External Beam Radiation Treatment Research Articles

Toxicity and Quality of Life After Locoregional Radiotherapy in Patients With Thyroid Cancer.

Locoregional external beam radiotherapy (EBRT) is selectively used in thyroid cancer patients to induce locoregional control. However, despite technological advances, EBRT remains associated with toxicities. We evaluated thyroid-cancer specific toxicities and long-term Quality of Life (QoL) post-EBRT. EBRT-treated thyroid cancer patients at Universal Medical Centre Groningen (2007-2023) were retrospectively evaluated (n = 66). Acute (< 6 weeks) and late (≥ 3 months) toxicities and QLQ-H&N35 results, prospectively collected as standard patient care, were analyzed (available in 24/66). Additionally, 17/66 living patients cross-sectionally completed the QLQ-H&N43 [renewed QLQ-H&N35] and SF-36-RAND-36. In 24/66 patients who completed questionnaires during EBRT treatment, most severe acute toxicities occurred around week 6 (91% dermatitis, 74% pain, 70% hoarseness, 65% dysphagia). Late toxicities included persisting acute toxicities and fibrosis. Six months post-treatment, only QLQ-H&N35 domains "social eating" (p = 0.031) and "dry mouth/sticky saliva" (p = 0.025) were affected, in comparison to pre-radiation. In the 10/17 patients who completed the QLQ-H&N35 6 months post-radiation and the cross-sectionally performed QLQ-H&N43, no long-term mitigation of assessed domains was identified in a longitudinal analysis. The most advanced EBRT technique was associated with better QLQ-H&N43 scores (p = 0.047). EBRT causes acute and late toxicities in most thyroid cancer patients and may be associated with a decreased QoL. As these patients generally survive for multiple years, there is a compelling need to minimize toxicities with more refined radiation techniques, such as proton therapy.

Reirradiation Practice in Gynecological Cancer: Insights from a National Survey in Spain.

Given the lack of standardisation in gynecological cancer reirradiation, the Gyneacologial Radiation Oncology (GINECOR) working group on behalf of the Spanish Society of Radiation Oncology (SEOR), works towards to inquire the current state of reirradiation practices among the radiation oncology departments in Spain. An online 37-question survey was sent to all GINECOR members, representing most Spanish centers. The survey addressed general aspects of reirradiation, including experience, reirradiation sites, and techniques used. It included seven clinical case scenarios on reirradiation, and a final section on technical aspects of external beam radiotherapy (EBRT) and brachytherapy (BT) treatment. Descriptive statistics were used for data analysis. Out of 58 centers, 29 responded, with 51.7% performing ≥ 5 reirradiation cases annually. While most centers offer multiple techniques, only 16/29 have access to BT. For in-field local relapse with surgery contraindicated, 79.3% performed BT in endometrial cancer, but only 27.5% treated with BT in cervical cancer recurrence. In this case, 17.2% used SBRT. For endometrial and cervical cancer, 44.8% and 65.4% of centers prescribed doses based on organ-at-risk tolerance, respectively. For pelvic wall/parametrial in-field relapse, 46.4% of the centres reirradiated with stereotactic body radiotherapy (SBRT), and 32.1% with BT. In nodal reirradiation, SBRT was preferred by 90% of centers. Variability was observed in target volume definitions for EBRT and proton therapy. Reirradiation for gynecological cancer remains unstandardized, presenting significant challenges in clinical practice. To improve reirradiation protocols in gynecological cancer, the GINECOR working group is currently conducting a systematic review and formulating Delphi recommendations.

On-Table Virtual Reality to Reduce Anxiety/Distress during Radiotherapy Treatments: A Pilot Randomized Trial.

We report the first randomized trial of a virtual reality (VR) headset used on-table during external beam radiotherapy treatments to reduce anxiety/distress during receipt of radiotherapy. A small pilot study was conducted among 10 patients, with VR randomized to start in the first week ('immediate VR') vs. second week ('delayed VR') of treatment. All patients (100%) in the immediate VR group had declines in measured distress scores after their first radiation treatment, compared to only 1 patient (16.7%) in the delayed VR group (P = .048), yet score declines generally did not meet the minimal clinically important difference threshold in the context of overall low distress scores at baseline. By day 5 of treatment, distress score changes were similar between immediate and delayed VR groups. Overall, 80% of patients in the study, including all patients with moderate or high level of baseline anxiety/distress, reported that on-table VR improved their radiotherapy experience and/or they would recommend VR to others. We propose that on-table VR is a readily-available, non-pharmacologic intervention that can be utilized to help reduce anxiety/distress associated with radiotherapy, and may be particularly helpful at the start of treatment among those with moderate/high baseline levels of anxiety/distress.

