Organs at risk radiation dose constraints

Extraction, purification, structural features, and pharmacological properties of polysaccharides from Houttuynia cordata: A review

Houttuynia cordata Thunb, also known as "Chinese medicine antibiotic", is a medicine food homology plant. It has functions of clearing heat, eliminating toxins, in folk medicine. The extraction purification and bioactivity of Houttuynia cordata polysaccharides (HCPs) have been of wide interest to researchers in recent years studies. Studies have confirmed that HCPs exhibit various biofunctionalities, such as anti-inflammatory, antiviral, antibacterial, antioxidant, immunomodulatory, regulation of gut microbiota, and gut-lung axis, as well as anti-radiation, and anti-cancer properties. Therefore, a comprehensive systematic review is needed to summarize the recent advances of HCPs and facilitate a better understanding of their biofunctionalities. This paper reviews the research progress of HCPs in extraction and purification methods, chemical structures, biological activities, possible mechanisms of action, and potential application prospects, which can provide some valuable insights and updated information for their further development and application of HCPs in the fields of therapeutic agents, functional foods, cosmetics, animal feeds.

Diagnosis and management of brain radiation necrosis

Brain radiation necrosis (BRN) is a significant and complex side effect of stereotactic radiotherapy (SRT). Differentiating BRN from local tumor recurrence is critical, requiring advanced diagnostic techniques and a multidisciplinary approach. BRN typically manifests months to years post-treatment, presenting with radiological changes on MRI and may produce neurological symptoms. Key risk factors include the volume of irradiated brain tissue, the radiation dose, and prior radiotherapy history. This manuscript reviews the diagnostic process for BRN, emphasizing the importance of assessing baseline risk, clinical evaluation, and advanced imaging modalities. Multimodal imaging enhances diagnostic accuracy and aids in distinguishing BRN from tumor relapse. Therapeutic management varies based on symptoms. Asymptomatic BRN may be monitored with regular imaging, while symptomatic BRN often requires corticosteroids to reduce inflammation. Emerging therapies like bevacizumab have shown promise in clinical trials, with significant radiographic and symptomatic improvement. Surgical intervention may be necessary for histological confirmation and severe, treatment-resistant cases. Ongoing research aims to improve diagnostic accuracy and treatment efficacy, enhancing patient outcomes and quality of life. This review underscores the need for a multidisciplinary approach and continuous advancements to address the challenges posed by BRN in brain tumor patients.

Cranio-Spinal Irradiation in low-middle income setting: A dosimetric comparison and literature review

INTRODUCTION

Volumetric modulated arc therapy (VMAT) is a relatively new treatment technique in the middle-east and north African region. More so, is its application for cranio-spinal irradiation (CSI). We report the experience of this implementation in Tunisia, by comparing dosimetric outcomes between VMAT and Three-Dimensional Conformal Radiotherapy (3DCRT) and evaluating their efficiency in terms of treatment delivery time.

METHODS

We conducted an in-silico dosimetric study, on 29 patients treated with CSI. Patients treated with 3DCRT were replanned in VMAT and vice-versa. Doses to target volumes (TV) and organs at risk (OAR) were collected from the Treatment Planning System (TPS). Recorded treatment time was extracted from the TPS and beam-on-times were calculated.

RESULTS

VMAT provided higher TV coverage for CSI PTV (V95 % = 97.4 % vs 93.4 %, p < 0.001) and for boost PTV (96.3 % vs 93.4 %, p = 0.005). VMAT demonstrated better conformity (0.97 vs 0.93) and homogeneity (0.1 vs 0.26) indexes (p < 0.001). Both techniques met constraints for OAR, but neither achieved recommended limits for the skin, lens, or pituitary gland. VMAT showed lower maximum doses for the majority of OAR and achieved lower mean doses to the cochlea, parotids, heart, oesophagus, pancreas and bladder. However, it resulted in higher low doses to non-target tissue (V5Gy = 45.6 % vs 27.5 %, p < 0.001). Recorded treatment time was longer with VMAT compared to 3DCRT (1387 vs 683 s; p < 0.001), as well as the beam-on-time (453 and 162 s, p < 0.001).

CONCLUSION

VMAT offered improved TV coverage, conformity, and homogeneity. It protected some OAR better. This came at the expense of higher low-dose exposure to non-target tissue. Treatment times were longer with VMAT.

IMPLICATIONS FOR PRACTICE

Our study suggests the feasibility of implementing VMAT for CSI in low-middle-income countries. Follow-up is required to study the clinical translation of the dosimetric outcomes of VMAT.

Thoracic Proton Minibeam Radiation Therapy: Tissue Preservation and Survival Advantage Over Conventional Proton Therapy

PURPOSE

Proton minibeam radiation therapy (pMBRT) is an innovative radiation therapy approach that highly modulates the spatial dimension of the dose delivery using narrow, parallel, and submillimetric proton beamlets. pMBRT has proven its remarkable healthy tissue preservation in the brain and skin. This study assesses the potential advantages of pMBRT for thoracic irradiations compared with conventional radiation therapy in terms of normal tissue toxicity. The challenge here was the influence of respiratory motion on the typical peak and valley dose patterns of pMBRT and its potential biologic effect.

METHODS AND MATERIALS

The whole thorax of naïve C57BL/6 mice received one fraction of high dose (18 Gy) pMBRT or conventional proton therapy (CPT) without any respiratory control. The development of radiation-induced pulmonary fibrosis was longitudinally monitored using cone beam computed tomography. Anatomopathologic analysis was carried out at 9 months postirradiation and focused on the reaction of the lungs' parenchyma and the response of cell types involved in the development of radiation-induced fibrosis and lung regeneration as alveolar type II epithelial cells, club cells, and macrophages.

RESULTS

pMBRT has milder effects on survival, skin reactions, and lung fibrosis compared with CPT. The pMBRT-induced lung changes were more regional and less severe, with evidence of potential reactive proliferation of alveolar type II epithelial cells and less extensive depletion of club cells and macrophage invasion than the more damaging effects observed in CPT.

CONCLUSIONS

pMBRT appears suitable to treat moving targets, holding a significant ability to preserve healthy lung tissue, even without respiratory control or precise targeting.

Tumor reirradiation: Issues, challenges and perspectives for radiobiology

The radiobiology of tumor reirradiation is poorly understood. It pertains to tumors and their sensitivity at the time of relapse, encompassing primary tumors, metastases, or secondary cancers developed in or proximal to previously irradiated tissues. The ability to control the pathology depends, in part, on understanding this sensitivity. To date, literature data remains limited regarding changes in the radiosensitivity of tissues after initial irradiation, and most proposals are based on conjecture. The response of healthy tissues at the site of irradiation raises concerns about radio-induced complications. Cumulative dose is likely a major factor in this risk, thus using equivalent dose calculations might help reduce the risk of complications. However, the correlation between mathematical equivalence formulas and clinical effects of radiobiological origin is weak, and the lack of knowledge of the alpha/beta (α/β) ratio of healthy tissues remains an obstacle to the extensive use of these formulas. However, tissues exposed to recovery dose may have a tolerance to irradiation much higher than assumed, thus further biological work remains to be developed. Also, the functionality of previously irradiated tissues could be useful in selecting the most suitable irradiation beams. Finally, research on the genomics of irradiated healthy tissues could improve the prediction of side effects and personalize radiotherapy.

