| 1. |
- Gunnarsson, Thorsteinn, 1967-, et al.
(author)
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Mobile computerized tomography scanning in the neurosurgery intensive care unit : increase in patient safety and reduction of staff workload
- 2000
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In: Journal of Neurosurgery. - : Journal of Neurosurgery Publishing Group (JNSPG). - 0022-3085 .- 1933-0693. ; 93:3, s. 432-436
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Journal article (peer-reviewed)abstract
- Object. Transportation of unstable neurosurgical patients involves risks that may lead to further deterioration and secondary brain injury from perturbations in physiological parameters. Mobile computerized tomography (CT) head scanning in the neurosurgery intensive care (NICU) is a new technique that minimizes the need to transport unstable patients. The authors have been using this device since June 1997 and have developed their own method of scanning such patients.Methods. The scanning procedure and radiation safety measures are described. The complications that occurred in 89 patients during transportation and conventional head CT scanning at the Department of Radiology were studied prospectively. These complications were compared with the ones that occurred during mobile CT scanning in 50 patients in the NICU. The duration of the procedures was recorded, and an estimation of the staff workload was made. Two patient groups, defined as high- and medium-risk cases, were studied. Medical and/or technical complications occurred during conventional CT scanning in 25% and 20% of the patients in the high- and medium-risk groups, respectively. During mobile CT scanning complications occurred in 4.3% of the high-risk group and 0% of the medium-risk group. Mobile CT scanning also took significantly less time, and the estimated personnel cost was reduced.Conclusions. Mobile CT scanning in the NICU is safe. It minimizes the risk of physiological deterioration and technical mishaps linked to intrahospital transport, which may aggravate secondary brain injury. The time that patients have to remain outside the controlled environment of the NICU is minimized, and the staff's workload is decreased.
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| 2. |
- Andersson, Karin M., 1989-, et al.
(author)
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Metal artefact reduction in CT imaging of hip prostheses-an evaluation of commercial techniques provided by four vendors
- 2015
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In: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 88:1052
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Journal article (peer-reviewed)abstract
- Objective: The aim of this study was to evaluate commercial metal artefact reduction (MAR) techniques in X-ray CT imaging of hip prostheses.Methods: Monoenergetic reconstructions of dual-energy CT (DECT) data and several different MAR algorithms, combined with single-energy CT or DECT, were evaluated by imaging a bilateral hip prosthesis phantom. The MAR images were compared with uncorrected images based on CT number accuracy and noise in different regions of interest.Results: The three MAR algorithms studied implied a general noise reduction (up to 67%, 74% and 77%) and an improvement in CT number accuracy, both in regions close to the prostheses and between the two prostheses. The application of monoenergetic reconstruction, without any MAR algorithm, did not decrease the noise in the regions close to the prostheses to the same extent as did the MAR algorithms and even increased the noise in the region between the prostheses.Conclusion: The MAR algorithms evaluated generally improved CT number accuracy and substantially reduced the noise in the hip prostheses phantom images, both close to the prostheses and between the two prostheses. The study showed that the monoenergetic reconstructions evaluated did not sufficiently reduce the severe metal artefact caused by large orthopaedic implants.Advances in knowledge: This study evaluates several commercially available MAR techniques in CT imaging of large orthopaedic implants.
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| 3. |
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| 4. |
- Fransson, Sven Göran, 1949-, et al.
(author)
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Patient radiation exposure during coronary angiography and intervention
- 2000
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In: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 41:2, s. 142-144
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Journal article (peer-reviewed)abstract
- Purpose: To prospectively register fluoroscopic and cine times in a random fashion, and to measure patient radiation exposure from routine coronary angiography and coronary balloon angioplasty. We also evaluated an optional dose reduction system used during interventions. Material and Methods: The incident radiation to the patient was measured as kerma area product (KAP) in Gycm2, obtained from an ionisation chamber mounted on the undercouch tube during 65 coronary angiography procedures and another 53 percutaneous transluminal coronary angioplasties (including 29 stent procedures), mostly directly following complete coronary angiography. Results and Conclusion: The values from coronary angiography were comparable to other reports with a mean fluoroscopic time of 4.4 min and a mean KAP value of 62.6 Gycm2. The corresponding figures from coronary balloon angioplasty without stenting were lower than otherwise reported, with 8.2 min and 47.9 Gycm2, respectively. The use of coronary stents did prolong the mean fluoroscopic time (10.5 min) but did not significantly enhance the patient mean radiation dose (51.4 Gycm2). The dose reduction technique resulted in a significant KAP value reduction of 57%. In conclusion, with regard to radiation exposure, coronary angiography and balloon angioplasty are considered safe procedures.
