Dose Optimization in Lumbar Spine Radiographic Examination by Air Gap Method at CR and DR Systems: A Phantom Study.

OBJECTIVE: This study aims at investigating the feasibility of replacing an antiscatter grid with an air gap to achieve dose reduction for lumbar spine radiography while retaining image quality at an acceptable diagnostic level. METHODS: Frontal and lateral projections of lumbar spine radiographic examinations were performed on an anthropomorphic phantom. Nongrid images of both the computed radiography (CR) and digital radiography (DR) systems with air gap thickness ranging from 0 to 25 cm were produced and compared with their corresponding grid images. Dose measurements using thermoluminescent dosimeters at the ovary and testes regions of the phantom were conducted. The image quality of all the images was evaluated by five radiographers using image quality score and visual grading analysis tests. Data on dose measurements and image quality tests were input for statistical analysis. The dose area product (DAP) of all the examinations was recorded and input for the computation of effective doses using a PC-based Monte Carlo program (PCXMC 2.0; STUK, Helsinki, Finland). RESULTS: Significant dose reduction effects on the ovaries of 60.2%-74.1% and 55.1%-73.3% were found, respectively, at the frontal and lateral projections of nongrid lumbar spine examinations compared with their corresponding grid ones in both the CR and DR systems. Results on the image quality score and visual grading analysis tests showed that nongrid images with 10-cm and 5-cm of air gap thicknesses respective to the frontal and lateral images of the lumbar spine were rated with the highest scores. In general, a dose reduction effect using the air gap method was found to be more pronounced in the CR system compared with the DR system. Nevertheless, the CR system delivered a 2.4-4.5 times higher ovary dose respective to the frontal and lateral projections of lumbar spine examinations compared with the DR system. CONCLUSIONS: Ten and 5 centimeters were found to be the optimal air gap thicknesses respective to the frontal and lateral lumbar spine radiographic examinations of the tested Rando phantom (Alderson Laboratories, Stamford, CT) in both the CR and DR systems. Significant dose reduction effects on both the ovary and testes regions of the nongrid examinations were shown. The effective dose computed from PCMCX 2.0 reflected that the risk of cancer induction was halved when an antiscatter grid was replaced by the nongrid method with an optimal air gap thickness in the tested examinations. Further reduction on cancer risk could be achieved by using DR instead of the CR system.

The effects of speed-dependent treadmill training and rhythmic auditory-cued overground walking on balance function, fall incidence, and quality of life in individuals with idiopathic Parkinson's disease: a randomized controlled trial.

OBJECTIVES: The purpose of this single-blinded, randomized controlled study was to examine and compare the immediate and retention effects of progressive speed-dependent treadmill training (SDTT) and rhythmic auditory-cued (RAC) training on balance function, fall incidence, and quality of life (QOL) in individuals with PD. METHODS: Twenty participants (mean age 66.1 yrs) with idiopathic PD were randomized into either SDTT (n = 10) or RAC (n = 10) progressive, interval-based locomotor training for 6 weeks. Measures included the Berg Balance Scale (BBS), Rapid Step-Up Test (RST), Activities-specific Balance Confidence Scale, Parkinson's Disease Questionnaire-39 (PDQ), and the NeuroCom Sensory Organization Test (SOT), Motor Control Test, and Limits of Stability (LOS). Fall incidence was assessed prospectively post-training based on six monthly self-report fall calendars. RESULTS: Significant gains in balance measures were observed post-training in BBS, RST and SOT for the RAC group and in RST, SOT and LOS for the SDTT group. Gains were retained at 3 months post-training in all measures for RAC group, but only the RST for the SDTT group. No clear trend in reduction in fall frequency was evident. CONCLUSION: Externally-cued locomotor training paradigms with progressive speed challenges produced significant improvements in dynamic balance function in persons with PD, with stronger retention of gains in RAC group.

Application of high-resolution radiochromic film dosimetry in verifying a small-field stereotactic radiosurgery plan.

A high-resolution radiochromic film dosimetry (Hr-RCFD) method has been applied to verify a small-field stereotactic radiosurgery (SRS) plan. This was done by exposing a RCF in a Perspex head phantom undergoing the same treatment plan as the patient. The dose distribution obtained by the Hr-RCFD was verified against that calculated by the stereotactic treatment planning system and the result was satisfactory. The Hr-RCFD method has been found to be an accurate and practical tool in verifying small-field SRS plans.