Publications by authors named "R W Rivest"

Purpose: Recently, dosimetri applications of the electronic portal imaging device (EPID) in radiotherapy have gained popularity. Confidence in the robust and reliable dosimetric performance of EPID detectors is essential for their clinical use. This study aimed to evaluate the dosimetric performance of the a-Si 1200 EPID and assess the long-term stability of its response.

View Article and Find Full Text PDF

Hip replacement is a common orthopedic surgery in the aging population. With the rising incidence of prostate cancer, metallic hip prosthetics can cause considerable beam hardening and streak artifacts, leading to difficulty in identifying the target volumes and planning process for radiation treatment. The growing use of Stereotactic Body Radiation Therapy (SBRT) to treat prostate cancer is now well established.

View Article and Find Full Text PDF

Deep Inspiration Breath Hold (DIBH) is a respiratory-gating technique adopted in radiation therapy to lower cardiac irradiation. When performing DIBH treatments, it is important to have a monitoring system to ensure the patient's breath hold level is stable and reproducible at each fraction. In this retrospective study, we developed a system capable of monitoring DIBH breast treatments by utilizing cine EPID images taken during treatment.

View Article and Find Full Text PDF

Internal target volume (ITV) margins were estimated by evaluating the movement of mesorectum and bladder during neoadjuvant long-course radiation therapy (RT) for rectal cancer. In this prospective study, 23 patients with rectal cancer had planning CT (pCT) and weekly cone beam CT (CBCT) in supine position during preoperative long-course RT. Mesorectal wall motion was analyzed based on the coordinates of the most anterior, posterior, left and right points on the pCT and CBCT.

View Article and Find Full Text PDF

Context Daily variations in bladder size and position can negatively impact the ability to accurately deliver radiation. Aims We attempted to quantify how bladder volumes and positions change over the course of radiotherapy for muscle invasive bladder cancer and the planning target volume (PTV) margins required to account for such changes. Methods and material Cone-beam computed tomography (CT) images of 28 patients during their first, second, and third fractions and weekly thereafter were acquired.

View Article and Find Full Text PDF