geant4.10.1.p02例子学习之-hadrontherapy

进来一段时间自己的兴趣突然迸发出来了，也就是对particle therapy 相当感兴趣，这一块正好是核物理跟医学物理相交叉的部分，正好是自己的兴趣和专业所在，所里面恰好有老师在做这一块相关课题，自己便试着找机会进入这个领域。医学物理模拟这一块发展的很快，有了很多这方面的软件和程序，比如，geant4/Fluka/Gate/GAMOS/Egs4...而自己用的比较多的是Geant4，有很多软件也是基于Geant4框架搭建的，比如说GAMOS，TOPAS等，这些软件省去了繁琐的C++编程，可以较快捷的得到模拟结果，但是版本更新慢，主要是用户群少，有很多小的bug，用的物理库也比较老，相比于geant4的日益健壮，它们很难突破。不过，因其脚本化的语言十分方便，可以先快速的建模模拟，得到一个结果，再使用geant4细节化模拟，然后对两者的结果进行比对，可以相互之间做个参照。

geant4的例子中就有很多关于microbeam和hadrontherapy的例子了，这省去了自己编程的很多麻烦，对于编程能力还有待长进的自己来说，实在是应该好好学习研究一下这方面的例子，为以后自己模拟做好基础。

在advanced example 里面有hadrontherapy的例子，里面有质子束和碳离子束，都是基于infn的装置。用户可以改变几何装备。

几个文件夹：

/experimentalData  实验上或理论分析上的参考数据；

/SimulationOutputs  当.mac文件执行时会有一个结果产生在这个文件夹中，与上个文件夹数据比对——可以通过/RootScripts 调用root比较

两种束都是被动束。

在束流线的终端是一个模体，内部有一个用户定义区域，该区域可以是立方体或是体元，体元大小可以改变。一个run后，初级和次级粒子在体元内的能量沉积被收集起来。

The default sizes of the active voxelized region are 40x40x40 mm and actually the default voxel configuration is 200 x 1 x 1, which means 200 slices with 0.2 mm of thickness.

the default configuration implies a cut value of 0.01 mm in the whole world (use the command /physic/setCuts 0.01 mm) and a stepMax of 0.01 mm just in the phantom (use the command /Step/waterPhantomStepMax 0.01 mm).In any case it is strongly recommended to use a stepMax value not biggernthan 5% of the dose slice thickness.

质子被动束主要有以下几个element构成：

• The SCATTERING SYSTEM: to transversally enlarge the original beam 被动散射束
  
• The COLLIMATORS: placed along the beam line to collimate the beam;准直
• The RANGE SHIFTERS: to decrease the energy of the primary proton beam to a specific value;减少初始质子能量
• The MODULATOR WHEEL: to modulate the energy of the primary and mono-energetic beam in to a wide spectrum. The energy modulation is necessary to homogeneously irradiate a tumour volume that can extends in depth up to 20 mm;调强，产生bragg peak；
  
• The MONITOR CHAMBERS: very thin ionisation chamber that permit the dose monitoring during the patient irradiation;电离室，照射时剂量管理
• The MOPI detector: microstrips, air free detector utilised for the check of the beam symmetry during the treatment;检查束流对称性
• The PATIENT COLLIMATOR: a brass, tumour-shaped collimator able to confine the proton irradiation field in order to irradiate just the tumour mass in the transverse direction;肿瘤形状的准直器

物理过程：三种方法用来选择物理模型

Approach 1:

Using the macro command:

/physic/addPhysics/.

In this case the models (for electromagnetic, hadronic elastic and hadronic inelastic) can be activated directly calling the name of the Physics Lists that are available inside the Geant4 kernel in the directory:

$G4INSTALL/source/physics_lists/builders/include

An example of the use of the Physics List can be found in the macro files:proton_therapy.mac and ion_therapy.mac

Approach 2:

A set of built-in physic models are also contained inside the Hadrontherapy directory. These are called Local*.cc and Local*.hh and can be activated using the macro command:

/physic/addPhysics/.

NOTE: we do not recommend the use of local physics lists while we recommend the use of the Physics Lists or of the Reference Physics Lists (Approach 1 or 3)

Approach 3:

We developed this approach in order to simplify the choice of the physic models tobe used in the application.With this approach the user must only insert a command line in his/her .mac file using the:

/physics/addPackage 

This permits to switch-on an already build physic package.Various packages are already present in the Geant4 tree: they are in the directory: geant4/source/physics_lists/lists/includeIn this case hadronic inelastic models are directly activated for every particle

可以做LET计算。Let.out 在run之后产生。To activate the LET computation (HadrontherapyLet.cc), you have to executethe following command:

/analysis/computeLet