Advances in radiotherapy & nuclear medicine最新文献

Breast cancer is the most prevalent malignancy among women worldwide, and radiotherapy (RT) plays a central role in reducing local recurrence and improving survival. Technological advances such as three-dimensional conformal RT (3D-CRT), intensity-modulated RT (IMRT), volumetric-modulated arc therapy (VMAT), and particle therapies have enhanced dose conformity and reduced exposure to surrounding healthy tissues, particularly the lungs. Nevertheless, radiation-induced lung injury (RILI) remains a clinically relevant concern because of the close anatomical relationship between the breast and lung. RILI is a biphasic process, comprising early radiation pneumonitis and late radiation-induced pulmonary fibrosis, with severity influenced by dose distribution and treatment modality. While 3D-CRT carries a moderate risk due to limited beam modulation, IMRT and VMAT improve target coverage but may increase low-dose exposure to larger lung volumes, potentially increasing the risks of subclinical injury and, in the long term, secondary malignancy. Adjunctive lung-sparing strategies, including deep inspiration breath-hold and image-guided techniques, further reduce pulmonary dose. Proton beam therapy, particularly pencil beam scanning, offers additional lung protection through Bragg peak-based dose deposition, minimizing exit dose and irradiation of non-target tissues. Early clinical data suggest a lower incidence of RILI with PBT, although long-term outcomes remain under investigation. Carbon ion RT remains investigational in breast cancer. This review summarizes current evidence on RILI risk across modern RT modalities. A deeper understanding of modality-specific risks is essential for guiding personalized treatment planning and implementing effective lung-sparing strategies.

The key metrics for positron emission tomography (PET) imaging devices include the capability to capture the maximum available amount of annihilation photon information while generating high-quality images of the radiation distribution. This capability carries clinical implications by reducing scanning time for imaging, thus reducing radiation exposure for patients. However, imaging quality is degraded by positron range effects and the non-collinearity of positron annihilation photons. Utilizing an edge-on configuration of cadmium zinc telluride (CZT) detector crystals offers a potential solution to increase PET sensitivity. The high cross-section of CZT and its capacity to detect both 511 keV annihilation gammas and high-energy prompt gammas, along with multiple photon interaction events, contribute to this increased sensitivity. In this study, we propose a dual-panel edge-on CZT detector system comprised of 4 × 4 × 0.5 cm³ CZT detectors, with panel dimensions of 20 × 15 cm² and a thickness of 4 cm. In this study, we demonstrate the increased sensitivity of our imaging system due to the detection of the Compton kinematics of high-energy gammas originating from prompt-gamma-emitting isotopes. This was achieved using Monte Carlo simulations of a prompt-gamma-emitting isotope,⁷²As, with mean positron ranges >3 mm. Our system's dynamic energy range, capable of detecting gammas up to 1.2 MeV, allows it to operate in a dual-mode fashion as both a Compton camera (CC) and standard PET. By presenting reconstructions of ⁷²As, we highlight the absence of positron range effects in CC reconstructions compared to PET reconstructions. In addition, we evaluate the system's increased sensitivity resulting from its ability to detect high-energy prompt gammas.