Photon Beam Radiotherapy Research Articles

Preoperative chemo-CIRT in Re/BRe pancreatic cancer: Insights from a multicenter prospective phase II clinical study (NCT03822936).

There is debate about the optimal management of borderline resectable (bRe) and resectable (Re) pancreatic ductal adenocarcinoma (PDAC). Both preclinical and clinical evidence showed that carbon ion radiotherapy (CIRT) produces superior control on radioresistant histologies compared to conventional photon beam radiotherapy (RT). However, so far there is a lack of data concerning the integration of CIRT in a multimodal approach with chemotherapy and surgery for bRe/Re. We recently presented the first analysis of a multicenter prospective phase II clinical study aimed at assessing the feasibility and effectiveness of a neoadjuvant chemotherapy + short course of CIRT followed by surgery and adjuvant chemotherapy in the management of bRe/Re PDAC. The study was terminated early due to low patient enrollment.Herein, we reported a post-hoc analysis focusing on toxicity, dosimetry and translational assessment. In our experience, CIRT can be integrated into a multimodal treatment strategy for bRe/Re PDAC, alongside chemotherapy and surgery. A case of fatal liver failure occurring three months post-surgery has been documented, likely related to the combination approach. Although the treatment plans were satisfactory according to the Local Effect Model (LEM) model, recalculations using the modified Microdosimetric Kinetic Model (mMKM) revealed suboptimal target coverage. Additionally, we observed an increased expression of PD-L1 following CIRT. This multimodal approach was well tolerated; however, clinicians should carefully monitor for vascular disorders during follow-up and further investigate surgical techniques after CIRT. The increased PD-L1 expression supports the immunogenic effects of particle therapy and lays the groundwork for future studies. To enhance the therapeutic ratio of CIRT treatments, integrating dose-averaged LETd (LETd-based objectives into the plan optimization process should be considered. ClinicalTrials.gov Identifier: NCT03822936.

Curcumin’s Radioprotective Effects on Zebrafish Embryos

Radiation modifiers are largely studied for their contribution to enlarging the treatment window. Curcumin is already known for its antioxidant properties; however, its role as a radioprotector in preclinical studies is affected by the well-known low absorption and bioavailability of curcumin. In this study, curcumin’s radioprotection ability has been evaluated in zebrafish larvae, by taking advantage of quantifying curcumin absorption and evaluating its fluorescence in transparent embryos. A curcumin range of 1–10 μM was tested to select the non-toxic concentrations to be used for a pre-treatment of photon beam irradiation using a 2–15 Gy range of doses. The post-treatment analysis within 120 h post-fertilization (hpf) included an assessment of mortality and malformation rates and behavioral and gene expression analysis. A total of 2.5 and 5 μM of curcumin pre-treatment showed a radioprotective role, significantly reducing the frequency of embryo malformations and damaged entities. This sparing effect disappeared using 15 Gy, showing the radiation effect’s prevalence. Gene expression analysis reconducted this radioprotective ability for antioxidant gene network activation. The curcumin-induced activation of the antioxidant gene network promoted radioprotection in zebrafish.

Characterisation of 3D-printable thermoplastics to be used as tissue-equivalent materials in photon and proton beam radiotherapy end-to-end quality assurance devices

