1
|
Schwarz M, Traneus E, Safai S, Kolano A, van de Water S. Treatment planning for Flash radiotherapy: general aspects and applications to proton beams. Med Phys 2022; 49:2861-2874. [PMID: 35213040 DOI: 10.1002/mp.15579] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Revised: 12/22/2021] [Accepted: 02/14/2022] [Indexed: 11/08/2022] Open
Abstract
The increased radioresistence of healthy tissues when irradiated at very high dose rates (known as the Flash effect) is a radiobiological mechanism that is currently investigated in order to increase the therapeutic ratio of radiotherapy treatments. To maximize the benefits of the clinical application of Flash, a patient-specific balance between different properties of the dose distribution should be found, i.e. Flash needs to be one of the variables considered in treatment planning. We investigated the Flash potential of three proton therapy planning and beam delivery techniques, each on a different anatomical region. Based on a set of beam delivery parameters, on hypotheses on the dose and dose rate thresholds needed for the Flash effect to occur, and on two definitions of Flash dose rate, we generated exemplary illustrations of the capabilities of current proton therapy equipment to generate Flash dose distributions. All techniques investigated could both produce dose distributions comparable with a conventional proton plan and reach the Flash regime, to an extent that was strongly dependent on the dose per fraction and the Flash dose threshold. The beam current, Flash dose rate threshold and dose rate definition typically had a more moderate effect on the amount of Flash dose in normal tissue. A systematic estimation of the impact of Flash on different patient anatomies and treatment protocols is possible only if Flash-specific treatment planning features become readily available. Planning evaluation tools such as a voxel-based dose delivery time structure, and the inclusion in the optimization cost function of parameters directly associated with Flash (e.g. beam current, spot delivery sequence and scanning speed), are needed to generate treatment plans that are taking full advantage of the potential benefits of the Flash effect. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Marco Schwarz
- Proton therapy Department, Trento Hospital and TIFPA-INFN, Trento, Italy
| | - Erik Traneus
- RaySearch Laboratories AB, Stockholm SE-103 65, Sweden
| | - Sairos Safai
- Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland
| | - Anna Kolano
- Advanced Oncotherapy plc, London, England - Application of Detectors and Accelerators to Medicine(ADAM), Geneva, Switzerland
| | - Steven van de Water
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
2
|
Fellin F, Artoni M, Righetto R, Bellinzona VE, Widesott L, Dionisi F, Farace P. An avoidance method to minimize dose perturbation effects in proton pencil beam scanning treatment of patients with small high-Z implants. Phys Med Biol 2020; 65:14NT01. [PMID: 32464619 DOI: 10.1088/1361-6560/ab9775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To implement a multi-field-optimization (MFO) technique for treating patients with high-Z implants in pencil beam scanning proton-therapy and generate treatment plans that avoids small implants. Two main issues were addressed: (i) the assessment of the optimal CT acquisition and segmentation technique to define the dimension of the implant and (ii) the distance of pencil beams from the implant (avoidance margin) to assure that it does not affect dose distribution. Different CT reconstruction protocols (by O-MAR or standard reconstruction and by 12 bit or 16 bit dynamic range) followed by thresholding segmentation were tested on a phantom with lead spheres of different sizes. The proper avoidance margin was assessed on a dedicated phantoms of different materials (copper/tantalum and lead), shape (square slabs and spheres) and detectors (two-dimensional array chamber and radio-chromic films). The method was then demonstrated on a head-and-neck carcinoma patient, who underwent carotid artery embolization with a platinum coil close to the target. Regardless the application of O-MAR reconstruction, the CT protocol with a full 16 bit dynamic range allowed better estimation of the sphere volumes, with maximal error around -5% in the greater sphere only. Except the configuration with a shallow target (which required a pre-absorber), particularly with a retracted snout, an avoidance margin of around 0.9-1.3 cm allowed to keep the difference between planned and measured dose below 5-10%. The patient plan analysis showed adequate plan quality and confirmed effective implant avoidance. Potential target under-dosage can be produced by patient misalignment, which could be minimized by daily alignment on the implant, identifiable on orthogonal kilovolt images. By implant avoidance MFO it was possible to minimize potential dose perturbation effects produced by small high-Z implants. An advantage of such approach lies in its potential applicability for any type of implant, regardless the precise knowledge of its composition.
