Dosimetric Validation of a System to Treat Moving Tumors Using Scanned Ion Beams That Are Synchronized With Anatomical Motion

PurposeThe purpose of this study was to validate the dosimetric performance of scanned ion beam deliveries with motion-synchronization to heterogenous targets.MethodsA 4D library of treatment plans, comprised of up to 10 3D sub-plans, was created with robust and conventional 4D optimization methods. Each sub-plan corresponded to one phase of periodic target motion. The plan libraries were delivered to a test phantom, comprising plastic slabs, dosimeters, and heterogenous phantoms. This phantom emulated range changes that occur when treating moving tumors. Similar treatment plans, but without motion synchronization, were also delivered to a test phantom with a stationary target and to a moving target; these were used to assess how the target motion degrades the quality of dose distributions and the extent to which motion synchronization can improve dosimetric quality. The accuracy of calculated dose distributions was verified by comparison with corresponding measurements. Comparisons utilized the gamma index analysis method. Plan quality was assessed based on conformity, dose coverage, overdose, and homogeneity values, each extracted from calculated dose distributions.ResultsHigh pass rates for the gamma index analysis confirmed that the methods used to calculate and reconstruct dose distributions were sufficiently accurate for the purposes of this study. Calculated and reconstructed dose distributions revealed that the motion-synchronized and static deliveries exhibited similar quality in terms of dose coverage, overdose, and homogeneity for all deliveries considered. Motion-synchronization substantially improved conformity in deliveries with moving targets. Importantly, measurements at multiple locations within the target also confirmed that the motion-synchronized delivery system satisfactorily compensated for changes in beam range caused by the phantom motion. Specifically, the overall planning and delivery approach achieved the desired dose distribution by avoiding range undershoots and overshoots caused by tumor motion.ConclusionsWe validated a dose delivery system that synchronizes the movement of the ion beam to that of a moving target in a test phantom. Measured and calculated dose distributions revealed that this system satisfactorily compensated for target motion in the presence of beam range changes due to target motion. The implication of this finding is that the prototype system is suitable for additional preclinical research studies, such as irregular anatomic motion.

Nuclear Fragmentation Imaging for Carbon-Ion Radiation Therapy Monitoring: an In Silico Study

Purpose This article presents an in vivo imaging technique based on nuclear fragmentation of carbon ions in irradiated tissues for potential real-time monitoring of carbon-ion radiation therapy (CIRT) treatment delivery and quality assurance purposes in clinical settings. Materials and Methods A proof-of-concept imaging and monitoring system (IMS) was devised to implement the technique. Monte Carlo simulations were performed for a prospective pencil-beam scanning CIRT nozzle. The development IMS benchmark considered a 5×5-cm2 pixelated charged-particle detector stack positioned downstream from a target phantom and list-mode data acquisition. The abundance and production origins, that is, vertices, of the detected fragments were studied. Fragment trajectories were approximated by straight lines and a beam back-projection algorithm was built to reconstruct the vertices. The spatial distribution of the vertices was then used to determine plan relevant markers. Results The IMS technique was applied for a simulated CIRT case, a primary brain tumor. Four treatment plan monitoring markers were conclusively recovered: a depth dose distribution correlated profile, ion beam range, treatment target boundaries, and the beam spot position. Promising millimeter-scale (3-mm, ≤10% uncertainty) beam range and submillimeter (≤0.6-mm precision for shifts <3 cm) beam spot position verification accuracies were obtained for typical therapeutic energies between 150 and 290 MeV/u. Conclusions This work demonstrated a viable online monitoring technique for CIRT treatment delivery. The method's strong advantage is that it requires few signal inputs (position and timing), which can be simultaneously acquired with readily available technology. Future investigations will probe the technique's applicability to motion-sensitive organ sites and patient tissue heterogeneities. In-beam measurements with candidate detector-acquisition systems are ultimately essential to validate the IMS benchmark performance and subsequent deployment in the clinic.

A Study of The Clinical Viability of A Prototype Compton Camera for Prompt Gamma Imaging Based Proton Beam Range Verification

We present Compton camera (CC) based PG imaging for proton range verification at clinical dose rates. PG emission from a tissue-equivalent phantom during irradiation with clinical proton beams was measured with a prototype CC. Images were reconstructed of the raw measured data and of data processed with a neural network (NN) trained to identify “true” and “false” PG events. From these images, we determine if PG images produced by the prototype CC could provide clinically useful information about the in vivo range of the proton beams delivered during proton beam radiotherapy. NN processing of the data was found necessary to allow identification of the proton beam path from the PG images. Furthermore, to allow the localization of the end of the proton beam range with a precision of ≤ 3mm with the prototype CC, ~1 x 109 protons would need to be delivered, which is on the order of magnitude delivered for a standard proton radiotherapy treatment field. To obtain higher precision in beam range determination and to allow imaging a single proton pencil beam delivered within the full treatment field, further improvements in PG detection rates by the CC, NN data processing, and image reconstruction algorithms are needed.

