Optimal Radiation Dose Research Articles

Contrast-enhanced CT Lymphangiography for Various Central Lymphatic Disorders.

Lymphatic leakage, manifesting as chylothorax or chylous ascites, arises from traumatic or nontraumatic causes and poses severe risks such as malnutrition and increased infection susceptibility. Accurate diagnosis and an effective treatment strategy necessitate comprehensive lymphatic imaging. Conventional lymphangiography and dynamic contrast-enhanced MR lymphangiography (DCMRL) have been widely used and studied as effective lymphatic imaging methods. Recently, CT lymphangiography (CTL) has been successfully implemented in animal studies and some patients, and the authors' institution now prioritizes CTL over DCMRL. Contrast-enhanced CTL offers a promising alternative, with advantages such as better accessibility and faster imaging. These advantages of CTL over traditional methods highlight its superior accessibility and fast acquisition time. Moreover, to reduce and optimize radiation dose, the stepwise propagation scanning method in CTL could be used, which is especially beneficial in pediatric patients. In this review, the authors suggest the protocol for CTL and interpretation methods for evaluation and therapeutic planning of central lymphatic disorders, focusing on the condition of lymphatic leakage. ©RSNA, 2024 The slide presentation from the RSNA Annual Meeting is available for this article.

Effects of electron beam irradiation on the sensory qualities and bioactive compounds of broccoli sprout juice

This study investigates the effects of electron beam irradiation at varying doses on the bioactive compounds and sensory qualities and of broccoli sprout juice (BSJ). A comprehensive analysis of volatile flavor components using GC-IMS and GC–MS identified 49 compounds, including esters, aldehydes, and olefins. Notably, the sulforaphane content exhibited a strong negative correlation with irradiation intensity (R2 = 0.9596), which is critical for predicting the impact of irradiation dose on sulforaphane degradation. Statistical analysis confirmed that 34 volatile compounds, like methyl acetate, 2-methylbutanal, hexanoic acid ethyl ester, etc., exhibited significant difference in different irradiation doses groups (P < 0.05). Sensory evaluation revealed that 6 kGy was the optimal irradiation dose, enhancing the sweetness and mushroom aroma while reducing undesirable spicy flavors. These findings provide valuable insights for balancing preservation techniques, sensory qualities, and nutritional integrity in BSJ, offering potential applications in both food and medicinal industries.

Optimum radiation dose for palliation in head and neck squamous cell carcinoma (OpRAH) – A phase 3 randomized controlled trial

PurposeRadiotherapy is frequently employed for palliative treatment in locally advanced head and neck squamous cell carcinoma (HNSCC) but radiation dose fractionation regimens are not well-defined. We designed this phase 3 randomized controlled trial to compare two weekly hypo fractionated regimes and study the effect on progression-free survival (PFS) in this subset of patients. Materials and MethodsNon-metastatic locally advanced HNSCC patients (n = 305) who were not suitable for curative treatment were randomized to Arm A (20 Gy/5#/5 days) and Arm B (30 Gy/5#/5 days). PFS and OS were recorded along with acute toxicity using patient-reported quality of life HN QLQ 43. ResultsFrom April 2020 to August 2023, 390 patients were randomized, of which 305 were eligible for final analysis. At a median follow-up of 13.9 months, PFS and median overall survival (OS) for the entire cohort was 7.4 and 10.03 months, respectively. PFS (p-0.553) and OS (p-0.203) did not differ significantly between the two groups. Toxicity rates were similar between the two arms and dose escalation was well tolerated. Patients with a better PS were found to have significantly better OS. No significant benefit in OS or PFS was observed in patients who received neoadjuvant chemotherapy (NACT), underwent definitive conversion, or received palliative chemotherapy at progression. ConclusionThis is the largest phase 3 RCT to analyze the safety and efficacy of weekly palliative radiotherapy regimens and has not demonstrated further improvement with dose escalation

Prognostic significance of adjuvant therapy and specific radiation dosages in Taiwanese patients with oral cavity cancer and extra-nodal extension: a nationwide cohort study