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| 5. |
- Geijer, Håkan, et al.
(author)
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Digital Radiography of Scoliosis with a Scanning Method : Initial Evaluation
- 2001
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In: Radiology. - 0033-8419 .- 1527-1315. ; 218, s. 402-410
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the radiation dose, image quality, and Cobb angle measurements obtained with a digital scanning method of scoliosis radiography.MATERIALS AND METHODS: Multiple images were reconstructed into one image at a workstation. A low-dose alternative was to use digital pulsed fluoroscopy. Dose measurements were performed with thermoluminescent dosimeters in an Alderson phantom. At the same time, kerma area-product values were recorded. A Monte Carlo dose calculation also was performed. Image quality was evaluated with a contrast-detail phantom and visual grading system. Angle measurements were evaluated with an angle phantom and measurements obtained on patient images.RESULTS: The effective radiation dose was 0.087 mSv for screen-film imaging, 0.16 mSv for digital exposure imaging, and 0.017 mSv for digital fluoroscopy; the corresponding kerma area-product values were 0.43, 0.87, and 0.097 Gy · cm2, respectively. The image quality of the digital exposure and screen-film images was about equal at visual grading, whereas fluoroscopy had lower image quality. The angle phantom had lower angle values with digital fluoroscopy, although the difference in measured angles was less than 0.5°. The patient images showed no difference in angles.CONCLUSION: The described digital scanning method has acceptable image quality and adequate accuracy in angle measurements. The radiation dose required for digital exposure imaging is higher than that required for screen-film imaging, but that required for digital fluoroscopy is much lower.
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| 6. |
- Geijer, Håkan, et al.
(author)
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Digital Radiography of Scoliosis with a Scanning Method : Radiation Dose Optimization
- 2003
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 13:3, s. 543-551
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Journal article (peer-reviewed)abstract
- The aim of this study was optimization of the radiation dose–image quality relationship for a digital scanning method of scoliosis radiography. The examination is performed as a digital multi-image translation scan that is reconstructed to a single image in a workstation. Entrance dose was recorded with thermoluminescent dosimeters placed dorsally on an Alderson phantom. At the same time, kerma area product (KAP) values were recorded. A Monte Carlo calculation of effective dose was also made. Image quality was evaluated with a contrast-detail phantom and Visual Grading. The radiation dose was reduced by lowering the image intensifier entrance dose request, adjusting pulse frequency and scan speed, and by raising tube voltage. The calculated effective dose was reduced from 0.15 to 0.05 mSv with reduction of KAP from 1.07 to 0.25 Gy cm2 and entrance dose from 0.90 to 0.21 mGy. The image quality was reduced with the Image Quality Figure going from 52 to 62 and a corresponding reduction in image quality as assessed with Visual Grading. The optimization resulted in a dose reduction to 31% of the original effective dose with an acceptable reduction in image quality considering the intended use of the images for angle measurements.
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| 7. |
- Geijer, Håkan, et al.
(author)
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Image quality vs radiation dose for a flat-panel amorphous silicon detector : a phantom study
- 2001
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 11:9, s. 1704-1709
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate the image quality for a flat-panel amorphous silicon detector at various radiation dose settings and to compare the results with storage phosphor plates and a screen-film system. A CDRAD 2.0 contrast-detail phantom was imaged with a flat-panel detector (Philips Medical Systems, Eindhoven, The Netherlands) at three different dose levels with settings for intravenous urography. The same phantom was imaged with storage phosphor plates at a simulated system speed of 200 and a screen-film system with a system speed of 160. Entrance surface doses were recorded for all images. At each setting, three images were read by four independent observers. The flat-panel detector had equal image quality at less than half the radiation dose compared with storage phosphor plates. The difference was even larger when compared with film with the flat-panel detector having equal image quality at approximately one-fifth the dose. The flat-panel detector has a very favourable combination of image quality vs radiation dose compared with storage phosphor plates and screen film.
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| 8. |
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| 9. |
- Geijer, Håkan, et al.