Impact of cyclophosphamide on the morphological and histological changes in polyglycolic acid spacers

In radiotherapy for pediatric abdominal tumors, determining the effect of concurrent chemotherapy on polyglycolic acid (PGA) spacers is crucial; yet this effect has not been validated. Therefore, we aimed to evaluate the impact of cyclophosphamide (CPA) chemotherapy on the PGA spacer using a rat model. Twenty-four rats were implanted with the spacer, and morphological changes in the spacer were assessed on CT for both the CPA-dosed group (40 mg/kg) and the control group. The size and volume of the spacer were quantified using CT, while the degree of adhesion and microscopic examination of the tissue were determined using pathology specimens. Morphologically, the size of the spacer decreased over time in both the CPA-dosed and control groups, with no significant differences observed between groups. No significant differences in adhesion were observed between the two groups. Macrophages were observed around the PGA fibers, suggesting their involvement in the degradation of the PGA spacer. These results suggest that CPA does not cause significant clinically problematic degradation or adverse tissue reactions to the PGA spacer. This study reinforced the benefits of PGA spacers; however, future research focusing on in vivo longitudinal monitoring of individual rats, as well as on humans, is required.

Proton Therapy Adaptation of Perisinusoidal and Brain Areas in the Cyclotron Centre Bronowice in Krakow: A Dosimetric Analysis

Applying a proton beam in radiotherapy enables precise irradiation of the tumor volume, but only for continuous assessment of changes in patient anatomy. Proton beam range uncertainties in the treatment process may originate not only from physical beam properties but also from patient-specific factors such as tumor shrinkage, edema formation and sinus filling, which are not incorporated in tumor volume safety margins. In this paper, we evaluated variations in dose distribution in proton therapy resulting from the differences observed in the control tomographic images and the dosimetric influence of applied adaptive treatment. The data from weekly computed tomography (CT) control scans of 21 patients, which serve as the basis for adaptive radiotherapy, were used for this study. Dosimetric analysis of adaptive proton therapy (APT) was performed on patients with head and neck (H&N) area tumors who were divided into two groups: patients with tumors in the sinus/nasal area and patients with tumors in the brain area. For this analysis, the reference treatment plans were forward-calculated using weekly control CT scans. A comparative evaluation of organ at risk (OAR) dose-volume histogram (DVH) parameters, as well as conformity and homogeneity indices, was conducted between the initial and recalculated dose distributions to assess the necessity of the adaptation process in terms of dosimetric parameters. Changes in PTV volume after replanning were observed in seventeen patient cases, showing a discrepancy of over 1 cm3 in ten cases. In these cases, tumor progression occurred in 30% of patients, while regression was observed in 70%. The statistical analysis indicates that the use of the adaptive planning procedure results in a statistically significant improvement in dose distribution, particularly in the PTV area. The findings led to the conclusion that the adaptive procedure provides significant advantages in terms of dose distribution within the treated volume. However, when considering the entire patient group, APT did not result in a statistically significant dose reduction in OARs (α = 0.05).

Radiotherapy for central neurocytoma: A multicentric retrospective study in France

PURPOSE

Neurocytomas represent 0.25 to 0.5% of primary brain tumours and are mainly found in young adults. These tumours have neuronal differentiation. The cornerstone treatment is neurosurgery. The efficacy of other therapies, including radiotherapy, is still unclear. The objective of this study was to evaluate the management of central neurocytomas and the role of radiotherapy.

MATERIALS AND METHODS

All adult patients (age 18 years or older) newly diagnosed with a histologically confirmed neurocytoma between 2006 and 2015 in France were included.

RESULTS

One hundred and sixteen patients were diagnosed with a central neurocytoma during the study period. All patients underwent surgical resection, and six received adjuvant radiotherapy. Eleven patients received radiotherapy due to progression. After a median follow-up of 68.7 months, local failure occurred in 29 patients. The 5-year local control rate was 73.4%. According to univariate analysis, marker of proliferation Ki67 index greater than 2% (hazard ratio [HR]: 1.48; confidence interval [CI]: 1.40-1.57; P=0.027) and subtotal resection (HR: 8.48; CI: 8.01-8.99; P<0.001) were associated with an increase in local failure. Gross total resection was associated with a higher risk of sequelae epilepsy (HR: 3.62; CI: 3.42-3.83; P<0.01) and memory disorders (HR: 1.35; CI: 1.07-1.20; P<0.01). Ten patients (8.6%) died during the follow-up. The 10-year overall survival rate was 89.0%. No prognostic factors for overall survival were found.

CONCLUSION

The analysis showed that patients who underwent subtotal surgical resection, particularly when the tumour had a Ki67 index greater than 2%, had an increased risk of local recurrence. These patients could benefit from adjuvant radiotherapy.

Organ at risk dose-volume metrics in a series of hypofractionated breast radiotherapy with integrated boost

Dose and volume metrics to organs at risk are used for evaluation and optimization in radiotherapy planning. However, the numerous choices of metrics can be confusing. In a series of patients treated with hypofractionation and an integrated boost for breast cancer, we aim to determine if a parsimonious selection of representative metrics can be identified. The dosimetries of 42 patients receiving 42 Gy to the breast, with or without nodal irradiation, and 51 Gy integrated boost to tumor bed in 15 fractions were reviewed. For each organ-heart, lungs, and contralateral breast-cumulative dose-volume histograms were used to extract values for 3 basic metric classes: Two additional classes were considered: Pearson correlation coefficient R was calculated between pairs of values within each basic class and with the 2 additional classes for each organ. The interquartile ranges of correlations for D.yy, Vrel.xx, and Vabs.xx were as follows: The mean dose correlated with all basic classes for the heart and lungs, and with dose D.yy and volumes at Vrel.10-Vabs.10 for the contralateral breast. The standard deviation correlated with Vrel.xx and Vabs.xx for the heart and lungs (R ≥ 0.70). Among the D.yy, D.50 (median dose) correlated with the mean and standard deviation for all organs (R = 0.65-0.96). The mean, standard deviation, and median doses were the preeminent correlators. These statistics appear to be parsimonious representatives of doses to organs. Further studies with other radiotherapy series will be necessary to validate these observations.

Application and dosimetric comparison of surface-guided deep inspiration breath-hold for lung stereotactic body radiotherapy

Respiratory motion management is the crucial challenge for safe and effective application of lung stereotactic body radiotherapy (SBRT). The present study implemented lung SBRT treatment in voluntary deep inspiration breath-hold (DIBH) with surface-guided radiotherapy (SGRT) system and evaluated the geometric and dosimetric benefits of DIBH to organs-at-risk (OARs), aiming to advising the choice between DIBH technology and conventional free breathing 4 dimensions (FB-4D) technology. Five patients of lung SBRT treated in DIBH with SGRT at our institution were retrospectively analyzed. CT scans were acquired in DIBH and FB-4D, treatment plans were generated for both respiratory phases. The geometric and dosimetry of tumor, ipsilateral lung, double lungs and heart were compared between the DIBH and FB-4D treatment plans. In terms of target coverage, utilizing DIBH significantly reduced the mean plan target volume (PTV) by 21.9% (p = 0.09) compared to FB-4D, the conformity index (CI) of DIBH and FB-4D were comparable, but the dose gradient index (DGI) of DIBH was higher. With DIBH expanding lung, the volumes of ipsilateral lung and double lungs were 2535.1 ± 403.0cm3 and 4864.3 ± 900.2cm3, separately, 62.2% (p = 0.009) and 73.1% (p = 0.009) more than volumes of ipsilateral lung (1460.03 ± 146.60cm3) and double lungs (2811.25 ± 603.64cm3) in FB-4D. The heart volume in DIBH was 700.0 ± 146.1cm3, 11.6% (p = 0.021) less than that in FB-4D. As for OARs protection, the mean dose, percent of volume receiving > 20Gy (V20) and percent of volume receiving > 5Gy (V5) of ipsilateral lung in DIBH were significantly lower by 33.2% (p = 0.020), 44.0% (p = 0.022) and 24.5% (p = 0.037) on average, separately. Double lungs also showed significant decrease by 31.1% (p = 0.019), 45.5% (p = 0.024) and 20.9% (p = 0.048) on average for mean dose, V20 and V5 in DIBH. Different from the lung, the mean dose and V5 of heart showed no consistency between DIBH and FB-4D, but lower maximum dose of heart was achieved in DIBH for all patients in this study. Appling lung SBRT in DIBH with SGRT was feasibly performed with high patient compliance. DIBH brought significant dosimetric benefits to lung, however, it caused more or less irradiated heart dose that depend on the patients' individual differences which were unpredictable.