Objective. To investigate the potential of 3D-printable thermoplastics as tissue-equivalent materials to be used in multimodal radiotherapy end-to-end quality assurance (QA) devices. Approach. Six thermoplastics were investigated: Polylactic Acid (PLA), Acrylonitrile Butadiene Styrene (ABS), Polyethylene Terephthalate Glycol (PETG), Polymethyl Methacrylate (PMMA), High Impact Polystyrene (HIPS) and StoneFil. Measurements of mass density ( ρ ), Relative Electron Density (RED), in a nominal 6 MV photon beam, and Relative Stopping Power (RSP), in a 210 MeV proton pencil-beam, were performed. Average Hounsfield Units (HU) were derived from CTs acquired with two independent scanners. The calibration curves of both scanners were used to predict average ρ, RED and RSP values and compared against the experimental data. Finally, measured data of ρ, RED and RSP was compared against theoretical values estimated for the thermoplastic materials and biological tissues. Main results. Overall, good ρ and RSP CT predictions were made; only PMMA and PETG showed differences >5%. The differences between experimental and CT predicted RED values were also <5% for PLA, ABS, PETG and PMMA; for HIPS and StoneFil higher differences were found (6.94% and 9.42/15.34%, respectively). Small HU variations were obtained in the CTs for all materials indicating good uniform density distribution in the samples production. ABS, PLA, PETG and PMMA showed potential equivalency for a variety of soft tissues (adipose tissue, skeletal muscle, brain and lung tissues, differences within 0.19%–8.35% for all properties). StoneFil was the closest substitute to bone, but differences were >10%. Theoretical calculations of all properties agreed with experimental values within 5% difference for most thermoplastics. Significance. Several 3D-printed thermoplastics were promising tissue-equivalent materials to be used in devices for end-to-end multimodal radiotherapy QA and may not require corrections in treatment planning systems’ dose calculations. Theoretical calculations showed promise in identifying thermoplastics matching target biological tissues before experiments are performed.

Postoperative radiotherapy for thymic epithelial tumors: a narrative review.

Thymic epithelial tumors (TETs), including thymomas and thymic carcinomas, are rare mediastinal tumors. Surgical resection is the treatment strategy for resectable TETs, and postoperative radiotherapy (PORT) is administered to improve local control in patients with a high risk of recurrence. The rarity of TETs has led to a lack of randomized controlled trials, and the current indications for PORT rely largely on retrospective studies. This review analyzes the literature on TETs, highlighting PORT, to guide current research and future investigations. Studies that focused on TETs, addressed topics on PORT, and had English abstracts accessible online were eligible for inclusion in our review. We excluded case reports or review articles, articles written in languages other than English, articles published >30 years ago, and articles concerning thymic neuroendocrine tumors. Masaoka or Masaoka-Koga staging, World Health Organization (WHO) histological subtype, and resection status indicate PORT in resected TETs. Current literature suggests that PORT does not improve overall survival in stage I-IIA TETs, with inconsistent results for stage IIB-III TETs. Patients with a higher risk, such as carcinomas or WHO type B, might benefit from PORT if they do not develop distant metastasis. Determining which patients will benefit most from PORT requires further investigation. For recurrent TETs, the significance of applying PORT is unclear because available data are limited. Given the long-term survival of TETs, late toxicities, including radiation pneumonitis, radiation-induced cardiotoxicities, and secondary malignancies, must be addressed. Proton beam radiotherapy might reduce toxicities by sparing organs at risk compared to conventional photon beam radiotherapy. The use of high-precision radiation therapy, along with emerging immunotherapy, targeted therapy, and minimally invasive surgery, could improve TET outcomes. This review consolidates the literature on PORT for TETs, factoring in the Masaoka-Koga staging, WHO histological subtypes, and resection status. Varying results regarding PORT efficacy have led to an undefined strategy for stage IIB-III TETs. Although advanced radiotherapy techniques promise to reduce radiation-induced toxicities, further research is needed to investigate the efficacy of PORT and combination therapy.

