Evaluation of intensity-modulated electron FLASH radiotherapy in a clinical setting using veterinary cases
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Evaluation of intensity-modulated electron FLASH radiotherapy in a clinical setting using veterinary cases. / Konradsson, Elise; Szecsenyi, Rebecka Ericsson; Adrian, Gabriel; Coskun, Mizgin; Børresen, Betina; Arendt, Maja Louise; Erhart, Kevin; Bäck, Sven Å.J.; Petersson, Kristoffer; Ceberg, Crister.
In: Medical Physics, Vol. 50, No. 10, 6569-6579, 2023.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Evaluation of intensity-modulated electron FLASH radiotherapy in a clinical setting using veterinary cases
AU - Konradsson, Elise
AU - Szecsenyi, Rebecka Ericsson
AU - Adrian, Gabriel
AU - Coskun, Mizgin
AU - Børresen, Betina
AU - Arendt, Maja Louise
AU - Erhart, Kevin
AU - Bäck, Sven Å.J.
AU - Petersson, Kristoffer
AU - Ceberg, Crister
N1 - Publisher Copyright: © 2023 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.
PY - 2023
Y1 - 2023
N2 - Purpose: The increased normal tissue tolerance for FLASH radiotherapy (FLASH-RT), as compared to conventional radiotherapy, was first observed in ultra-high dose rate electron beams. Initial clinical trials in companion animals have revealed a high risk of developing osteoradionecrosis following high-dose single-fraction electron FLASH-RT, which may be related to inhomogeneities in the dose distribution. In the current study, we aim to evaluate the possibilities of intensity-modulated electron FLASH-RT in a clinical setting to ensure a homogeneous dose distribution in future veterinary and human clinical trials. Methods: Our beam model in the treatment planning system electronRT (.decimal, LLC, Sanford, FL, USA) was based on a 10-MeV electron beam from a clinical linear accelerator used to treat veterinary patients with FLASH-RT in a clinical setting. In electronRT, the beam can be intensity-modulated using tungsten island blocks in the electron block cutout, and range-modulated using a customized bolus with variable thickness. Modulations were first validated in a heterogeneous phantom by comparing measured and calculated dose distributions. To evaluate the impact of intensity modulation in superficial single-fraction FLASH-RT, a treatment planning study was conducted, including eight canine cancer patient cases with simulated tumors in the head-and-neck region. For each case, treatment plans with and without intensity modulation were created for a uniform bolus and a range-modulating bolus. Treatment plans were evaluated using a target dose homogeneity index (HI), a conformity index (CI), the near-maximum dose outside the target ((Formula presented.)), and the near-minimum dose to the target ((Formula presented.)). Results: By adding intensity modulation to plans with a uniform bolus, the HI could be improved (p = 0.017). The combination of a range-modulating bolus and intensity modulation provided a further significant improvement of the HI as compared to using intensity modulation in combination with a uniform bolus (p = 0.036). The range-modulating bolus also improved the CI compared to using a uniform bolus, both with an open beam (p = 0.046) and with intensity modulation (p = 0.018), as well as increased the (Formula presented.) (p = 0.036 with open beam and p = 0.05 with intensity modulation) and reduced the median (Formula presented.) (not significant). Conclusions: By using intensity-modulated electron FLASH-RT in combination with range-modulating bolus, the target dose homogeneity and conformity in canine patients with simulated tumors in complex areas in the head-and-neck region could be improved. By utilizing this technique, we hope to decrease the dose outside the target volume and avoid hot spots in future clinical electron FLASH-RT studies, thereby reducing the risk of radiation-induced toxicity.
AB - Purpose: The increased normal tissue tolerance for FLASH radiotherapy (FLASH-RT), as compared to conventional radiotherapy, was first observed in ultra-high dose rate electron beams. Initial clinical trials in companion animals have revealed a high risk of developing osteoradionecrosis following high-dose single-fraction electron FLASH-RT, which may be related to inhomogeneities in the dose distribution. In the current study, we aim to evaluate the possibilities of intensity-modulated electron FLASH-RT in a clinical setting to ensure a homogeneous dose distribution in future veterinary and human clinical trials. Methods: Our beam model in the treatment planning system electronRT (.decimal, LLC, Sanford, FL, USA) was based on a 10-MeV electron beam from a clinical linear accelerator used to treat veterinary patients with FLASH-RT in a clinical setting. In electronRT, the beam can be intensity-modulated using tungsten island blocks in the electron block cutout, and range-modulated using a customized bolus with variable thickness. Modulations were first validated in a heterogeneous phantom by comparing measured and calculated dose distributions. To evaluate the impact of intensity modulation in superficial single-fraction FLASH-RT, a treatment planning study was conducted, including eight canine cancer patient cases with simulated tumors in the head-and-neck region. For each case, treatment plans with and without intensity modulation were created for a uniform bolus and a range-modulating bolus. Treatment plans were evaluated using a target dose homogeneity index (HI), a conformity index (CI), the near-maximum dose outside the target ((Formula presented.)), and the near-minimum dose to the target ((Formula presented.)). Results: By adding intensity modulation to plans with a uniform bolus, the HI could be improved (p = 0.017). The combination of a range-modulating bolus and intensity modulation provided a further significant improvement of the HI as compared to using intensity modulation in combination with a uniform bolus (p = 0.036). The range-modulating bolus also improved the CI compared to using a uniform bolus, both with an open beam (p = 0.046) and with intensity modulation (p = 0.018), as well as increased the (Formula presented.) (p = 0.036 with open beam and p = 0.05 with intensity modulation) and reduced the median (Formula presented.) (not significant). Conclusions: By using intensity-modulated electron FLASH-RT in combination with range-modulating bolus, the target dose homogeneity and conformity in canine patients with simulated tumors in complex areas in the head-and-neck region could be improved. By utilizing this technique, we hope to decrease the dose outside the target volume and avoid hot spots in future clinical electron FLASH-RT studies, thereby reducing the risk of radiation-induced toxicity.
KW - conformity
KW - electrons
KW - FLASH
KW - homogeneity
KW - treatment planning
U2 - 10.1002/mp.16737
DO - 10.1002/mp.16737
M3 - Journal article
C2 - 37696040
AN - SCOPUS:85170701743
VL - 50
JO - Medical Physics
JF - Medical Physics
SN - 0094-2405
IS - 10
M1 - 6569-6579
ER -
ID: 369306157