Management of Graves' ophthalmopathy by radiotherapy: A literature review

Orbital radiotherapy for Graves' ophthalmopathy is an example of non-oncological radiotherapy. First introduced in the 1930s, this treatment has become widely used since the 1980s with several studies showing proof of both effectiveness and safety: a decrease of soft tissue involvement in 70 to 80% of patients and an improvement of ocular mobility in 30 to 80% of patients. Nowadays, it's one of the second line treatment options recognized by the European Group on Graves' orbitopathy in the management of a moderate to severe and active disease after failure of glucocorticoids. In that setting, orbital radiotherapy should be combined with glucocorticoids. To our knowledge, there are no practical recommendations on how orbital radiotherapy should be planned and conducted for Graves' ophthalmopathy. Optimal dose is not defined however the most frequent regimen consists of 20Gy in ten fractions of 2Gy, though other options may yield better results. Lastly, the use of modern technique of radiotherapy such as intensity-modulated radiation therapy may allow a better sparing of organs at risk compared to three-dimensional radiotherapy using lateral opposing fields.

Complications and Risk Factors in Patients with Soft Tissue Sarcoma of the Extremities Treated with Radiotherapy

INTRODUCTION

Soft tissue sarcomas of the extremities (ESTSs) pose significant challenges in treatment and management due to their diverse nature and potential complications. This study aimed to assess complications associated with multimodal treatments involving surgery and radiotherapy (RT) and to identify potential risk factors.

METHODS

We retrospectively analyzed nonmetastatic ESTS patients treated with surgery and pre- or post-operative RT between 2007 and 2020 in Strasbourg, France. Complications, including wound complications (WCs), lymphedema, acute and chronic RT-related complications, and fractures, were meticulously evaluated.

RESULTS

A total of 169 patients diagnosed with localized ESTSs were included, with a median age of 64 years (range 21-94 years). ESTSs primarily occurred proximally (74.6%) and in the lower limbs (71%). The median follow-up was 5.5 years. WCs occurred in 22.5% of patients, with proximal and lower extremity tumors being significant risk factors. Acute RT-related complications included radiodermatitis, with grade ≥ 2 occurring in 43.1% of patients, which was associated with superficial tumors. Three patients had an edema grade ≥ 2. Chronic complications included telangiectasias (21.7%) and fibrosis (38.7%), with higher rates associated with larger PTVs and higher RT doses, respectively. Fractures occurred in 5 patients, mainly in the tibia (40%).

CONCLUSIONS

Multimodal treatment of ESTSs demonstrated excellent tolerance, with manageable side effects. Numerous risk factors have been highlighted, providing insights for optimizing treatment strategies and enhancing patient care in this rare disease.

A dosiomics model for prediction of radiation-induced acute skin toxicity in breast cancer patients: machine learning-based study for a closed bore linac

BACKGROUND

Radiation induced acute skin toxicity (AST) is considered as a common side effect of breast radiation therapy. The goal of this study was to design dosiomics-based machine learning (ML) models for prediction of AST, to enable creating optimized treatment plans for high-risk individuals.

METHODS

Dosiomics features extracted using Pyradiomics tool (v3.0.1), along with treatment plan-derived dose volume histograms (DVHs), and patient-specific treatment-related (PTR) data of breast cancer patients were used for modeling. Clinical scoring was done using the Common Terminology Criteria for Adverse Events (CTCAE) V4.0 criteria for skin-specific symptoms. The 52 breast cancer patients were grouped into AST 2 + (CTCAE ≥ 2) and AST 2 - (CTCAE < 2) toxicity grades to facilitate AST modeling. They were randomly divided into training (70%) and testing (30%) cohorts. Multiple prediction models were assessed through multivariate analysis, incorporating different combinations of feature groups (dosiomics, DVH, and PTR) individually and collectively. In total, seven unique combinations, along with seven classification algorithms, were considered after feature selection. The performance of each model was evaluated on the test group using the area under the receiver operating characteristic curve (AUC) and f1-score. Accuracy, precision, and recall of each model were also studied. Statistical analysis involved features differences between AST 2 - and AST 2 + groups and cutoff value calculations.

RESULTS

Results showed that 44% of the patients developed AST 2 + after Tomotherapy. The dosiomics (DOS) model, developed using dosiomics features, exhibited a noteworthy improvement in AUC (up to 0.78), when spatial information is preserved in the dose distribution, compared to DVH features (up to 0.71). Furthermore, a baseline ML model created using only PTR features for comparison with DOS models showed the significance of dosiomics in early AST prediction. By employing the Extra Tree (ET) classifiers, the DOS + DVH + PTR model achieved a statistically significant improved performance in terms of AUC (0.83; 95% CI 0.71-0.90), accuracy (0.70), precision (0.74) and sensitivity (0.72) compared to other models.

CONCLUSIONS

This study confirmed the benefit of dosiomics-based ML in the prediction of AST. However, the combination of dosiomics, DVH, and PTR yields significant improvement in AST prediction. The results of this study provide the opportunity for timely interventions to prevent the occurrence of radiation induced AST.

Preliminary investigation into the impact of BPA on osteoblast activity and bone development: In vitro and in vivo models

Bisphenol A (BPA), an ingredient in consumer products, has been suggested that it can interfere with bone development and maintenance, whereas the molecule mechanism remains unclear. The objective of this study is to investigate the effect of BPA on early bone differentiation and metabolism, and its potential molecule mechanism by employing hFOB1.19 cell as an in vitro model, as well as larval zebrafish as an in vivo model. The in vitro experiments indicated that BPA decreased cell viability, inhibited osteogenic activity (such as ALP, RUNX2), increased ROS production, upregulated transcriptional or protein levels of apoptosis-related molecules (such as Caspase 3, Caspase 9), while suppressed transcriptional or protein levels of pyroptosis-specific markers (TNF-α, TNF-β, IL-1β, ASC, Caspase 1, and GSDMD). Moreover, the evidences from in vivo model demonstrated that exposure to BPA distinctly disrupted pharyngeal cartilage, craniofacial bone development, and retarded bone mineralization. The transcriptional level of bone development-related genes (bmp2, dlx2a, runx2, and sp7), apoptosis-related genes (bcl2), and pyroptosis-related genes (cas1, nlrp3) were significantly altered after treating with BPA in zebrafish larvae. In summary, our study, combining in vitro and in vivo models, confirmed that BPA has detrimental effects on osteoblast activity and bone development. These effects may be due to the promotion of apoptosis, the initiation of oxidative stress, and the inhibition of pyroptosis.

The research progress on radiation resistance of cervical cancer

Cervical carcinoma is the most prevalent gynecology malignant tumor and ranks as the fourth most common cancer worldwide, thus posing a significant threat to the lives and health of women. Advanced and early-stage cervical carcinoma patients with high-risk factors require adjuvant treatment following surgery, with radiotherapy being the primary approach. However, the tolerance of cervical cancer to radiotherapy has become a major obstacle in its treatment. Recent studies have demonstrated that radiation resistance in cervical cancer is closely associated with DNA damage repair pathways, the tumor microenvironment, tumor stem cells, hypoxia, cell cycle arrest, and epigenetic mechanisms, among other factors. The development of tumor radiation resistance involves complex interactions between multiple genes, pathways, and mechanisms, wherein each factor interacts through one or more signaling pathways. This paper provides an overview of research progress on an understanding of the mechanism underlying radiation resistance in cervical cancer.

