Friday, August 30, 2013

Conventional proton radiotherapy to fight against cancer

Tags

Conventional proton radiotherapy to fight against cancer -

The future face of modern anti-cancer therapy with charged particles such as protons could potentially involve the use of laser accelerators. However, these facilities must be reduced in size and cost compared to conventional ones. In the journal, Applied Physics B , Dresden Medical Physicist Umar Masood was the first to introduce a new design for the entire complex machine - the accelerator on the radiation site. In the process, he managed to reduce the size of the installation in half.

In the fight against cancer, proton therapy is particularly accurate and is better able to spare healthy tissues compared to establish high-level, hard X on the basis of the radiation rays. An installation of conventional radiotherapy proton usually consists of a cycle of accelerator plus a gigantic steel construction called a gantry with 360 degree rotation capability. Between, the protons are sent flying in a long line of light where heavy electromagnets keep on track

In Germany, only two universities - Heidelberg and Essen - are currently offering proton therapy as a treatment option . Dresden is about to operating its own installation of any new start. Professor Michael Baumann, director of the new Proton Therapy Dresden University and OncoRay - National Center for Radiation Research in Oncology highlights the reason behind this: "On the one hand, the application of proton therapy beam in different types cancer does not to further explore ;. 15 to 20 percent of all patients radiotherapy, proton beam therapy will most likely be a considerable advantage over the established form of the other radiation therapy, the necessary facilities are quite large and expensive. Thus, this treatment option will be more widely accepted, becomes more compact and cheapest equipment available "

for this it is necessary to reduce the three main components -. Throttle, beamline, and the porch - and a doctoral student Omar Masood has managed to do just that in its design study initially, he went ahead and replaced the classic ring accelerator. with a new type of laser accelerator, where the distance along which the particles are accelerated to high energy levels is of the order of several millimeters. as part of its design study, and work in closely with other researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the Technische Universit t-Dresden (University of Technology), and the Dresden University hospital - together, these parties are the OncoRay Center -. Masood was the first to significantly reduce the size of the individual components that are beyond the accelerator

"We will have to rearrange all the different components from scratch in the coming years," Masood said. Indeed, laser beams based particles have properties which differ from those produced by ring accelerators. They have a lot more energy distribution. At first glance, this seems like an obvious disadvantage. method of radiotherapy is established based on the premise that a tumor is scanned fragmentary using a beam pencil-shaped with a narrow energy window, starting with higher energy, which is then reduced gradually. As such, the proton beam is able to target each unique location within the total mass of the tumor. As he gives off the majority of its energy only at the end of the distance, the healthy tissue that lies beyond the tumor is spared.

volume of more targeted tumor in a short time

Given the energy window wide when radiation using protons laser accelerated, much of protons must be removed from the beam to achieve a relatively narrow energy window. This undermines the effectiveness. However, Omar Masood came up with an innovative solution to this dilemma: He not only uses the largest energy distribution, but also naturally larger diameter of the proton beam, which thus emits its dose in a larger volume. This translates into a greater number of cancer cells that are irradiated simultaneously in the same unit of time. Technische Universit-t M-nchen is currently developing a particular type of software to help calculate the dose deposition in the patient when planning the optimized treatment for laser beams of accelerated protons.

Another property of laser accelerated protons lies in the fact that we are not looking at a continuous particle beam here, but rather to impulses of individual particles. For pulsed beams, more powerful magnets can be used to guide the accelerator beam to the patient - an important prerequisite for reducing and, more importantly, the overall size of the massive portico of the beamline. Dresden on account of pulsed magnets from Dresden High Magnetic field Laboratory HZDR has extensive experience with these.

Stay on track by using pulsed magnets

Omar Masood had to run tests on a number of different incarnations of his idea to be able coming up with a concept to guide the laser beams of protons accelerated in the first place. First, a magnetic coil mode a proton beam which has been accelerated directly inside the gantry using the intense laser light. Then, a dipole magnet directs the beam around a 0 degree curve while ensuring that the protons with an inadequate energy window are cut off. A focusing quadrupole magnets group called, that are also activated only for about 100 milliseconds at a time, keep the beam on track. Transport of a pulsed beam with an energy distribution on the scale can be difficult because there are at least six dimensions to support. A second dipole redirects the beam in a direction opposite to the initial acceleration to the examination table in the porch of the center.

Despite the fact that now, for the first time, a full installation was modeled on the basis of a laser accelerator, there are still many obstacles to overcome before such a facility can become a reality. As such, the different pulsed magnets must first be developed and tested. In addition, at this time, the energies of laser accelerated protons are below target deep-lying tumors inside the patient's body. Which is why the own laser DRACO HZDR currently undergoing an upgrade and is also getting a new big sister, PENELOPE, which in a time of 1 petawatt take its place among the most powerful lasers of the world. Professor Ulrich Schramm, head of laser-particle acceleration HZDR group, is quite certain that "follows some five years of intense research using DRACO we believe that we will finally be able to achieve the necessary parameters for radiation therapy patients."


EmoticonEmoticon