BackgroundThe evidence for adjuvant chemoradiotherapy (CRT) of oral cavity squamous cell carcinoma (OCSCC) with extra-nodal extension (ENE) in National Comprehensive Cancer Network (NCCN) guidelines is derived from patients with head and neck cancer. The guidelines further suggest a radiation dose ranging from 6000 to 6600 cGy. In this nationwide study, we sought to evaluate the prognostic significance of adjuvant therapy and the specific radiation dosage in Taiwanese patients with pure OCSCC and ENE.MethodsA retrospective analysis of 1577 OCSCC patients with ENE who underwent resection and received adjuvant CRT or radiotherapy (RT) between January 2011 and December 2020 was conducted.ResultsMultivariable analysis revealed that adjuvant RT, more than four pathologically positive nodes, and radiation dosage below 6000 cGy were independent risk factors for unfavorable 5-year disease-specific survival (DSS) and overall survival (OS). Comparing patients who received CRT (n = 1453) to those treated with RT (n = 124) before and after propensity score (PS) matching, the 5-year outcomes were as follows: before PS matching, DSS (54% versus 30%, p < 0.0001), OS (42% versus 18%, p < 0.0001); after PS matching (n = 111 in each group), DSS (52% versus 30%, p = 0.0016), OS (38% versus 21%, p = 0.0019). For patients who underwent CRT, the 5-year outcomes for different radiation dose groups (6600 − 7000 cGy, n = 1155 versus 6000 − 6500 cGy, n = 199) were as follows: before PS matching, DSS (52% versus 54%, p = 0.1904), OS (43% versus 46%, p = 0.1610); after PS matching (n = 199 in each group), DSS (55% versus 54%, p = 0.8374), OS (46.5% versus 46.3%, p = 0.7578).ConclusionsFor OCSCC patients with ENE, our study shows CRT improved survivals than RT alone, underscoring the clinical significance of chemotherapy. Patients undergoing CRT with irradiation doses ranging from 6000 to 6500 cGy exhibited comparable survival outcomes to those receiving doses of 6600–7000 cGy. This observation suggests that irradiation doses exceeding the 6600 cGy may not confer the survival advantage in these patients. Further research is needed to confirm our results and explore the optimal irradiation dose for managing these patients.

Oligotrophic state reduces the time dependence of the observed survival fraction for heavy ion beam-irradiated Saccharomyces cerevisiae and provides new insights into DNA repair.

Heavy ion beam (HIB) irradiation is widely utilized in studies of cosmic rays-induced cellular effects and microbial breeding. Establishing an accurate dose-survival relationship is crucial for selecting the optimal irradiation dose. Typically, after irradiating logarithmic-phase cell suspensions with HIB, the survival fraction (SF) is determined by the ratio of clonal-forming units in irradiated versus control groups. However, our findings indicated that SF measurements were time sensitive. For the Saccharomyces cerevisiae model, the observed SF initially declined and subsequently increased in a eutrophic state; conversely, in an oligotrophic state, it remained relatively stable within 120 minutes. This time effect of SF observations in the eutrophic state can be ascribed to HIB-exposed cells experiencing cell cycle arrest, whereas the control proliferated rapidly, resulting in an over-time disproportionate change in viable cell count. Therefore, an alternative involves irradiating oligotrophic cells, determining SF thereafter, and transferring cells to the eutrophic state to facilitate DNA repair-mutation. Transcriptomic comparisons under these two trophic states yield valuable insights into the DNA damage response. Although DNA repair was postponed in an oligotrophic state, cells proactively mobilized specific repair pathways to advance this process. Effective nutritional supplementation should occur within 120 minutes, beyond this window, a decline in SF indicates an irreversible loss of repair capability. Upon transition to the eutrophic state, S. cerevisiae swiftly adapted and completed the repair. This study helps to minimize time-dependent variability in SF observations and to ensure effective damage repair and mutation in microbial breeding using HIB or other mutagens. It also promotes the understanding of microbial responses to complex environments.IMPORTANCEMutation breeding is a vital means of developing excellent microbial resources. Consequently, understanding the mechanisms through which microorganisms respond to complex environments characterized by mutagens and specific physiological-biochemical states holds significant theoretical and practical values. This study utilized Saccharomyces cerevisiae as a microbial model and highly efficient heavy ion beam (HIB) radiation as a mutagen, it revealed the time dependence of observations of survival fractions (SF) in response to HIB radiation and proposed an alternative to avoid the indeterminacy that this variable brings. Meanwhile, by incorporating an oligotrophic state into the alternative, this study constructed a dynamic map of gene expression during the fast-repair and slow-repair stages. It also highlighted the influence of trophic states on DNA repair. The findings apply to the survival-damage repair-mutation effects of single-celled microorganisms in response to various mutagens and contribute to elucidating the biological mechanisms underlying microbial survival in complex environments.

Abdominal Applications of Photon-Counting CT.