FLIP: a novel method for patient-specific dose quantification in circulating blood in large vessels during proton or photon external beam radiotherapy treatments

Purpose.To provide a novel and personalized method (FLIP, FLowand Irradiation Personalized) using patient-specific circulating blood flows and individualized time-dependent irradiation distributions, to quantify the dose delivered to blood in large vessels during proton or photon external beam radiotherapy.Methods.Patient-specific data were obtained from ten cancer patients undergoing radiotherapy, including the blood velocity field in large vessels and the temporal irradiation scheme using photons or protons. The large vessels and the corresponding blood flow velocities are obtained from phase-contrast MRI sequences. The blood dose is obtained discretizing the fluid into individual blood particles (BPs). A Lagrangian approach was applied to simulate the BPs trajectories along the vascular velocity field flowlines. Beam delivery dynamics was obtained from beam delivery machine measurements. The whole IS is split into a sequence of successive IEs, each one with its constant dose rate, as well as its corresponding initial and final time. Calculating the dose rate and knowing the spatiotemporal distribution of BPs, the dose is computed by accumulating the energy received by each BP as the time-dependent irradiation beams take place during the treatment.Results.Blood dose volume histograms from proton therapy and photon radiotherapy patients were assessed. The irradiation times distribution is obtained for BPs in both modalities. Two dosimetric parameters are presented: (i)D3%, representing the minimum dose received by the 3% of BPs receiving the highest doses, and (ii)V0.5 Gy, denoting the blood volume percentage that has received at least 0.5 Gy.Conclusion.A novel methodology is proposed for quantifying the circulating blood dose along large vessels. This methodology involves the use of patient-specific vasculature, blood flow velocity field, and dose delivery dynamics recovered from the irradiation machine. Relevant parameters that affect the dose received, as the distance between large vessels and CTV, are identified.

Multislit gamma camera for external beam radiotherapy assistance: Experimental proof of concept

The orthogonal computed tomography (OrthoCT) concept, based on orthogonal ray imaging, is a low-dose imaging technique currently under investigation to potentially aid in external-beam radiation therapy treatments. This technique involves detecting radiation scattered within the patient and emitted at approximately 90&amp;deg; from the direction of the incoming beam. This scattered radiation can be collected by a 1D-detector system with a multisliced collimator positioned perpendicular to the incident beam axis. Such a system holds promise for on-board imaging with the patient positioned and prepared for treatment, as well as for real-time treatment monitoring. In this study, a multi-slice OrthoCT detector prototype was developed and tested under in-beam irradiation. The system utilizes gadolinium orthosilicate scintillator crystals coupled to photomultiplier tubes and a collimator made of lead slices. Experimental measurements were conducted using a heterogeneous phantom made of acrylic with an air cavity inside. The phantom was irradiated with a TrueBeam linac operating at 6 MV in the flattening-filter-free mode. The findings of this study indicate that this innovative imaging technique is capable of providing morphological images of the phantom. This accomplishment is achieved without the need to rotate the X-ray source around the object to be irradiated, demonstrating the feasibility of such a system.

948: An assessment of Quality of Life following external beam radiotherapy treatment in Malta

948: An assessment of Quality of Life following external beam radiotherapy treatment in Malta

Qualitative exploration of patients’ experiences with Intrabeam TARGeted Intraoperative radioTherapy (TARGIT-IORT) and External-Beam RadioTherapy Treatment (EBRT) for breast cancer

ObjectiveTo gather a deep qualitative understanding of the perceived benefits and impacts of External-Beam RadioTherapy (EBRT) and TARGeted Intraoperative radioTherapy (TARGIT-IORT) using Intrabeam to assess how the treatments affected patient/care...