An in-silico planning study of stereotactic body radiation therapy for polymetastatic patients with more than ten extra-cranial lesions

Background and purpose

Limited data is available about the feasibility of stereotactic body radiation therapy (SBRT) for treating more than five extra-cranial metastases, and almost no data for treating more than ten. The aim of this study was to investigate the feasibility of SBRT in this polymetatstatic setting.

Materials and methods

Consecutive metastatic melanoma patients with more than ten extra-cranial metastases and a maximum lesion diameter below 11 cm were selected from a single-center prospective registry for this in-silico planning study. For each patient, SBRT plans were generated to treat all metastases with a prescribed dose of 5x7Gy, and dose-limiting organs (OARs) were analyzed. A cell-kill based inverse planning approach was used to automatically determine the maximum deliverable dose to each lesion individually, while respecting all OARs constraints.

Results

A total of 23 polymetastatic patients with a medium of 17 metastases (range, 11-51) per patient were selected. SBRT plans with sufficient target coverage and respected OARs dose constraints were achieved in 16 out of 23 patients. In the remaining seven patients, the lungs V5Gy < 80 % and the liver D700 cm3 < 15Gy were most frequently the dose-limiting constraints. The cell-kill based planning approach allowed optimizing the dose administration depending on metastases total volume and location.

Conclusion

This retrospective planning study shows the feasibility of definitive SBRT for 70% of polymetastatic patients with more than ten extra-cranial lesions and proposes the cell-killing planning approach as an approach to individualize treatment planning in polymetastatic patients'.

Comparative study of dynamic conformal arc therapy and volumetric modulated arc therapy for treating single brain metastases: A retrospective analysis of dosimetric and clinical outcomes

Background and purpose

Stereotactic radiation therapy (SRT) is commonly used to treat brain metastases (BMs). This retrospective study compared two SRT techniques, dynamic conformal arc therapy (DCAT) and volumetric modulated arc therapy (VMAT), for single BM treatments.

Material and methods

Data of patients treated between January 2010 and June 2020 were considered. Patients with multiple BMs, resected BMs, reirradiation, whole-brain radiation therapy and brainstem metastases were excluded. We focused our analysis on 97 patients who received 23.1 Gy in three fractions. Acute toxicities and follow-up outcomes were recorded. Dosimetric data were analyzed in two subgroups (PTV ≤ 10 cc and PTV > 10 cc).

Results

DCAT and VMAT were used in 70 (72.2 %) and 27 (27.8 %) patients, respectively. Acute toxicities were not significantly different between groups (p = 0.259), and no difference was detected in the incidence rate of radionecrosis, local recurrence and cerebral recurrence (p > 0.999, p > 0.999 and p = 0.682, respectively). PTV coverage was better with DCAT for small volumes (PTV ≤ 10 cc). Mean conformity index (CI) was significantly higher with VMAT and mean gradient index (GI) was significantly lower with DCAT whatever volume subgroups (p < 0.001). DCAT had more heterogeneous plans and VMAT required more monitor units. DCAT resulted in reduced low and intermediate doses, whereas VMAT led to decreased high doses.

Conclusion

DCAT and VMAT are two effective and safe SRT techniques for BMs treatment. In the era of re-irradiation, it is important to reduce the doses delivered to healthy tissues. Further prospective studies are needed to validate these findings.

Prediction of Acute Radiation-Induced Lung Toxicity After Stereotactic Body Radiation Therapy Using Dose-Volume Parameters From Functional Mapping on Gallium 68 Perfusion Positron Emission Tomography/Computed Tomography

PURPOSE

The aim of this work was to compare anatomic and functional dose-volume parameters as predictors of acute radiation-induced lung toxicity (RILT) in patients with lung tumors treated with stereotactic body radiation therapy.

METHODS AND MATERIALS

Fifty-nine patients treated with stereotactic body radiation therapy were prospectively included. All patients underwent gallium 68 lung perfusion positron emission tomography (PET)/computed tomography (CT) imaging before treatment. Mean lung dose (MLD) and volumes receiving x Gy (VxGy, 5-30 Gy) were calculated in 5 lung volumes: the conventional anatomic volume (AV) delineated on CT images, 3 lung functional volumes (FVs) defined on lung perfusion PET imaging (FV50%, FV70%, and FV90%; ie, the minimal volume containing 50%, 70%, and 90% of the total activity within the AV), and a low FV (LFV; LFV = AV - FV90%). The primary endpoint of this analysis was grade ≥2 acute RILT at 3 months as assessed with National Cancer Institute Common Terminology Criteria for Adverse Events version 5. Dose-volume parameters in patients with and without acute RILT were compared. Receiver operating characteristic curves assessing the ability of dose-volume parameters to discriminate between patients with and without acute RILT were generated, and area under the curve (AUC) values were calculated.

RESULTS

Of the 59 patients, 10 (17%) had grade ≥2 acute RILT. The MLD and the VxGy in the AV and LFV were not statistically different between patients with and without acute RILT (P > .05). All functional parameters were significantly higher in acute RILT patients (P < .05). AUC values (95% CI) for MLD AV, LFV, FV50%, FV70%, and FV90% were 0.66 (0.46-0.85), 0.60 (0.39-0.80), 0.77 (0.63-0.91), 0.77 (0.64-0.91), and 0.75 (0.58-0.91), respectively. AUC values for V20Gy AV, LFV, FV50%, FV70%, and FV90% were 0.65 (0.44-0.87), 0.64 (0.46-0.83), 0.82 (0.69-0.95), 0.81 (0.67-0.96), and 0.75 (0.57-0.94), respectively.

CONCLUSIONS

The predictive value of PET perfusion-based functional parameters outperforms the standard CT-based dose-volume parameters for the risk of grade ≥2 acute RILT. Functional parameters could be useful for guiding radiation therapy planning and reducing the risk of acute RILT.

Stereotactic body radiation therapy for adrenal gland metastases: A multi-institutional outcome analysis

Aim

The adrenal gland is a common site of metastasis with a rate of up to 27% in autopsy series. The incidence of these metastases is increasing due to greater use of Positron Emission Tomography scans and improved overall survival of patients with metastatic cancers. Stereotactic body radiation therapy (SBRT) is a non-invasive treatment option for metastasis. The aim of this study is to assess prognostic factors influencing local control, progression-free and overall survival in oligometastatic patients treated with SBRT for an adrenal metastasis.

Methods

In this multicentric retrospective study, we included patients with adrenal metastases treated with SBRT between 2010 and 2021 in eleven french centers. All primary tumors were included.

Results

A total of 110 patients treated for 121 adrenal lesions were included. Non-small-cell lung cancer was the predominant histologic type (55.4 %). Eighty-two percent of patients had at least 2 metastatic sites. The median Planning Target Volume was 70 cm3 with a median prescription dose of 40 Gray (Gy). The mean Biologically Effective Dose (BED) 10 dose was 74.2 Gy. Local control at 1 and 2 years was 85.9 % and 72.5 % respectively. The median overall survival and progression-free survival were 31.6 and 8.5 months respectively. Local control was significantly improved by systemic treatment one month before or after SBRT (p = 0.009) and by a BED10 greater than or equal to 50 Gy (p = 0.003).In multivariate analysis, oligometastatic presentation (p = 0.009) and a metachronous metastatic presentation (p = 0.008) were independent factors for progression-free survival.Tolerance was excellent, no grade 3 and 4 toxicities were described due to SBRT.

Conclusion

Stereotactic radiotherapy of adrenal metastases makes possible a local control of more than 85% at one year and was well tolerated. The factors influencing survival in oligometastatic patients still need to be found in order to better select those who benefit the most from this type of treatment.

