Two-dimensional and quasi-three-dimensional dosimetry of hadron and photon beams with the Magic Cube and the Pixel Ionization Chamber

Abstract

Two detectors for fast two-dimensional (2D) and quasi-three-dimensional (quasi-3D) verification of the dose delivered by radiotherapy beams have been developed at University and Istituto Nazionale di Fisica Nucleare (INFN) of Torino. The Magic Cube is a stack of strip-segmented ionization chambers interleaved with water-equivalent slabs. The parallel plate ionization chambers have a sensitive area of 24 x 24 cm2, and consist of 0.375 cm wide and 24 cm long strips. There are a total of 64 strips per chamber. The Magic Cube has been tested with the clinical proton beam at Loma Linda University Medical Centre (LLUMC), and was shown to be capable of fast and precise quasi-3D dose verification. The Pixel Ionization Chamber (PXC) is a detector with pixel anode segmentation. It is a 32 x 32 matrix of 1024 cylindrical ionization cells arranged in a square 24 x 24 cm2 area. Each cell has 0.4 cm diameter and 0.55 cm height, at a pitch of 0.75 cm separates the centre of adjacent cells. The sensitive volume of each single ionization cell is 0.07 cm3. The detectors are read out using custom designed front-end microelectronics and a personal computer-based data acquisition system. The PXC has been used to verify dynamic intensity-modulated radiotherapy for head-and-neck and breast cancers.

3D reconstruction of scintillation light emission from proton pencil beams using limited viewing angles—a simulation study

“…To obtain three-dimensional (3D) dosimetry, Cirio et al (2004) developed a complex detector system of multiple parallel-plate ionization chambers to achieve quasi-3D dosimetry. Karger et al (1999) used an array of up to 24 pinpoint ionization chambers for 3D dose verification.…”

Quality assurance of proton beams using a multilayer ionization chamber system

“…Early studies on MLIC systems resulted in devices such as the ionization chamber telescope, produced at the Lawrence Berkeley Laboratories in the 1980s to measure helium and neon ion beams, and the Magic Cube, developed using a stack of strip-segmented ionization chambers interleaved with water-equivalent slabs. 6,7 These MLIC systems were used primarily for experimental studies. Other devices based on scintillator plates, [8][9][10][11] radiochromic films, [12][13][14] and alanine detectors 14,15 have also been studied; they have limitations, however, as described in a recent review by Karger et al 16 Recently, Nichiporov et al 17 developed an MLIC device that has a short setup time and can quickly measure the depth-dose distributions of proton beams.…”

A GEM-based dose imaging detector with optical readout for proton radiotherapy

“…In an attempt to address many of these issues, detectors such as the Magic Cube, pixel-segmented and strip-segmented ionization chambers [11][12][13][14][15] were proposed for measuring transverse and depth-dose distributions in real time. Commercially available detectors based on two-dimensional ion chamber arrays such as the MatriXX detector [16] and OCTAVIUS 729 XDR [17] are sometimes used, although they were developed mainly for photon radiotherapy.…”