In a typical treatment plan for<unk> , the spread out Bragg peak (SOBP, dashed blue line) shows how the radiation is distributed. The SOBP is the sum of several individual Bragg peaks (thin blue lines) at staggered depths. Note that the vast majority of the<unk>  radiation is delivered to the tumor, not to the skin and shallow tissues in front of the tumor or to the deep tissues behind the tumor. The red line shows the depth-dose plot of an X-ray beam <unk>  or conventional radiation therapy) for comparison. The pink area represents additional doses of X-ray radiotherapy in front and behind the tumor – which can damage normal tissues and cause secondary cancers, especially of the skin.<unk>  is a type of external beam radiotherapy that uses ionizing radiation. In<unk> , medical personnel use a particle accelerator to target a tumor with a beam of<unk> s. These charged particles damage the DNA of cells, ultimately killing them by stopping their reproduction and thereby eliminating the tumor. Cancerous cells are particularly vulnerable to attacks on DNA because of their high rate of division and their limited abilities to repair DNA damage. Some cancers with specific defects in DNA repair may be more sensitive to<unk>  radiation.<unk>  offers physicians the ability to deliver a highly conformal beam, i.e., delivering radiation that conforms to the shape and depth of the tumor and sparing much of the surrounding, normal tissue. For example, when comparing<unk>  to the most advanced types of<unk> —intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT)—proton therapy can deliver similar or higher radiation doses to the tumor with a 50%-60% lower total body radiation dose.<unk> s have the ability to focus energy delivery to conform to the tumor shape, delivering only low-dose radiation to surrounding tissue. As a result, the patient experiences fewer side effects. All<unk> s of a given energy have a certain penetration range; very few<unk> s penetrate beyond that distance. Furthermore, the dose delivered to tissue is maximized only over the last few millimeters of the particle's range; this maximum is called the spread out Bragg peak, often referred to as the SOBP (see visual). To treat tumors at greater depths, the<unk>  accelerator must produce a beam with higher energy, typically given in eV (electron volts). Accelerators used for<unk>  typically produce<unk> s with energies in the range of 70 to 250 MeV. Adjusting<unk>  energy during the treatment maximizes the cell damage the<unk>  beam causes within the tumor. Tissue closer to the surface of the body than the tumor receives reduced radiation, and therefore reduced damage. Tissues deeper in the body receive very few<unk> s, so the dosage becomes immeasurably small. In most treatments,<unk> s of different energies with Bragg peaks at different depths are applied to treat the entire tumor. These Bragg peaks are shown as thin blue lines in the figure in this section. It is important to understand that, while tissues behind (or deeper than) the tumor receive almost no radiation from<unk> , the tissues in front of (shallower than) the tumor receive radiation dosage based on the SOBP. Equipment Most installed<unk>  systems utilise isochronous cyclotrons. Cyclotrons are considered simple to operate, reliable and can be made compact, especially with the use of superconducting magnets. Synchrotrons can also be used, with the advantage of easier production at varying energies. Linear accelerators, as used for<unk>  radiation therapy, are becoming commercially available as limitations of size and cost are resolved. Modern<unk>  systems incorporate high-quality imaging for daily assessment of tumor contours, treatment planning software illustrating 3D dose distributions, and various system configurations, e.g. multiple treatment rooms connected to one accelerator. Partly because of these advancements in technology, and partly because of the continually increasing amount of<unk>  clinical data, the number of hospitals offering<unk>  continues to increase. FLASH radiotherapy is a technique under development for<unk>  and<unk>  treatments, utilising very high dose rates (necessitating large beam currents). If applied clinically, it could shorten treatment time to just one to three one-second sessions, while further reducing side effects.
Proton therapy
Gestalt therapy
Hormone therapy
Vasectomy reversal
Masculinizing hormone therapy
Estrogen deprivation therapy
Antihormone therapy
Carboxytherapy