Stereotactic body radiation therapy for liver metastases in oligometastatic disease

Oligometastatic cancers designate cancers in which the number of metastases is less than five, corresponding to a particular biological entity whose prognosis is situated between a localized and metastatic disease. The liver is one of the main sites of metastases. When patients are not suitable for surgery, stereotactic body radiotherapy provides high local control rate, although these data come mainly from retrospective studies, with no phase III study results. The need for a high therapeutic dose (biologically effective dose greater than 100Gy) while respecting the constraints on the organs at risk, and the management of respiratory movements require expertise and sufficient technical prerequisites. The emergence of new techniques such as MRI-guided radiotherapy could further increase the effectiveness of stereotactic radiotherapy of liver metastases, and thus improve the prognosis of these oligometastatic cancers.

Radiotherapy in the management of lung oligometastases

In recent years, the development of both medical imaging and new systemic agents (targeted therapy and immunotherapy) have revolutionized the field of oncology, leading to a new entity: oligometastatic disease. Adding local treatment of oligometastases to systemic treatment could lead to prolonged survival with no significant impact on quality of life. Given the high prevalence of lung oligometastases and the new systemic agents coming with increased pulmonary toxicity, this article provides a comprehensive review of the current state-of-art for radiotherapy of lung oligometastases. After reviewing pretreatment workup, the authors define several radiotherapy regimen based on the localization and size of the oligometastases. A comment on the synergistic combination of medical treatment and radiotherapy is also made, projecting on future steps in this specific clinical setting.

Monte Carlo Dosimetry Validation for X-Ray Guided Endovascular Procedures

BACKGROUND

Endovascular treatment is continuously gaining ground in vascular surgery procedures. However, current patient radiation dose estimation does not take into account the exact patient morphology and organs' composition. Monte Carlo (MC) simulation can accurately estimate the dose by recreating the irradiation process generated during X-ray-guided interventions. This study aimed to validate the MC simulation models by comparing simulated and measured dose distributions in endovascular aortic aneurysm repair (EVAR) procedures.

METHODS

We conducted a clinical study in patients treated for EVAR. Patient dose measurements were taken with passive dosimeters using Optically Stimulated Luminescence technology in 4 specific anatomical points on the skin: xiphoid process, pubic symphysis, right and left iliac crest. Dose measurements were compared to the corresponding simulated doses with the Geant4 Application for Emission Tomography (GATE) and GPU Geant4-based Monte Carlo Simulations (GGEMS) MC simulations softwares. The MC simulation took as input the computed tomography scan of the patient and the parameters of the imaging system (orientation angles, tube voltage, and aluminum filtration) and gives as output the three-dimensional (3D) dose map for each patient and angulation.

RESULTS

A good agreement with real doses was found for doses simulated by the MC GATE method (P < 0.0001; r = 0.97; 95% confidence interval [CI] [0.96-0.98]), as well as for doses simulated by the GGEMS method (P < 0.0001; r = 0.96; 95% CI [0.94-0.97]). The mean relative error for all measurements was 5 ± 5% in the MC GATE group and 6 ± 5% in the GGEMS group. Process execution on GGEMS (6 sec) was faster than the GATE MC simulation (5 hr).

CONCLUSION

Considering the current imaging settings, this study shows the potential of using the GATE and GGEMS MC simulations platforms to model the 3D dose distributions during EVAR procedures.

Enhancing dosimetric practices through knowledge-based predictive models: a case study on VMAT prostate irradiation

Introduction

Acquisition of dosimetric knowledge by radiation therapy planners is a protracted and complex process. This study delves into the impact of empirical predictive models based on the knowledge-based planning (KBP) methodology, aimed at detecting suboptimal results and homogenizing and improving existing practices for prostate cancer. Moreover, the dosimetric effect of implementing these models into routine clinical practice was also assessed.

Materials and methods

Based on the KBP method, we analyzed 25 prostate treatment plans performed using VMAT by expert operators, aiming to correlate dose indicators with patient geometry. The D a v g C a v ( G y ) , V 45 G y C a v ( c c ) , and V 15 G y C a v ( c c ) of the peritoneal cavity and the V 60 G y ( % ) and V 70 G y ( % ) of the rectum and bladder were linked to geometric characteristics such as the distance from the planning target volume (PTV) to the organs at risk (OAR), the volume of the OAR, or the overlap between the PTV and the OAR. In the second phase, the KBP was used in routine clinical practice in a prospective cohort of 25 patients and compared with the 41 patient plans calculated before implementing the tool.

Results

Using linear regression, we identified strong geometric predictive factors for the peritoneal cavity, rectum, and bladder (R 2   > 0.8), with an average prescribed dose of 97.8%, covering 95% of the target volume. The use of the model led to a significant dose reduction ( Δ ) for all evaluated OARs. This trend was most notable for Δ V 15 G y C a v = - 171.5  cc  ( p = 0.003 ) . Significant reductions were also obtained in average doses to the rectum and bladder, Δ D a v g R e c t =   - 2.3   G y   ( p = 0.040 ) , and Δ D a v g V e s s =   - 3.3   G y   ( p = 0.039 ) respectively. Based on this model, we reduced the number of plans with OAR constraints above the clinical recommendations from 19% to 8%.

Conclusions

The KBP methodology established a robust and personalized predictive model for dose estimation to organs at risk in prostate cancer. Implementing the model resulted in improved sparing of these organs. Notably, it yields a solid foundation for harmonizing dosimetric practices, alerting us to suboptimal results, and improving our knowledge.

And Yet It Moves: Clinical Outcomes and Motion Management in Stereotactic Body Radiation Therapy (SBRT) of Centrally Located Non-Small Cell Lung Cancer (NSCLC): Shedding Light on the Internal Organ at Risk Volume (IRV) Concept

The internal organ at risk volume (IRV) concept might improve toxicity profiles in stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC). We studied (1) clinical aspects in central vs. peripheral tumors, (2) the IRV concept in central tumors, (3) organ motion, and (4) associated normal tissue complication probabilities (NTCPs). We analyzed patients who received SBRT for NSCLC (clinical aspects, n = 78; motion management, n = 35). We found lower biologically effective doses, larger planning target volume sizes, higher lung doses, and worse locoregional control for central vs. peripheral tumors. Organ motion was greater in males and tall patients (bronchial tree), whereas volume changes were lower in patients with a high body mass index (BMI) (esophagus). Applying the IRV concept (retrospectively, without new optimization), we found an absolute increase of >10% in NTCPs for the bronchial tree in three patients. This study emphasizes the need to optimize methods to balance dose escalation with toxicities in central tumors. There is evidence that organ motion/volume changes could be more pronounced in males and tall patients, and less pronounced in patients with higher BMI. Since recent studies have made efforts to further subclassify central tumors to refine treatment, the IRV concept should be considered for optimal risk assessment.

Dosimetrically triggered adaptive radiotherapy for head and neck cancer: Considerations for the implementation of clinical protocols

PURPOSE

Defining dosimetric rules to automatically detect patients requiring adaptive radiotherapy (ART) is not straightforward, and most centres perform ad-hoc ART with no specific protocol. This study aims to propose and analyse different steps to design a protocol for dosimetrically triggered ART of head and neck (H&N) cancer. As a proof-of-concept, the designed protocol was applied to patients treated in TomoTherapy units, using their available software for daily MVCT image and dose accumulation.

