Laryngeal Preservation Rate and Salvage Therapy Following Initial Recurrence in a Real-world Setting After Definitive Radiation Therapy in Patients With Locally Advanced Laryngeal Squamous Cell Carcinoma.

Background/Aim: The larynx plays a pivotal role in vocalization and airway protection, and laryngeal cancer manifests through various symptoms. Contemporary strategies focus on laryngeal preservation, particularly through non-surgical modality therapies that utilize radiotherapy. The aim of this study was to assess the laryngeal preservation rate after definitive radiation therapy in patients with locally advanced laryngeal squamous cell carcinoma and investigate salvage therapy subsequent to the initial recurrence in a real-world context. Patients and Methods: Analysis included a total of 40 patients with locally advanced laryngeal squamous cell carcinoma who were treated with definitive radiotherapy in the University of Tokyo Hospital. Treatment involved external beam radiotherapy (70 Gy in 35 fractions) with elective nodal irradiation. The main study outcomes were assessment of survival, overall survival, local control, and the factors influencing laryngeal preservation. Results: The patients exhibited a median age of 64.5 years, and 80% of them were men. Chemotherapy was administered to 82.5% of the patients. The 3-year overall survival, progression-free, and laryngeal preservation survival rates were 86.3%, 66.8%, and 78.4%, respectively. Univariate and multivariate analyses identified chemotherapy to be significantly associated with favorable laryngeal preservation survival (p<0.001). Conclusion: Definitive radiotherapy results in favorable outcomes for laryngeal preservation in locally advanced laryngeal squamous cell carcinoma. This study emphasizes the importance of chemotherapy in comprehensive patient management. Nevertheless, larger prospective studies are crucial to validate and optimize therapeutic approaches for this condition.

Radiotherapy for Solitary Bony or Extramedullary Plasmacytoma.

Background/Aim: This study aimed to determine the oncological outcomes associated with curative radiotherapy for solitary bony or extramedullary plasmacytomas by drawing on clinical data from a single tertiary center. This study aimed to provide a comprehensive understanding of the efficacy of radiotherapeutic interventions and delineate the patterns of disease recurrence. Patients and Methods: Eleven consecutive patients diagnosed with solitary bony or extramedullary plasmacytomas and treated between May 2007 and November 2023 were retrospectively screened. Different radiotherapy doses and fractionations were employed, and statistical analyses were performed to assess overall survival (OS) and disease-free survival (DFS). Results: Among the 11 patients (9 males and 2 females), primary tumors were located within the bone in seven patients, whereas extramedullary tumors were observed in four patients. The median prescribed radiation dose was 46 Gy. The 5-year OS and DFS were 83.3% and 28.9%, respectively. Progression to multiple myeloma occurred in four patients with primary bony plasmacytoma. Local control rate was 88.9%, and one patient experienced distant metastasis after 32 months. Bony plasmacytoma has a high tendency of leading to multiple myeloma rather than extramedullary plasmacytoma (5-year progression to multiple myeloma-free survival rate, 20.8% vs. 100%, p=0.08). Conclusion: Radiotherapy is effective for solitary plasmacytomas with favorable local control and high objective response rates. A comparison with the existing literature supports the role of radiotherapy in the management of these conditions. The differences in outcomes between bony and extramedullary plasmacytomas emphasize the need for personalized treatment approaches.

The role of upfront neck dissection in definitive radiotherapy for locally advanced hypopharyngeal squamous cell carcinoma: A single-center retrospective analysis.