Diffusion decrease in normal-appearing white matter structures following photon or proton irradiation indicates differences in regional radiosensitivity

PurposeRadio(chemo)therapy (RCT) as part of the standard treatment of glioma patients, inevitably leads to radiation exposure of the tumor-surrounding normal-appearing (NA) tissues. The effect of radiotherapy on the brain microstructure can be assessed by magnetic resonance imaging (MRI) using diffusion tensor imaging (DTI). The aim of this study was to analyze regional DTI changes of white matter (WM) structures and to determine their dose- and time-dependency. MethodsAs part of a longitudinal prospective clinical study (NCT02824731), MRI data of 23 glioma patients treated with proton or photon beam therapy were acquired at three-monthly intervals until 36 months following irradiation. Mean, radial and axial diffusivity (MD, RD, AD) as well as fractional anisotropy (FA) were investigated in the NA tissue of 15 WM structures and their dependence on radiation dose, follow-up time and distance to the clinical target volume (CTV) was analyzed in a multivariate linear regression model. Due to the small and non-comparable patient numbers for proton and photon beam irradiation, a separate assessment of the findings per treatment modality was not performed. ResultsFour WM structures (i.e., internal capsule, corona radiata, posterior thalamic radiation, and superior longitudinal fasciculus) showed statistically significantly decreased RD and MD after RT, whereas AD decrease and FA increase occurred less frequently. The posterior thalamic radiation showed the most pronounced changes after RCT [i.e., ΔRD = −8.51 % (p = 0.012), ΔMD = −6.14 % (p = 0.012)]. The DTI changes depended significantly on mean dose and time. ConclusionSignificant changes in DTI for WM substructures were found even at low radiation doses. These findings may prompt new radiation dose constraints sparing the vulnerable structures from damage and subsequent side-effects.

Cascade energy reemission by the silver atom ionized by 0.01–100 keV photons. Possible application of silver-based radiosensitizing agents in photon beam radiation therapy

A method of straightforward construction and analysis of the cascade decay trees is applied to study the cascade energy reemission by silver atoms upon photoionization in the incident photon energy range of 0.01–100 keV. Cascade electrons and photons emitted during the cascade relaxation of an inner-shell vacancy carry away a significant part of the energy initially acquired by the silver atom in a photoionization act. The energies redistributed through following channels were calculated as functions of incident photon energy: energy absorbed by the silver atom itself (a), and energies carried away by the cascade electrons (b) and photons (c). Channel (a) is dominant only at small incident photon energies up to the M5 ionization threshold. Channel (b) dominates between M and K thresholds making 57–85 % of the acquired energy. Above the K threshold, the weight of channel (b) is still significant, 24 %, however, dominant is channel (c).

Investigation of ionization chamber-specific beam quality correction factor (kQ,Q0) used for absorbed dose determination in megavoltage photon beams

In the recent past (Andreo et al., 2020), new ionization chamber-specific beam quality correction factors (kQ,Q0) were published in the literature for the determination of the absorbed dose to water in high energy radiotherapy photon beams. In a previous experimental investigation, made at our laboratory, five various Farmer-type cylindrical ionization chambers, i.e. Exradin A12, IBA FC65-G, NE-2571, PTW 30011 and PTW 30012, were studied to examine their responses with reference to the determination of the absorbed dose to water in an inter-chamber comparison. In the present work, measurements were made to experimentally study the relation or ratio of the kQ,Q0 correction factors using the five various types of the ionization chambers employed in our previous investigation. In total, nine ionization chambers, two of each type, were included in the present study, with the exception of a single PTW 30011 ionization chamber. The photon beams employed were the 6 MV and the 15 MV beam. The outcomes of this work displayed excellent agreement between the ratio of the ionization chamber-specific kQ,Q0 correction factors, for the ionization chambers utilized, and the corresponding ratio calculated using the published kQ,Q0 correction factors. The discrepancy obtained in these comparisons was within 0.1%, for both the photon beams examined, which is much smaller than the uncertainty associated with the determination of this relationship.