METHODS

An initial protocol was designed by a multidisciplinary team, with a set of flagging criteria based only on dose-volume metrics, including two action levels: (1) surveillance (orange flag), and (2) immediate verification (red flag). This protocol was adapted to the clinical needs following an iterative process. First, the protocol was applied to 38 H&N patients with daily imaging. Automatic software generated the daily contours, recomputed the daily dose and flagged the dosimetric differences with respect to the planning dose. Second, these results were compared, by a sensitivity/specificity test, to the answers of a physician. Third, the physician, supported by the multidisciplinary team, performed a self-analysis of the provided answers and translated them into mathematical rules in order to upgrade the protocol. The upgraded protocol was applied to different definitions of the target volume (i.e. deformed CTV + 0, 2 and 4 mm), in order to quantify how the number of flags decreases when reducing the CTV-to-PTV margin.

RESULTS

The sensitivity of the initial protocol was very low, specifically for the orange flags. The best values were 0.84 for red and 0.15 for orange flags. After the review and upgrade process, the sensitivity of the upgraded protocol increased to 0.96 for red and 0.84 for orange flags. The number of patients flagged per week with the final (upgraded) protocol decreased in median by 26% and 18% for red and orange flags, respectively, when reducing the CTV-to-PTV margin from 4 to 2 mm. This resulted in only one patient flagged at the last fraction for both red and orange flags.

CONCLUSION

Our results demonstrate the value of iterative protocol design with retrospective data, and shows the feasibility of automatically-triggered ART using simple dosimetric rules to mimic the physician's decisions. Using a proper target volume definition is important and influences the flagging rate, particularly when decreasing the CTV-to-PTV margin.

Predictors of toxicity after curative reirradiation with intensity modulated radiotherapy or proton therapy for recurrent head and neck carcinoma: new dose constraints for pharyngeal constrictors muscles and oral cavity

BACKGROUND

Our study aims to identify predictive factors of moderate to severe (grade ≥ 2) late toxicity after reirradiation (reRT) of recurrent head and neck carcinoma (HNC) and explore the correlations between dose organs at risk (OAR) and grade ≥ 2 toxicity.

MATERIAL AND METHODS

Between 09/2007 and 09/2019, 55 patients were re-irradiated with IMRT or proton therapy with curative intent for advanced HNC. Our study included all patients for whom data from the first and second irradiations were available. Co-variables, including interval to reRT, size of re-irradiated PTV, and dose to OAR, were analyzed as potential predictors for developing moderate to severe long-term toxicity with death as a competing risk. Receiver-operator characteristics (ROC) analysis assessed the association between dose/volume parameters and the risk of toxicity.

RESULTS

Twenty-three patients participated in our study. After a median follow-up of 41 months, 65% of the patients experienced grade ≥ 2 late toxicity. The average dose to pharyngeal constrictor muscles (PCM) at the time of reRT showed an association with the risk of grade ≥ 2 dysphagia: AUC = 0.78 (95% CI: 0.53-1), optimal cut-off value = 36.7 Gy (sensitivity 62%/specificity 100%). The average dose to the oral cavity at the time of reRT showed an association with the risk of grade ≥ 2 dysgeusia: AUC = 0.96 (0.89-1), optimal cut-off value = 20.5 Gy (sensitivity 100%/specificity 88%).

CONCLUSION

Our analysis depicted an association between the dose to OAR and the risk of developing moderate to severe dysphagia and dysgeusia and proposed new dose constraints for PCM (36.7 Gy) and oral cavity (20.5 Gy).

Practical Guideline for Prevention of Patchy Hair Loss following CyberKnife Stereotactic Radiosurgery for Calvarial or Scalp Tumors: Retrospective Analysis of a Single Institution Experience

INTRODUCTION

Patchy alopecia is a common adverse effect of stereotactic radiosurgery (SRS) on the calvarium and/or scalp, yet no guidelines exist for its prevention. This study aims to investigate the incidence and outcomes of patchy alopecia following SRS for patients with calvarial or scalp lesions and establish preventive guidelines.

METHODS

The study included 20 patients who underwent CyberKnife SRS for calvarial or scalp lesions, resulting in a total of 30 treated lesions. SRS was administered as a single fraction for 8 lesions and hypofractionated for 22 lesions. The median SRS target volume was 9.85 cc (range: 0.81-110.7 cc), and the median prescription dose was 27 Gy (range: 16-40 Gy), delivered in 1-5 fractions (median: 3). The median follow-up was 15 months.

RESULTS

Among the 30 treated lesions, 11 led to patchy alopecia, while 19 did not. All cases of alopecia resolved within 12 months, and no patients experienced other adverse radiation effects. Lesions resulting in alopecia exhibited significantly higher biologically effective dose (BED) and single-fraction equivalent dose (SFED) on the overlying scalp compared to those without alopecia. Patients with BED and SFED exceeding 60 Gy and 20 Gy, respectively, were 9.3 times more likely to experience patchy alopecia than those with lower doses. The 1-year local tumor control rate for the treated lesions was 93.3%. Chemotherapy was administered for 26 lesions, with 11 lesions receiving radiosensitizing agents. However, no statistically significant difference was found.

CONCLUSION

In summary, SRS is a safe and effective treatment for patients with calvarial/scalp masses regarding patchy alopecia near the treated area. Limiting the BED under 60 Gy and SFED under 20 Gy for the overlying scalp can help prevent patchy alopecia during SRS treatment of the calvarial/scalp mass. Clinicians can use this information to inform patients about the risk of alopecia and the contributing factors.

[Ethical stakes of information in radiation oncology: Thinking the risk and building the therapeutic alliance]

Informing patients before receiving radiation therapy is a fundamental ethical imperative. As a condition of the possibility of autonomy, information allows people to make health decisions concerning themselves, which is required by French law. This information includes in particular the potential risks due to radiation therapy. It is therefore necessary to think about what risk is, and how to define and assess it, in order to finally communicate it. The practice of informing people involves many ethical issues relating to the very content of the information, the form in which it is transmitted or even the intention that leads the health professional to say (or not to say) the risk. The transmission of information also questions the way to build a relationship of trust with the patients and how to integrate their own representations about these treatments. Between the risks of paternalism or even defensive medicine, this practice is at the heart of our professional practice.

Stereotactic radiotherapy for ultracentral lung tumours

Ultracentral (UC) lung lesions are generally defined by the presence of the tumour or the Planning Target Volume (PTV) abutting proximal bronchial tree (PBT) or the esophagus. Initial reports rose awareness regarding the potential toxicity of stereotactic body radiotherapy (SBRT) when delivered to UC lesions. Major concerns include necrosis, stenosis, and bleeding of the PBT. Technological improvements now enable the delivery of more accurate treatments, possibly redefining the historical "no-fly zone". In this review, studies focusing on the treatment of UC lesions with SBRT are presented. The narrow therapeutic window requires a multidisciplinary approach.

[Stereotactic body radiation therapy for primary kidney cancer]

The incidence of primary renal cancer is increasing, particularly in elderly patients who may have comorbidities and/or a surgical contraindications. Stereotactic body radiotherapy has primarily been evaluated retrospectively to date. The most commonly used dose schedules are 40Gy in five fractions, 42Gy in three fractions, and 26Gy in one fraction. The results in terms of local control and toxicity are very encouraging. The advantages of stereotactic body radiotherapy compared to thermal ablative treatments are its non-invasive nature, absence of general anesthesia, ability to treat larger lesions, and those close to the renal hilum. Prospective evaluations are still necessary.

Curative high-dose reirradiation for patients with recurrent head and neck adenoid cystic carcinomas: outcomes and analysis of patterns of failure

BACKGROUND

To investigate the outcomes of patients who underwent curative reirradiation (reRT), with intensity-modulated radiation therapy (IMRT) or proton therapy (PT) for unresectable recurrent or second primary head and neck adenoid cystic carcinoma (HNACC).

METHODS

Ten patients, mostly KPS 90%, were reirradiated (3/10 with IMRT and 7/10 with PT) at a median maximum dose to the CTV of 64.2 Gy from July 2011 to November 2021. Locations at the time of reRT were mainly the sinus (4/10) and the salivary glands (including the parotid and submandibular gland, 3/10). CTCAEv5 was used to assess acute and late toxicities. Follow-up was the time between the end of reRT and the date of last news.

