An updated look at petroleum well leaks, ineffective policies and the social cost of methane in Canada's largest oil-producing province.

Unlabelled: Temporarily plugged or "suspended" wells pose environmental and economic risks due to the large volume of methane gas leaked. In the Canadian Province of Alberta, which, by far, has the largest number of petroleum wells in Canada, there are no regulations stipulating the maximum length of time a well can be left suspended. In recent years, an increasing number of wells have been put into the suspended state by owners.

The use of RapidArc volumetric-modulated arc therapy to deliver stereotactic radiosurgery and stereotactic body radiotherapy to intracranial and extracranial targets.

Twenty-three targets in 16 patients treated with stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT) were analyzed in terms of dosimetric homogeneity, target conformity, organ-at-risk (OAR) sparing, monitor unit (MU) usage, and beam-on time per fraction using RapidArc volumetric-modulated arc therapy (VMAT) vs. multifield sliding-window intensity-modulated radiation therapy (IMRT). Patients underwent computed tomography simulation with site-specific immobilization.

Residual setup errors and dose variations with less-than-daily image guided patient setup in external beam radiotherapy for esophageal cancer.

Background And Purpose: To evaluate residual patient setup errors and daily dose variations of different less-than-daily image guidance (IG) strategies in the delivery of external beam radiotherapy for esophageal cancer.

Material And Methods: Daily image-guided setup data for 25 consecutive esophageal cancer patients treated with helical tomotherapy were evaluated. Seven less-than-daily IG strategies with different imaging frequencies were simulated.

Daily electronic portal imaging of implanted gold seed fiducials in patients undergoing radiotherapy after radical prostatectomy.

Purpose: The aim of this study was to measure interfraction prostate bed motion, setup error, and total positioning error in 10 consecutive patients undergoing postprostatectomy radiotherapy.

Methods And Materials: Daily image-guided target localization and alignment using electronic portal imaging of gold seed fiducials implanted into the prostate bed under transrectal ultrasound guidance was used in 10 patients undergoing adjuvant or salvage radiotherapy after prostatectomy. Prostate bed motion, setup error, and total positioning error were measured by analysis of gold seed fiducial location on the daily electronic portal images compared with the digitally reconstructed radiographs from the treatment-planning CT.