Synchrotron radiation external beam rotational radiotherapy of breast cancer: proof of principle

Abstract

The principle of rotational summation of the absorbed dose for breast cancer treatment with orthovoltage X-ray beams was proposed by J. Boone in 2012. Here, use of X-ray synchrotron radiation for image guided external beam rotational radiotherapy treatment of breast cancer is proposed. Tumor irradiation occurs with the patient in the prone position hosted on a rotating bed, with her breast hanging from a hole in the bed, which rotates around a vertical axis passing through the tumor site. Horizontal collimation of the X-ray beam provides for whole breast or partial breast irradiation, while vertical translation of the bed and successive rotations allow for irradiation of the full tumor volume, with dose rates which permit also hypofractionated treatments. In this work, which follows a previous preliminary report, results are shown of a full series of measurements on polyethylene and acrylic cylindrical phantoms carried out at the Australian Synchrotron, confirmed by Geant4 Monte Carlo simulations, intended to demonstrate the proof of principle of the technique. Dose measurements were carried out with calibrated ion chambers, radiochromic films and thermoluminescence dosimeters. The photon energy investigated was 60 keV. Image guidance may occur with the transmitted beam for contrast-enhanced breast computed tomography. For a horizontal beam collimation of 1.5 cm and rotation around the central axis of a 14 cm-diameter polyethylene phantom, a periphery-to-center dose ratio of 14% was measured. The simulations showed that under the same conditions the dose ratio decreases with increasing photon energy down to 10% at 175 keV. These values are comparable with those achievable with conventional megavoltage radiotherapy of breast cancer with a medical linear accelerator. Dose painting was demonstrated with two off-center `cancer foci' with 1.3 Gy and 0.6 Gy target doses. The use of a radiosensitizing agent for dose enhancement is foreseen.

External beam radiation therapy with kilovoltage x-rays

“…Rotational kV-EBRT permitted a periphery-to-center dose ratio from 13% to 9% in homogeneous breast phantoms of 14-cm in diameter for beams of ~ 1 cm in size. Earlier the group investigated breast EBRT with a synchrotron beam termed synchrotron radiation rotational radiotherapy (SR 3 T) by means of MC simulations and experiments with the same 14-cm diameter phantom [48,49]. They performed Geant4 simulations and measurements with Gafchromic films, ionization chambers and TLD of phantom dose delivered with monoenergetic 60-175 keV synchrotron x-ray beams at the Australian Synchrotron IMBL.…”

Breast radiotherapy with kilovoltage photons and gold nanoparticles as radiosensitizer: An in vitro study

“…Recently, we started the project SR 3 T (Synchrotron Radiation Rotational RadioTherapy) 24 , 25 , 26 for investigating breast RT using a kV photon beam and AuNPs dose enhancement. The proposed setup adopts a configuration in which the patients are in prone position with the breast hanging from a hole in the bed.…”

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

“…One potential solution is the use of lower energy kilovoltage (kV) x-rays in place of megavoltage (MV) x-rays from clinical linear accelerators (linacs), since the technology required to produce kV x-rays is less expensive and requires less infrastructure and less shielding to ensure a safe treatment environment. Recently, a number of groups have investigated various methods of adapting kV x-rays to treat deep-seated lesions [5][6][7][8]. Additionally, various research groups have studied the use of kilovoltage x-rays for stereotactic radiotherapy [9][10][11][12][13].…”