Preclinical photon minibeam radiotherapy using a custom collimator: Dosimetry characterization and preliminary in-vivo results on a glioma model.

PURPOSE: The purpose of this study is to investigate the dosimetric characteristics of a collimator for minibeam radiotherapy (MBRT) with film dosimetry and Monte Carlo (MC) simulations. The outcome of MBRT with respect to conventional RT using a glioma preclinical model was also evaluated. METHODS: A multi-slit collimator was designed to be used with commercial small animal irradiator. The collimator was built by aligning 0.6 mm wide and 5 mm thick parallel lead leaves at 0.4 mm intervals. Dosimetry characteristics were evaluated by Gafchromic (CG) films and TOPAS Monte Carlo (MC) code. An in vivo experiment was performed using a glioma preclinical model by injecting two million GL261cells subcutaneously and treating with 25 Gy, single fraction, with MBRT and conventional RT. Survival curves and acute radiation damage were measured to compare both treatments. RESULTS: A satisfactory agreement between experimental results and MC simulations were obtained, the measured FWHM and distance between the peaks were respectively 0.431 and 1.098 mm. In vivo results show that MBRT can provide local tumor control for three weeks after RT treatment and a similar survival fraction of open beam radiotherapy. No severe acute effects were seen for the MBRT group. CONCLUSIONS: We developed a minibeam collimator and presented its dosimetric features. Satisfactory agreement between MC and GC films was found with differences consistent with uncertainties due to fabrication and set-up errors. The survival curves of MBRT and open field RT are similar while atoxicity is dramatically lower with MBRT, preliminarily confirming the expected effect.

Awareness Level of Cervical Cancer Patients Referred to Radiation Oncology Outpatient Clinics-A Multicenter Study.

OBJECTIVE: The study aimed to assess the level of knowledge of patients with cervical cancer referred to radiation oncology outpatient clinics in Turkey regarding screening methods and human papillomavirus (HPV) vaccination and increase social awareness based on the findings. METHODS: A descriptive cross-sectional survey was conducted from January to June 2022 involving 300 patients in various regions. Data on demographics, cervical cancer screening and HPV vaccination knowledge, and recommendations to relatives were collected through a questionnaire-based interview. Univariate logistic regression analyzed the impact of independent variables on knowledge levels. RESULTS: Among the participants, 57% were unaware of cervical cancer screening, and 66% had no knowledge of the HPV vaccine. Higher knowledge levels were associated with higher education, older age at marriage and first birth, and previous gynecological checkups. Lower knowledge levels were observed in patients treated at state institutions, with no formal education, and diagnosed with cervical cancer at age 60 or older. A significant inverse correlation was found between knowledge levels and the stage of cancer at diagnosis, with higher awareness in earlier stages. CONCLUSION: The study revealed limited awareness among cervical cancer patients in Turkey regarding screening and HPV vaccination. Lower knowledge levels were associated with specific demographic factors, emphasizing the importance of targeted educational campaigns to reduce the burden of cervical cancer and promote early detection. Efforts to enhance vaccination coverage and encourage early screening can significantly improve outcomes. Comprehensive awareness surveys are essential in guiding policymaking and implementing effective early detection and prevention strategies for cervical cancer.

Neoadjuvant intermediate-course versus long-course chemoradiotherapy in T3-4/N0+ rectal cancer: Istanbul R-02 phase II randomized study.

Radiation therapy (RT) is typically applied using one of two standard approaches for preoperative treatment of resectable locally advanced rectal cancer (LARC): short-course RT (SC-RT) alone or long-course RT (LC-RT) with concurrent fluorouracil (5-FU) chemotherapy. The Phase II single-arm KROG 11-02 study using intermediate-course (IC) (33 Gy (Gray)/10 fr (fraction) with concurrent capecitabine) preoperative chemoradiotherapy (CRT) demonstrated a pathologically complete response rate and a sphincter-sparing rate that were close to those of LC-CRT. The current trial aim to compare the pathological/oncological outcomes, toxicity, and quality of life results of LC-CRT and IC-CRT in cases of LARC. The prescribed dose was 33 Gy/10 fr for the IC-CRT group and 50.4 Gy/28 fr for the LC-CRT group. Concurrent chronomodulated capecitabine (Brunch regimen) 1650 mg/m2/daily chemotherapy treatment was applied in both groups. The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Colorectal Cancer Module (EORTC QLQ-CR29) was administered at baseline and at three and six months after CRT. A total of 60 patients with LARC randomized to receive IC-CRT (n = 30) or LC-CRT (n = 30) were included in this phase II randomized trial. No significant difference was noted between groups in terms of pathological outcomes, including pathological response rates (ypT0N0-complete response: 23.3% vs. 16.7%, respectively, and ypT0-2N0-downstaging: 50% for each; p = 0.809) and Dworak score-based pathological tumor regression grade (Grade 4-complete response: 23.3 vs. 16.7%, p = 0.839). The 5-year overall survival (73.3 vs. 86.7%, p = 0.173) rate was also similar. The acute radiation dermatitis (p < 0.001) and any hematological toxicity (p = 0.004) rates were significantly higher in the LC-CRT group, while no significant difference was noted between treatment groups in terms of baseline, third month, and sixth month EORTC QLQ-CR29 scores.

The effect of using virtual bolus on VMAT plan quality for left-sided breast cancer patients.

In breast cancer radiotherapy treatment with Volumetric Modulated Arc Therapy (VMAT), the respiratory motion may lead to underdosing of the target and overdosing of critical organs such as the heart and lungs. This study aims to investigate the effect of using Virtual Bolus with different thicknesses on VMAT plan quality for patients with 20 advanced left-sided breast cancers. The result of the study showed that using Virtual Bolus for VMAT treatment planning is a viable method to avoid any missing target coverage.