Non-coplanar lung SABR treatments delivered with a gantry-mounted x-ray tube.

To create two non-coplanar, stereotactic ablative radiotherapy (SABR) lung patient treatment plans compliant with the radiation therapy oncology group (RTOG) 0813 dosimetric criteria using a simple, isocentric, therapy with kilovoltage arcs (SITKA) system designed to provide low cost external radiotherapy treatments for low- and middle-income countries (LMICs).A treatment machine design has been proposed featuring a 320 kVp x-ray tube mounted on a gantry. A deep learning cone-beam CT (CBCT) to synthetic CT (sCT) method was employed to remove the additional cost of planning CTs.

Dosimetry of a novel converging X-ray source for kilovoltage radiotherapy.

Purpose: The objective of this work was to evaluate phantom dosimetry of a novel kilovoltage (kV) X-ray source, which employs a stationary tungsten anode and a linearly swept scanning electron beam. The source utilizes converging X-ray collimation along with orthogonal mechanical rotation to distribute surface flux over large area. In this study, this was investigated as a potential solution to fast-falloff limitations expected with kV radiotherapy.

External beam radiation therapy with kilovoltage x-rays.

Kilovoltage (kV) x-rays are most commonly used for diagnostic imaging due to their sensitivity to tissue composition. In radiation therapy (RT), due to their fast attenuation, kV x-rays are typically only used for superficial irradiation of skin cancer and for intra-operative RT (IORT). Recently, however, a number of kV RT techniques have emerged.

Monte Carlo calculated kilovoltage x-ray arc therapy plans for three lung cancer patients.

: The intent of this work was to evaluate the ability of our 200 kV kilovoltage arc therapy (KVAT) system to treat realistic lung tumors without exceeding dose constraints to organs-at-risk (OAR).: Monte Carlo (MC) methods and the McO optimization framework generated and inversely optimized KVAT treatment plans for 3 SABR lung cancer patients. The KVAT system was designed to treat deep-seated lesions with kilovoltage photons.

Inverse optimization of low-cost kilovoltage x-ray arc therapy plans.

Purpose: The objective of this work was to investigate the benefits of using inverse optimization treatment planning for kilovoltage arc therapy (KVAT) and to assess the dosimetric limitations of KVAT.

Methods: Monte Carlo (MC) calculated, inversely optimized KVAT plans of spherical, idealized breast, lung, and prostate lesions were calculated using the EGSnrc/BEAMnrc and DOSXYZnrc MC codes. The dose delivered with the KVAT system, which generates 200-225 kV photon beamlets, was calculated and inversely optimized using an optimization framework developed at McGill University.

Monte Carlo simulations of a kilovoltage external beam radiotherapy system on phantoms and breast patients.

Purpose: To determine the most suitable lesion size and depth for radiotherapy treatments with a prototype kilovoltage x-ray arc therapy (KVAT) system through Monte Carlo simulations of the dose delivered to lesion, dose homogeneity, and lesion-to-skin ratio.

Methods: Monte Carlo simulations were used to calculate dose distributions generated by a novel low-energy kilovoltage x-ray system to a variety of clinically relevant lesion sizes and depths in phantoms and for hypothetical partial breast irradiations of patients in supine and prone positions. The treatments by 200 kV KVAT system were modeled for four sizes of tumor (1-4 cm diameter) at three depths (superficial, middle, and deep) in two sizes of cylindrical water phantoms (16.

Feasibility of external beam radiation therapy to deep-seated targets with kilovoltage x-rays.

Purpose: Radiation therapy to deep-seated targets is typically delivered with megavoltage x-ray beams generated by medical linear accelerators or Co sources. Here, we used computer simulations to design and optimize a lower energy kilovoltage x-ray source generating acceptable dose distributions to a deep-seated target.

Methods: The kilovoltage arc therapy (KVAT) x-ray source was designed to treat a 4-cm diameter target located at a 10-cm depth in a 40-cm diameter homogeneous cylindrical phantom.

Radiochromic film dosimetry of contrast-enhanced radiotherapy (CERT).

Contrast-enhanced radiotherapy (CERT) employs elevated concentrations of high-Z contrast media in targets to dramatically increase the absorbed dose of radiation relative to the surrounding tissues. However, it is difficult to measure the dose enhancement with routine clinical instruments because the photoelectrons and Auger electrons produced by the interaction of kilovoltage x-rays with the contrast agent travel extremely short distances. We have developed a technique utilizing unlaminated radiochromic film to measure the maximum dose enhancement factor attainable in solutions of contrast agent with iodine concentrations ranging from 0% to 37% (w/v).

Primitive neuroectodermal tumors/medulloblastoma.

The therapy for medulloblastoma/primitive neuroectodermal tumors of the central nervous system is surgery, followed by combination chemo-radiotherapy. The radiation field is the entire craniospinal axis, which is only avoided when treating infants. The treatment is, therefore, lengthy and toxic.