Reduced Risk of Severe Radiation-Induced Lymphopenia in Carbon Ion Radiation Therapy for Locally Advanced Pancreatic Cancer: A Comparative Analysis of Carbon Versus Photon Therapy

Radiation-induced lymphopenia (RIL) is associated with poor prognosis in patients with locally advanced pancreatic cancers. However, there are no reports comparing the effects of carbon ion radiation therapy (CIRT) and photon beam radiation therapy (RT) on the development of RIL. Differences in RIL after CIRT or photon beam RT and predictive factors for RIL in patients with locally advanced pancreatic cancer were investigated. This retrospective study cohort included 834 patients who received concurrent chemoradiotherapy (CCRT) in 2 separate institutions: 337 and 497 in the CIRT and photon beam RT groups, respectively. Severe RIL was defined as an absolute lymphocyte count (ALC) <0.5 × 109 cells/L. A 1:1 propensity score-matching analysis was performed between the CIRT and photon beam RT groups. Patients were categorized into 3 groups according to the development of recovery from severe RIL: no severe RIL (Group A), recovery from severe RIL (Group B), and no recovery from severe RIL (Group C). Logistic regression analysis was performed to identify the predictive value of severe RIL. The prognostic factors of overall survival (OS) were determined using Cox regression analysis. After propensity score matching, the baseline ALC and planning target volume of the CIRT and photon beam RT groups were comparable. During CCRT, the ALC of the entire cohort decreased and was significantly lower in the photon beam RT group than in the CIRT group (P < .001). Multivariate logistic regression analysis showed that CIRT reduced severe RIL more than photon beam RT. After adjusting for other factors, the RT modality and RIL were significantly associated with OS. Photon beam RT showed a significantly worse OS than CIRT, and Group C showed a significantly worse OS than Group A. CIRT seems to reduce the development of severe RIL. The RT modality and development/recovery from severe RIL were associated with OS in patients who received CCRT for locally advanced pancreatic cancer. The reduction of severe RIL through optimized RT may be essential for improving treatment outcomes.

Characterization of a commercial PIN diode for radiotherapy photon beam dosimetry

The dosimetric characterization of a commercial diode (BPW-34) was performed using a True Beam accelerator (Varian), with flattening filter (FF) photon beams of 6 and 15 MV and flattening filter free (FFF) of 6 MVFFF. The main performance characteristics, namely dose response, energy and dose rate dependence, field output factor, and percentage depth dose profile (PDD), were compared with those available in the literature and, whenever possible, benchmarked against the Varian Eclipse treatment planning system (TPS) predictions. Regardless of the energy, the results showed that the dose response curves are linear (R2 = 1) with nonlinearity parameters less than 0.1% and 0.3% of repeatability. Furthermore, the average dose rate effect (0.7%) is almost negligible within the range of 20–600 MU/min (6 MV, 15 MV) and 400–1400 MU/min (6 MVFFF). Despite these good results, the charge sensitivity measurements evidenced that the diode response depends slightly on the energy, being within 5% for 6 MV–15 MV. It is important to underline that all these results adhere to the standard radiotherapy dosimetry protocols. Moreover, the general output field factor measurements and the percentage depth dose profiles, which are in excellent agreement with the Eclipse TPS calculations, also demonstrated that the diode BPW-34 is a low-budget alternative radiotherapy photon beam dosimeter.

The clinical roadmap in a dual-beam hadrontherapy centre: tumour-based and patient-tailored selection criteria, management of range uncertainties and oncological patient pathway

PurposeIn the present short report, we encompass the radiobiological and dosimetric advantages of particle beam radiotherapy and we illustrate the oncological pathway for patients eligible for hadrontherapy being used at the National Center for Oncological Hadrontherapy (CNAO).MethodsWith a narrative approach, we examined the clinical and practical aspects of hadrontherapy compared to traditional photon beam radiotherapy. We described the need to select patients considering the intrinsic characteristics both of the tumour and the patient. Moreover, we described the decisional oncological tree and the patient pathway by our facility.ResultsConsidering the dosimetric and radiobiological characteristics of particle beam radiotherapy, the selection of patients can not be done regardless of the intrinsic tumour and patient hallmarks. In particular, the tumour radioresistance, the patient radiosensitivity and the need to avoid post-actinic toxicities in long-term survivors should guide the clinical indication. The finite range of particles should be considered to avoid treatment uncertainties. Multidisciplinary national and international collaboration is crucial to better manage patients to treat with hadrontherapy and to create robust clinical evidence.ConclusionHadrontherapy, with its distinctive physical and biological advantages, heralds a promising era in the field of precision radiotherapy. Patients’ radiosensitivity, tumour radioresistance, and treatment uncertainties should be considered to enhance the efficacy and to ameliorate the selection of patients.

