6 research outputs found
A modular data acquisition system for reconstruction of radiation dose spatial distribution in radiotherapy treatment planning
Positronium imaging with the novel multiphoton PET scanner
In vivo assessment of cancer and precise location of altered tissues at
initial stages of molecular disorders are important diagnostic challenges.
Positronium is copiously formed in the free molecular spaces in the patient's
body during positron emission tomography (PET). The positronium properties vary
according to the size of inter- and intramolecular voids and the concentration
of molecules in them such as, e.g., molecular oxygen, O2; therefore,
positronium imaging may provide information about disease progression during
the initial stages of molecular alterations. Current PET systems do not allow
acquisition of positronium images. This study presents a new method that
enables positronium imaging by simultaneous registration of annihilation
photons and deexcitation photons from pharmaceuticals labeled with
radionuclides. The first positronium imaging of a phantom built from cardiac
myxoma and adipose tissue is demonstrated. It is anticipated that positronium
imaging will substantially enhance the specificity of PET diagnostics.Comment: 10 pages, 5 figure
Preclinical investigations towards the first spacer gel application in prostate cancer treatment during particle therapy at HIT
BACKGROUND: The application of spacer gel represents a promising approach to reliably spare the rectal frontal wall during particle therapy (IJROBP 76:1251-1258, 2010). In order to qualify the spacer gel for the clinical use in particle therapy, a variety of measurements were performed in order to ensure the biological compatibility of the gel, its physical stability during and after the irradiation, and a proper definition of the gel in terms of the Hounsfield Unit (HU) values for the treatment planning system. The potential for the use of the spacer gel for particle therapy monitoring with off-line Positron Emission Tomography (PET) was also investigated. RESULTS: The spacer gel implanted to the prostate patient in direct neighbourhood to the clinical target volume does not interfere with the particle therapy treatment planning procedure applied at Heidelberg Ion Beam Therapy Centre (HIT). The performed measurements show that Bragg-peak position of the particles can be properly predicted on the basis of computed tomography imaging with the treatment planning system used at HIT (measured water equivalent path length of 1.011 ±0.011 (2σ), measured Hounsfield Unit of 28.9 ±6.1 (2σ)). The spacer gel samples remain physically unchanged after irradiation with a dose exceeding the therapeutic dose level. The independently measured Bragg-Peak position does not change within the time interval of 10 weeks. CONCLUSIONS: As a result of the presented experiments, the first clinical application of spacer gel implant during prostate cancer treatment with carbon ions and protons was possible at HIT in 2012. The reported pre-clinical investigations demonstrate that use of spacer gel is safe in particle therapy in presence of therapy target motion and patient positioning induced particle range variations. The spacer gel injected between prostate and rectum enlarge the distance between both organs, which is expected to clinically significantly decrease the undesirable exposure of the most critical organ at risk, i.e. rectal frontal wall. Further research on the composition of spacer gel material might lead to additional clinical benefits by validation of particle therapy of prostate via post-therapeutic PET-imaging or by patient positioning based on the gel as a radio-opaque marker