The dilemma of parotid gland and pharyngeal constrictor muscles preservation-Is daily online image guidance required? A dosimetric analysis.

With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs. Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients׳ plans were created and mapped to weekly CBCTs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D95 and D98 for the target volumes, mean dose (MD) and V30Gy for the PGs, and V50Gy and MD for the PCMs. Results were deemed statistically significant if p < 0.05. No significant time trends were established for these OARs. A significant decrease in V50Gy was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. Regarding target volumes, a highly significant decrease in MD (MD = 20Gy, CI: -20.310 to -19.820) in D98 of the high-dose planning target volume (PTV [70Gy]; PTVD98% = 70Gy) for case 3 was found (p ≤ 0.001). A nonpredictable, yet significant dosimetric effect was found. A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG.

The Supreme Court of Canada Ruling on Physician-Assisted Death: Implications for Psychiatry in Canada.

On February 6, 2015, the Supreme Court of Canada ruled that the prohibition of physician-assisted death (PAD) was unconstitutional for a competent adult person who "clearly consents to the termination of life" and has a "grievous and irremediable (including an illness, disease, or disability) condition that causes enduring suffering that is intolerable to the individual in the circumstances of his or her condition." The radically subjective nature of this ruling raises important questions about who will be involved and how this practice might be regulated. This paper aims to stimulate discussion about psychiatry's role in this heretofore illegal practice and to explore how psychiatry might become involved in end-of-life care in a meaningful, patient-centred way. First, I will review existing international legislation and professional regulatory standards regarding psychiatry and PAD. Second, I will discuss important challenges psychiatry might face regarding capacity assessment, the notion of rational suicide, and the assessment of suffering.