(author)
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Radiation dose optimization in coronary angiography and percutaneous coronary intervention (PCI) : II. Clinical evaluation
- 2002
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 12:11, s. 2813-2819
-
Journal article (peer-reviewed)abstract
- In a previous part of this study, the fluoroscopy dose rate was reduced in a cardiac catheterization laboratory. The objectives of the present study were to evaluate the effects in a clinical population undergoing percutaneous coronary intervention (PCI) of the dose-reducing measures detailed previously. Kerma area-product (KAP) values were first recorded for 154 patients undergoing PCI. Then, the fluoroscopy KAP rate was reduced from 44 to 16 mGy cm2/s by increasing filtration and reducing the image intensifier dose request. After this optimization, KAP was recorded for another 138 PCI procedures. After adjustment for differing proportions of combined procedures (coronary angiography+PCI), the total KAP was reduced to 67% of the original value with a 95% confidence interval from 57 to 78%, statistically significant. The mean total KAP values were 93.6 Gy cm2 before and 69.1 Gy cm2 after optimization. The KAP for digital acquisition did not change significantly. It is possible to make a large dose reduction in PCI by reducing the fluoroscopy dose rate. This dose reduction is beneficial for both patients and staff.
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| 10. |
- Geijer, H, et al.
(author)
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Radiation exposure and patient experience during percutaneous coronary intervention using radial and femoral artery access
- 2004
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 14:9, s. 1674-1680
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Journal article (peer-reviewed)abstract
- The aim of this study was to evaluate radiation dose and patient discomfort/pain in radial artery access vs femoral artery access in percutaneous coronary intervention (PCI). Dose-area product (DAP) was measured non-randomised for 114 procedures using femoral access and for 55 using radial access. The patients also responded to a questionnaire concerning discomfort and pain during and after the procedure. The mean DAP was 69.8 Gy cm2 using femoral access and 70.5 Gy cm2 using radial access. Separating the access site from confounding factors with a multiple regression, there was a 13% reduction in DAP when using radial access (p=0.038). Procedure times did not differ (p=0.81). Bed confinement was much longer in the femoral access group (448 vs 76 min, p=0.000). With femoral access, there was a significantly higher patient grading for chest (p=0.001) and back pain (p=0.003) during the procedure and for access site (p=0.000) and back pain (p=0.000) after the procedure. Thirty-two femoral access patients (28%) were given morphine-type analgesics in the post-procedure period compared to three radial access patients (5%, P=0.001). DAP does not increase when using radial instead of femoral access and the patients grade discomfort and pain much lower when using radial access. Radial access is thus beneficial to use.
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| 11. |
- Geijer, H, et al.
(author)
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Varied tube potential with constant effective dose at lumbar spine radiography using a flat-panel digital detector
- 2005
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In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 240-245
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Journal article (peer-reviewed)abstract
- The purpose of the study was to evaluate the image quality at different tube potential (kV) settings using anteroposterior lumbar spine radiography as a model. An Alderson phantom was used with a flat-panel detector. The tube potential varied between 48 and 125 kV while the tube charge (mAs) was adjusted to keep an effective dose of 0.11 mSv. Image quality was assessed with a visual grading analysis and with a CDRAD contrast-detail phantom together with a computer program. The VGA showed inferior image quality for the higher kV settings, ≥ 96 kV with similar results for the contrast-detail phantom. When keeping the effective dose fixed, it seems beneficial to reduce kV to get the best image quality despite the fact that the mAs is not as high as with automatic exposure. However, this cannot be done with automatic exposure, which is set for a constant detector dose.
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| 12. |
- Johansson, Bengt, 1958-, et al.
(author)
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Long term results from a uniform clinical series on pulsed dose rate brachytherapy as the boost to external beam irradiation in base of tongue cancer
-
Other publication (other academic/artistic)abstract
- Background and purpose: To evaluate the long time outcome with regard to local tumour control, side effects and quality of life of a combined pulsed dose rate (PDR) boost and hyperfractionated accelerated external beam radiotherapy (EBRT) for primary base of tongue (BOT) cancers.Patients and methods: Between 1994 and 2007 we treated 83 patients, median age 60 (38-82) years, with primary T1-T4 BOT cancers. Seven patients (8 %) were T1-2N0 (AJCC stage I-II) and 76 (92 %) patients were T1-2N+ or T3-4N0-3 (AJCC stage III-IV). The mean estimated primary tumour volume was 15 (1-75) cm3. EBRT was given with 1.7 Gy twice daily to 40,8 Gy to primary tumour and bilateral neck lymph nodes in 2.5 weeks. A PDR boost of 35 Gy and a neck dissection in clinical node positive cases was performed 2-3 weeks later. The patients were followed for a median of 54 (2-168) months.Results: The 2-, 5- and 10-years rates of actuarial local control were 91 %, 89 % and 85 %, overall survival 85 %, 65 % and 44 %, disease free survival 86 %, 80 % and 76 % respectively. The regional contral rate was 95 %. Six patients (7 %) developed distant metastases. Analysis of dosimetry showed a mean treated volume of 58 cm3. In a review of late complications we found 11 (13 %) minor and 4 (5 %) major soft tissue necroses and 6 (7 %) osteoradionecroses. The patients median subjective SOMA/LENT scoring at last follow up was; grade 0 for pain and trismus, grade 1 for dysphagia and taste alteration and grade 2 for xerostomia. Global visual-analog-scale (VAS) scoring of quality of life was 8.Conclusions: Local and regional tumour control rate was excellent in this treatment protocol. The data support that PDR boost is at least as effective as published continuous low dose rate (CLDR) results.
