was the most strongly prognostic for inferior RFS, with a hazard ratio of 6.41 for MDCT /TD > 1/3 versus ≤1/3 on MVA (p = .02). CONCLUSION: LMA according to MVCT  > 200 mL, MDCT  > 10 cm, and MDCT /TD > 1/3 is associated with poor prognosis in advanced-stage HL patients with SER. The normalized mediastinal diameter, MDCT /TD > 1/3 appears to be the strongest predictor of inferior RFS.

Importance of Central Imaging Review in a Pediatric Hodgkin Lymphoma Trial Using Positron Emission Tomography Response Adapted Radiation Therapy.

PURPOSE: We investigated the effects of central review of the interim fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scan response (iPET) assessment on treatment allocation in the risk-based, response-adapted, Children's Oncology Group study AHOD1331 (ClinicalTrials.gov identifier: NCT02166463) for pediatric patients with high-risk Hodgkin lymphoma. METHODS AND MATERIALS: Per protocol, after 2 cycles of systemic therapy, patients underwent iPET, with visual response assessment by 5-point Deauville score (DS) at their treating institution and a real-time central review, with the latter considered the reference standard. An area of disease with a DS of 1 to 3 was considered a rapid-responding lesion, whereas a DS of 4 to 5 was considered a slow-responding lesion (SRL). Patients with 1 or more SRLs were considered iPET positive, whereas patients with only rapid-responding lesions were considered iPET negative. We conducted a predefined exploratory evaluation of concordance in iPET response assessment between institutional and central reviews of 573 patients. The concordance rate was evaluated using the Cohen κ statistic (κ > 0.80 was considered very good agreement and κ > 0.60-0.80, good agreement). RESULTS: The concordance rate (514 of 573 [89.7%]) had a κ of 0.685 (95% CI, 0.610-0.759), consistent with good agreement. In terms of the direction of discordance, among the 126 patients who were considered iPET positive by institutional review, 38 (30.2%) were categorized as iPET negative by central review, preventing overtreatment with radiation therapy. Conversely, among the 447 patients who were considered iPET negative by institutional review, 21 patients (4.7%) were categorized as iPET positive by the central review and would have been undertreated without radiation therapy. CONCLUSIONS: Central review is integral to PET response-adapted clinical trials for children with Hodgkin lymphoma. Continued support of central imaging review and education about DS are needed.

Development and Validation of Risk Prediction Models for Coronary Heart Disease and Heart Failure After Treatment for Hodgkin Lymphoma.

PURPOSE: Previous efforts to predict absolute risk of treatment-related cardiovascular diseases (CVDs) have mostly focused on childhood cancer survivors. We aimed to develop prediction models for risk of coronary heart disease (CHD) and heart failure (HF) for survivors of adolescent/adult Hodgkin lymphoma (HL). METHODS: For model development, we used a multicenter cohort including 1,433 5-year HL survivors treated between 1965 and 2000 and age 18-50 years at HL diagnosis, with complete data on administered chemotherapy regimens, radiotherapy volumes and doses, and cardiovascular follow-up. Using cause-specific hazard models, covariate-adjusted cumulative incidences for CHD and HF were estimated in the presence of competing risks of death because of other causes than CHD and HF. Age at HL diagnosis, sex, smoking status, radiotherapy, and anthracycline treatment were included as predictors. External validation for the CHD model was performed using a Canadian cohort of 708 HL survivors treated between 1988 and 2004 and age 18-50 years at HL diagnosis. RESULTS: After a median follow-up of 24 years, 341 survivors had developed CHD and 102 had HF. We were able to predict CHD and HF risk at 20 and 30 years after treatment with moderate to good overall calibration and moderate discrimination (areas under the curve: 0.68-0.74), which was confirmed by external validation for the CHD model (areas under the curve: 0.73-0.74). On the basis of our model including prescribed mediastinal radiation dose, 30-year risks ranged from 4% to 78% for CHD and 3% to 46% for HF, depending on risk factors. CONCLUSION: We developed and validated prediction models for CHD and HF with good overall calibration and moderate discrimination. These models can be used to identify HL survivors who might benefit from targeted screening for CVD and early treatment for CVD risk factors.