RESULTS

The median time between the two irradiations was 53.5 months (IQR: 18-84). After a median follow-up of 26 months (range, 12.5-51.8 months), six patients had developed a locoregional recurrence (LR), of which four occurred within the previously irradiated volume. Two and three-year locoregional failure-free survival (LFFS) and overall survival (OS) were 55.6% [95%CI: 31-99.7%], and 41% [18.5-94%] and 66.7% [42-100%] and 44.4% [21.4-92.3%], respectively. LFFS and OS were significantly better in the subgroup of sinus tumors (p = .013) and the subgroup of patients re-irradiated more than two years after the first course of irradiation (p = .01). Seven patients had impairments before the start of reRT, including hearing impairment (3/10) and facial nerve impairment (3/10). The most severe late toxicities were brain necrosis (2/10), osteoradionecrosis (1/10) and vision decreased (1/10).

CONCLUSION

Curative reRT for HNACC is possible for selected cases, but the LR rate in the irradiated field and the risk of severe toxicity remain high. Improved selection criteria and more carefully defined target volumes may improve outcome in these patients. A further study including larger cohort of patients would be useful to confirm these results.

Effects on the Hypothalamo-Pituitary Axis in Patients with CNS or Head and Neck Tumors following Radiotherapy

BACKGROUND

Knowledge about the precise effects of radiotherapy on hypothalamo-pituitary functions is limited. Reduction of side effects is a major goal of advanced radiotherapy modalities. We assessed strategies for monitoring and replacement of hormone deficiencies in irradiated patients.

METHODS

A search strategy was systematically conducted on PubMed®. Additional articles were retrieved to describe endocrine mechanisms.

RESULTS

45 studies were evaluated from 2000 to 2022. They were predominantly retrospective and highly heterogeneous concerning patient numbers, tumor types, radiotherapy technique and follow-up. Endocrine deficiencies occurred in about 40% of patients within a median follow-up of 5.6 years without a clear difference between radiotherapy modalities. Somatotropic and thyrotropic axes were, respectively, the most and least radiosensitive.

CONCLUSIONS

Current pituitary gland dose constraints may underestimate radiation-induced endocrine deficiencies, thus impairing quality of life. Little difference might be expected between radiation techniques for PG tumors. For non-PG tumors, dose constraints should be applied more systematically.

Brain radiotherapy in patients treated for a newly diagnosed primary central nervous system lymphoma: professional practice evaluation in 19 French centers

INTRODUCTION

The objective of this study was a multicentric evaluation of professional practices, analyzing the irradiation technique itself and its impact on survival and recurrence sites, in primary central nervous system lymphomas (PCNSLs).

METHODS

We retrospectively analyzed the technical and clinical records of 79 PCNSL patients included in the database of the national expert network for oculocerebral lymphoma ('LOC') who were treated with brain radiotherapy as first-line treatment for newly diagnosed primary central nervous system lymphoma between 2011 and 2018.

RESULTS

The number of patients treated with brain radiotherapy gradually decreased over time. The heterogeneity of radiotherapy prescriptions was significant, and 55% of them did not comply with published recommendations in terms of irradiation dose and/or volume. The proportion of complete responders to induction chemotherapy treated with reduced-dose radiotherapy increased over time. Partial brain radiotherapy was associated with significantly lower overall survival in univariate analysis. In partial responders to induction chemotherapy, increasing the total dose to the brain >30 Gy and adding a boost to the WBRT induced a trend toward improved progression-free and overall survival. Five recurrences (13%) occurred exclusively in the eyes, all in patients whose eyes had been excluded from the irradiation target volume and including 2 patients without ocular involvement at diagnosis.

CONCLUSION

The visibility of recommendations for prescribing brain radiotherapy for the treatment of newly diagnosed primary central nervous system lymphoma needs to be improved to harmonize practices and improve their quality. We propose an update of the recommendations.

[Limits of dose constraint definition for organs at risk specific to stereotactic radiotherapy]

Stereotactic radiotherapy is a very hypofractionated radiotherapy (>7.5Gy per fraction), and therefore is more likely to induce late toxicities than conventional normofractionated irradiations. The present study examines four frequent and potentially serious late toxicities: brain radionecrosis, radiation pneumonitis, radiation myelitis, and radiation-induced pelvic toxicities. The critical review focuses on the toxicity scales, the definition of the dose constrained volume, the dosimetric parameters, and the non-dosimetric risk factors. The most commonly used toxicity scales remain: RTOG/EORTC or common terminology criteria for adverse events (CTCAE). The definition of organ-at-risk volume requiring protection is often controversial, which limits the comparability of studies and the possibility of accurate dose constraints. Nevertheless, for the brain, whatever the indication (arteriovenous malformation, benign tumor, metastasis of solid tumors...), the association between the volume of brain receiving 12Gy (V12Gy) and the risk of cerebral radionecrosis is well established for both single and multi-fraction stereotactic irradiation. For the lung, the average dose received by both lungs and the V20 seem to correlate well with the risk of radiation-induced pneumonitis. For the spinal cord, the maximum dose is the most consensual parameter. Clinical trial protocols are useful for nonconsensual dose constraints. Non-dosimetric risk factors should be considered when validating the treatment plan.

Proton therapy and/or helical tomotherapy for locally advanced sinonasal skull base adenoid cystic carcinoma: Focus on experience of the Institut Curie and review of literature

BACKGROUND

Sinonasal adenoid cystic carcinomas (SNACC) have high propensity for skull base (SB) infiltration. Unresectability or incomplete surgical resection in such cases make radiotherapy treatment paramount. Curative dose escalation is challenging because of adjacent organs at risk, especially in locally advanced cases.

METHODS

Eighteen patients that had locally advanced SB SNACC with unresectable or incomplete surgical resection treated by proton therapy and/or helical tomotherapy at Institut Curie between 3/2010 and 8/2020 were retrospectively included.

RESULTS

After median follow-up of 52 months, 5-year OS, LRRFS, DMFS, DFS rates were, respectively, 47% (95%CI: 26-83), 50% (95%CI: 36-88), 39% (95%CI: 26-81), 33% (95%CI: 22-73). One patient had grade 4 late optic nerve disorder. Eight patients had grade 3 late toxicity including mainly hearing impairments.

CONCLUSION

Proton therapy and helical tomotherapy are effective and safe methods for curative dose escalation of locally advanced SB SNACC, which are a poor prognosis subgroup. Available literature suggests carbon-ion therapy could be an efficient alternative.

Management of reirradiations: A clinical and technical overview based on a French survey

INTRODUCTION

The reirradiation number increased due to systemic therapies and patient survival. Few guidelines regarding acceptable cumulative doses to organs at risk (OARs) and appropriate dose accumulation tools need, made reirradiation challenging. The survey objective was to present the French current technical and clinical practices in reirradiations.

METHODS

A group of physician and physicists developed a survey gathering major issues of the topic. The questionnaire consisted in 4 parts: data collection, demographic, clinical and technical aspects. It was delivered through the SFRO and the SFPM. Data collection lasted 2 months and were gathered to compute statistical analysis.

RESULTS

48 institutions answered the survey. Difficulties about patient data collection were related to patient safety, administrative and technical limitations. Half of the institutions discussed reirradiation cases during a multidisciplinary meeting. It mainly aimed at discussing the indication and the new treatment total dose (92%). 79% of the respondents used various references but only 6% of them were specific to reirradiations. Patients with pain and clinical deficit were ranked as best inclusion criteria. 54.2% of the institutions considered OARs recovery, especially for spinal cord and brainstem. A commercial software was used for dose accumulation for 52% of respondents. Almost all institutions performed equivalent dose conversion (94%). A quarter of the institutions estimated not to have the appropriate equipment for reirradiation.

