Support for the "Vancouver call for action to strengthen expertise in radiological protection worldwide": the position of organisations in formal relations with the International Commission on Radiological Protection (ICRP).

The International Commission on Radiological Protection (ICRP), recently expressed concern that "a shortage of investment in training, education, research, and infrastructure seen in many sectors and countries may compromise society's ability to properly manage radiation risks" and in 2022 announced the "Vancouver call for action to strengthen expertise in radiological protection worldwide". As representatives of organisations in formal relations with ICRP, we decided to promote this position paper to declare and emphasise that strengthening the expertise in radiological protection is a collective priority for all of us.

Calculation method for novel upright CT scanner isodose curves.

Purpose: A computational method based on Monte-Carlo calculations is presented and used to calculate isodose curves for a new upright and tilting CT scanner useful for radiation protection purposes.

Methods: The TOPAS code platform with imported CAD files for key components was used to construct a calculation space for the scanner. A sphere of water acts as the patient would by creating scatter out of the bore.

Anatomical changes in the male pelvis between the supine and upright positions-A feasibility study for prostate treatments in the upright position.

Treating and imaging patients in the upright orientation is gaining acceptance in radiation oncology and radiology and has distinct advantages over the recumbent position. An IRB approved study to investigate the positions and orientations of the male pelvic organs between the supine and upright positions was conducted. The study comprised of scanning 15 male volunteers (aged 55-75 years) on a 0.

The use of image synthesis techniques in target and roi delineation in the upright position.

The use of multi-modality imaging technologies such as CT, MRI, and PET imaging is state of the art for radiation therapy treatment planning. Except for a limited number of low magnetic field MR scanners the majority of such imaging technologies can only image the patient in a recumbent position. Delivering radiation therapy treatments with the patient in an upright orientation has many benefits and several companies are now developing upright patient positioners combined with upright diagnostic helical CT scanners to facilitate upright radiation therapy treatments.

On proton CT reconstruction using MVCT-converted virtual proton projections.

Purpose: To describe a novel methodology of converting megavoltage x-ray projections into virtual proton projections that are otherwise missing due to the proton range limit. These converted virtual proton projections can be used in the reconstruction of proton computed tomography (pCT).

Methods: Relations exist between proton projections and multispectral megavoltage x-ray projections for human tissue.

Bragg peak prediction from quantitative proton computed tomography using different path estimates.

This paper characterizes the performance of the straight-line path (SLP) and cubic spline path (CSP) as path estimates used in reconstruction of proton computed tomography (pCT). The GEANT4 Monte Carlo simulation toolkit is employed to simulate the imaging phantom and proton projections. SLP, CSP and the most-probable path (MPP) are constructed based on the entrance and exit information of each proton.

Proof of principle of ocular sparing in dogs with sinonasal tumors treated with intensity-modulated radiation therapy.

Intensity-modulated radiation therapy (IMRT) allows optimization of radiation dose delivery to complex tumor volumes with rapid dose drop-off to surrounding normal tissues. A prospective study was performed to evaluate the concept of conformal avoidance using IMRT in canine sinonasal cancer. The potential of IMRT to improve clinical outcome with respect to acute and late ocular toxicity was evaluated.

On the use of a proton path probability map for proton computed tomography reconstruction.

Purpose: To describe a method to estimate the proton path in proton computed tomography (pCT) reconstruction, which is based on the probability of a proton passing through each point within an object to be imaged.

Methods: Based on multiple Coulomb scattering and a semianalytically derived model, the conditional probability of a proton passing through each point within the object given its incoming and exit condition is calculated in a Bayesian inference framework, employing data obtained from Monte Carlo simulation using GEANT4. The conditional probability at all of the points in the reconstruction plane forms a conditional probability map and can be used for pCT reconstruction.

Intensity-modulated x-ray (IMXT) versus proton (IMPT) therapy for theragnostic hypoxia-based dose painting.

In this work the abilities of intensity-modulated x-ray therapy (IMXT) and intensity-modulated proton therapy (IMPT) to deliver boosts based on theragnostic imaging were assessed. Theragnostic imaging is the use of functional or molecular imaging data for prescribing radiation dose distributions. Distal gradient tracking, an IMPT method designed for the delivery of non-uniform dose distributions, was assessed.

Megavoltage computed tomography: an emerging tool for image-guided radiotherapy.

Background: Helical tomotherapy is a unique approach to image-guided IMRT that combines features of a linear accelerator and a CT scanner. This design allows generation of megavoltage CT (MVCT) images, which among other uses, are used to verify daily setup. In this study, we assessed the image-quality, absorbed radiation doses, and clinical practicality of MVCT from our helical tomotherapy prototype unit.

PET/CT following intensity-modulated radiation therapy for primary lung tumor in a dog.

A primary lung tumor in a dog treated with intensity-modulated radiation therapy was imaged approximately 6 weeks and 1-year posttreatment with combined positron emission tomography (PET) and computed tomography, utilizing the radiotracers 18F-fluorodeoxyglucose and 18F-fluorothymidine. These two tracers allowed discrimination of tumor from inflammation, and demonstrated spread of tumor along airways over time after treatment. Fusion of functional imaging with anatomic imaging is a useful tool, particularly in the field of oncology, with the potential for PET markers that delineate tumor from normal or reactive tissue, and potential or actual response to therapy.

Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion.

The interplay between a constant scan speed and intrafraction oscillatory motion produces interesting fluence intensity modulations along the axis of motion that are sensitive to the motion function, as originally shown in a classic paper by Yu et al. [Phys. Med.

Confirmation, refinement, and extension of a study in intrafraction motion interplay with sliding jaw motion.

The interplay between a constant scan speed and intrafraction oscillatory motion produces interesting fluence intensity modulations along the axis of motion that are sensitive to the motion function, as originally shown in a classic paper by Yu et al. [Phys. Med.

Technical note: A novel boundary condition using contact elements for finite element based deformable image registration.

Deformable image registration is an important tool for image-guided radiotherapy. Physics-model-based deformable image registration using finite element analysis is one of the methods currently being investigated. The calculation accuracy of finite element analysis is dependent on given boundary conditions, which are usually based on the surface matching of the organ in two images.

Plastic scintillation dosimetry: optimization of light collection efficiency.

Practical contemporary radiotherapy dosimetry systems used for dose measurement and verification are ionization chambers (which typically have at least a 0.1 cm3 air cavity volume), thermoluminescent dosimeters (TLDs) and silicon diodes. However, during the last decade, there has been an increased interest in scintillation dosimetry using small water-equivalent plastic scintillators, due to their favourable characteristics when compared with other more commonly used detector systems.

Helical tomotherapy: an innovative technology and approach to radiation therapy.

Helical tomotherapy represents both a novel radiation treatment device and an innovative means of delivering radiotherapy. The helical tomotherapy unit itself is essentially a hybrid between a linear accelerator and a helical CT scanner for the purpose of delivering intensity-modulated radiation therapy (IMRT). The imaging capacity conferred by the CT component allows targeted regions to be visualized prior to, during, and immediately after each treatment.