The carbon footprint of external beam radiotherapy and its impact in health technology assessment

BackgroundThe major drivers of carbon dioxide (CO2eq) emissions of external beam radiation therapy (EBRT) are not well known and limit our ability to initiate mitigation strategies. Material and methodsWe describe the carbon footprint of four typical centers. We explore direct EBRT associated factors such as the impact of fractionation and use of MRI-LINAC, as well as indirect factors (e.g. patient rides). Treatment strategy related CO2eq emissions are included in a health technology assessment analysis that takes into account CO2eq emissions. ResultsA typical EBRT treatment emits from 185 kgCO2eq to 2066 kgCO2eq. CO2eq emissions are mostly driven by (i) accelerator acquisition and maintenance (37.8 %), (ii) patients and workers rides (32.7 %), (iii) drugs and medical devices (7.3 %), (iv) direct energy consumption (6.1 %), and (v) building and bunker construction (5.6 %) with a substantial heterogeneity among centers. Hypofractionation has a strong impact to mitigate emissions. MRI-LINAC is associated with a substantial increase in CO2eq emissions per fraction and requires ultra hypofractionation in 5 fractions to achieve a similar carbon footprint compared to 20 fractions treatment schemes. The expected limited small increase in toxicities due to hypofractionation (when existing) are in the same range as avoided detrimental effects to future people’s health thanks to CO2eq mitigation. ConclusionCarbon footprint of EBRT is not neglectable and could be mitigated. When safely feasible, hypofractionation is one of the main factors to decrease this impact. Taking into account CO2eq emissions has a substantial impact on the health technology assessment of EBRT, favoring hypofractionated regimens.

Urinary Organs at Risk for Prostate Cancer External Beam Radiation Therapy: Contouring Guidelines on Behalf of the Francophone Group of Urological Radiation Therapy

PurposeOccurrence of genitourinary (GU) toxicity is a common adverse event observed after external beam radiotherapy (EBRT) for prostate cancer (PCa). Recent findings suggest that the dose delivered to specific urinary organs-at-risk (OARs) such as ureters, bladder trigone, and urethra is involved in the development of GU toxicity. Methods and materialsA multidisciplinary task force including three radiation oncologists, a uroradiologist, and a urologist was created in 2022. First, OARs potentially involved in GU toxicity were identified and discussed. A literature review was performed, addressing several questions relative to urinary OARs: anatomical and radiological definition, radiation-induced injury, dose-volume parameters. Secondly, results were presented and discussed with a panel of radiation oncologists, members of the “Francophone Group of Urological Radiation Therapy” (GFRU). Thereafter, GFRU experts were asked to answer a dedicated questionnaire, including 35 questions on the controversial issues related to the delineation of urinary OARs. ResultsThe following structures were identified as critical for PCa EBRT: ureters, bladder, bladder neck, bladder trigone, urethra (intraprostatic, membranous, spongious), striated sphincter, and post-enucleation or post-transurethral resection of the prostate (TURP) cavity. A consensus was obtained for 32 out of 35 items. ConclusionThis consensus highlights contemporary urinary structures in both upper and lower urinary tract to be considered for EBRT treatment planning of PCa. The current recommendations also propose a standardized definition of urinary OARs, for both daily practice and future clinical trials.

Improvement of accumulated dose distribution in combined cervical cancer radiotherapy with deep learning-based dose prediction.

Difficulties remain in dose optimization and evaluation of cervical cancer radiotherapy that combines external beam radiotherapy (EBRT) and brachytherapy (BT). This study estimates and improves the accumulated dose distribution of EBRT and BT with deep learning-based dose prediction. A total of 30 patients treated with combined cervical cancer radiotherapy were enrolled in this study. The dose distributions of EBRT and BT plans were accumulated using commercial deformable image registration. A ResNet-101-based deep learning model was trained to predict pixel-wise dose distributions. To test the role of the predicted accumulated dose in clinic, each EBRT plan was designed using conventional method and then redesigned referencing the predicted accumulated dose distribution. Bladder and rectum dosimetric parameters and normal tissue complication probability (NTCP) values were calculated and compared between the conventional and redesigned accumulated doses. The redesigned accumulated doses showed a decrease in mean values of V50, V60, and D2cc for the bladder (-3.02%, -1.71%, and -1.19 Gy, respectively) and rectum (-4.82%, -1.97%, and -4.13 Gy, respectively). The mean NTCP values for the bladder and rectum were also decreased by 0.02‰ and 0.98%, respectively. All values had statistically significant differences (p < 0.01), except for the bladder D2cc (p = 0.112). This study realized accumulated dose prediction for combined cervical cancer radiotherapy without knowing the BT dose. The predicted dose served as a reference for EBRT treatment planning, leading to a superior accumulated dose distribution and lower NTCP values.