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| 13. |
- Johansson, Bengt, 1958-, et al.
(author)
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Long term results of PDR brachytherapy for lip cancer
- 2011
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In: Journal of Contemporary Brachytherapy. - : Termedia Publishing House. - 1689-832X .- 2081-2841. ; 3:2, s. 65-69
-
Journal article (peer-reviewed)abstract
- Purpose: To evaluate the long time outcome with regard to local tumour control and side effects of a pulsed dose rate (PDR) monobrachytherapy of primary or recurrent cancer of the lip.Material and methods: Between 1995 and 2007 we treated 43 patients with primary or recurrent clinical T1-T3N0 lip cancers. There were 22 T1 patients (51%), 16 T2 (37%) and 5 T3 cases (12%). A median dose of 60 (55-66) Gy was given, depending on the tumour volume. The PDR treatment was delivered with 0.83 Gy/pulse every second hour for 5.5-6.5 days. The patients were followed for a median of 55 (1-158) months.Results: The 2-, 5- and 10-year rates of actuarial local control were 97.6%, 94.5% and 94.5%, overall survival 88.0%, 58.9% and 39.1%, disease free survival 92.7%, 86.4% and 86.4% respectively. The regional control rate was 93%. One patient (2%) developed distant metastases. A dosimetrical analysis showed a mean treated volume of 14.9 (3.0-56.2) cm(3). Long-term side effects were mild and the cosmetic outcome excellent, except for 1 case (2%) of soft tissue necrosis and 1 case (2%) of osteoradionecrosis.Conclusions: Local outcome is excellent and similar to other published studies of continuous low dose rate (cLDR) brachytherapy.
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| 14. |
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| 15. |
- Johansson, Bengt, 1958-, et al.
(author)
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Phantom study of radiation doses outside the target volume brachytherapy versus external radiotherapy of early breast cancer
- 2003
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In: Radiotherapy and Oncology. - Amsterdam : Elsevier. - 1879-0887 .- 0167-8140. ; 69:1, s. 107-112
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Journal article (peer-reviewed)abstract
- Background and purpose: Brachytherapy is sometimes suggested as an adjuvant treatment after surgery of some tumours. When introducing this, it would be useful to have an estimate of the dose distribution to different body sites, both near and distant to target, comparing conventional external irradiation to brachytherapy. The aim of the present study was to determine radiation doses with both methods at different body sites, near and distant to target, in an experimental situation on an operated left sided breast cancer on a female Alderson phantom. Methods: Five external beam treatments with isocentric tangential fields were given by a linear accelerator. A specified dose of 1.0 Gy was given to the whole left sided breast volume. Five interstitial brachytherapy treatments were given to the upper, lateral quadrant of the left breast by a two plane, 10 needles implant. A dose of 1.0 Gy specified according to the Paris system was administered by a pulsed dose rate afterloading machine. Absorbed dose in different fixed dose points were measured by thermoluminescence dosimeters. Results: Both methods yielded an absorbed dose of the same size to the bone marrow and internal organs distant to target, 1.0-1.4% of the prescribed dose. There was a trend of lower doses to the lower half of the trunk and higher doses to the upper half of the trunk, respectively, by brachytherapy. A 90% reduction of absorbed dose with brachytherapy compared to external irradiation was found in the near-target region within 5 cm from target boundary where parts of the left lung and the heart are situated. If an adjuvant dose of 50 Gy is given with the external radiotherapy and brachytherapy, the absorbed dose in a part of the myocardium could be reduced from 31.8 to 2.1 Gy. Conclusions: Near target, brachytherapy yielded a considerably lower absorbed dose which is of special importance when considering radiation effects on the myocard and lungs. We could not demonstrate any difference of importance, in absorbed dose to dose points distant to target. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
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| 16. |
- Johansson, Bengt, 1958-, et al.