BACKGROUND: Hypopharyngeal cancer, constituting 3%-5% of head and neck cancers, predominantly presents as squamous cell carcinoma, with a 5-year overall survival rate of approximately 40%. Treatment modalities for locally advanced cases include chemoradiotherapy; however, the role of upfront neck dissection (UND) remains controversial. This study aimed to investigate the effect of UND on definitive radiotherapy in locally advanced hypopharyngeal carcinoma. METHODS: This retrospective analysis included consecutive patients with locally advanced hypopharyngeal squamous cell carcinoma who were treated in our department between January 2007 and June 2023. All patients underwent definitive radiotherapy (dRT) at a total dose of 70 Gy in 35 fractions. The patients were categorized into two groups: dRT (radiotherapy with or without chemotherapy) and UND-dRT (surgical neck dissection followed by radiotherapy). Univariate Cox models and multivariate analyses were conducted to investigate the independent prognostic factors for overall survival and locoregional control rate. RESULTS: This study included 115 patients, predominantly male (109/115), with a median age of 66 years. Clinical stage and chemotherapy distribution differed significantly between the dRT and UND-dRT groups. The 3-year overall survival and locoregional control rates for all patients were 63.8% and was 63.3%, respectively. The UND-dRT group exhibited a trend toward improved locoregional control, although this difference was not statistically significant. The multivariate analysis revealed that UND was an independent factor significantly associated with improved overall survival and locoregional control. CONCLUSION: This study provided evidence supporting the effectiveness of UND in conjunction with definitive radiotherapy for locally advanced hypopharyngeal carcinoma. Future research should focus on validating and refining these findings through well-designed prospective multicenter trials.

Sustaining consistent cobalt-60 dose rate enhances radiosurgical outcomes in brain arteriovenous malformation management.

BACKGROUND AND PURPOSE: The impact of cobalt-60 dose rate (Co-60 DR) on outcomes of stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs) remains fully elucidated. This study explored the association between Co-60 DR and SRS outcomes in AVM treatment. MATERIALS AND METHODS: 772 AVM patients from 1990 to 2020 were included. High DR was defined as ≥ 2.4 Gy/min. AVM patients were categorized into 3 cohorts based on the nidus volume: small (<5 mL), medium (≥5 mL and < 10 mL), and large (≥10 mL). The primary endpoint was AVM obliteration; secondary endpoints included post-SRS hemorrhage. RESULTS: Cumulative obliteration rates of the large AVM were significantly increased in the high DR group than those in the low DR group (84 % vs. 45 % at 5 years, log-rank test; p = 0.011). Multivariable analysis showed that the obliteration rate was significantly elevated for the high DR group in the large AVM cohort with an adjusted hazard ratio (HR) of 1.78 (95 % confidence interval [CI]: 1.00-3.17, p = 0.049). Post-SRS hemorrhage rates of the entire cohort were significantly decreased in the high DR group than in the low DR group (2.5 % vs. 5.3 % at 5 years, log-rank test; p = 0.035). Multivariable analysis revealed post-SRS hemorrhage was reduced in the high DR group with an adjusted HR of 0.47 (95 % CI: 0.24-0.92, p = 0.026). CONCLUSION: High DR may lead to increased efficiency for large AVMs and decreased post-SRS hemorrhage in all AVM cases. Sustaining a higher Co-60 DR could potentially yield favorable outcomes for SRS for AVMs.

Comparative analysis of treatment decision-making in patients with localized prostate and cervical cancer: what influences receiving surgery or radiotherapy?

PURPOSE: This study focused on identifying the factors influencing the decision-making process in patients with localized prostate and cervical cancer in Japan and specifically examining the choice between surgery and radiotherapy. METHODS: Patients with specific cancer stages registered with a healthcare research company for whom radical surgery or radiotherapy was equally effective and recommended participated in this cross-sectional online survey. RESULTS: The responses of 206 and 231 patients with prostate and cervical cancer, respectively, revealed that both groups relied heavily on the physicians' recommendations (prostate: odds ratio (OR) = 40.3, p < 0.001; cervical: OR = 5.59, p < 0.001) and their impression of radiotherapy (prostate: OR = 9.22, p < 0.001; cervical: OR = 2.31, p < 0.001). Factors such as hypertension (OR = 6.48, p < 0.05), diabetes mellitus (OR = 9.68, p < 0.05), employment status (OR = 0.08, p < 0.01), and impressions of surgery (OR = 0.14, p < 0.01) also played a significant role in patients with prostate cancer. In contrast, the specialty of the physician (OR = 4.55, p < 0.05) proposing the treatment influenced the decision-making process of patients with cervical cancer. Information sources varied between the two groups: patients with prostate cancer were more inclined towards printed materials, whereas patients with cervical cancer were more inclined towards interpersonal relationships. CONCLUSION: Although several limitations, such as the sample and recall bias, were noted, this study emphasizes the role of psychosocial factors in the decision-making process and the requirement for tailored information sources.