Gene Abnormalities and Modulated Gene Expression Associated with Radionuclide Treatment: Towards Predictive Biomarkers of Response.

Molecular radiotherapy (MRT), also known as radioimmunotherapy or targeted radiotherapy, is the delivery of radionuclides to tumours by targeting receptors overexpressed on the cancer cell. Currently it is used in the treatment of a few cancer types including lymphoma, neuroendocrine, and prostate cancer. Recently reported outcomes demonstrating improvements in patient survival have led to an upsurge in interest in MRT particularly for the treatment of prostate cancer. Unfortunately, between 30% and 40% of patients do not respond. Further normal tissue exposure, especially kidney and salivary gland due to receptor expression, result in toxicity, including dry mouth. Predictive biomarkers to select patients who will benefit from MRT are crucial. Whilst pre-treatment imaging with imaging versions of the therapeutic agents is useful in demonstrating tumour binding and potentially organ toxicity, they do not necessarily predict patient benefit, which is dependent on tumour radiosensitivity. Transcript-based biomarkers have proven useful in tailoring external beam radiotherapy and adjuvant treatment. However, few studies have attempted to derive signatures for MRT response prediction. Here, transcriptomic studies that have identified genes associated with clinical radionuclide exposure have been reviewed. These studies will provide potential features for seeding multi-component biomarkers of MRT response.

Differences in real-world outcomes by risk classification for localized prostate cancer patients after radiation therapy.

Limited real-world evidence exists on the long-term clinical outcomes of patients with localized prostate cancer (LPC) who received external beam radiation therapy (EBRT) as the initial treatment. This study evaluated clinical outcomes of US patients with high-risk LPC (HR-LPC) and low/intermediate-risk LPC (LIR-LPC) who received EBRT. This retrospective study using Surveillance, Epidemiology, and End Results-Medicare linked data from 2012 to 2019 included patients ≥ 65 years old who received EBRT as initial therapy. Baseline patient characteristics were summarized, metastasis-free survival (MFS), overall survival, and time to initiation of advanced prostate cancer treatment were compared using Kaplan-Meier (KM) and adjusted Cox proportional hazard (PH) models. 5-year survival probabilities stratified by race/ethnicity (non-Hispanic [NH] White, NH Black, NH Asian, and Hispanic) were assessed. Of 11,313 eligible patients, 41% (n = 4600) had HR-LPC and 59% (n = 6713) had LIR-LPC. Patient characteristics for both groups were comparable, with mean age at EBRT initiation > 70 years, 86% white, and mean follow-up time >40 months. More patients in the HR-LPC than LIR-LPC groups (78% vs 34%) had concurrent androgen deprivation therapy use and for a longer duration (median 10.4 months vs. 7.4 months). A higher proportion of HR-LPC patients developed metastasis, died, or received advanced prostate cancer treatment. Adjusted Cox PH survival analyses showed significantly (p < 0.0001) higher risk of mortality (hazard ratios[HR], 1.57 [1.38, 2.34]), metastasis or death (HR, 1.97 [1.78, 2.17]), and advanced prostate cancer therapy use (HR, 2.57 [2.11, 3.14]) for HR-LPC than LIR-LPC patients. Within 5 years after the initial EBRT treatment, 18%-26% of patients with HR-LPC are expected to have died or developed metastasis. The 5-year MFS rate in the HR-LPC group was lower than the LIR-LPC group across all racial/ethnic subgroups. NH Black patients with HR-LPC had the highest all-cause mortality rate and lowest rate of receiving advanced prostate cancer treatment, compared to other racial/ethnic subgroups. This real-world study of clinical outcomes in patients with LPC treated with EBRT suggests substantial disease burden in patients with HR-LPC and highlights the need for additional treatment strategies to improve clinical outcomes in patients with HR-LPC.