Photon-counting computed tomography (PCCT) has shown promising advancements in abdominal imaging in clinical use. Though more peer-reviewed primary literature is needed, this commentary explores PCCT's potential applications, focusing on enhancing diagnostic accuracy, optimizing radiation dose management, and improving patient care. PCCT offers improved spatial and contrast resolution, lower image noise, and reduced radiation dose. Increased spatial resolution provides better detail in abdominal imaging, aiding in the detection of small lesions and subtle pathological changes. However, this generates more images per scan, raising concerns about "image overload" in PACS, potentially leading to longer reading times and increased stress for radiologists. PCCT's improved contrast resolution enhances tissue differentiation, reducing the need for intravenous contrast agents. The technology's advanced tissue characterization provides several advantages, such as non-invasive and opportunistic liver disease evaluation and improved differentiation of renal and adrenal masses. PCCT's optimized radiation dose management is crucial for patients requiring frequent scans. Enhanced diagnostic accuracy through spectral information aids in tissue differentiation, improving confidence in diagnoses. Streamlined workflows, particularly in emergency settings, and oncologic imaging, are potential benefits, reducing the need for additional imaging studies. Future integration of PCCT into clinical practice requires collaboration, education, and research to fully harness its potential, ensuring optimized abdominal imaging and improved patient care.

Metabolomics approach to exploring the effects of changes in substance composition induced by different irradiation doses on the sensory quality of saozi

In order to ensure the quality of saozi and expand its usage scenarios, it is necessary to determine the appropriate dose of irradiation. Non-targeted metabonomics method was used to explore the influence of changes in composition induced by different irradiation doses on the sensory characteristics of saozi. With increased irradiation dose (0, 2, 5, and 8 kGy), the TBARS value of saozi increased, whereas aroma, taste, and overall acceptability scores of saozi significantly decreased (p < 0.05). A total of 147 differential components including amino acids, organic acids, fatty acids, purines, and pyrimidines were screened from different irradiation doses of saozi. Twenty significant change pathways were identified in the KEGG enrichment results, most of which involve amino acids, nucleotide substances, acidic substances, among others, indicating that radiation-induced changes in these substances were one of the main reasons affecting the sensory scores of saozi. Considering the sensory scores and changes in the composition of saozi, when using cobalt 60 for the irradiation treatment of saozi, the optimal irradiation dose should be less than 5 kGy.

Computed Tomography Diagnostic Reference Levels for Routine Pediatric Examinations in Saudi Arabia: A Systematic Review.

This work aims to review the diagnostic reference levels reported for pediatric patients who underwent routine CT exams in Saudi Arabia. The literature search was conducted in prominent search engines,including PubMed, Science Direct, Google Scholar, EBSCO, ProQuest, and Saudi Digital Library (SDL), which serve as important sources in the fields of radiology, radiography, and medical physics. The search was conducted to identify previous studies that have reported diagnostic reference levels (DRLs) for pediatric CT examinations. Only studies that specifically assessed DRLs in pediatric patients were considered for inclusion. On careful evaluation, eight publications were ultimately chosenout of the 31 that were originally considered. An assessment was made on the volume computed tomographic dose index (CTDIvol) and the dose-length product (DLP) values. The reported range of mean values for DLP (mGy.cm) included in this review for brain, chest, abdomen, abdomen and pelvis, and CAP (chest,abdomen,and pelvis) was 172-1881, 27.3-458.9, 94.5-790.1, 78-236, and 94.2, respectively. Moreover, the reported range of mean values for CTDIvol (mGy) included in this review for the brain, chest, abdomen, abdomenand pelvis, and CAP were 11.7-79.9, 1.2-20.1, 7.4-22.6, 2.6-5.5, and 3.6, respectively. The review emphasizes the need for standardized imaging protocols and DRLsin pediatric CT examinations to optimize radiation doses and patient safety. It recommends the development of annually reviewed comprehensive national DRLs in Saudi Arabia and improved training for technologists and physicians involved in pediatric CT imaging.