Definitive Radiotherapy for Stage I Gastric Mucosa-Associated Lymphoid Tissue Lymphoma: A Retrospective Cohort of Unique-Dose Administration of 30 Gy in 15 Fractions and Analysis of Remission Duration.

Background: Gastric mucosa-associated lymphoid tissue (MALT) lymphoma constitutes a significant proportion of primary stomach lymphomas. The optimal dosage for radiotherapy and standardized follow-up protocols are yet to be universally established. This study focuses on stage I gastric MALT lymphoma patients, presenting clinical outcomes of radiotherapy with a unique dose of 30 Gy in 15 fractions and analyzing remission time. Methods: A retrospective cohort study, approved by the institutional review board, included consecutive stage I gastric MALT lymphoma patients undergoing curative radiotherapy between 2008 and 2022. Staging followed the Lugano Modification of the Ann Arbor Staging System. The prescribed dose was uniform dose of 30 Gy in 15 fractions. Results: Fifty-three patients were eligible, with a median age of 63 years. All achieved complete remission (CR), with a median CR time of 3.9 months. At a median follow-up of 56.8 months, no deaths occurred, and three recurrences were noted. The 5-year overall survival, local control survival, and disease-free survival rates were 100%, 100%, and 97.7%, respectively. No severe acute adverse events were observed. Conclusion: The study demonstrates sustained and favorable long-term disease control with a 30 Gy dose in 15 fractions for stage I gastric MALT lymphoma. Comparisons with existing literature highlight the efficacy and safety of radiotherapy in achieving durable remission. Ongoing efforts explore dose reduction and technological advancements to minimize toxicity. This study emphasizes the importance of awaiting clinical response confirmation to validate these outcomes in patients with gastric MALT lymphoma.

Early-stage hypopharyngeal squamous cell carcinoma treated with radical radiotherapy at a uniform dose of 70 Gy in 35 fractions: a single-center study.

INTRODUCTION: Hypopharyngeal squamous cell carcinoma (HSCC) is often undetected until advanced stages, which contributes to poor survival rates. Recent advances in diagnostic techniques have enhanced the feasibility of early detection, and this study evaluated the efficacy and safety of radical radiotherapy that specifically targets early stage HSCC. METHODS: This retrospective cohort study consecutively analyzed patients with clinical stage I or II HSCC between December 2008 and February 2023. These patients underwent radical radiotherapy with a uniform dose of 70 Gy delivered in 35 fractions to the primary site, followed by elective nodal irradiation. We assessed clinical outcomes, including overall survival (OS), disease-free survival (DFS), and 5-year locoregional control (LRC). Multivariate analyses were performed to identify the independent prognostic factors for OS. RESULTS: The 5-year OS rate of the entire cohort was 80.7% (95% confidence interval [CI] = 66.5-89.4%), with no significant difference between patients with clinical stage I and II HSCC. Stratified by subsite, the 5-year OS for pyriform sinus, posterior pharyngeal wall, and postcricoid region were 81.6, 68.2, and 100%, respectively. The ECOG-Performance status (PS) was identified as an independent risk factor for OS (hazard ratio [HR] = 8.457; 95% CI 1.325-53.970; p = 0.024). DFS at 5 years was 66.4%, with local recurrence being the most frequent, and LRC rate at 5 years was 79.3%. Acute and late-phase toxicities were predominantly mild to moderate, with no grade 3 or higher toxicities reported. CONCLUSION: This study supports radical radiotherapy as an effective approach for optimal tumor control in patients with early stage HSCC. Despite the limitations of this study, including its retrospective design and single-center confinement, our results revealed the effectiveness and feasibility of radical radiotherapy in the management of early stage HSCC.