Feasibility assessment of polycrystalline CsPbI3 relative dosimeters in photon and electron beam radiotherapy

Volumetric modulated arc therapy represents the latest technology in radiotherapy. It involves continuous modification of the multi-leaf collimator spatial distribution, dose rate, and gantry rotational speed, necessitating a dosimeter with high spatial resolution and exceptional sensitivity per unit volume. In particular, cesium-based inorganic perovskites have been studied for various applications, spanning from photoconductor solar cells to radiation detectors. These perovskites are renowned for their outstanding attributes, including thermal stability, inorganic stability, and light absorption capacity. Despite such advantageous characteristics, CsPbI3 materials have only been investigated in radiodiagnostics, with limited exploration in radiotherapy. To address this gap, this study verified the viability of CsPbI3 materials, note for their outstanding radiation detection efficiency, as dosimeters capable of measuring the radiation detection performance for radiotherapy devices. The reproducibility, linearity, and percent depth dose (PDD) were evaluated under the application of photon and electron beams in linear accelerators. The reproducibility assessment revealed impressive results, with the relative standard deviation registering at 0.53%, 0.32%, and 0.38% under electron beam energies of 6, 9, and 12 MeV and 0.45%, and 0.89% under photon beam energies of 6 and 15 MV. Moreover, the linearity test revealed an R 2 value of 0.9999, indicating high linearity, at 6, 9, and 12 MeV and at 6 and 15 MV. The PDD graphs drawn for the CsPbI3 dosimeter fabricated in this study showed that the D max points were consistent. The novel CsPbI3 dosimeter demonstrated a level of detection performance that satisfied all criteria; reproducibility, linearity, and PDD. The results collectively indicated that the CsPbI3 dosimeter can be used for dosimeters in radiotherapy devices.

Dosimetric feasibility study (“proof of concept”) of refractory ventricular tachycardia radioablation using proton minibeams

PurposePreclinical data demonstrated that the use of proton minibeam radiotherapy reduces the risk of toxicity in healthy tissue. Ventricular tachycardia radioablation is an area under clinical investigation in proton beam therapy. We sought to simulate a ventricular tachycardia radioablation with proton minibeams and to demonstrate that it was possible to obtain a homogeneous coverage of an arrhythmogenic cardiac zone with this technique. Material and methodsAn arrhythmogenic target volume was defined on the simulation CT scan of a patient, localized in the lateral wall of the left ventricle. A dose of 25Gy was planned to be delivered by proton minibeam radiotherapy, simulated using a Monte Carlo code (TOPAS v.3.7) with a collimator of 19 0.4 mm-wide slits spaced 3mm apart. The main objective of the study was to obtain a plan ensuring at least 93% of the prescription dose in 93% of the planning target volume without exceeding 110% of the prescribed dose in the planning target volume. ResultsThe average dose in the planning treatment volume in proton minibeam radiotherapy was 25.12Gy. The percentage of the planning target volume receiving 93% (V93%), 110% (V110%), and 95% (V95%) of the prescribed dose was 94.25%, 0%, and 92.6% respectively. The lateral penumbra was 6.6mm. The mean value of the peak-to-valley-dose ratio in the planning target volume was 1.06. The mean heart dose was 2.54Gy versus 5.95Gy with stereotactic photon beam irradiation. ConclusionThis proof-of-concept study shows that proton minibeam radiotherapy can achieve a homogeneous coverage of an arrhythmogenic cardiac zone, reducing the dose at the normal tissues. This technique, ensuring could theoretically reduce the risk of late pulmonary and breast fibrosis, as well as cardiac toxicity as seen in previous biological studies in proton minibeam radiotherapy.

