ABSTRACT
Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50_Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry.
Subject(s)
Carcinoma, Squamous Cell/radiotherapy , Head and Neck Neoplasms/radiotherapy , Head/radiation effects , Neck/radiation effects , Organ Sparing Treatments , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-Modulated , Female , Humans , Male , Middle Aged , Monte Carlo Method , Neoplasm Staging , Radiotherapy, Conformal , Relative Biological EffectivenessABSTRACT
This article traces the history of two clinical cases. The first case describes a substance abusing patient who enacted the part of a narcotics addict. This enactment was affirmed by both alcohol and narcotic treatment programs, leading to a misdiagnosis. The second case describes a substance using client misdiagnosed as a result of assumptions made by the referral source. Biases inherent in the assessment of drug involved patients are illustrated and the utility of the hypotheses testing approach as a method of diagnostic error reduction and correction is discussed.
Subject(s)
Opioid-Related Disorders/diagnosis , Substance-Related Disorders/diagnosis , Adult , Attitude of Health Personnel , Countertransference , Diagnostic Errors , Female , Humans , Male , Opioid-Related Disorders/psychology , Substance-Related Disorders/psychologyABSTRACT
Measurements of peak flow, vital capacity, FEV1 and flow volume studies were performed in healthy volunteers for 20 weeks following intranasal vaccination with live-attenuated A/Victoria/3/75 recombinants or placebo. Despite differing attenuation of the two candidate strains, no effect on pulmonary function was detected.
