3D prompt gamma imaging for proton beam range verification

Abstract

We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC placed at three different locations along the proton beam path. We evaluated the ability of the CC to produce images at each location for two clinical scenarios: (1) the delivery of a single 2 Gy pencil beam from a hypo-fractionated treatment (~9 × 10 protons), and (2) a single pencil beam from a standard treatment (~1 × 10 protons). Additionally, the data measured at each location were combined to simulate measurements with a larger scale, clinical CC and its ability to image shifts in the Bragg peak (BP) range for both clinical scenarios. With our prototype CC, the location of the distal end of the BP could be seen with the CC placed up to 4 cm proximal or distal to the BP distal falloff. Using the data from the simulated full scale clinical CC, 3D images of the PG emission were produced with the delivery of as few as 1 × 10 protons, and shifts in the proton beam range as small as 2 mm could be detected for delivery of a 2 Gy spot. From these results we conclude that 3D PG imaging for proton range verification under clinical beam delivery conditions is possible with a single CC.

Compact Method for Proton Range Verification Based on Coaxial Prompt Gamma-Ray Monitoring: A Theoretical Study

“…The literature about the cost of PGI prototypes is scarce due to early stage of research development and the several years remaining until a final product is actually commercialized. Some rough estimates state an overall material cost of at least 200 k$ [29] and up to 1 M$ [84], not accounting for development, commissioning and maintenance. Furthermore, these costs do not include the potential integration in the rotating gantry structure, for covering several beam incidence angles.…”

Classification of the source of treatment deviation in proton therapy using prompt‐gamma imaging information

“…The detection of prompt-gamma rays, which are emitted in consequence of nuclear reactions in the patient during irradiation, 7-9 can be utilized to noninvasively verify the proton range near real time without depositing additional dose to the patient. 1,4 Currently, several prompt-gamma based techniques for range verification exist, 10 each exploiting either spectral, temporal, or spatial distribution of prompt-gamma rays, namely prompt-gamma spectroscopy, 11,12 prompt-gamma timing, 13,14 and prompt-gamma imaging (PGI), [15][16][17][18][19][20][21][22] respectively. However, only a PGI systemthe so-called PGI slit camerahas so far been applied in clinical practice.…”

Visualization of Low-Level Gamma Radiation Sources Using a Low-Cost, High-Sensitivity, Omnidirectional Compton Camera

“…In this technique, the energy and cone-direction of incident gamma-rays emitted from the radiation source are measured by the detector for each event, and then the gamma-ray source direction can be reconstructed by back-projection 3 . Previous studies have developed Compton camera systems aimed at the application of a new diagnostic device in nuclear medicine and/or a new gamma-ray telescope in astrophysics 4,5,6,7,8,9,10,11,12,13,14 , as well as image reconstruction techniques for Compton cone data by analytical 15,16 and statistical 17 approaches. More expensive, state-of-the-art devices with complicated electronics are often adopted to obtain high angular resolution within a standard deviation of a few degrees, but this precision makes it difficult to simultaneously achieve high detection efficiency.…”