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.

Separation surgery for metastatic spine tumors: How less became more.

Metastatic epidural spinal cord compression (MESCC) is an increasingly common clinical entity in cancer patients and is associated with significant morbidity and neurologic sequalae. Management of MESCC has undergone many significant paradigms shifts over the past 50 years and was at times managed exclusively with either surgery or radiation. Historically, aggressive surgical techniques to achieve en bloc or intralesional gross tumor resections were pursued but were associated with significant morbidity and poor tumor control rates when combined with conventional external beam radiation. However, improvements in radiation treatment delivery in the form of stereotactic body radiation therapy have allowed for the safe delivery of high-dose conformal photon beam radiation providing histology-independent ablative responses. This shifted the goals of surgery away from maximal tumor resection toward simple spinal cord decompression with reconstitution of the thecal to create a tumor target volume capable of being irradiated within the constraints of spinal cord tolerance. This new approach of creating space between the thecal sac and the tumor was termed separation surgery and when combined with postoperative SBRT, it is referred to as hybrid therapy. Herein, we will describe the evolution of the management of MESCC, the technique of separation surgery and its outcomes, and finish with an illustrative case example.

Physical and Dosimetric Characterization of Silicone Rubber Bolus for Head Photon-Beam Radiotherapy.

This study assesses the physical properties of the silicone rubber (SR) bolus, compares its dosimetric characterization with those of gel and thermoset boluses, aiming to evaluate the feasibility and stability of utilizing SR bolus for head photon-beam radiotherapy. Three types of boluses (gel, thermoset, and SR) were prepared with same dimensions. Firstly, the physical properties of SR bolus (density, tensile strength and hardness) were assessed pre-irradiation and post-irradiation. Secondly, the percentage of depth dose (PDD) curve was calculated using the treatment planning system (TPS) and measured with a plane-parallel. Thirdly, these three boluses were individually placed on the head phantom, followed by computed tomography (CT) scans to delineate the customized target area and organs at risk (OARs) for treatment planning. Over the subsequent three weeks, fan-beam CT (FBCT) images were obtained weekly and registered with the initial CT to modify the target area and OARs. Fourthly, the adhesion differences, dose distributions, and inter-fraction reproducibility of the three boluses were compared and evaluated. The results observed that post-irradiated SR bolus exhibited higher hardness values (p < .01) than the pre-irradiated one, with no significant differences in tensile strength and density. The PDD curves of all three boluses showed similarity within a difference range less than ±1%. The air gaps between the SR, thermoset, and gel boluses and skin surfaces were measured as 0.07 cm3, 2.96 cm3, and 4.82 cm3, respectively. Compared with gel bolus and thermoset bolus, the SR bolus demonstrated noticeable inter-fraction reproducibility. The SR bolus can be fabricated at room temperature, adheres to irregular body surfaces, and retains its physical properties post-irradiation. Additionally, this bolus has comparable dosimetric characterization to other commercial boluses, and may provide notable protection for OARs. Therefore, the SR bolus is recommended as a feasible and stable material for head photon-beam radiotherapy.

An initial study on common concrete, titanium dioxide and tungsten dioxide for shielding of a standard external photon beam radiotherapy room

