Image-Guided Stereotactic Spine Radiosurgery on a Conventional Linear Accelerator

Stereotactic radiosurgery for spinal metastasis consists of a high radiation dose delivered to the tumor in 1 to 5 fractions. Due to the high radiation dose in a single or fewer treatments, the precision of tumor localization and dose delivery is of great concern. Many groups have published their experiences of spinal radiosurgery with the use of CyberKnife System (Accuray Inc.). In this study, we report in detail our approach to stereotactic spine radiosurgery (SSRS) using a conventional linear accelerator (Varian Trilogy), utilizing the features of kilovolt on-board imaging (kV-OBI) and cone beam computed tomography (CBCT) for image guidance. We present our experience in various aspects of the SSRS procedure, including patient simulation and immobilization, intensity-modulated radiation treatment (IMRT) planning and beam selection, portal dosimetry for patient planning quality assurance (QA), and the use of image guidance in tumor localization prior to and during treatment delivery.     

Impact on and use of an inner-city London Infectious Diseases Department by international migrants: a questionnaire survey

Background  

The UK has witnessed a considerable increase in immigration in the past decade. Migrant may face barriers to accessing appropriate health care on arrival and the current focus on screening certain migrants for tuberculosis on arrival is considered inadequate. We assessed the implications for an inner-City London Infectious Diseases Department in a high migrant area.     

Carcinoma of the maxillary antrum — A 10 year experience

A retrospective analysis was performed of 250 cases of carcinoma of the maxillary antrum seen over a 10 years period (1975–1984). 98.24% patients were seen in T3 and T4 stages (UICC 1985). 40.7% patients presented with clinically palpable nodes. 42.9% patients were treated by radical radiation and 18.6% by a combination of preoperative radiation followed by surgery. Rest 38.5% patients were treated with palliative intention. Three year disease free survival was 39.58% with radiation alone and 51.91% with combined modality treatment which includes patients salvaged by surgery. Failures were mainly at the local site, 75.86% with radiation alone and 60% with combined modality treatment. Combined modality treatment, preferably preoperative radiation followed by radical surgery, gives the best results in the management of carcinoma of the maxillary antrum. Based upon paper read at 8th Congress of Association of Radiation Oncologists of India, Bombay, December 5–8, 1986.     

An observer study for direct comparison of clinical efficacy of electronic to film portal images

: To directly compare clinical efficacy of electronic to film portal images.

: An observer study was designed to compare clinical efficacy of electronic to film portal images acquired using a liquid matrix ion-chamber electronic portal imaging device and a conventional metal screen-film system. Both images were acquired simultaneously for each treatment port and the electronic portal images were printed on gray-level thermal paper. Four radiation oncologists served as observers and evaluated a total ot 44 sets of images for four different treatment sites: lung, pelvis, brain, and head/neck. Each set of images included a simulation image, a double-exposure portal film, and video paper prints of electronic portal images. Eight to nine anatomical landmarks were selected from each treatment site. Each observer was asked to rate each landmark in terms of its clinical visibility and to rate the ease of making the pertinent verification decision in the corresponding electronic and film portal images with the aid of the simulation image.

Resultings for the vesibility of landmarks and for the verification decision of treatment ports were similar for electronic and film images for most landmarks. However, vertebral bodies and several landmarks in the pelvis suchs as the acetabulum and pubic symphsis were more visible in the portal film images than in the electronic portal images.

The visibility of landmarks in electronic portal images is comparable to that in film portal images. Verification of treatment ports based only on electronic portal images acquired using an electronic portal imaging device is generally achievable.     

Mitochondrial electron transport chain complexes in aging rat brain and lymphocytes

Several lines of evidence suggest thatmitochondria not only plays a key role in thecausation of aging, but it is also the mostadversely affected organelle during aging. Theaim of the present study was to examine therole of mitochondria in the aging process bydetermining whether the activities of various`electron transport chain' (ETC) complexes aredeleteriously affected during aging in the ratbrain and lymphocytes. The enzyme activity ofETC complexes I–V, and citrate synthase (CS)were assayed from discrete brain areas viz.,cerebral hemisphere (CH), cerebellum (CB),brain stem (BS) and diencephalon (DC), along withthe lymphocytes from four different age groups ofrats, namely, 1-month-old rats, 3–4-month-oldadults, 12-month-old adults and24-month-old aged rats. Significant decline wasobserved in all the enzyme activities in 12 and24-month-old rats as compared to 3–4-month-oldadult rats. Moreover, one-month-old ratsshowed lower levels of ETC complexes ascompared to three to four-month-old rats. Lymphocytes anddiscrete brain areas showed a parallel patternof age-related alterations in the mitochondrialETC complexes and CS. The analysis of suchalterations is important in determining theultimate basis of neuronal dysfunctionassociated with aging, and defining thenature of these changes may also help to developtherapeutic means to cure not only the elderly butalso individuals suffering from certain organicor psychiatric disorders.     

Bone morphogenetic proteins: relevance in spine surgery

Bone morphogenetic proteins (BMPs) are low molecular weight glycoproteins that play a vital role in the development and maturation of skeletal tissue. Bone morphogenetic protein-induced mesenchymal cell recruitment and differentiation leads to the formation of chondroblasts and osteoblasts leading to the formation of de novo bone. Overwhelming pre-clinical and clinical evidence has suggested a promising role for BMPs for anterior and posterolateral spinal fusion. Strength of this approach lies in the potential ability of these growth factors to reverse inhibitory conditions common in the clinical setting and enabling predictable fusion. However, several issues related to carriers, costs, and dosages still need to be consecutively addressed. Gene therapy techniques producing in vivo osteoinductive factors and utilizing minimally invasive approaches are attractive options being developed for the future.