Measurements and simulations of focused beam for orthovoltage therapy

Abbas, Hassan; Mahato, Dip N.; Satti, Jahangir; MacDonald, Carolyn A.

doi:10.1118/1.4866224

Cited by 12 publications

(15 citation statements)

References 15 publications

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“…A focused kV x-ray beam, however, could concentrate the dose within the tumor, several centimeters below the entry surface. 2 Since focusing would result in spreading the beam across the skin surface, lower energy photons may still be employed with desired skin sparing. Polycapillary focusing and collimating lenses are widely used in x-ray fluorescence and x-ray diffraction applications.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo dosimetry modeling of focused kV x‐ray radiotherapy of eye diseases with potential nanoparticle dose enhancement

Sun

et al. 2018

Medical Physics

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Compared to eye plaque brachytherapy, the proposed focused kV x-ray technique is noninvasive and shows great advantage in sparing healthy critical organs without sacrificing the tumor control. The NP radiation dose enhancement is considerable at our proposed kV range even with a low NP concentration in the tumor, providing better critical structure protection and more flexibility for treatment planning.

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Section: Introductionmentioning

confidence: 99%

Monte Carlo dosimetry modeling of focused kV x‐ray radiotherapy of eye diseases with potential nanoparticle dose enhancement

Sun

et al. 2018

Medical Physics

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“…It has been demonstrated that a polycapillary-lens-focused kV x-ray beam could pass through a water equivalent medium and maintain focus at a target several cm below the entry surface. 37 A polycapillary x-ray lens consists of a large number of small hollow glass tubes. X rays are guided through these curved and tapered tubes by multiple total reflections, similar to those in light-transmitting fiber optics.…”

Section: B Focused Kv X-ray Treatmentmentioning

confidence: 99%

Dosimetry modeling of focused kV x‐ray radiotherapy for wet age‐related macular degeneration

Sun

Mruthyunjaya

et al. 2020

Medical Physics

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Purpose: Wet (neovascular) age-related macular degeneration (AMD) is the leading cause of blindness in the United States. The mainstay treatment requires monthly intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) drugs, associated with multiple visits, high cost, and the risk of procedural injury and infection. Anti-VEGF drugs inhibit the formation of neovasculature but do not directly attack it. Radiotherapy can destroy neovasculature and potentially also inhibit wet-AMD associated inflammation and fibrosis not addressed by VEGF inhibitors. However, the current collimation-based radiotherapy device uses fixed 4 mm beams, which are prone to overtreat or undertreat the choroidal neovascularization (CNV) lesions because of their various sizes and shapes. This simulation study evaluates personalized conformal treatment with focused kV radiation using cutting-edge polycapillary x-ray optics. Methods: Simulation of the polycapillary optics was achieved via Monte Carlo (MC)-based three-dimensional (3D) geometric ray tracing. Phase-space files modeling the focused photons were generated. The method was previously verified by phantom measurements. The ultrasmall~0.2 mm beam focal spot perpendicular to the beam direction enables spatially fractionated grid therapy, which has been shown to preferentially damage abnormal neovascular blood vessels vs normal ones. Geant4based MC simulations of scanning while rotating beam delivery were performed to conformally treat three clinical cases of large, medium, and small CNV lesions with regular and grid deliveries. Dose delivery uncertainties due to positioning errors were analyzed, including AE0.75 mm displacement in the three orthogonal directions and AE5°vertical/horizontal rotation of the eyeball. Results: The simulated CNV treatments by 60-kVp focused x-ray beams show highly conformal delivery of dose to the lesion plus margin (0.75 mm) with sharp dose fall-offs and controllable spatial modulation patterns. The 90%-10% isodose penumbra is <0.5 mm. With a prescription dose of 16 Gy to the lesions, the critical structure doses are well below the tolerance. The average CNV dose varies within 10% (mostly within 4%) due to 0.75-mm linear displacements and 5-degree gaze angle rotation of the eyeball. Conclusion: Focused kV technique allows personalized treatment of CNV lesions and reduces unwanted radiation to adjacent healthy tissue. The simulated dose distribution is superior to currently available techniques.

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“…However, in the case where a tumour is extended in both traversal directions (x and y), a pure linear scan of the beam would cause a shift of the peak dose towards the phantom surface. This effect is due to the superposition of the beams and can be avoided by associating a rotation with each translation of the beam, as reported by Abbas et al (2014). So far, we have considered a target localized at a depth z f of 4.75 cm within the phantom.…”

Section: Tablementioning

confidence: 99%

“…This method requires a LINAC and could be used to focus photons within the energy range 0.4-4 MeV (Figueroa & Valente, 2015). A further approach to obtain a convergent X-ray beam for radiotherapy application consists of using an X-ray tube and a polycapillary lens as a focusing device (Mahato & MacDonald, 2010;Abbas et al, 2014). A polycapillary lens exploits multiple total reflections of X-rays inside many hollow glass channels to focus the photon beam towards a target.…”

Section: Introductionmentioning

confidence: 99%

Laue lens to focus an X-ray beam for radiation therapy

et al. 2016

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A Laue lens is an optical component composed of a set of crystals that produce a convergent beam exploiting X-ray diffraction in transmission geometry. Employment of a system formed by a properly designed Laue lens coupled with an X-ray unit to selectively irradiate tumours is proposed. A convergent beam leads to a depth dose profile with a pronounced peak at the focal depth, which may result in a high precision of the dose delivery. Using a custom-made Monte Carlo code and the GAMOS code, we carried out a design study to determine the geometry and the optimal features of the crystals composing the lens. As an application, a Laue lens capable of focusing a 80keV beam 50cm downstream of the lens has been designed. The lens is composed of an ensemble of Si crystals with curved diffracting planes. The lens produces a focal spot of 2mm enclosing 7.64 × 106 photons for an electron charge of 1mC impinging on the surface of the X-ray tube anode. The combination of these important figures of merit makes the proposed system suitable for irradiating both sub-cm and larger tumour masses efficiently. A dose of 2Gy can be delivered to a small tumour in a few seconds, sparing at the same time the surrounding tissues

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Measurements and simulations of focused beam for orthovoltage therapy

Abstract: Low energy focused x-ray beams could be used to irradiate tumors inside soft tissue within 5 cm of the surface.

Cited by 12 publications

References 15 publications

Monte Carlo dosimetry modeling of focused kV x‐ray radiotherapy of eye diseases with potential nanoparticle dose enhancement

Monte Carlo dosimetry modeling of focused kV x‐ray radiotherapy of eye diseases with potential nanoparticle dose enhancement

Dosimetry modeling of focused kV x‐ray radiotherapy for wet age‐related macular degeneration

Laue lens to focus an X-ray beam for radiation therapy

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