Deep-Learning for Rapid Estimation of the Out-of-Field Dose in External Beam Photon Radiation Therapy – A Proof of Concept

Background and purpose: The dose deposited outside of the treatment field during external photon beam radiotherapy treatment, also known as out-of-field dose, is the subject of extensive study as it may be associated with a higher risk of developing a second cancer, and could have deleterious effects on the immune system which compromise the efficiency of combined radio-immunotherapy treatments. Out-of-field dose estimation tools developed today in research, including Monte Carlo simulations and analytical methods, are not suited to the requirements of clinical implementation because of their lack of versatility and their cumbersome application. We propose a proof of concept based on deep learning for out-of-field dose map estimation that addresses the above limitations.Materials and methods: For this purpose, a 3D U-Net, considering as inputs the in-field dose, as computed by the treatment planning system, and the patient's anatomy, was trained to predict out-of-field dose maps. The cohort used for learning and performance evaluation included 3151 pediatric patients from the [XXXX] database, treated in 5 clinical centers, whose whole-body dose maps were previously estimated with an empirical analytical method. The test set, composed of 433 patients, was split into 5 subdatasets, each containing patients treated with devices unseen during the training phase. Root mean square deviation (RMSD) evaluated only on non-zero voxels located in the out-of-field areas was computed as performance metric.Results: RMSD of 0.28 and 0.41 cGy.Gy−1 were obtained for the training and validation datasets, respectively. Values of 0.27, 0.26, 0.28, 0.30 and 0.45 cGy.Gy−1 were achieved for the 6 MV linac, 16 MV linac, Alcyon cobalt irradiator, Mobiletron cobalt irradiator, and betatron devices test sets, respectively.Conclusion: This proof-of-concept approach using a convolutional neural network has demonstrated unprecedented generalizability for this task, although it remains limited, and brings us closer to an implementation compatible with clinical routine.

Voxel-Level Dosimetry for Combined Iodine 131 Radiopharmaceutical Therapy and External Beam Radiation Therapy Treatment Paradigms for Head and Neck Cancer

PurposeTargeted radiopharmaceutical therapy (RPT) in combination with external beam radiotherapy (EBRT) shows promise as a method to increase tumor control and mitigate potential high-grade toxicities associated with re-treatment for patients with recurrent head and neck cancer. This work establishes a patient-specific dosimetry framework that combines Monte Carlo based dosimetry from the two radiation modalities at the voxel level using deformable image registration (DIR) and radiobiological constructs for patients enrolled in a phase I clinical trial combining EBRT and RPT. MethodsSerial SPECT/CT patient scans performed at approximately 24, 48, 72, and 168 hours post-injection of 577.2 MBq/m2 (15.6 mCi/m2) iodine-131 containing RPT agent called XXX 131. Clinical EBRT treatment plans were created on a treatment planning CT (TPCT) using RayStation; SPECT/CT images were deformably registered to the TPCT using the Elastix DIR module in 3D Slicer and assessed by measuring mean activity concentrations and absorbed doses. Monte Carlo EBRT dosimetry was computed using EGSnrc. RPT dosimetry was conducted using a GEANT4 based RPT dosimetry platform named XXX. Radiobiological metrics (BED, EQD2) were utilized to combine the two radiation modalities. ResultsThe DIR method provided good agreement for the activity concentrations and calculated absorbed dose in the tumor volumes for the SPECT/CT and TPCT; the maximum mean absorbed dose difference was -11.2%. Based on the RPT absorbed dose calculations, two to four EBRT fractions were removed from patients’ EBRT treatments. From the combined treatment, the absorbed dose to target volumes ranged from 57.14 – 75.02 Gy. When including partial volume corrections (PVC), the mean EQD2 to the PTV from EBRT+RPT was -3.11% to 1.40% different compared to EBRT alone. ConclusionThis work demonstrated the clinical feasibility of performing combined EBRT+RPT dosimetry on TPCTs. Dosimetry guides treatment decisions for EBRT and this work provides a bridge for the same paradigm to be implemented within the rapidly emerging clinical RPT space.

Developing a novel quasi-3D movable water phantom for radiation therapy workable in the magnetic resonance environment.