Exploring the Correlation Between Health Literacy and Knowledge of Cervical Cancer and Radiotherapy Among Japanese Women: A Web-Based Survey.

Health literacy (HL) plays a vital role in an individual's ability to make informed health decisions. Japan faces several challenges in cervical cancer control, including low human papillomavirus (HPV) vaccination and screening rates, underutilization of radiotherapy, and limited HL. This study explored the association between HL and knowledge of cervical cancer and radiotherapy, particularly among young Japanese women. We conducted a web-based survey among users of LunaLuna, a popular women's healthcare application, to assess their HL and knowledge about cervical cancer and radiotherapy through a 46-question survey. We compared three groups in terms of HL (inadequate, problematic, and sufficient & excellent). Multiple regression analysis was used to identify factors associated with knowledge. In total, 1468 respondents were included in this study. HL was positively correlated with knowledge scores (inadequate: 51.8%; problematic: 56.3%; sufficient & excellent: 60%). Participants displayed relatively low accuracy for treatment-related questions. Higher HL (ß = 0.15, p < 0.01), education (ß = - 0.11, p < 0.01), cervical cancer screening (ß = - 0.11, p < 0.01), income (ß = 0.09, p < 0.01), and employment (ß = - 0.06, p = 0.04) were significant factors affecting knowledge of cervical cancer and radiotherapy. Our findings underscore the pivotal role of HL in promoting cervical cancer prevention and providing a better understanding of radiotherapy. Despite factors such as age, education, and history of cervical cancer screening, HL showed the strongest association with knowledge of cervical cancer and radiotherapy. The enhancement of HL and knowledge dissemination may be critical for promoting cervical cancer prevention and radiotherapy in Japan.

Comparing health literacy and behavioral changes in adulthood: A pilot study on alumni of a single school cancer education program.

Cancer education programs are regularly conducted in schools in Japan. Previous reports on their effectiveness were based on surveys conducted several months after the education. We aimed to evaluate whether cancer education for children influenced their behavioral changes in adulthood. We targeted schools where the Japan Cancer Society has conducted the programs since 2011 and the program participants are older than 21 years currently. Invitations were sent to the participants and controls who graduated one year before or after the participants, and answers were obtained using an online questionnaire. Data were collected on the willingness to undergo cancer screening, sociodemographic characteristics, healthy behaviors, and health literacy. We compared the data from the program participants with those from controls. We requested cooperation from 13 schools; however, only one agreed. The common reason for refusal was privacy concerns. In the all-boys participating school in Tokyo, there was no significant difference in background information between the cancer education (38 participants) and control (55 participants) groups. Multiple linear regression showed that healthcare or welfare education background (ß = 0.25, p = 0.01) and health literacy (ß = 0.24, p = 0.02) were significant predictors of cancer screening intention, while the presence of cancer education (p = 0.25) was not. Despite severe selection bias, this is the first study to examine the long-term impacts of cancer education. We found no significant impacts on the measured outcome. However, the educational content at that time differed from that of today, and the program's efficacy should not be negated.

Variation in Hounsfield unit calculated using dual-energy computed tomography: comparison of dual-layer, dual-source, and fast kilovoltage switching technique.