A pilot study of machine-learning based automated planning for primary brain tumours.

PURPOSE: High-quality radiotherapy (RT) planning for children and young adults with primary brain tumours is essential to minimize the risk of late treatment effects. The feasibility of using automated machine-learning (ML) to aid RT planning in this population has not previously been studied. METHODS AND MATERIALS: We developed a ML model that identifies learned relationships between image features and expected dose in a training set of 95 patients with a primary brain tumour treated with focal radiotherapy to a dose of 54 Gy in 30 fractions. This ML method was then used to create predicted dose distributions for 15 previously-treated brain tumour patients across two institutions, as a testing set. Dosimetry to target volumes and organs-at-risk (OARs) were compared between the clinically-delivered (human-generated) plans versus the ML plans. RESULTS: The ML method was able to create deliverable plans in all 15 patients in the testing set. All ML plans were generated within 30 min of initiating planning. Planning target volume coverage with 95% of the prescription dose was attained in all plans. OAR doses were similar across most structures evaluated; mean doses to brain and left temporal lobe were lower in ML plans than manual plans (mean difference to left temporal, - 2.3 Gy, p = 0.006; mean differences to brain, - 1.3 Gy, p = 0.017), whereas mean doses to right cochlea and lenses were higher in ML plans (+ 1.6-2.2 Gy, p < 0.05 for each). CONCLUSIONS: Use of an automated ML method to aid RT planning for children and young adults with primary brain tumours is dosimetrically feasible and can be successfully used to create high-quality 54 Gy RT plans. Further evaluation after clinical implementation is planned.

Patterns of Initial Relapse from a Phase 3 Study of Response-Based Therapy for High-Risk Hodgkin Lymphoma (AHOD0831): A Report from the Children's Oncology Group.

PURPOSE: The Children's Oncology Group protocol AHOD0831, for pediatric patients with high-risk classical Hodgkin lymphoma (cHL), used response-adapted radiation fields, rather than larger involved-field radiation therapy (IFRT) that were historically used. This retrospective analysis of patterns of relapse among patients enrolled in the study was conducted to study the potential effect of a reduction in RT exposure. METHODS AND MATERIALS: From December 2009 to January 2012, 164 eligible patients under 22 years old with stage IIIB (43%) and stage IVB (57%) enrolled on AHOD0831. All patients received 4 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide (ABVE-PC). Those patients with a slow early response (SER) after the first 2 ABVE-PC courses were nonrandomly assigned to 2 intensification cycles with ifosfamide/vinorelbine before the final 2 ABVE-PC cycles. Response-adapted RT (21 Gy) was prescribed to initial areas of bulky disease and SER sites. Rapid early response (RER) sites without bulk were not targeted. Imaging studies at the time of progression or relapse were reviewed centrally for this retrospective analysis. Relapses were characterized with respect to site (initial, new, or both; and initial bulk or initial nonbulk), initial chemotherapy response, and radiation field (in-field, out-of-field, or both). RESULTS: Of the entire cohort, 140 patients were evaluable for the patterns of failure analyses. To investigate the pattern of failure, this analysis focuses on 23 patients who followed protocol treatment and suffered relapses at a median 1.05 years with 7.97-year median follow-up time. These 23 patients (11 RER and 12 SER) experienced a relapse in 105 total sites (median, 4; range, 1-11). Of the 105 relapsed sites, 67 sites (64%) occurred within an initial site of involvement, with 12 of these 67 sites (18%) at an initial site of bulky disease and 63 of these 67 relapses (94%) occurring in sites that were not fluorodeoxyglucose (FDG)-avid after 2 cycles of ABVE-PC (PET2-negative). Of the 105 relapsed sites, 34 sites (32%) occurred in a new site of disease (that would not have been covered by RT); and, overall, only 4 of 140 patients (2.8%) (occurring in 3 RER and 1 SER) experienced isolated out-of-field relapses that would have been covered by historical IFRT. CONCLUSIONS: For a cohort of high-risk patients with cHL patients, most failures occurred in nonbulky, initially involved sites, largely due to response-based consolidation RT delivered to patients with bulky disease. In this analysis, we discovered low rates of failures outside of these modern risk-adapted radiation treatment volumes. Also, FDG uptake on PET2 did not identify most relapse sites.