429 - Early Radiation Dose Warning System Improves Patient Safety And Radiation Dose Optimization In Neuro Interventional Procedures At Professor Ngoerah Public Hospital, Bali, Indonesia

429 - Early Radiation Dose Warning System Improves Patient Safety And Radiation Dose Optimization In Neuro Interventional Procedures At Professor Ngoerah Public Hospital, Bali, Indonesia

Quality Control Procedure of Different Parameters of X-Rays System and Optimization of Radiation Doses to the Patient

Quality control helps radio-diagnostic facilities achieve appropriate radiological information with little dose and cost. In this study, quality control tests included Kilovoltage kVp accuracy and reproducibility, KVp and timer reproducibility, taking voltage verses radiation doses checking and reproducibility, milliampere(mA) and timer linearity, milliampere second mAs reproducibility and output doses verses mAs, light-radiation collimator integrity, Perpendicularity, and HVL These results were compared to established methods. A certified physicist should do this test. Equipment functionality was determined via the status test. This was done shortly following the acceptance test. The test is repeated after repair that affects functional status, like the acceptance test. A certified physicist performs the status test, which involves absolute measurements. All processes at AECH DINAR D.I. Khan were within acceptable limits.

Establishing Diagnostic Reference Levels for Single-Photon Emission Computed Tomography (SPECT) Imaging: A Preliminary Study in Indian Healthcare Settings.

Introduction In nuclear medicine, there is a critical need to balance the control and optimization of radiation doses to ensure patient safety while achieving high-quality diagnostic outcomes. However, diagnostic reference levels (DRLs) for nuclear medicine imaging studies have not been established in India. This study aims to fill this gap by establishing institutional DRLs and assessing radiation dose data specifically for Nuclear Medicine SPECT examinations. Methods This research was a cross-sectional observational study conducted in a single tertiary care setting, involving 1,250 patients. Data on the administered activity for 18 common single photon emission computed tomography (SPECT) procedures were gathered from 2019 to 2021. The 75th percentile (Q3) was established as the baseline for the institutional DRLs. Furthermore, the study conducted comparative analyses with established international DRLs. Results The study proposed institutional DRLs based on 18 SPECT nuclear medicine imaging examinations. The highest Q3 DRLs were identified for 99mTc-sestamibi (1193 MBq), followed by 99mTc-methylene diphosphonate (747 MBq) and 99mTc-ethyl cysteinate dimer (608 MBq). The lowest DRL was recorded for 99mTc gastric emptying imaging (37 MBq). Comparisons with international DRLs indicated close alignment with European Association of Nuclear Medicine Medical Internal Radiation Dose guidelines, while DRLs set by the National Council on Radiation Protection and Measurements (NCRP) were identified as distinct in several key aspects when compared to other established DRLs. Conclusion This research marks a significant step toward standardizing SPECT procedure doses in India, contributing to improved patient safety and care in nuclear medicine. The established DRLs will enhance the optimization of administered activities, ensure adherence to international standards, and improve diagnostic quality while reducing radiation exposure. These institutional DRLs will serve as the foundation for developing a roadmap to establish national DRLs.

Optimal radiation dose intensity: low vs high dose in the neoadjuvant treatment of locally advanced esophageal cancer

Optimal radiation dose intensity: low vs high dose in the neoadjuvant treatment of locally advanced esophageal cancer

Low-dose 60Co-γ-ray irradiation promotes the growth of cucumber seedlings by inducing CsSAUR37 expression.

Cucumber (Cucumis sativus L.) is a major vegetable crop grown globally, with a cultivation history of more than 3000years. The limited genetic diversity, low rate of intraspecific variation, and extended periods of traditional breeding have resulted in slow progress in their genetic research and the development of new varieties. Gamma (γ)-ray irradiation potentially accelerates the breeding progress; however, the biological and molecular effects of γ-ray irradiation on cucumbers are unknown. Exposing cucumber seeds to 0, 50, 100, 150, 200, and 250Gy doses of 60Co-γ-ray irradiation, this study aimed to investigate the resulting phenotype and physiological characteristics of seedling treatment to determine the optimal irradiation dose. The results showed that low irradiation doses (50-100Gy) enhanced root growth, hypocotyl elongation, and lateral root numbers, promoting seedling growth. However, high irradiation doses (150-250Gy) significantly inhibited seed germination and growth, decreasing the survival rate of seedlings. More than 100Gy irradiation significantly decreased the total chlorophyll content while increasing the malondialdehyde (MDA) and H2O2 content in cucumber. Transcriptome sequencing analysis at 0, 50, 100, 150, 200, and 250Gy doses showed that gene expression significantly differed between low and high irradiation doses. Gene Ontology enrichment and functional pathway enrichment analyses revealed that the auxin response pathway played a crucial role in seedling growth under low irradiation doses. Further, gene function analysis revealed that small auxin up-regulated gene CsSAUR37 was a key gene that was overexpressed in response to low irradiation doses, promoting primary root elongation and enhancing lateral root numbers by regulating the expression of protein phosphatase 2Cs (PP2Cs) and auxin synthesis genes.

