Experimental prompt gamma-ray timing data for proton treatment verification in a clinical facility using a fixed beam

This dataset comprises the data reported on by Werner et al. (2019) in Phys. Med. Biol. 64 105023, 20pp (https://doi.org/10.1088/1361-6560/ab176d). Please refer to this publication for details on the experimental setup, data acquisition and preprocessing. The process is summarised in the following.

A static, pulsed pencil beam was delivered to a target without and with cylindrical air cavities of 5 to 20 mm thickness and prompt gamma-ray timing distributions were acquired.

<strong>Experimental setup</strong>:

A homogeneous cylindrical phantom comprised of poly(methylmethacrylate) was used. Air cavities of varying thickness ∆R ∈ {0 mm, 5 mm, 10 mm, 20 mm} were successively introduced into the phantom to mimic anatomical variations leading to range deviations. For each air cavity thickness, the phantom was irradiated with proton pencil beams of two different kinetic energies (E_1 = 162 MeV and E_2 = 227 MeV) and a micropulse repetition rate of 106.3 MHz. Prompt-gamma ray timing distributions were measured with a detection unit consisting of a single ∅2 ” × 2 ” CeBr_3 crystal by Scionix, a Hamamatsu R13089-100 photomultiplier and a U100 digital spectrometer by Target Systemelektronik, which was placed at a backward angle of 130° . A static pencil beam was directed centrally at the phantom. The beam was pulsed in spots with a spot duration of 69 ms, a period of 72 ms and 1e9 (!) protons per spot (corresponding approximately to the combined signal of 8 prompt-gamma ray detection units for one strongly weighted clinical pencil beam scanning spot). One measurement consisted of 100 spots. Overall, the experiment comprised eight measurements covering the set of four cavity thicknesses ∆R and two beam energies E_1 and E_2. Experiments were carried out in the patient treatment room of OncoRay, Dresden.

<strong>Data preprocessing</strong>:

The raw data of each measurement was preprocessed as follows: The binary data was converted to ROOT. The photomultiplier gain drift was corrected for and the integral signal charge was converted into deposited energy. Time digitalisation nonlinearities were corrected for. The calibrated data was then saved in list-mode format. The data was assigned to the spot number and the detection time relative to the accelerator radiofrequency (fine time) was used to populate a prompt gamma-ray timing histogram for each spot. No background or phase shift correction were applied.

<strong>Data structure</strong>:

The dataset contains one root file for each measurement, named by the detector number in the format u100-p00XX and the measurement time. The spreadsheet MeasurementIndex_20160716_SingleSpot.xlsx contains the details of each measurement. The corrected and calibrated PGT spectra can be found in the root file at analysis/05_PGT_for_Layers_and_Spots.

Each root file contains the following directories:

analysis

01_Layers_and_Spots_Detection: association between spot number and measurement time

02_Gain_Correction: energy gain drift correction curve

03_Energy_Calibration: energy calibration curve

04_Fine_Time_Linearization: timing non-linearity calibration curve

<strong>05_PGT_for_Layers_and_Spots</strong>: final PGT spectra - for each spot of each layer:

PGT_*_all: timing spectrum of the whole energy range

PGT_*_2,5to7MeV:  timing spectrum for events between 2.5 and 7 MeV only

PGT_*_3to5MeV: timing spectrum for events between 3 and 5 MeV only

ESpec: energy spectrum

EoT: two-dimensional energy-timing spectrum

data: list-mode data (not histogrammed)

uncorrected: before the correction and calibration steps

corrected: after the correction and calibration steps

meta: measurement meta data (log file containing applied detector HV etc.)

histograms: selected example histograms

For further questions, please refer to the contact persons stated in the Contributors section.

本数据集包含Werner等人于2019年发表于《物理医学与生物学》（Phys. Med. Biol.）第64卷第105023期（共20页，https://doi.org/10.1088/1361-6560/ab176d）的报道数据。有关实验装置、数据采集与预处理的详细信息，请参阅该文献，下文将对该流程进行简要概述。

本实验针对有无厚度为5~20 mm的圆柱形空气腔的靶体，输送静态脉冲质子笔形束，并采集瞬发γ射线时间分布谱。

<strong>实验装置</strong>：
本实验采用由聚甲基丙烯酸甲酯（poly(methylmethacrylate)）制成的均质圆柱形体模。依次在体模内引入厚度∆R ∈ {0 mm、5 mm、10 mm、20 mm}的空气腔，以模拟导致射程偏差的解剖学变异。针对每种空气腔厚度，分别采用两种不同动能的质子笔形束（E₁=162 MeV、E₂=227 MeV）对体模进行辐照，微脉冲重复频率为106.3 MHz。

瞬发γ射线时间分布谱由一套探测单元完成采集，该单元包含Scionix生产的单台直径2英寸×2英寸溴化铈（CeBr₃）晶体、滨松（Hamamatsu）R13089-100型光电倍增管，以及Target Systemelektronik生产的U100型数字能谱仪，探测单元以130°后向角度放置。静态质子笔形束对准体模中心照射。笔形束以光斑形式脉冲输送，单个光斑持续时间为69 ms，周期为72 ms，每光斑含1×10⁹个质子（原文标注感叹号），其信号强度近似等同于临床强权重笔形束扫描光斑对应的8台瞬发γ射线探测单元的总信号。单次测量包含100个光斑。本实验共完成8次测量，覆盖4种空气腔厚度与2种束流能量的全部组合。实验在德累斯顿OncoRay的患者治疗机房内完成。

<strong>数据预处理</strong>：
单次测量的原始数据按以下流程进行预处理：将二进制数据转换为ROOT格式；校正光电倍增管增益漂移，并将积分信号电荷转换为沉积能量；校正时间数字化非线性。经标定的数据随后以列表模式格式存储。将数据按光斑编号进行分配，并以相对于加速器射频的探测时间（精细时间）为每个光斑生成瞬发γ射线时间分布直方图。本流程未进行背景或相移校正。

<strong>数据结构</strong>：
本数据集为每次测量对应一个ROOT文件，文件名由探测器编号（格式为u100-p00XX）与测量时间组成。电子表格MeasurementIndex_20160716_SingleSpot.xlsx包含每次测量的详细信息。经校正与标定的瞬发γ射线时间谱（Prompt Gamma-ray Timing, PGT）可在ROOT文件的analysis/05_PGT_for_Layers_and_Spots路径下找到。

每个ROOT文件包含以下目录：

analysis
01_Layers_and_Spots_Detection：光斑编号与测量时间的关联信息
02_Gain_Correction：能量增益漂移校正曲线
03_Energy_Calibration：能量标定曲线
04_Fine_Time_Linearization：时间非线性校正曲线
<strong>05_PGT_for_Layers_and_Spots</strong>：最终瞬发γ射线时间谱——针对每个层的每个光斑：
PGT_*_all：全能量范围时间谱
PGT_*_2.5to7MeV：仅2.5~7 MeV区间内事件的时间谱
PGT_*_3to5MeV：仅3~5 MeV区间内事件的时间谱
ESpec：能谱
EoT：二维能量-时间谱

data：列表模式原始数据（未做直方图化处理）
uncorrected：校正与标定前的原始数据
corrected：校正与标定后的处理数据

meta：测量元数据（包含探测器高压等参数的日志文件）
histograms：精选示例直方图

如有进一步疑问，请参阅贡献者部分所列的联系人信息。