The use of magnetic resonance linear accelerators (MR-LINACs) for clinical treatment has opened up new possibilities and challenges in the field of radiation oncology. However, annual quality assurance (QA) is relatively understudied due to practical considerations. Thus, to overcome the difficulty of measuring the dose with a small water phantom for TRS-398 or TG-51 in all external beam radiation treatment unit environments, such as MR compatibility, we designed a remote phantom with a three-axis changeable capacity for QA. The designed water phantom was tested under an MR environment. The water phantom system comprised of three parts: a phantom box, a dose measurement tool, and a PMD401 drive system. The UNIDOSE universal dosimeter was used to collect beam data. The manufacturer's developer tools were utilized to position the measurement. To ensure magnetic field homogeneity, a distortion phantom was prepared using sixty fish oil capsules aligned radially to distinguish the oil and free air. The phantom was scanned in both the MR simulator and computed tomography (CT), and the acquired images were analyzed to determine the position shift. The dimensions of the device are 30 cm in the X-axis, 20 cm in the Y-axis, and 17 cm in the Z-axis. Total cost of materials was no more than $10,000 US dollars. Our results indicate that the device can function normally in a regular 1.5 T MR environment without interference from the magnetic field. The water phantom's traveling speed was found to be approximately 5 mm/s with a position difference confined within 6 cm intervals during normal use. The distortion test results showed that the prepared MR environment has uniform magnetic field homogeneity. In this study, we constructed a prototype water phantom device that can function in an MR simulator without interference between the magnetic field and electronic components. Compared to other commercially available MR-LINAC water phantoms, our device offers a more cost-effective solution for routine monthly QA. It can shorten the duration of QA tests and relieve the burden on medical physicists.

External beam radiotherapy in treatment of high-volume metastatic hormone-sensitive prostate cancer: clinical case

The standard treatment for metastatic hormone-sensitive prostate cancer does not include external beam radiotherapy (EBRT) and radionuclide therapy with radium-223.The article describes a clinical case of successful use of EBRT and radionuclide therapy with radium-223 in a patient with primary high-volume metastatic hormone-sensitive prostate cancer.The patient received diagnosis of prostate cancer сT3bN1M1b (Gleason score 8 (4 + 4)), stage IV (metastases in the bones, extraperitoneal and intrathoracic lymph nodes; prostate specific antigen (PSA) level was 4280 ng/mL). Between October of 2017 and January of 2018, the patient received 6 cycles of chemohormonal therapy (degarelix + docetaxel). Bilateral orchiectomy was performed on 05.02.2018, and the patient underwent palliative EBRT on cervical vertebrae between 04.10.2017 and 19.10.2017 with total dose of 32.6 Gy (equivalent to 38.5 Gy). The patient received systemic radiotherapy with one injection of samarium oxabifor (153Sm) 40 mCi (21.03.2018) and radium-223 (4 injections once a month (17.04.2018, 15.05.2018, 14.06.2018, 10.07.2018) + 2 injections 1 time per 3 months (October 2018, January 2019)). Partial response was achieved in the form of PSA decrease from 4280 ng/mL (September 2017) to 0.505 ng/mL (May 2019). Palliative EBRT for the prostate and pelvis was performed between 14.11.2018 and 19.12.2018 for total dose of 62.5 Gy (equivalent to 69 Gy). For 2 years remission was observed with PSA level of 0.3–0.5 ng/mL. In December of 2020, biochemical recurrence was diagnosed: PSA level increased from 0.61 ng/mL in October to 1.43 ng/mL on 28.12.2020. The second course of radionuclide therapy with radium-223 5,500 MBq/mL was performed (22.01.2021, 05.03.2021, 02.04.2021) with increase of PSA level to 1.92 ng/mL (May of 2021) and independent decrease to 0.542 ng/mL (June of 2022). In December of 2022, biochemical recurrence was observed with a small increase of PSA level to 1.67 ng/mL. Currently, the disease is stabilized.

PAEDIATRIC-15 MANAGEMENT OF PEDIATRIC CENTRAL NERVOUS SYSTEM TUMORS BY A NEURO-ONCOLOGY MULTIDISCIPLINARY TEAM : OUR EXPERIENCE

