Development of Ultra-High Dose-Rate (FLASH) Particle Therapy

Kim, Michele M.; Darafsheh, Arash; Schuemann, Jan; Đokić, Ivana; Lundh, Olle; Zhao, Tianyu; Ramos-Méndez, Jose; Dong, Lei; Petersson, Kristoffer

doi:10.1109/trpms.2021.3091406

Cited by 32 publications

(23 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For ion beams there are difficulties with reaching the required dose rates, which demand an increase in beam current by several orders of magnitude for rapid irradiation of a clinically relevant volume. A number of CPT facilities have been able to modify their accelerators (mostly isochronous cyclotrons and synchrocyclotrons) for FLASH with proton beams (171), and photon beams have been studied at large scale synchrotron research facilities (172). FLASH with different ions such as carbon and helium is also being examined (173)(174)(175).…”

Section: Flashmentioning

confidence: 99%

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

2021

View full text Add to dashboard Cite

The physical and clinical benefits of charged particle therapy (CPT) are well recognized. However, the availability of CPT and complete exploitation of dosimetric advantages are still limited by high facility costs and technological challenges. There are extensive ongoing efforts to improve upon these, which will lead to greater accessibility, superior delivery, and therefore better treatment outcomes. Yet, the issue of cost remains a primary hurdle as utility of CPT is largely driven by the affordability, complexity and performance of current technology. Modern delivery techniques are necessary but limited by extended treatment times. Several of these aspects can be addressed by developments in the beam delivery system (BDS) which determines the overall shaping and timing capabilities enabling high quality treatments. The energy layer switching time (ELST) is a limiting constraint of the BDS and a determinant of the beam delivery time (BDT), along with the accelerator and other factors. This review evaluates the delivery process in detail, presenting the limitations and developments for the BDS and related accelerator technology, toward decreasing the BDT. As extended BDT impacts motion and has dosimetric implications for treatment, we discuss avenues to minimize the ELST and overview the clinical benefits and feasibility of a large energy acceptance BDS. These developments support the possibility of advanced modalities and faster delivery for a greater range of treatment indications which could also further reduce costs. Further work to realize methodologies such as volumetric rescanning, FLASH, arc, multi-ion and online image guided therapies are discussed. In this review we examine how increased treatment efficiency and efficacy could be achieved with improvements in beam delivery and how this could lead to faster and higher quality treatments for the future of CPT.

show abstract

Section: Flashmentioning

confidence: 99%

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

2021

View full text Add to dashboard Cite

show abstract

“…However, all the commercially available active dosimeters have been shown to suffer from serious issues at UH-DPP values, such as dose rate dependence, saturation effect, and strong nonlinearity of their response. 22,28,29,34 Ionization chambers (ICs) are well assessed reference dosimeters in conventional radiation therapy techniques. However, a noticeable decrease in their ion collection efficiency has been observed when the DPP value exceeds 0.1 Gy/pulse, [34][35][36][37][38] due to direct recombination and polarization effects.…”

Section: Introductionmentioning

confidence: 99%

Design, realization, and characterization of a novel diamond detector prototype for FLASH radiotherapy dosimetry

Marinelli

Felici²,

Galante³

et al. 2022

Medical Physics

View full text Add to dashboard Cite

Purpose FLASH radiotherapy (RT) is an emerging technique in which beams with ultra‐high dose rates (UH‐DR) and dose per pulse (UH‐DPP) are used. Commercially available active real‐time dosimeters have been shown to be unsuitable in such conditions, due to severe response nonlinearities. In the present study, a novel diamond‐based Schottky diode detector was specifically designed and realized to match the stringent requirements of FLASH‐RT. Methods A systematic investigation of the main features affecting the diamond response in UH‐DPP conditions was carried out. Several diamond Schottky diode detector prototypes with different layouts were produced at Rome Tor Vergata University in cooperation with PTW‐Freiburg. Such devices were tested under electron UH‐DPP beams. The linearity of the prototypes was investigated up to DPPs of about 26 Gy/pulse and dose rates of approximately 1 kGy/s. In addition, percentage depth dose (PDD) measurements were performed in different irradiation conditions. Radiochromic films were used for reference dosimetry. Results The response linearity of the diamond prototypes was shown to be strongly affected by the size of their active volume as well as by their series resistance. By properly tuning the design layout, the detector response was found to be linear up to at least 20 Gy/pulse, well into the UH‐DPP range conditions. PDD measurements were performed by three different linac applicators, characterized by DPP values at the point of maximum dose of 3.5, 17.2, and 20.6 Gy/pulse, respectively. The very good superimposition of three curves confirmed the diamond response linearity. It is worth mentioning that UH‐DPP irradiation conditions may lead to instantaneous detector currents as high as several mA, thus possibly exceeding the electrometer specifications. This issue was properly addressed in the case of the PTW UNIDOS electrometers. Conclusions The results of the present study clearly demonstrate the feasibility of a diamond detector for FLASH‐RT applications.