The purpose of the study is to investigate the variation in Hounsfield unit (HU) values calculated using dual-energy computed tomography (DECT) scanners. A tissue characterization phantom inserting 16 reference materials were scanned three times using DECT scanners [dual-layer CT (DLCT), dual-source CT (DSCT), and fast kilovoltage switching CT (FKSCT)] changing scanning conditions. The single-energy CT images (120 or 140 kVp), and virtual monochromatic images at 70 keV (VMI70) and 140 keV (VMI140) were reconstructed, and the HU values of each reference material were measured. The difference in HU values was larger when the phantom was scanned using the half dose with wrapping with rubber (strong beam-hardening effect) compared with the full dose without the rubber (reference condition), and the difference was larger as the electron density increased. For SECT, the difference in HU values against the reference condition measured by the DSCT (3.2 ± 5.0 HU) was significantly smaller (p < 0.05) than that using DLCT with 120 kVp (22.4 ± 23.8 HU), DLCT with 140 kVp (11.4 ± 12.8 HU), and FKSCT (13.4 ± 14.3 HU). The respective difference in HU values in the VMI70 and VMI140 measured using the DSCT (10.8 ± 17.1 and 3.5 ± 4.1 HU) and FKSCT (11.5 ± 21.8 and 5.5 ± 10.4 HU) were significantly smaller than those measured using the DLCT120 (23.1 ± 27.5 and 12.4 ± 9.4 HU) and DLCT140 (22.3 ± 28.6 and 13.1 ± 11.4 HU). The HU values and the susceptibility to beam-hardening effects varied widely depending on the DECT scanners.

Central Neurocytoma Treated Using Supratentorial Ventricle Radiotherapy: A Single-Institution Analysis of Five Cases in Adjuvant or Salvage Settings After Surgery.

INTRODUCTION: Central neurocytoma (CN) is an extremely rare tumor primarily located in the supratentorial ventricular system, categorized as a glioneuronal or neuronal tumor. METHODS: This study presented a retrospective analysis of five CN patients who received adjuvant or salvage radiotherapy. Patients, aged 31-59 years, underwent radiation doses ranging from 60 Gy to 50.4 Gy over 27-30 fractions. RESULTS: All patients achieved effective local tumor control without severe complications. The median follow-up period was 51.7 months, demonstrating 100% overall and progression-free survival rates. DISCUSSION: Our study's clinical outcomes align with previous research, despite the limitation of a small sample size. Emphasizing the necessity for additional research, our findings added to the potential evidence of radiotherapy in managing CN. Larger, long-term studies were needed to confirm these promising results.

Curative Radiotherapy for Oropharyngeal Squamous Cell Carcinoma Stratified by p16 Status, According to the Eighth Edition American Joint Committee on Cancer Staging Manual: A Retrospective Study.

Background/Aim: The prevalence of oropharyngeal squamous cell carcinoma (OPSCC) is increasing worldwide. This retrospective study aimed to investigate the clinical outcomes of patients with OPSCC undergoing definitive radiotherapy, stratified according to their p16 status. Patients and Methods: A retrospective analysis was conducted on consecutive patients with OPSCC treated with curative external beam radiotherapy between May 2015 and September 2023. Clinical staging was determined by the eighth edition AJCC staging manual for p16 positive and negative OPSCC. All patients were treated with radiotherapy using a simultaneous integrated boost (SIB) with helical tomotherapy. The fractionation scheme, with or without chemotherapy, for the primary site and nodal lesions consisted of 2 Gy per fraction for a total dose of 70 Gy in 35 fractions over seven weeks. Results: This study included 76 patients with a median age of 66 years. With a median follow-up time of 32.6 months, the 3-year progression-free survival rate was significantly higher in p16 positive patients compared to p16 negative patients (79.6% vs. 42.5%, p<0.001). Concerning 54 patients with p16-positive tumors, the overall survival rates indicated excellent clinical outcomes for stage I, II, and III with results of 100%, 100%, and 88.1%, respectively. Conclusion: This retrospective study revealed the clinical outcomes of patients with OPSCC treated with radical radiotherapy, emphasizing the significance of p16 status. While acknowledging the limitations of the retrospective nature of this study, future prospective studies with larger cohorts and extended follow-up periods are needed to enhance evidence quality.

Safety evaluation of sinus patency after stereotactic radiosurgery for transverse-sigmoid sinus dural arteriovenous fistulas: implications of treatment options for patients with Borden type I fistulas.

OBJECTIVE: This study aimed to assess the efficacy and safety of stereotactic radiosurgery (SRS) in treating transverse-sigmoid sinus dural arteriovenous fistulas (TSS DAVFs), and to investigate post-SRS sinus patency, focusing on the risk factors associated with treated sinus occlusion. METHODS: Data from 34 patients treated with SRS between January 2006 and April 2023 were analyzed. Detailed angioarchitecture was confirmed using digital subtraction angiography before SRS. Angiography of the ipsilateral internal carotid artery and vertebral artery was performed to evaluate whether the involved side of the TSS was used for normal venous drainage. TSS stenosis was defined as sinus diameter < 50% of the normal proximal diameter. DAVF shunt obliteration, TSS occlusion, neurological status, and adverse events were also evaluated. RESULTS: Of the 34 patients, 21 had Borden type I and 14 had Borden type II DAVFs. The median age at SRS was 64 years (interquartile range 54-71 years), and the follow-up period was 31 months (interquartile range 15-94 months). Complete shunt obliteration was achieved in 24 (70.6%) patients. The cumulative 2-, 3-, and 5-year shunt obliteration rates were 49.6%, 71.2%, and 86.0%, respectively. Borden type I had higher obliteration rates (60.5%, 83.1%, and 94.4%, respectively) than Borden type II (41.7%, 51.4%, and 75.7%, respectively; p = 0.034). TSS occlusion occurred in 5 patients (14.7%). The cumulative 1-, 5-, and 10-year TSS occlusion rates were 2.9%, 8.3%, and 23.6%, respectively, across the entire cohort. All occlusions occurred exclusively in the sinuses that were not used for normal venous drainage. Cox proportional analyses revealed that TSS stenosis and the sinus not being used for normal venous drainage were significantly associated with a greater risk of TSS occlusion after SRS (HR 9.44, 95% CI 1.01-77.13; p = 0.049). CONCLUSIONS: SRS is effective and safe for TSS DAVF and results in favorable shunt obliteration, symptom improvement, and low complication rates. TSS occlusion after SRS is asymptomatic and is limited to sinuses that are not used for normal venous drainage.

Risk factors for local recurrence of keloids and hypertrophic scars after postoperative electron beam radiotherapy.

OBJECTIVE: Keloids and hypertrophic scars are benign fibroproliferative lesions that occur as a result of skin injury. Postoperative radiation therapy is used to reduce the recurrence rate because of the high recurrence rate with surgical treatment alone. This study aimed to identify the risk factors for recurrence after postoperative electron beam radiotherapy. MATERIALS AND METHODS: Patients with keloid or hypertrophic scars with at least one lesion and who underwent postoperative electron beam radiotherapy at our institution from June 2013 to March 2022 were included in the study, while patients with a follow-up period of fewer than three months were excluded. RESULTS: A retrospective analysis was performed on 94 lesions in 81 patients. Exactly two years after the treatment, the actuarial local control rate was 86.4%. The chest wall, shoulder, and suprapubic area were identified as high-risk recurrence sites. Compared to other body sites, these sites had significantly lower local control rates (two-year local control rates: 75.5% vs. 95.2%, P = 0.005). After multivariate analysis, treatment site (P = 0.014), male gender (P = 0.019), and younger age (P = 0.029) were revealed to be statistically significant risk factors for local recurrence. Risk factors for keloid recurrence after postoperative electron beam radiotherapy were therefore identified. CONCLUSION: This result could be used for follow-up and as a determinant for the optimal dose/fractionation of postoperative radiotherapy.

Prognostic value of radiomic features in patients with esophageal cancer treated with chemoradiotherapy.

BACKGROUND: The aim of the present study was to evaluate the prognostic value of radiomic features in patients who underwent chemoradiotherapy for esophageal cancer. METHODS: In this retrospective study, two independent cohorts of esophageal cancer patients treated with chemoradiotherapy were included. Radiomics features of each patient were extracted from pre-treatment computed tomography (CT) images. Radiomic features were selected by employing univariate and multivariate analyses in the test cohort. Selected radiomic features were verified in the validation cohort. The endpoint of the present study was overall survival. RESULTS: A total of 101 esophageal cancer patients were included in our study, with 71 patients in the test cohort and 30 patients in the validation cohort. Univariate analysis identified 158 radiomic features as prognostic factors for overall survival in the test cohort. A multivariate analysis revealed that root mean squared and Low-High-High (LHH) median were prognostic factors for overall survival with a hazard ratio of 2.23 (95% confidence interval [CI]: 1.16-4.70, P = 0.017) and 0.26 (95% CI: 0.13-0.54, P < 0.001), respectively. In the validation cohort, root mean squared high/LHH median low group had the most preferable prognosis with a median overall survival of 73.30 months (95% CI: 32.13-NA), whereas root mean squared low/LHH median low group had the poorest prognosis with a median overall survival of 9.72 months (95% CI: 2.50-NA), with a P value of < 0.001. CONCLUSIONS: We identified two radiomic features that might be independent prognostic factors of overall survival of esophageal cancer patients treated with chemoradiotherapy.

Role of stereotactic radiosurgery for recurrent skull base acinic cell carcinoma: illustrative case.

BACKGROUND: Acinic cell carcinomas (AcCCs), rare malignancies of the salivary glands, often recur and metastasize, particularly in the skull base. Conventional radical resection can be invasive for skull base AcCCs adjacent to cranial nerves and major vasculature, and the effectiveness of stereotactic radiosurgery (SRS) as an alternative is not well established. OBSERVATIONS: This case report details the application of SRS for recurrent skull base AcCCs. A 71-year-old male with a history of resection for a right mandibular AcCC 23 years earlier experienced tumor recurrence involving the right cavernous sinus and nasal cavity. He underwent endoscopic transnasal surgery followed by SRS targeting different tumor locations-the cavernous sinus to the pterygopalatine fossa, maxillary sinus, and clivus-each with a prescribed dose of 20 Gy to the 40% to 50% isodose line. After the first skull base metastasis, additional sessions of localized SRS after endoscopic surgery led to a 12-year survival without sequela. LESSONS: This is a report indicating that SRS for skull base AcCCs can achieve favorable local control, functional preservation, and long-term survival. SRS may be suitable for skull base AcCC given the lesion's tendency toward multiple local recurrences. Further investigation is needed to validate the treatment's efficacy.

Long-term geometric quality assurance of radiation focal point and cone-beam computed tomography for Gamma Knife radiosurgery system.

To investigate the geometric accuracy of the radiation focal point (RFP) and cone-beam computed tomography (CBCT) over long-term periods for the ICON Leksell Gamma Knife radiosurgery system. This phantom study utilized the ICON quality assurance tool plus, and the phantom was manually set on the patient position system before the implementation of treatment for patients. The deviation of the RFP position from the unit center point (UCP) and the positions of the four ball bearings (BBs) in the CBCT from the reference position were automatically analyzed. During 544 days, a total of 269 analyses were performed on different days. The mean ± standard deviation (SD) of the deviation between measured RFP and UCP was 0.01 ± 0.03, 0.01 ± 0.03, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively. The deviations with offset values after the cobalt-60 source replacement (0.00 ± 0.03, -0.01 ± 0.01, and -0.01 ± 0.01 mm in the X, Y, and Z directions, respectively) were significantly (p = 0.001) smaller than those before the replacement (0.02 ± 0.03, 0.02 ± 0.01, and -0.02 ± 0.01 mm in the X, Y, and Z directions, respectively). The overall mean ± SD of four BBs was -0.03 ± 0.03, -0.01 ± 0.05, and 0.01 ± 0.03 mm in the X, Y, and Z directions, respectively. Geometric positional accuracy was ensured to be within 0.1 mm on most days over a long-term period of more than 500 days.