Optimization of CT radiation dose: Insight into DLP and CTDI

The computed tomography dose index (CTDI) and dose–length product (DLP) are critical for monitoring and optimizing radiation doses. CTDI estimates the dose per slice, whereas DLP calculates the total dose across the scanned area. These measures enhance consistency in dose assessments, make comparisons easier, and assist in keeping doses within regulatory limits. This article explores the functions of CTDI and DLP in CT imaging, focusing on their importance in dosage optimization and patient safety. Understanding and monitoring this information allows healthcare professionals to strike a compromise between high-quality imaging and reduced radiation exposure, assuring patient care and regulatory compliance.

Localized Radiotherapy for Classic Kaposi's Sarcoma: An Analysis of Lesion Characteristics and Treatment Response.

Classic Kaposi's sarcoma (CKS) is a rare malignancy with diverse clinical presentations, lacking a standard treatment. While localized therapies are commonly used for symptomatic lesions, radiotherapy (RT) has demonstrated effectiveness. This study aims to evaluate the efficacy of RT for treating skin lesions in CKS. A retrospective analysis was conducted on patients with KS treated between April 2012 and January 2024. In total, 69 lesions in 16 patients were included. Treatment response was defined as follows: complete response (CR) indicated the absence of clinically detectable skin lesions and symptoms; partial response (PR) was a reduction in lesion height by more than half or a lighter lesion color compared to before treatment. In-field recurrence was the appearance of new lesions within a previously irradiated field. Logistic regression analysis was used to investigate factors influencing response and in-field recurrence. The median follow-up period was 52 months (range, 3-138 months). The overall response rate was 100%, with 92.8% of the patients achieving CR and 7.2% receiving PR. PR was observed in three patients with five lesions, all of which remained stable. In-field recurrence occurred in two patients with initially advanced disease, and all recurrent lesions responded to RT. No variables were significantly associated with response or in-field recurrence. RT for CKS showed a 100% response rate, with complete symptom relief in all cases. The effectiveness of RT was evident, even in cases involving disseminated lesions. Further research is needed to determine the optimal RT dose and fractionation.

Radiation dose and image quality optimization in lumbar spine digital radiography for overweight and obese patients: Phantom study

Background: Lumbar spine radiography plays an important role in routine use for clinical practice in overweight and obese patients. The radiographer is responsible for setting suitable exposure factors for the tradeoffs between radiation dose and image quality (IQ). Objective: To investigate the effect of different kVp values combined with AEC used on radiation dose and IQ for routine lumbar spine radiography in overweight and obese patients. Materials and methods: A 1.5 and 3 cm thickness of frozen pork lard was placed on a pelvis phantom to simulate an overweight and obese patient, respectively. The phantom was imaged at 10 kVp intervals in combination with AEC used. For IQ evaluation, CNR and SNR were calculated, and the observer study was determined using visual grading scores (VGS) with a 5-point Likert scale. The radiation dose was measured using a DAP meter, and then the figure of merit (FOM) was calculated. Results: SNR and CNR for both AP and lateral projection showed a slightly decreasing trend when kVp increased in all groups. The DAP values decreased when the higher kVp was selected with AEC used in each group. The VGS by five radiographers showed good image quality in all groups, while the FOM at 100 and 109 kVp was the highest score for both AP and lateral projections. Conclusion: The optimal kVp setting in this study ranged from 100 to 109 kVp in combination with AEC used, indicating minimal radiation dose, while maintaining diagnostic IQ.

Analisis Distribusi Dosis pada Treatment Planning System Pasien Kanker Payudara dengan Sumber Foton 6 MV pada Instalasi Radioterapi Rumah Sakit X

The internship at X Hospital aimed to gain practical experience as a medical physicist over two months, particularly in the treatment planning system activities in the radiotherapy unit. Additionally, this internship aimed to evaluate the Dose Volume Histogram (DVH) and analyze the effectiveness of the isodose lines. The treatment planning system is a simulation of cancer or tumor treatment using radiation with 3D conformal radiotherapy (3D-CRT) techniques. The patient study object was a woman with post-mastectomy breast cancer who was to undergo adjuvant curative therapy. The prescribed dose was 50 Gy, divided into 25 fractions, using a 6 MV photon source. The irradiation was conducted with four fields, gantry angle 129° with collimator angle 270°, 310° with collimator angle 90°, 130° with collimator angle 0°, and 270° with collimator angle 0°, field size 14 x 14 cm, and irradiation distance of 100 cm. The TPS simulation results indicated that the dose received by the Planning Target Volume (PTV) covered more than 90% of the target volume (special treatment), while the dose received by the Organ at Risk (OAR) tended to be below the threshold limit, and the isodose lines ensured optimal radiation dose distribution to the breast cancer target area. This was demonstrated by the DVH curve.