A Population-Based Study of COVID-19 Infection Among Childhood Cancer Survivors.

Childhood cancer survivors are known to be at risk of chronic co-morbidities, although their risk of COVID-19 infection remains uncertain. Understanding the risk of COVID-19 in this population is necessary to counsel survivors and inform potential mitigation strategies. The objective of this study was to determine whether the rates of COVID-19 infection differed between childhood cancer survivors and the general population. Administrative health care data from a population-based registry of children and adolescents diagnosed with cancer in Ontario, Canada, were linked with a universal health insurance registry and a repository of laboratory data. Rates of COVID-19 testing, test positivity and infection between March 1, 2020 and March 31, 2021 among childhood cancer survivors (n = 10 242) were compared to matched controls from the general population (n = 49 068). Compared to the general population, childhood cancer survivors were more likely to have COVID-19 testing (35.9% [95% CI, 34.5-37.4%] vs. 32.0% [95% CI, 31.4-32.6%]), but had a lower likelihood of positive COVID-19 result among those tested (4.3% [95% CI, 3.6-4.9%] vs. 5.5% [95% CI, 5.1-5.8%]) and a similar rate of infection among all subjects at risk (1.5% [95% CI, 1.3-1.8%] vs. 1.7% [95% CI, 1.6-1.9%]). These findings can inform counseling of survivors and clinician recommendations for this population.

Integration of Pediatric Hodgkin Lymphoma Treatment and Late Effects Guidelines: Seeing the Forest Beyond the Trees.

The successful integration of clinical trials into pediatric oncology has led to steady improvement in the 5-year survival rate for children diagnosed with Hodgkin lymphoma (HL). It is estimated that >95% of children newly diagnosed with HL will become long-term survivors. Despite these successes, survival can come at a cost. Historically, long-term survivors of HL have a high risk of late-occurring adverse health effects and increased risk of nonrelapse mortality compared with the general population. The recognition of late-occurring events paired with the decades of life remaining for children cured of HL have made paramount the need to develop effective treatments that minimize the risk of late toxicity. Toward this goal, multiple, dose-intense, risk- and response-based regimens that use lower cumulative doses of chemotherapy and radiation have been developed. Appropriate frontline treatment selection requires a level of familiarity with the efficacy, acute toxicity, convenience, and late effects of treatments that may be impractical for providers who infrequently treat children with HL. There is an increasing need for guideline developers to begin to merge considerations from both frontline treatment and survivorship guidelines into practical documents that integrate potential long-term health risks. Herein, we take the first steps toward doing so by aligning cumulative treatment exposures, anticipated risks of late toxicity, and suggested surveillance recommendations for NCCN-endorsed Pediatric HL Guidelines. Future studies that integrate simulation modeling will strengthen this integrated approach and allow for opportunities to incorporate regimen-specific risks, health-related quality of life, and cost-effectiveness into decision tools to optimize HL therapy.

Intellectual changes after radiation for children with brain tumors: which brain structures are most important?

BACKGROUND: The objective of this study was to evaluate the contribution of radiation dose to different intracranial structures on changes in intellectual function for children with brain tumors. METHODS: We evaluated children with brain tumors treated in 2005-2017 who had longitudinal neuropsychological assessments and available photon dosimetric data (if radiation therapy [RT] given). Full Scale Intelligence Quotient (FSIQ) and index scores were evaluated (perceptual reasoning index [PRI], processing speed index [PSI], verbal comprehension index [VCI], and working memory index [WMI]). Multivariable linear mixed effects models were used to model endpoints, with age at RT and dose to different brain regions as fixed effects and patient-specific random intercepts. P-values (P*) were adjusted for multiple comparisons. RESULTS: Sixty-nine patients were included, 56 of whom received RT. Median neuropsychological follow-up was 3.2 years. Right temporal lobe mean dose was strongly associated with decline in FSIQ (P* = 0.005); with each gray increase in mean dose, there was a decrease of 0.052 FSIQ points per year. Dose to 50% (D50) of the supratentorial brain was associated with decline in PSI (P* = 0.006) and WMI (P* = 0.001). Right and left hippocampus D50 were individually strongly associated with declines in VCI (P* = 0.009 for each). Presence of a ventriculoperitoneal shunt decreased FSIQ by 10 points. CONCLUSIONS: We reported associations between dosimetry to specific brain regions and intellectual outcomes, with suggested avoidance structures during RT planning. These models can help clinicians anticipate changes in neurocognition post-RT and guide selection of an optimal RT plan.