CONCLUSION

This survey showed the various approaches and tools used in reirradiation management. It highlighted issues in collecting data, and the guidelines necessity for safe practices, to increase clinicians confidence in retreating patients.

Reproducibility of surface-based deep inspiration breath-hold technique for lung stereotactic body radiotherapy on a closed-bore gantry linac

Background and purpose

Tumor motion and delivery efficiency are two main challenges of lung stereotactic body radiotherapy (SBRT). The present work implemented the deep inspiration breath hold technique (DIBH) with surface guided radiation therapy (SGRT) on closed-bore linacs and investigated the correlation between SGRT data and internal target position.

Materials and methods

Thirteen lung SBRT patients treated in DIBH using a closed-bore gantry linac and a ring-mounted SGRT system were retrospectively analysed. Visual coaching was used to achieve DIBH with a ± 1 mm threshold window in the anterior-posterior direction. Three kV-CBCTs were added to the treatment workflow and examined offline to verify intra-fraction tumor position. Surface-based DIBH was analysed using SGRT treatment reports and an in-house python script. Data from 73 treatment sessions and 175 kV-CBCTs were studied. Correlations between target and surface positions were studied with Linear Mixed Models.

Results

Median intra-fraction tumor motion was 0.8 mm (range: 0.7-1.3 mm) in the anterior-posterior direction, 1.2 mm (range: 1-1.7 mm) in the superior-inferior direction, and 1 mm (range: 0.7-1.1 mm) in the left-right direction, with rotations of <1° (range: 0.6°-1.1°) degree in all three directions. Planned target volumes and healthy lung volumes receiving 12.5 Gy and 13.5 Gy were reduced on average by 67% and 54%, respectively.

Conclusions

Lung SBRT in DIBH with the ring-mounted SGRT system proved reproducible. The surface monitoring provided by SGRT was found to be a reliable surrogate for internal target motion. Moreover, the implementation of DIBH technique helped reduce target volumes and lung doses.

A Feasibility Study of Functional Lung Volume Preservation during Stereotactic Body Radiotherapy Guided by Gallium-68 Perfusion PET/CT

The aim of this study was to assess the feasibility of sparing functional lung areas by integration of pulmonary functional mapping guided by 68Ga-perfusion PET/CT imaging in lung SBRT planification. Sixty patients that planned to receive SBRT for primary or secondary lung tumors were prospectively enrolled. Lung functional volumes were defined as the minimal volume containing 50% (FV50%), 70% (FV70%) and 90% (FV90%) of the total activity within the anatomical volume. All patients had a treatment planning carried out in 2 stages: an anatomical planning blinded to the PET results and then a functional planning respecting the standard constraints but also incorporating “lung functional volume” constraints. The mean lung dose (MLD) in functional volumes and the percentage of lung volumes receiving xGy (VxGy) within the lung functional volumes using both plans were calculated and compared. SBRT planning optimized to spare lung functional regions led to a significant reduction (p < 0.0001) of the MLD and V5 to V20 Gy in all functional volumes. Median relative difference of the MLD in the FV50%, FV70% and FV90% was −8.0% (−43.0 to 1.2%), −7.1% (−34.3 to 1.2%) and −5.7% (−22.3 to 4.4%), respectively. Median relative differences for VxGy ranged from −12.5% to −9.2% in the FV50%, −11.3% to −7.2% in the FV70% and −8.0% to −5.3% in the FV90%. This study shows the feasibility of significantly decreasing the doses delivered to the lung functional volumes using 68Ga-perfusion PET/CT while still respecting target volume coverage and doses to other organs at risk.

Re-Irradiation after Radical Dose Radiotherapy: A Case Report Challenging an Established Dogma

Traditionally, external beam radiation therapy has a dogma pronouncing that re-irradiation of a region previously exposed to radical dose radiotherapy is contraindicated due to unacceptable risk to surrounding tissues. This edict is often zealously maintained to the detriment of certain, carefully selected patients that may benefit from re-irradiation. Liposarcoma is a high-grade malignancy with a poor prognosis and high rates of recurrence. A case is described of multiply recurrent liposarcoma that we treated with re-irradiation of an extended field encompassing the gross recurrent tumor mass and including the previously irradiated region. The patient had a very good cosmetic outcome and remained disease-free after 3 years of follow-up. The case demonstrates the potential to significantly improve patient care if established dogmas are challenged related to the re-irradiation of recurrent high-grade tumors. We propose that with careful patient selection, re-irradiation can be delivered safely to patients with recurrent tumors and contribute to improved clinical outcomes.

High dose craniospinal irradiation as independent risk factor of permanent alopecia in childhood medulloblastoma survivors: cohort study and literature review

PURPOSE

Our aim was to determine the main risk factors related to the occurrence of permanent alopecia in childhood medulloblastoma (MB) survivors.

METHODS

We retrospectively analyzed the clinical features of all consecutive MB survivors treated at our institute. We divided the patients into 3 groups depending on the craniospinal irradiation (CSI) dose received and defined permanent alopecia first in terms of the skin region affected (whole scalp and nape region), then on the basis of the toxicity degree (G). Any relationship between permanent alopecia and other characteristics was investigated by a univariate and multivariate analysis and Odds ratio (OR) with confidence interval (CI) was reported.

RESULTS

We included 41 patients with a mean10-year follow-up. High dose CSI resulted as an independent factor leading to permanent hair loss in both groups: alopecia of the whole scalp (G1 p-value 0.030, G2 p-value 0.003) and of the nape region (G1 p-value 0.038, G2 p-value 0.006). The posterior cranial fossa (PCF) boost volume and dose were not significant factors at multivariate analysis neither in permanent hair loss of the whole scalp nor only in the nuchal region.

CONCLUSION

In pediatric patients with MB, the development of permanent alopecia seems to depend only on the CSI dose ≥ 36 Gy. Acute damage to the hair follicle is dose dependent, but in terms of late side effects, constant and homogeneous daily irradiation of a large volume may have a stronger effect than a higher but focal dose of radiotherapy.

Dose-Volume Constraints fOr oRganS At risk In Radiotherapy (CORSAIR): An "All-in-One" Multicenter-Multidisciplinary Practical Summary

BACKGROUND

The safe use of radiotherapy (RT) requires compliance with dose/volume constraints (DVCs) for organs at risk (OaRs). However, the available recommendations are sometimes conflicting and scattered across a number of different documents. Therefore, the aim of this work is to provide, in a single document, practical indications on DVCs for OaRs in external beam RT available in the literature.

MATERIAL AND METHODS

A multidisciplinary team collected bibliographic information on the anatomical definition of OaRs, on the imaging methods needed for their definition, and on DVCs in general and in specific settings (curative RT of Hodgkin's lymphomas, postoperative RT of breast tumors, curative RT of pediatric cancers, stereotactic ablative RT of ventricular arrythmia). The information provided in terms of DVCs was graded based on levels of evidence.

RESULTS

Over 650 papers/documents/websites were examined. The search results, together with the levels of evidence, are presented in tabular form.

CONCLUSIONS

A working tool, based on collected guidelines on DVCs in different settings, is provided to help in daily clinical practice of RT departments. This could be a first step for further optimizations.

Research Value of Intensity Modulated Radiation Therapy in Alleviating Parotid Gland Function Injury in Patients with Stage N0 Nasopharyngeal Carcinoma from Physical and Dosimetric Aspects

Objective

To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N₀ nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects.

Methods

All the clinical data of 77 patients with pathologically confirmed T_1-4N₀M₀ NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later.

Results

Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group.

Conclusion

IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N₀ NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages.