Proton FLASH: Impact of Dose Rate and Split Dose on Acute Skin Toxicity in a Murine Model.

Purpose: Preclinical studies have shown a preferential normal tissue sparing effect of FLASH radiation therapy with ultra-high dose rates. The aim of the present study was to use a murine model of acute skin toxicity to investigate the biologic effect of varying dose rates, time structure, and introducing pauses in the dose delivery.

Methods And Materials: The right hind limbs of nonanaesthetized mice were irradiated in the entrance plateau of a pencil beam scanning proton beam with 39.

Oxygen Enhancement Ratio-Weighted Dose Quantitatively Describes Acute Skin Toxicity Variations in Mice After Pencil Beam Scanning Proton FLASH Irradiation With Changing Doses and Time Structures.

Purpose: The aim of this work was to investigate the ability of a biological oxygen enhancement ratio-weighted dose, D, to describe acute skin toxicity variations observed in mice after proton pencil beam scanning irradiations with changing doses and beam time structures.

Methods And Materials: In five independent experiments, the right hind leg of a total of 621 CDF1 mice was irradiated previously in the entrance plateau of a pencil beam scanning proton beam. The incidence of acute skin toxicity (of level 1.

Time-resolved dose rate measurements in pencil beam scanning proton FLASH therapy with a fiber-coupled scintillator detector system.

Background: The spatial and temporal dose rate distribution of pencil beam scanning (PBS) proton therapy is important in ultra-high dose rate (UHDR) or FLASH irradiations. Validation of the temporal structure of the dose rate is crucial for quality assurance and may be performed using detectors with high temporal resolution and large dynamic range.

Purpose: To provide time-resolved in vivo dose rate measurements using a scintillator-based detector during proton PBS pre-clinical mouse experiments with dose rates ranging from conventional to UHDR.

Pencil beam scanning proton FLASH maintains tumor control while normal tissue damage is reduced in a mouse model.

Purpose: Preclinical studies indicate a normal tissue sparing effect when ultra-high dose rate (FLASH) radiation is used, while tumor response is maintained. This differential response has promising perspectives for improved clinical outcome. This study investigates tumor control and normal tissue toxicity of pencil beam scanning (PBS) proton FLASH in a mouse model.

Time structure of pencil beam scanning proton FLASH beams measured with scintillator detectors and compared with log files.

Purpose: Key factors in FLASH treatments are the ultra-high dose rate (UHDR) and the time structure of the beam delivery. Measurement of the time structure in pencil beam scanning (PBS) proton FLASH treatments is challenging for many types of detectors since high temporal resolution is needed. In this study, a fast scintillator detector system was developed and used to measure the individual spot durations as well as the time when the beam moves between two positions (transition duration) during PBS proton FLASH and UHDR treatments.

In vivo validation and tissue sparing factor for acute damage of pencil beam scanning proton FLASH.

Background And Purpose: Preclinical studies indicate a normal tissue sparing effect using ultra-high dose rate (FLASH) radiation with comparable tumor response. Most data so far are based on electron beams with limited utility for human treatments. This study validates the effect of proton FLASH delivered with pencil beam scanning (PBS) in a mouse leg model of acute skin damage and quantifies the normal tissue sparing factor, the FLASH factor, through full dose response curves.