Practical Radiation Oncology最新文献

Purpose: Incorporating Cherenkov imaging can improve radiotherapy treatment verification through both real-time monitoring and retrospective analysis of beam delivery. In bilateral breast radiotherapy, a medial gap between opposing beams is intentionally planned to avoid unwanted overlap in the midline region. We present the first in-vivo analysis of Cherenkov images from bilateral breast radiotherapy.

Methods: All patients were treated with a single-isocenter, 3D conformal plan utilizing a deep-inspiration breath hold technique. Cherenkov emissions were recorded with a ceiling-mounted camera. Optical phantom experiments were conducted to identify the appropriate choice of imaging thresholding. The minimum distance across the medial gap was measured using the Cherenkov imaging data for three patients recorded across a total of 23 treatment fractions.

Results: Analysis of the Cherenkov beam footprints demonstrated a discernible gap for all delivered fractions. The average minimum gap size computed in each of the patient treatment plans was 1.1 cm, 1.0 cm and 2.0 cm. The average minimum gap size for each patient during radiotherapy measured with Cherenkov imaging was 1.0 cm ± 0.4 cm, 0.9 cm ± 0.2 cm, and 2.0 cm ± 0.6 cm, respectively. Intrapatient gap size variability is thought to be due to patient breath-hold differences across sessions.

Conclusions: This study provides the use of Cherenkov imaging to verify the daily medial field gap in bilateral breast radiotherapy patients. Regular offline review of these images could enable direct feedback to the treatment team in cases of potential field overlap, while also reducing the need for radiochromic film or detector-based in-vivo dosimetry.

Purpose: Recent national policies have championed new standards in family and medical leave for graduate medical trainees. We hypothesize there remains variability in residency program leave policies. Project PARENT aimed to create a database of parental leave policies at United States (US) radiation oncology and medical physics residency programs.

Methods and materials: A mixed methods design was used in this study, consisting of a 29-question survey was distributed in 2024 to all US radiation oncology physician (RO) and medical physics (MP) residency programs by email and remained open for 6 weeks. For programs that did not supply a survey response, Document Analysis (data abstraction) was performed with information from program websites. All programs were offered a data verification opportunity.

Results: The survey was distributed to 84 US RO, 107 MP therapy, and 43 MP imaging residency programs. Composite survey responses were completed by 32/84 (38%) physician residencies, and 75/100 (50%) MP programs (62 therapy + 13 imaging); Altogether website data abstraction for programs without responses resulted in a final program representation of 99% and 100% in RO and MP programs, respectively. Among programs who provided a specific value, the median "maximum parental leave" provided was 12 weeks (IQR 8-12) for RO birthing parents, 12 weeks (IQR 12-12) for MP birthing parents, 12 weeks (IQR 6-12) for RO non-birthing parents, and 12 weeks (IQR 8-12) for MP non-birthing parents; the median length of paid leave provided to all parents in RO and MP was 6 weeks.

Conclusion: Project PARENT is the first comprehensive parental leave information source in any medical specialty. We anticipate this family leave program policy database will empower residency program leaders and applicants to navigate family leave policies to the mutual benefit of all.

Purpose/objective(s): Radiation therapy (RT) positioning and planning are vital to minimizing toxicity in patients with synchronous bilateral breast cancer (SBBC). We studied clinical outcomes and setup reproducibility in SBBC patients treated in the prone position.

Materials/methods: This retrospective study analyzed SBBC patients treated prone between 2012-2022. Demographics, clinical RT dose/field, dosimetry, on-treatment imaging, toxicity, and outcomes data were collected. RT delivery was standardized, with left breast treated first. After 2014, radiochromic (GaF) films were placed fractions 1-5 to evaluate field overlap, prompting re-simulation or re-planning if consistent overlap was detected. Positional shifts during setup were collected for bilateral whole breast irradiation (WBI) and partial breast irradiation (PBI).

Results: 45 patients were included. Median age was 67 years old and median follow-up was 64 months. 35, 5, and 5 patients received bilateral WBI (1 with low axilla), bilateral PBI, a combination of WBI and PBI, respectively. The most common WBI dose was 40.5 Gy, with a simultaneous tumor bed boost to 48 Gy. PBI patients received 30 Gy in 5 fractions (n=4) or 40.05 Gy in 15 fractions (n=1). All patients who developed grade 2 (17.7%) and grade 3 (2%) dermatitis received bilateral WBI except for 1. 6 patients had acute dermatitis in the sternal area with overlap on GaF seen in 2 patients. Of 20 patients with late toxicity follow-up, 25% had late grade 1-2 dermatitis (20% received WBI). One patient recurred locally and distantly. Mean positional shifts were mostly sub-centimeter or sub-degree. Only 10% of patients had field overlap on GaF.

Conclusion: To our knowledge, this is the first study examining patients treated for SBBC in the prone position. Prone bilateral RT is feasible with minimal shifts and overlap. However, higher rates of acute dermatitis occurred in bilateral WBI patients (vs. PBI), and overlap wasn't seen on GaF in all patients who developed midline dermatitis.

Purpose: We sought to characterize outcomes from a large institutional database of patients treated with 3-fraction spine stereotactic body radiation therapy (SBRT) after prior overlapping RT.

Materials and methods: The primary outcome of interest was local failure (LF) in the treated lesion, defined based on MRI. We also characterized toxicities such as vertebral compression fracture (VCF) and radiation myelitis (RM).

Results: There were 83 patients treated to 87 spinal lesions between 2014-2023. Median follow-up was 14.2 (interquartile range (IQR) 6-29.4) months and median overall survival was 20.5 (95% confidence interval (CI) 16.5-29.9) months. Most lesions were treated with 27 Gy in 3 fractions (n=78; 90%). Most lesions had been treated with prior conventionally fractionated RT (59%), and the most common histology was prostate cancer (n=15; 17%). The 1- and 2-year LF rate was 8.4% (95% CI 3.7-16%) and 15% (95% CI 8.1-24%), respectively. On univariable analysis, lower minimum dose (DMin) to the planning target volume (PTV) (HR 0.85, 95% CI 0.74-0.99, p=0.03) and colorectal, cholangio-, or hepatocellular carcinoma histology (HR 5.6, 95% CI 1.11-28.4, p=0.037) were associated with risk of LF. There was 1 case of RM (1.3%) and 5 cases (5.5%) of VCF.

Conclusion: Re-irradiation with spine SBRT in 3 fractions appears safe and is associated with a 2-year local control rate of 85%. Lower PTV DMin and gastrointestinal histology were associated with increased risk of LF. Further work is needed to identify the optimal dose-fractionation regimen for re-irradiation with spine SBRT.