Abstract The outcome of pediatric central nervous system tumors has improved over the past decades due to advances in diagnostic testing, treatment and increased understanding of the disease biology. Nevertheless, the probability of survival of this tumors remains much lower in low-to middle-income countries. The gaps that prevent optimal clinical management of brain tumors are multifactorial and mostly related to underdiagnosis; a lack of specialized and dedicated radiologic, histopathologic, neurosurgical, radiotherapeutic, and oncology services, and a deficiency of coordinated multidisciplinary care in many centers. The aim of this report was to evaluate the impact of multidisciplinary team meetings on the clinical management of pediatric central nervous system tumors in Abidjan (Côte d'Ivoire). We retrospectively reviewed the clinical data of pediatric patients (aged &amp;lt;15 years) with central nervous system tumors diagnosed and treated in the Neurosurgery Department and National Center of Radiotherapy between 2019 (the year a neuro-oncological multidisciplinary staff was established) and 2023. Data on patient demographics, clinical notes, imaging studies, tumor characteristics and multidisciplinary team decision were collected from the multidisciplinary team database. During the multidisciplinary team meetings era, 40 pediatric central nervous system tumors were diagnosed and treated. The median age at diagnosis was 8.5 years. The mostly histological types were high grade and low grade gliomas. Decision-making was largely consistent with available guidelines. Therapeutic were surgery, external beam radiation treatment with concurrent and adjuvant chemotherapy. Benefits of neuro-oncology multidisciplinary team include coordination, direction for complicated cases, education, and a forum for communication, and clinical trials.

Predictive Value of Tumor Volume on Local Control in Hepatocellular Carcinoma Treated with Image Guided Hypofractionated Radiation Treatment

External beam radiation treatment (EBRT) is an important local treatment in liver-confined hepatocellular carcinoma (HCC) patients who are not candidates for curative therapy. EBRT dose, technique and prognostic factors are evolving. We hypothesized that tumor volume to liver volume ratio can be a predictor of local control (LC) in patients treated with hypo-fractionated radiation (HFRT) in HCC MATERIALS/METHODS: We retrospectively reviewed 50 patients of HCC treated with HFRT at our institution. HFRT schedule was chosen such that the radiation dose to the remaining liver and other organs at risk (OAR) met the standard dosimetric constraints. Image guided techniques were used for motion management, internal target volume (ITV) and planning target volume (PTV) delineation. Tumor to Liver Ratio (TLR) was defined as ratio of PTV volume to whole liver volume. TLR ≤ 0.3 was considered as low volume disease and TLR > 0.3 was considered as high-volume disease. The radiation dose ranged from 45 Gy to 67.5 Gy in 5 - 15 fractions. The biologically equivalent dose (BED) for tumor ranged from 58.5 Gy10 to 100 Gy10. Local control (LC) was evaluated by Kaplan-Meier analysis, with log-rank test for groups stratified as per TLR. Multivariate Cox regression analysis was performed to identify additional prognostic factors. The mean duration of follow-up was 24 months. The median age was 69 years (range 50 - 90) and 76% were males. 32 patients had CP-A class cirrhosis while 17 had CP-B and 1 had CP-C class. BCLC stage A, B, C and D was seen in 2, 14, 33 and 2 patients, respectively. Portal vein thrombosis was present in 9 patients and prior trans-arterial chemo embolization (TACE) was done in 23 patients. The median volume of PTV was 551 cc (range 52 - 1990 cc). The TLR ranged from 0.04 - 0.67 with a median of 0.29. The median BED radiation dose was 78.4 Gy10 (range - 58.5 Gy10 to 100 Gy10). Nine patients had local recurrence with overall LC rate of 82%. The LC was better in low volume tumors, with the TLR cut-off of 0.3 as a significant factor associated with LC (p = 0.007). The 1-year actuarial LC with TLR ≤ 0.3 was 88% as compared 61% in TLR of > 0.3 (p = 0.007). BED ≥60 Gy10 was associated with better 1 year LC as compared to BED < 60 Gy10 (89% vs 62%; p = 0.11). ALBI grade 1 was associated with better 1 year LC as compared to ALBI grade 2 (80% versus 75%; p = 0.40). On multivariate analysis, high volume disease and TLR >0.3 were significant prognostic factor for LC. HFRT has good 1-year local control of 82% in carefully selected unresectable HCC. Radiation with BED greater than 60 Gy10 and ALBI grade 1 showed a trend towards better LC. Smaller tumors had better LC with a PTV to liver ratio (TLR) of < 0.3. This information can help in identifying the poor responders, intensifying the radiation treatment and adding additional therapy to improve the oncological outcomes.