Design and Build Setup Mode Microcontroller-Based in Cars

People want a vehicle that is ready to use without having to wait for long or in the sense that the performance of an activity can run efficiently. With a remote control that can control the vehicle remotely, activities in setup mode will be more efficient. In general, remote control is used in motorized vehicles using Infra-red or Bluetooth communication with communication distance 60meters. So we need LoRa module that has longer beam range. The purpose of research is to design remote control and receiver that can control the vehicle such as opening vehicle door lock, activating the AC, to the starter mode on the car contact with a wider range of sending and receiving information. The results of research indicate that LoRa module has received signal strength value (RSSI) of -65dBm when LOS (line of sight) at distance 10meters and RSSI of -66dBm at non-LOS (non-line of sight) at the same distance. SNR of 9.25dB when LOS and SNR of 6.0dB when non-LOS at distance 10meters. The research results of sending and receiving remote control data have a maximum distance when non-LOS with obstacles 5mm thick glass and 20 cars is 100 meters with a received signal strength of -112dBm. It can be concluded that for non-LOS connectivity between the LoRa SX1278 has an effectiveness distance at 50meters with an RSSI value of -99dBm and an SNR of 0.25dB, for a LOS condition it has an effectiveness at distance 50meters with RSSI value of -96dBm and SNR of 9dB.

Experimental Study of Using a 3-D Position Sensitive CdZnTe Detector for Proton Beam Range Verification

<p><i>Position sensitive CdZnTe Compton imaging cameras are currently being studied for their use of proton beam range verification for radiotherapy applications. This work presents the use of an experimental large volume CdZnTe detector for the detection of prompt gamma rays that are emitted from proton-nuclei interaction within plastic (C2H4) targets. Two experiments were conducted where the incident angle and the dose profile of the beam were varied. The energy spectra from these experiments show that the angle at which the beam enters the target can influence the photopeak to Compton continuum ratios, resulting in more than 18% increase at 718 keV when the beam is parallel to the detector. Images of the 718 keV and 4.44 MeV characteristic prompt gamma ray emission from carbon-proton interactions are reconstructed using list-mode maximum likelihood expectation maximization (MLEM). Images from these prompt gamma emissions line up well with the expected location of the proton beam within the plastic targets.</i><br></p>

PAPRICA: The Pair Production Imaging Chamber—Proof of Principle

In Particle Therapy, safety margins are applied around the tumor to account for the beam range uncertainties and ensure an adequate dose coverage of the tumor volume during the therapy. The reduction of safety margins is in great demand in order to diminish the Particle Therapy side effects especially in the case of treatment of tumors close to Organs at Risk (OAR) and of pediatric patients. To this aim, beam range monitoring techniques are being developed by the scientific community, most of all based on the detection of secondary particles produced by the nuclear interactions of the beam with the patient’s tissue nuclei. In this contribution, a novel beam range monitoring technique is proposed, based on the detection of prompt photons exploiting the pair production mechanism. The proof of principle of the PAir PRoduction Imaging ChAmber (PAPRICA) is studied through the development of a Monte Carlo simulation and the detector performances toward a more realistic scenario are determined.

Experimental Study of Using a 3-D Position Sensitive CdZnTe Detector for Proton Beam Range Verification

This manuscript discusses the use of a large volume array CZT detector for experimental prompt gamma-ray imaging. Namely, the 718 keV and the 4.44 MeV photopeaks produced from proton-carbon interactions are imaged using maximum likelihood expectation maximization (MLEM). Various proton beam irradiations are used to characterize the feasibility of using both photopeaks for beam range verification.

Experimental Study of Using a 3-D Position Sensitive CdZnTe Detector for Proton Beam Range Verification

This manuscript discusses the use of a large volume array CZT detector for experimental prompt gamma-ray imaging. Namely, the 718 keV and the 4.44 MeV photopeaks produced from proton-carbon interactions are imaged using maximum likelihood expectation maximization (MLEM). Various proton beam irradiations are used to characterize the feasibility of using both photopeaks for beam range verification.

Experimental Study of Using a 3-D Position Sensitive CdZnTe Detector for Proton Beam Range Verification

This manuscript discusses the use of a large volume array CZT detector for experimental prompt gamma-ray imaging. Namely, the 718 keV and the 4.44 MeV photopeaks produced from proton-carbon interactions are imaged using maximum likelihood expectation maximization (MLEM). Various proton beam irradiations are used to characterize the feasibility of using both photopeaks for beam range verification.