Radiation dose analysis in interventional neuroradiology of unruptured aneurysm cases

This study aimed to evaluate the radiation doses (peak skin dose (PSD) and bilateral lens dose) for each interventional neuroradiology procedure. A direct measurement system consisting of small radiophotoluminescence glass dosimeter chips and a dosimetry cap made of thin stretchable polyester was used for radiation dosimetry. The mean PSDs for each procedure were 1565 ± 590 mGy (simple technique coil embolization (STCE) cases), 1851 ± 825 mGy (balloon-assisted coil embolization (BACE) cases), 2583 ± 967 mGy (stent-assisted coil embolization (SACE) cases), 1690 ± 597 mGy (simple flow-diverter stenting (FDS) cases), and 2214 ± 726 mGy (FDS + coiling cases). The mean PSD was higher in SACE cases than in STCE, BACE, and simple FDS cases. Moreover, the PSD exceeded 2000 mGy and 3000 mGy in 46 (67.6%) and 19 (27.9%) SACE cases, respectively. The left lens doses for each procedure were 126 ± 111 mGy (STCE cases), 163 ± 152 mGy (BACE cases), 184 ± 148 mGy (SACE cases), 144 ± 60 mGy (simple FDS cases), and 242 ± 178 mGy (FDS + coiling cases). The left lens dose in SACE cases was higher than that in STCE cases and exceeded 500 mGy in 3 (4.4%) patients. In FDS + coiling cases, the mean PSD and left lens dose were 2214 ± 726 mGy and 242 ± 178 mGy, respectively. The left lens dose was higher than that in the STCE and BACE cases, with two (15.4%) patients receiving doses >500 mGy in FDS + coiling cases. The detailed data obtained in this study are expected to contribute to the promotion of radiation dose optimization.

481: OPRAH: Phase 3 trial of optimum radiation dose for palliation in head and neck carcinoma

481: OPRAH: Phase 3 trial of optimum radiation dose for palliation in head and neck carcinoma

Systematic Review and Meta-Analysis of Adjuvant Radiation Dose for Pediatric Patients (≤22 years) with Nonmetastatic Intracranial Ependymomas

Ependymomas are the third most common brain tumors in children. Standard of care is surgery followed by adjuvant radiotherapy. Controversy in the literature still exists over optimal radiotherapy dose. We completed a systematic review and meta-analysis to determine the optimal dose for local control (LC), event-free survival (EFS), and overall survival (OS) in pediatric patients. We searched MEDLINE (PubMed), Cochrane Database of Systematic Reviews, and Web of Science through January 2024. We included cohort studies that compared adjuvant radiotherapy of ≤54Gy to >54Gy in pediatric patients (≤22 years) with non-metastatic intracranial ependymomas. We assessed study quality using the Newcastle-Ottawa Quality Assessment Scale of Cohort Studies. We pooled studies using a random effects meta-analysis for hazard ratios (HR), 95% confidence intervals (CI), and assessed statistical heterogeneity via I2. When HRs were unavailable, we transformed risks using established methods. We narratively summarized qualitative outcomes. Seven studies met our inclusion criteria, covering a combined 1321 patients. Studies included a range of doses from 45-66.6Gy. Compared with >54Gy, we found no difference in LC for those receiving ≤54Gy (HR=0.83, 95% CI 0.56-1.24, I2=49.1%), in EFS (HR=1.02, 95% CI 0.95-1.09, I2=0.00%), and OS (HR=0.99, 95% CI 0.82-1.20, I2=37.5%). Two studies reported on subtotal resection by radiotherapy dose, neither study reporting statistical differences in LC, EFS, or OS, though the number of patients was small (n≤30). Five studies reported on late effects, with brainstem radionecrosis, radiation-induced vasculopathy, and secondary tumors being the most frequent. Overall study quality was high, though lower scores were consistently seen in comparability of cohorts. No studies reported on molecular subgroups. We found no difference in LC, EFS, or OS for those treated with ≤54Gy compared to >54Gy. There was insufficient data to complete a subgroup meta-analysis on radiotherapy dosing based on extent of resection or molecular subgroups.