Dose-response relationships for radiation-related heart disease: Impact of uncertainties in cardiac dose reconstruction.

BACKGROUND AND PURPOSE: Radiation-related heart disease (RRHD) can occur many decades after thoracic radiotherapy for Hodgkin lymphoma (HL) or childhood cancer (CC). To quantify the likely risk of RRHD for patients treated today, dose-response relationships derived from patients treated in previous decades are used. Publications presenting these dose-response relationships usually include estimates of uncertainties in the risks but ignore the effect of uncertainties in the reconstructed cardiac doses. MATERIALS/METHODS: We assessed the systematic and random uncertainties in the reconstructed doses for published dose-response relationships for RRHD risk in survivors of HL or CC. Using the same reconstruction methods as were used in the original publications, we reconstructed mean heart doses and, wherever possible, mean left-ventricular doses for an independent case-series of test patients. These patients had known, CT-based, cardiac doses which were compared with the reconstructed doses to estimate the magnitude of the uncertainties and their effect on the dose-response relationships. RESULTS: For all five reconstruction methods the relationship between reconstructed and CT-based doses was linear. For all but the simplest reconstruction method, the dose uncertainties were moderate, the effect of the systematic uncertainty on the dose-response relationships was less than 10%, and the effects of random uncertainty were small except at the highest doses. CONCLUSIONS: These results increase confidence in the published dose-response relationships for the risk of RRHD in HL and CC survivors. This may encourage doctors to use these dose-response relationships when estimating individualised risks for patients-an important aspect of personalising radiotherapy treatments today.

Practice patterns and recommendations for pediatric image-guided radiotherapy: A Children's Oncology Group report.

This report by the Radiation Oncology Discipline of Children's Oncology Group (COG) describes the practice patterns of pediatric image-guided radiotherapy (IGRT) based on a member survey and provides practice recommendations accordingly. The survey comprised of 11 vignettes asking clinicians about their recommended treatment modalities, IGRT preferences, and frequency of in-room verification. Technical questions asked physicists about imaging protocols, dose reduction, setup correction, and adaptive therapy. In this report, the COG Radiation Oncology Discipline provides an IGRT modality/frequency decision tree and the expert guidelines for the practice of ionizing image guidance in pediatric radiotherapy patients.

Minimizing General Anesthetic Use in Pediatric Radiation Therapy.

PURPOSE: At our institution, a multifaceted approach is used to reduce general anesthetic (GA) use for children receiving photon radiation therapy (RT) as standard-of-care treatment. The purpose of this study was to evaluate the effectiveness of our methods. METHODS AND MATERIALS: Patients treated as part of the pediatric radiation therapy program from 2010 to 2018 were retrospectively reviewed. GA use was defined as need for intravenous propofol or inhaled gaseous anesthetic for at least 1 simulation or RT session. Methods to reduce GA use included presence of a dedicated pediatric nurse for procedural preparation, audiovisual distraction (television during RT), and 2-way audio communication with caregivers. RESULTS: There were 779 unique patients who received RT over 14 163 fractions of radiation. GA utilization was 90% in those under age 3, 28% in those age 3 to 6, 1% in those age 7 to 11, and <1% in those ≥12 years of age. Four years of age is a cutoff age at which the majority of patients switch from needing GA (56.6% for those aged 3) to not needing GA (29.8% for those aged 4). Younger age, use of total body irradiation, and craniospinal irradiation were independently associated with requiring GA. CONCLUSIONS: Using methods designed to reduce GA use, most children aged 4 years or older were able receive RT awake. Our GA rates compare favorably to other literature reports; thus, pediatric RT centers should consider adopting specific interventions to reduce GA use.