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Background Recently, total hip arthroplasty (THA) has come to focus on restoration of individual anatomy including femoral neck anteversion and global offset (femoral and acetabular offset). Three-dimensional (3D) computed tomography (CT) data could provide a better basis for preoperative templating. The use of CT has been hampered by high radiation dose. Purpose To evaluate the effective dose used in pelvis and hip CT for THA templating. Material and Methods CT data from two clinical trials of THA were evaluated for CT scan length and volume CT dose index (CTDIvol). The effective doses from hip-knee-ankle CT and pelvis and hip radiography were compared. Conversion factors for effective dose for radiography were calculated using the PCXMC software. Results A reduced dose CT protocol for pelvis imaging gave a substantial dose reduction compared with standard CT, while maintaining sufficient image quality. Between the two clinical trials there was a significant reduction in effective CT dose corresponding to changes in the CT protocol ( P Conclusion Although the CT dose remained higher than for radiography, potential reductions in scan length could reduce the dose further so that CT would have a comparable level of risk to radiography with the added benefit of 3D templating.

Thoracic spine radiography becomes more difficult with age. Tomosynthesis is a low-dose tomographic extension of radiography which may facilitate thoracic spine evaluation. This study assessed the added value of tomosynthesis in imaging of the thoracic spine in the elderly. Four observers compared the image quality of 50 consecutive thoracic spine radiography and tomosynthesis data sets from 48 patients (median age 67 years, range 55–92 years) on a number of image quality criteria. Observer variation was determined by free-marginal multirater kappa. The conversion factor and effective dose were determined from the dose–area product values. For all observers significantly more vertebrae were seen with tomosynthesis than with radiography (mean 12.4/9.3, P

Tomosynthesis (digital tomography) is a recently introduced low-dose alternative to CT in the evaluation of the lungs in patients with cystic fibrosis and pulmonary nodules. Previous studies have reported an adult effective dose of 0.12-0.13 mSv for chest tomosynthesis. The aim of this study was to determine the paediatric effective dose from the dose-area-product. During a 3-y period, 38 children with cystic fibrosis and 36 paediatric oncology patients were examined with chest tomosynthesis, totally 169 posteroanterior and 17 anteroposterior examinations (40 boys and 34 girls, mean age 13.7 y, range 7-20 y). Using recently reported paediatric chest tomosynthesis conversion factors (0.23-1.09 mSv Gy cm(-2)) corrected for sex, age and energy, the mean posteroanterior effective dose calculated was 0.17 mSv; using the proposed simplified conversion factors of 0.6 (8-10 y), 0.4 (11-14 y) and 0.3 mSv Gy cm(-2) (15-19 y), the mean posteroanterior effective dose calculated was 0.15 mSv. As the difference in the calculated effective dose was minor, it is recommendable to use the simplified conversion factors. Using the conversion factor for adult chest tomosynthesis (0.26 mSv Gy cm(-2)), the mean effective dose was 0.11 mSv. Anteroposterior exposures had considerably higher effective dose. By using conversion factors adapted for children, the calculated risks from radiologic procedures will be more accurate.

Dose calculations with a collapsed cone algorithm implemented in a clinical treatment planning system have been studied. The algorithm has been evaluated in homogeneous as well as in heterogeneous media, and the results have been compared to measurements and Monte Carlo simulations. Commonly encountered clinical beam configurations as well as more complex geometries have been pursued to test the limitations of the model. The results show that the accuracy level reached allows for clinical use. Some situations, e.g., large wedge beams and dose calculations in the build up region, not specific to the collapsed cone model, show deviations (outside ±3%) compared to measurements. PACS number(s): 87.53.Bn, 87.53.–j, 87.66.–a

The approach in treatment planning of applying beam quality correction factors to model compensator-induced depth-hardening effects is investigated and the present work comprises a dosimetric verification of the model for a common compensator material. Lead sheet modulators for four different phantom shapes were designed using a treatment planning system based on the model. The modulators were designed to yield homogeneous dose in a plane. The calculated modulation created by the lead sheets was re-imported into the treatment planning system and applied to a water phantom geometry for verification purposes. Comparing measurements, a total of 31 different geometries were measured, with calculations in this geometry showing good agreement for depth doses, dose profiles and output data with a maximum deviation of 4% except locally in the penumbra region and close to the edges of the cut lead sheets.

The use of a transport system for out-of-treatment room set-up in external beam radiotherapy has been verified. We have looked into the vibrations which a patient is subject to during movement of the trolley as well as the accuracy achieved when using a reclining table for patient set-up and immobilization. The accuracy that can be achieved by the reclining approach is compared to conventional methods currently in use.

Purpose: To develop and evaluate a method to convert the greyscale intensity values from CBCT images acquired on an Elekta XVI into HU for treatment planning dose calculations.

Large, colorectal polyps or those that are difficult to access may be unamenable to conventional snare polypectomy and may require surgical resection. This study was designed to evaluate the resection of such lesions by the use of combined laparoscopic–endoscopic resections (CLER). Patients who had received CLER for colorectal polyps between January 1997 and December 2006 were identified from a prospectively maintained database. Patients with biopsies consistent with invasive cancer were excluded from the combined approach. Baseline characteristics, surgical, pathological, postoperative, and follow-up data of patients and lesions were reviewed. A total of 146 consecutive patients underwent CLER for 154 lesions, and 120 (82%) patients underwent local excision (i.e., laparoscopy-assisted endoscopic resection, endoscopy-assisted wedge resection, and endoscopy-assisted transluminal resection). Twenty-six (18%) patients received endoscopy-assisted segmental colon resection. Conversion rate was 5% and intraoperative complications occurred in two patients (1%). Major postoperative complications occurred in five patients (3%), necessitating surgical reintervention in four of them. Follow-up colonoscopy revealed metachronous adenomas in 33 patients, of which 8 patients showed macroscopic or microscopic characteristics of advanced lesions. One patient, who had been converted to open resection because of incomplete laparoscopic resection of an adenoma, developed relapse of the initial adenoma and was successfully treated with repeat CLER accounting for a local recurrence rate of 0.9%. Combined laparoscopic–endoscopic resection is an efficient, safe, and minimally invasive alternative to open resection for selected patients with difficult polyps, but it should be restricted to benign disease.