Collapse
|
3
|
Righetto R, Clemens LP, Lorentini S, Fracchiolla F, Algranati C, Tommasino F, Dionisi F, Cianchetti M, Schwarz M, Farace P. Accurate proton treatment planning for pencil beam crossing titanium fixation implants. Phys Med 2020; 70:28-38. [PMID: 31954210 DOI: 10.1016/j.ejmp.2020.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To present a planning strategy for proton pencil-beam scanning when titanium implants need to be crossed by the beam. METHODS We addressed three issues: the implementation of a CT calibration curve to assign to titanium the correct stopping power; the effect of artefacts on CT images and their reduction by a dedicated algorithm; the differences in dose computation depending on the dose engine, pencil-beam vs Monte-Carlo algorithms. We performed measurement tests on a simple cylinder phantom and on a real implant. These phantoms were irradiated with three geometries (single spots, uniform mono-energetic layer and uniform box), measuring the exit dose either by radio-chromic film or multi-layer ionization chamber. The procedure was then applied on two patients treated for chordoma. RESULTS We had to set in the calibration curve a mass density equal to 4.37 g/cm3 to saturated Hounsfield Units, in order to have the correct stopping power assigned to titanium in TPS. CT artefact reduction algorithm allowed a better reconstruction of the shape and size of the implant. Monte-Carlo resulted accurate in computing the dose distribution whereas the pencil-beam algorithm failed due to sharp density interfaces between titanium and the surrounding material. Finally, the treatment plans obtained on two patients showed the impact of the dose engine algorithm, with 10-20% differences between pencil-beam and Monte-Carlo in small regions distally to the titanium screws. CONCLUSION The described combination of CT calibration, artefacts reduction and Monte-Carlo computation provides a reliable methodology to compute dose in patients with titanium implants.
Collapse
Affiliation(s)
- Roberto Righetto
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy.
| | | | - Stefano Lorentini
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| | - Francesco Fracchiolla
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| | - Carlo Algranati
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| | - Francesco Tommasino
- Department of Physics, University of Trento, Povo, Italy; Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics, (INFN), Povo, Italy
| | - Francesco Dionisi
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| | - Marco Cianchetti
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| | - Marco Schwarz
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy; Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics, (INFN), Povo, Italy
| | - Paolo Farace
- Proton Therapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy
| |
Collapse
|
4
|
Farace P, Bizzocchi N, Righetto R, Fellin F, Fracchiolla F, Lorentini S, Widesott L, Algranati C, Rombi B, Vennarini S, Amichetti M, Schwarz M. Supine craniospinal irradiation in pediatric patients by proton pencil beam scanning. Radiother Oncol 2017; 123:112-118. [DOI: 10.1016/j.radonc.2017.02.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/19/2017] [Accepted: 02/12/2017] [Indexed: 10/20/2022]
|
5
|
Bian C, Chen N, Li XL, Zhou XG, Lin H, Jiang LB, Liu WM, Chen Q, Dong J. Surgery Combined with Radiotherapy to Treat Spinal Tumors: A Review of Published Reports. Orthop Surg 2017; 8:97-104. [PMID: 27384717 DOI: 10.1111/os.12230] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 02/07/2016] [Indexed: 12/11/2022] Open
Abstract
Spinal tumors result in high morbidity and a high rate of lower limb paralysis. Both surgical therapy and radiation therapy (RT) are used to treat spinal tumors; however, how best to combine these two therapies to maximize the benefits and minimize the risks is still being debated. It is also difficult to decide the optimal timing, course and dose of RT, especially in pregnant women and children. The aim of this review is to assist surgeons who are dealing with spinal tumors by providing comprehensive information about advanced techniques for administering RT with greater precision and safety, and about the impact of various ways of combining surgery and RT on therapeutic outcomes. We here review published reports about treating spinal tumors with a combination of these two forms of therapy and attempt to draw appropriate conclusions concerning selection of optimal treatment protocols. Our conclusion is that postoperative radiotherapy, especially with high-precision, low-dose and multiple fractions, and brachytherapy are promising therapies to combined with surgery.
Collapse
Affiliation(s)
- Chong Bian
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Nong Chen
- Department of Orthopaedic Surgery, Zhongshan Hospital Qingpu Branch, Fudan University, Shanghai, China
| | - Xi-Lei Li
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xiao-Gang Zhou
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Hong Lin
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Li-Bo Jiang
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Wang-Mi Liu
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qian Chen
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jian Dong
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| |
Collapse
|