show abstract

“…9 The mechanism of FLASH radiotherapy in sparing normal tissues is not well understood; several hypotheses based on basic radiation physics and chemistry of reactive oxygen species (ROS) and tumor versus normal cell redox metabolism have been proposed in the literature to explain the FLASH effect. [10][11][12][13][14][15] FLASH radiation beams have been achieved using x-rays in a research synchrotron facility, 6 electrons by using medical linear accelerators, [3][4][5]16,17 protons by clinical isochronous cyclotrons [18][19][20][21][22] and a clinical synchrocyclotron. 23 In our previous work, 23 we demonstrated the feasibility of delivering proton beams at a FLASH dose rate in a pristine Bragg peak pattern using a clinical synchrocyclotron as a first step toward realizing an experimental platform for preclinical studies.…”

Section: Introductionmentioning

confidence: 99%

“…The safety and feasibility of treating a first human patient with FLASH radiotherapy was shown in 2019 9 . The mechanism of FLASH radiotherapy in sparing normal tissues is not well understood; several hypotheses based on basic radiation physics and chemistry of reactive oxygen species (ROS) and tumor versus normal cell redox metabolism have been proposed in the literature to explain the FLASH effect 10‐15 …”

Section: Introductionmentioning

confidence: 99%

Spread‐out Bragg peak proton FLASH irradiation using a clinical synchrocyclotron: Proof of concept and ion chamber characterization

et al. 2021

Self Cite

View full text Add to dashboard Cite

Purpose The purpose of this work is to (a) demonstrate the feasibility of delivering a spread‐out Bragg peak (SOBP) proton beam in ultra‐high dose rate (FLASH) using a proton therapy synchrocyclotron as a major step toward realizing an experimental platform for preclinical studies, and (b) evaluate the response of four models of ionization chambers in such a radiation field. Methods A clinical Mevion HYPERSCAN® synchrocyclotron was adjusted for ultra‐high dose rate proton delivery. Protons with nominal energy of 230 MeV were delivered in pulses with temporal width ranging from 12.5 μs to 24 μs spanning from conventional to FLASH dose rates. A boron carbide absorber and a range modulator block were placed in the beam path for range modulation and creating an SOBP dose profile. The radiation field was defined by a brass aperture with 11 mm diameter. Two Faraday cups were used to determine the number of protons per pulse at various dose rates. The dosimetric response of two cylindrical (IBA CC04 and CC13) and two plane‐parallel (IBA PPC05 and PTW Advanced Markus®) ionization chambers were evaluated. The dose rate was measured using the plane‐parallel ionization chambers. The integral depth dose (IDD) was measured with a PTW Bragg Peak® ionization chamber. The lateral beam profile was measured with EBT‐XD radiochromic film. Monte Carlo simulation was performed in TOPAS as the secondary check for the measurements and as a tool for further optimization of the range modulators’ design. Results Faraday cups measurement showed that the maximum protons per pulse is 39.9 pC at 24 μs pulse width. A good agreement between the measured and simulated IDD and lateral beam profiles was observed. The cylindrical ionization chambers showed very high ion recombination and deemed not suitable for absolute dosimetry at ultra‐high dose rates. The average dose rate measured using the PPC05 ionization chamber was 163 Gy/s at the pristine Bragg peak and 126 Gy/s at 1 cm depth for the SOBP beam. The SOBP beam range and modulation were measured 24.4 mm and 19 mm, respectively. The pristine Bragg peak beam had 25.6 mm range. Simulation results showed that the IDD and profile flatness can be improved by the cavity diameter of the range modulator and the number of scanned spots, respectively. Conclusions Feasibility of delivering protons in an SOBP pattern with >100 Gy/s average dose rate using a clinical synchrocyclotron was demonstrated. The dose heterogeneity can be improved through optimization of the range modulator and number of delivered spots. Plane‐parallel chambers with smaller gap between electrodes are more suitable for FLASH dosimetry compared to the other ion chambers used in this work.

show abstract

Development of Ultra-High Dose-Rate (FLASH) Particle Therapy

Cited by 32 publications

References 87 publications

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

Future Developments in Charged Particle Therapy: Improving Beam Delivery for Efficiency and Efficacy

Design, realization, and characterization of a novel diamond detector prototype for FLASH radiotherapy dosimetry

Spread‐out Bragg peak proton FLASH irradiation using a clinical synchrocyclotron: Proof of concept and ion chamber characterization

Contact Info

Product

Resources

About