Pencil-beam scanning


Pencil beam scanning is the practice of steering a beam of radiation or charged particles across an object. It is often used in proton therapy, to reduce unnecessary radiation exposure to surrounding non-cancerous cells.

Ionizing radiation

Ionizing radiation photons or x-rays use pencil beam scanning to precisely target a tumor. Bone scan densitometry uses a fan scan system that replaces a pencil beam system. Radiation treatment planning has pencil beam scanning as one of its modalities. mean free path is involved in IMRT planning. Also used in Monte Carlo method for photon transport. Another three sources are: Hybrid theory for photon transport in tissue which is a combination of Diffusion theory and the Monte Carlo method all using, in part, pencil beam scanning. Photon pencil beam scans are defined as crossing of two beams to a fine point.

Charged particles

Several charged particles devices used with Proton therapy cancer centers use pencil beam scanning. The newer proton therapy machines use a pencil beam scanning technology.
This technique is also called spot scanning. The Paul Scherrer Institute was the developer of spot beam. Here is a Scripps Health . Mayo clinic has a demonstrating pencil-beam techniques.

Intensity Modulated Proton Therapy

Varian's IMPT system uses all pencil-beam controlled protons where the beam intensity can also be controlled at this small level. This can be done by going back and forth over a previously radiated area during the same radiation session. This is using the same Raster scan technique that is used in an obsolete cathode ray tube television set and other electronic applications.