Hypofractionated Radiotherapy as a Standalone Treatment Modality for Locally Advanced Type B2 Thymoma in an Octogenarian Patient: 45 Gy in 15 Fractions.

Thymic epithelial tumors (TETs), particularly type B2 thymomas, are rare neoplasms primarily found in the anterior mediastinum. The current therapeutic approach includes surgery, chemotherapy, and radiotherapy, but there is limited research on radiotherapy as a standalone treatment. This case report aims to elucidate the clinical outcomes of hypofractionated radiotherapy as a standalone treatment for locally advanced type B2 thymoma, offering insights into its potential efficacy and role in clinical practice.

Initial validation of a diaphragm tracking system for multiple breath-hold volumetric modulated arc therapy of abdominal tumors: A phantom study.

BACKGROUND: The breath-hold radiotherapy has been increasingly used to mitigate interfractional and intrafractional breathing impact on treatment planning and beam delivery. Previous techniques include body surface measurements or radiopaque metal markers, each having known disadvantages. PURPOSE: We recently proposed a new markerless technique without the disadvantages, where diaphragm was registered between DRR and fluoroscopic x-ray projection images every 180 ms during VMAT delivery. An initial validation of the proposed diaphragm tracking system (DiaTrak) was performed using a chest phantom to evaluate its characteristics. METHODS: Diaphragm registration was performed between DRR and projection streaming kV x-ray images of a chest phantom during VMAT delivery. Streaming data including the projection images and the beam angles were transferred from a linac system to an external PC, where the diaphragm registration accuracy and beam-off latency were measured based on image cross correlation between the DRR and the projection images every 180 ms. RESULTS: It was shown that the average of the beam-off latency was 249.5 ms and the average of the diaphragm registration error was 0.84 mm CONCLUSIONS: Initial validation of the proposed DiaTrak system for multiple breath-hold VMAT of abdominal tumors has been successfully completed with a chest phantom. The resulting beam-off latency and the diaphragm registration error were regarded clinically acceptable.

Relationship between hydrogel spacer distribution and dosimetric parameters in linear-accelerator-based stereotactic body radiotherapy for prostate cancer.

PURPOSE: To explore the potential of quantitative parameters of the hydrogel spacer distribution as predictors for separating the rectum from the planning target volume (PTV) in linear-accelerator-based stereotactic body radiotherapy (SBRT) for prostate cancer. METHODS: Fifty-five patients underwent insertion of a hydrogel spacer and were divided into groups 1 and 2 of the PTV separated from and overlapping with the rectum, respectively. Prescribed doses of 36.25-45 Gy in five fractions were delivered to the PTV. The spacer cover ratio (SCR) and hydrogel-implant quality score (HIQS) were calculated. RESULTS: Dosimetric and quantitative parameters of the hydrogel spacer distribution were compared between the two groups. For PTV, D99% in group 1 (n = 29) was significantly higher than that in group 2 (n = 26), and Dmax, D0.03cc, D1cc, and D10% for the rectum were significantly lower in group 1 than in group 2. The SCR for prostate (89.5 ± 12.2%) in group 1 was significantly higher (p < 0.05) than that in group 2 (74.7 ± 10.3%). In contrast, the HIQS values did not show a significant difference between the groups. An area under the curve of 0.822 (95% confidence interval, 0.708-0.936) for the SCR was obtained with a cutoff of 93.6%, sensitivity of 62.1%, and specificity of 100%. CONCLUSIONS: The SCR seems promising to predict the separation of the rectum from the PTV in linear-accelerator-based SBRT for prostate cancer.