High-energy ionizing radiations have several applications including the treatment of various types of cancer. Advanced techniques such as IMRT (Intensity Modulated Radiation Therapy) and VMAT (Volumetric Modulated Arc Therapy) using high-energy photon beams have been largely used for radiation therapy of cancer. An important issue in radiotherapy is the evaluation of the shielding of the walls of the facility room housing a linear accelerator that produces high-energy photon beams. In this study we performed an estimation of the thicknesses of a standard radiotherapy room considering three different materials: common concrete, titanium dioxide (TiO2) and tungsten dioxide (WO2). It is assumed that patients are treated with photon beams of energies varying from 4 to 30 MeV and considering two types of treatments, only conventional and conventional plus IMRT and VMAT treatment. Results have shown an overall growth of thicknesses with energy, workload, area and type of treatment. At 1,000 Gy/week and 30 MeV photon energy the primary barrier thickness using concrete as the shielding material showed to be substantially higher as compared to TiO2 (143%) and WO2 (1,360%). Results have also indicated an overall linear increasing of volumes with the area used to construct the facility room.

Radiotherapy of Orbital and Ocular Adnexa Lymphoma: Literature Review and University of Catania Experience.

Orbital and ocular adnexa lymphomas are rare neoplasms confined to the orbital region. The prognosis is generally favorable, with a high proportion of localized disease, indolent clinical course, prolonged disease-free intervals, and low lymphoma-related mortality rate. We report our experience on eleven patients with confirmed histological diagnosis of lymphoma stage IE-IIE, treated between 2010 and 2021 with radiotherapy alone or in association with chemotherapy or immunotherapy. Eight patients were treated with primary radiotherapy only, while three received previous systemic treatments. Six patients were treated with Proton beam therapy (PBT), and five with external beam radiotherapy (EBRT). The five-year local control rate was 98%; only one patient developed an out-of-field recurrence. We also conducted a comprehensive literature review using electronic databases (PubMed, EMBASE, and Cochrane Library). Articles were selected based on their pertinence to treatment of the ocular and adnexal lymphoma focusing on radiotherapy techniques (electron beam radiotherapy, photon beam radiotherapy, or proton beam radiotherapy), treatment total dose, fractionation schedule, early and late radio-induced toxicities, and patient's clinical outcome. Radiotherapy is an effective treatment option for orbital lymphoma, especially as standard treatment in the early stage of orbital lymphoma, with excellent local control rate and low rates of toxicity.

Enhancing Precision in L-band Electron Paramagnetic Resonance Tooth Dosimetry: Incorporating Digital Image Processing and Radiation Therapy Plans for Geometric Correction.

Following unforeseen exposure to radiation, quick dose determination is essential to prioritize potential patients that require immediate medical care. L-band electron paramagnetic resonance tooth dosimetry can be efficiently used for rapid triage as this poses no harm to the human incisor, although geometric variations among human teeth may hinder accurate dose estimation. Consequently, we propose a practical geometric correction method using a mobile phone camera. Donated human incisors were irradiated with calibrated 6-MV photon beam irradiation, and dose-response curves were developed by irradiation with a predetermined dose using custom-made poly(methyl methacrylate) slab phantoms. Three radiation treatment plans for incisors were selected and altered to suit the head phantom. The mean doses on tooth structures were calculated using a commercial treatment planning system, and the electron paramagnetic resonance signals of the incisors were measured. The enamel area was computed from camera-acquired tooth images. The relative standard uncertainty was rigorously estimated both with and without geometric correction. The effects on the electron paramagnetic resonance signal caused by axial and rotational movements of tooth samples were evaluated through finite element analysis. The mean absolute deviations of mean doses both with and without geometric correction showed marginal improvement. The average relative differences without and with geometric correction significantly decreased from 21.0% to 16.8% (p = 0.01). The geometric correction method shows potential in improving dose precision measurement with minimal delay. Furthermore, our findings demonstrated the viability of using treatment planning system doses in dose estimation for L-band electron paramagnetic resonance tooth dosimetry.

Dose profile evaluation for small fields of a LINAC 6 MV beam using a solid water phantom

Radiotherapy is basically used in oncology and consists of the use of ionizing radiation to stop neoplastic cells from reproducing or to kill cells. Radiotherapy is one of the three main modalities of treatment for malignant diseases such as cancer, the other two are chemotherapy and radiosurgery. Unlike other medical specialties that rely primarily on the clinical knowledge and experience of specialist physicians, radiotherapy relies heavily on modern technology and the collaborative effort of several professionals whose coordinated team approach greatly influences the outcome of treatment. Linear accelerators with jaw or multileaf (MLC) field colimators are used to irradiate patients undergoing therapy and use fields with dimensions ranging from 4×4 to 40×40 cm². However, looking for the delivery of prescribed doses increasingly conforming to the target volume, small field beam openings are being used in advanced photon beam radiotherapy. In this work, the absorbed dose distribution of an X-ray beam was recorded using a solid water phantom. This phantom was irradiated using small fields with 1×1, 2×2, 3×3 and 5×5 cm². The 6 MV X-ray beam was generated on a Synergy Platform model linear accelerator from the manufacturer Elekta, and sheets of radiochromic film were used to record the dose profiles within the phantom. The solid water phantom loaded with radiochromic film was positioned 1.0 m away from the focus of the X-ray beam. The longitudinal profile of absorbed dose obtained showed the maximum dose value at 1.26 cm (peak) depth inside the phantom. The smaller field size (1×1) generated a smaller maximum absorbed dose (peak). Axial dose profiles were recorded at 1 cm depth and showed a plateau in the central region of the field. The mean absorbed dose at the plateau measured at 1 cm depth ranged from 98% to 90% of the maximum dose for the 5x5 and 1x1 cm² fields, respectively. The experiments performed showed a variations in the absorbed dose values due to the size of the fields. These variations occurred as in the amplitude of peak value in the depth profile as in the axial plane of distribution.

Detection of Early Myocardial Dysfunction by Imaging Biomarkers in Cancer Patients Undergoing Photon Beam vs. Proton Beam Radiotherapy: A Prospective Study.

1. Background: We sought to determine acute and subacute changes in cardiac function after proton beam (PBT) and photon beam (PhT) radiotherapy (RT) using conventional and two-dimensional speckle tracking echocardiography (2D-STE) in patients with malignant breast and thoracic tumors. 2. Methods: Between March 2016 and March 2017, 70 patients with breast or thoracic cancer were prospectively enrolled and underwent transthoracic echocardiography with comprehensive strain analysis at pretreatment, mid-treatment, end of treatment, and 3 months after RT. 3. Results: PBT was used to treat 44 patients; PhT 26 patients. Mean ± SD age was 55 ± 12 years; most patients (93%) were women. The median (interquartile range) of the mean heart dose was lower in the PBT than the PhT group (47 [27-79] vs. 217 [120-596] cGy, respectively; p < 0.001). Ejection fraction did not change in either group. Only the PhT group had reduced systolic tissue Doppler velocities at 3 months. 2D-STE showed changes in endocardial and epicardial longitudinal, radial, and circumferential early diastolic strain rate (SRe) in patients undergoing PhT (global longitudinal SRe, pretreatment vs. end of treatment (p = 0.04); global circumferential SRe, pretreatment vs. at 3-month follow-up (p = 0.003); global radial SRe, pretreatment vs. at 3-month follow-up (p = 0.02) for endocardial values). Epicardial strain values decreased significantly only in patients treated with PhT. Patients in the PhT group had a significant decrease in epicardial global longitudinal systolic strain rate (GLSRs) (epicardial GLSRs, at baseline vs. at end of treatment [p = 0.009]) and in GCSRe and GRSRe (epicardial GCSRe, at baseline vs. at 3-month follow-up (p = 0.02); epicardial GRSRe, at baseline vs. at 3-month follow-up (p = 0.03)) during treatment and follow-up. No changes on 2D-STE were detected in the PBT group. 4. Conclusions: Patients who underwent PhT but not PBT had reduced tissue Doppler velocities and SRe values during follow-up, suggesting early myocardial relaxation abnormalities. PBT shows promise as a cardiac-sparing RT technology.