Pencil Beam Scanning Bragg Peak FLASH Technique for Ultra-High Dose Rate Intensity-Modulated Proton Therapy in Early-Stage Breast Cancer Treatment.
Grant LatteryTyler KaulfersChingyun ChengXingyi ZhaoBalaji SelvarajHaibo LinCharles B Simone IiJ Isabelle ChoiJenghwa ChangMinglei KangPublished in: Cancers (2023)
Bragg peak FLASH-RT can deliver highly conformal treatment and potentially offer improved normal tissue protection for radiotherapy patients. This study focused on developing ultra-high dose rate (≥40 Gy × RBE/s) intensity-modulated proton therapy (IMPT) for hypofractionated treatment of early-stage breast cancer. A novel tracking technique was developed to enable pencil beaming scanning (PBS) of single-energy protons to adapt the Bragg peak (BP) to the target distally. Standard-of-care PBS treatment plans of consecutively treated early-stage breast cancer patients using multiple energy layers were reoptimized using this technique, and dose metrics were compared between single-energy layer BP FLASH and conventional IMPT plans. FLASH dose rate coverage by volume (V 40Gy/s ) was also evaluated for the FLASH sparing effect. Distal tracking can precisely stop BP at the target distal edge. All plans ( n = 10) achieved conformal IMPT-like dose distributions under clinical machine parameters. No statistically significant differences were observed in any dose metrics for heart, ipsilateral lung, most ipsilateral breast, and CTV metrics ( p > 0.05 for all). Conventional plans yielded slightly superior target and skin dose uniformities with 4.5% and 12.9% lower dose maxes, respectively. FLASH-RT plans reached 46.7% and 61.9% average-dose rate FLASH coverage for tissues receiving more than 1 and 5 Gy plan dose total under the 250 minimum MU condition. Bragg peak FLASH-RT techniques achieved comparable plan quality to conventional IMPT while reaching adequate dose rate ratios, demonstrating the feasibility of early-stage breast cancer clinical applications.
Keyphrases
- early stage
- high dose
- high resolution
- health insurance
- healthcare
- newly diagnosed
- radiation therapy
- low dose
- end stage renal disease
- minimally invasive
- ejection fraction
- sentinel lymph node
- chronic kidney disease
- atrial fibrillation
- small cell lung cancer
- stem cell transplantation
- machine learning
- quality improvement
- chronic pain
- rectal cancer
- pain management
- prognostic factors