The Environmental Impact of Radiation Oncology: The "Footprint" of External Beam Radiation Therapy

There is a growing concern for the healthcare sector's impact on the environment. Prior carbon impact studies in radiation oncology have been limited in scope and methodology. This study aims to fill this gap by using an internationally recognized cradle-to-grave life cycle assessment (LCA) approach to quantify all environmental impacts from raw material extraction to product disposal for external beam radiation therapy (EBRT) in treating the most commonly diagnosed cancers. This LCA was performed in accordance with ISO 14040 and 14044 at a single academic medical center. It quantified the environmental impact of EBRT across four categories: global warming potential (GWP), carcinogenic and non-carcinogenic human toxicity, and respiratory effects (PM2.5), from initial consultation to the completion of the last EBRT fraction for each disease site. Data collection involved weighing all materials used, measuring/calculating building and equipment electricity usage (e.g., HVAC and Linacs), and recording patient and staff transit. The study analyzed the impact of both minimum and maximum fractionations for each disease site and simulated alternative clinical scenarios such as telemedicine, renewable energy use and hypofractionation. Regardless of disease site, there were significant differences in the environmental impacts associated with transit, electricity and supplies for EBRT treatment cycles. Staff and patient transport contributed the most, accounting for >92% of the total environmental impact including GWP (5.02x102 ± 9.38x101 kgCO2eq), carcinogenic (6.25x10-5 ± 1.23x10-5 CTUh) and non-carcinogenic human toxicity (1.16x10-4 ± 2.35x10-5 CTUh). Electricity accounted for 1-13% of the total impact, with most impact arising from respiratory effects (3.05x10-2 kg ± 2.72x10-3 PM2.5). The impact of supplies and materials was less than 3% across all categories. Alternative scenario modeling showed that telemedicine had a maximum impact reduction of 3.5% (2.54x 101kgCO2eq) for GWP, while renewable energy use had a maximum impact reduction of 8% (2.37 x 10-2 PM2.5) for respiratory effects. Reducing the number of total treatment days via hypofractionation can reduce GWP by 67-78% and carcinogenic emissions by 63-77% (3.48 x 102 - 5.53 x 102 kgCO2eq) and (3.73 x 10-5 - 6.85 x 10-5CTUh), respectively, with variation depending on the total number of fractions. This study provides a comprehensive environmental impact assessment for EBRT among the most commonly treated disease sites, establishing a baseline metric and identifying targets for impact reduction. We are currently performing a multi-center validation study to be completed by June 2023. Our findings fill an important gap in cancer care and are critical for developing sustainable practices in the face of increasing demand for radiotherapy in a changing climate. LCAs evaluating all aspects of cancer care will be essential for promoting equitable and sustainable care.

Evaluation of a Deep Learning-based Algorithm for Post-Radiotherapy Prostate Cancer Local Recurrence Detection Using Biparametric MRI

ObjectiveTo evaluate a biparametric MRI (bpMRI)-based artificial intelligence (AI) model for the detection of local prostate cancer (PCa) recurrence in patients with radiotherapy history. Materials and MethodsThis study included post-radiotherapy patients undergoing multiparametric MRI and subsequent MRI/US fusion-guided and/or systematic biopsy. Histopathology results were used as ground truth. The recurrent cancer detection sensitivity of a bpMRI-based AI model, which was developed on a large dataset to primarily identify lesions in treatment-naïve patients, was compared to a prospective radiologist assessment using the Wald test. Subanalysis was conducted on patients stratified by the treatment modality (external beam radiation treatment [EBRT] and brachytherapy) and the prostate volume quartiles. ResultsOf the 62 patients included (median age = 70 years; median PSA = 3.51 ng/ml; median prostate volume = 27.55 ml), 56 recurrent PCa foci were identified within 46 patients. The AI model detected 40 lesions in 35 patients. The AI model performance was lower than the prospective radiology interpretation (Rad) on a patient-(AI: 76.1% vs. Rad: 91.3%, p = 0.02) and lesion-level (AI: 71.4% vs. Rad: 87.5%, p = 0.01). The mean number of false positives per patient was 0.35 (range: 0–2). The AI model performance was higher in EBRT group both on patient-level (EBRT: 81.5% [22/27] vs. brachytherapy: 68.4% [13/19]) and lesion-level (EBRT: 79.4% [27/34] vs. brachytherapy: 59.1% [13/22]). In patients with gland volumes >34 ml (n = 25), detection sensitivities were 100% (11/11) and 94.1% (16/17) on patient- and lesion-level, respectively. ConclusionThe reported bpMRI-based AI model detected the majority of locally recurrent prostate cancer after radiotherapy. Further testing including external validation of this model is warranted prior to clinical implementation.