Frameless stereotactic body radiation therapy for multiple lung metastases

Abstract

Two patients with multiple lung metastases (≥ 5) were treated using frameless stereotactic body radiation therapy (SBRT) on an Elekta Axesse linear accelerator equipped with an interdigitation‐capable multileaf collimator and four‐dimensional cone‐beam CT (4D CBCT). The technique and the early clinical outcomes were evaluated. Patient A with five lung metastases and Patient B with seven lung metastases underwent SBRT (48 Gy/8 fractions for Patient A, 42 Gy/7 fractions for Patient B). The treatments were administered using a 6 MV photon beam. The nominal dose rate was 660 MUs/min. Patients were positioned and immobilized using thermoplastic masks and image guidance was done using 4D CBCT. The targets were delineated on the images of the 4D CT, and the positron emission tomography‐computed tomography (PET‐CT) images were taken as references. A two‐step, volumetric‐modulated arc therapy (VMAT) plan was designed for each patient. Step 1: the lesions in one lung were irradiated by a 210° arc field; Step 2: the rest of the lesions in the other lung were irradiated by a 120° arc field. Plans were evaluated using conformity index (CI) and homogeneity index (HI). Patients were followed up and adverse events were graded according to the Common Terminology Criteria for Adverse Events v4.0 (CTCAE v4.0). The beam‐on time of each treatment was less than 10 min. The CI and HI for the two plans were 0.562, 0.0709 and 0.513, 0.0794, respectively. Pulmonary function deteriorated slightly in both patients, and the patient with seven lung lesions was confirmed to have Grade 1 radiation pneumonitis. The technique was fast, accurate, and well tolerated by patients, and the two‐step plan is a helpful design in reducing the dose to the lungs.PACS numbers: 87.55‐x, 87.56.J‐, 87.56.‐v, 87.56.nk, 87.57.qp

Improving treatment efficiency via photon optimizer (PO) MLC algorithm for synchronous single‐isocenter/multiple‐lesions VMAT lung SBRT

“…However, elderly patients who developed multiple primary or oligometastases (<5 lesions) lung lesions with associated co‐morbidities may not retain their treatment position for traditional long SBRT treatment times with an individual isocenter placed for each lesion. Treating multiple lung lesions synchronously with a single‐isocenter plan, either using intensity‐modulated radiation therapy (IMRT) or volumetric arc therapy (VMAT), has been studied by a few researchers . Furthermore, utilizing flattening filter free (FFF) beam for single‐isocenter multiple‐lesion VMAT lung stereotactic body radiation therapy (SBRT) treatment was fast and efficient, improved the patient comfort and is gaining popularity in clinical practice …”

‘Compromise position’ image alignment to accommodate independent motion of multiple clinical target volumes during radiotherapy: A high risk prostate cancer example

“…A sliding scale is then used to find the best ‘compromise’ match between the two surrogates. Successful application of this software has been reported for patients receiving radiotherapy for lung cancer and regional lymph nodes, multiple lung metastases and for post‐prostatectomy surgical bed …”

“…A sliding scale is then used to find the best 'compromise' match between the two surrogates. Successful application of this software has been reported for patients receiving radiotherapy for lung cancer and regional lymph nodes, 36 multiple lung metastases 37 and for post-prostatectomy surgical bed. 38 In conclusion, for disease sites that require the concurrent irradiation of multiple, independently moving CTVs, there is a complex geometric interplay between the magnitude of CTV displacement differences, the PTV margins and the image guidance strategy applied.…”

Estimation of effective imaging dose and excess absolute risk of secondary cancer incidence for four‐dimensional cone‐beam computed tomography acquisition

“…Likewise, our research group has reported the ability of 4D‐CBCT to acquire highly accurate images from a respiratory motion phantom . Several studies have reported that 4D‐CBCT can be used to manage respiratory motion in clinical cases . They stated that 4D‐CBCT can observe the internal margin and the motion of a tumor during treatment with high accuracy, and that 4D‐CBCT can be used for stereotactic body radiotherapy as an IGRT device.…”