(author)
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Pulsed dose rate brachytherapy as the boost in combination with external beam irradiation in base of tongue cancer : Long-term results from a uniform clinical series
- 2011
-
In: Journal of Contemporary Brachytherapy. - Poznan, Poland : Termedia Publishing House. - 1689-832X .- 2081-2841. ; 3:1, s. 11-17
-
Journal article (peer-reviewed)abstract
- Purpose: To evaluate long time outcome with regard to local tumour control, side effects and quality of life of combined pulsed dose rate (PDR) boost and hyperfractionated accelerated external beam radiotherapy (EBRT) for primary base of tongue (BOT) cancers.Material and methods: Between 1994 and 2007, the number of 83 patients were treated with primary T1-T4 BOT cancers. Seven patients (8%) were T1-2N0 (AJCC stage I-II) and 76 (92%) patients were T1-2N+ or T3-4N0-2 (AJCC stage III-IV). The mean estimated primary tumour volume was 15.4 (1-75) cm(3). EBRT was given with 1.7 Gy bid to 40.8 Gy to primary tumour and bilateral neck lymph nodes in 2.5 weeks. PDR boost of 35 Gy and a neck dissection in clinical node positive case was performed 2-3 weeks later. The patients were followed for a median of 54 (2-168) months.Results: The 2-, 5- and 10-years rates of actuarial local control were 91%, 89% and 85%, overall survival 85%, 65% and 44%, disease free survival 86%, 80% and 76%, respectively. The regional control rate was 95%. Six patients (7%) developed distant metastases. A dosimetric analysis showed a mean of 100% isodose volume of 58.2 (16.7-134) cm(3). In a review of late complications 11 cases of minor (13%) and 5 of major soft tissue necroses (6%), as well as 6 cases of osteoradionecroses (7%) were found. The patients median subjective SOMA/LENT scoring at last follow up was as follow: grade 0 for pain and trismus, grade 1 for dysphagia and taste alteration, and grade 2 for xerostomia. Global visual-analogue-scale (VAS) scoring of quality of life was 8.Conclusion: Local and regional tumour control rate was excellent in this treatment protocol. The data shows the PDR boost as at least as effective as published continuous low dose rate (CLDR) results.
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| 17. |
- Johansson, Bengt, 1958-, et al.
(author)
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Pulsed dose rate brachytherapy as the sole adjuvant radiotherapy after breast-conserving surgery of T1-T2 breast cancer : first long time results from a clinical study
- 2009
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In: Radiotherapy and Oncology. - Amsterdam : Elsevier. - 0167-8140 .- 1879-0887. ; 90:1, s. 30-35
-
Journal article (peer-reviewed)abstract
- BACKGROUND AND PURPOSE: To evaluate the long time outcome with regard to local tumour control, cosmetic outcome and side effects of a short (5 days) accelerated interstitial brachytherapy treatment delivered to the surroundings of the operated sector. PATIENTS AND METHODS: Between 1993 and 2003 we treated 50 women with early T1 and T2 breast cancer. Radical sector resection was performed and followed later with an interstitial pulsed dose rate (PDR) brachytherapy of 50Gy in 5 days. The treatment was centred on the tumour with a margin of 30mm. One patient was treated bilaterally. The patients were followed for a median of 86 (32-126) months. RESULTS: Ipsilateral breast cancer recurrence was seen in 3 patients (6%). Two of them occurred outside the treated volume. The 5- and 7-year rates of actuarial local control were 96% and 96%, respectively, overall survival 88% and 85%, disease free survival 88% and 88%, respectively. A dosimetrical analysis showed that the partial breast irradiation covered a median of 31% of the total breast volume. Fat necrosis was seen in 12% and local (moderate-strong) fibrosis in 26% of the patients. Independent cosmetic scoring showed good or excellent result in 56% of the patients. CONCLUSIONS: Local outcome is favourable and very similar to other published studies of accelerated partial breast irradiation. Our long time cosmetic results are lower than other published results.
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| 18. |
- Johansson, Bengt, 1958-, et al.
(author)
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Pulsed dose rate monobrachytherapy for cancer of the lip : first long time results from a clinical study
-
Other publication (other academic/artistic)abstract
- Background and purpose: To evaluate the long time outcome with regard to local tumour control and side effects of a pulsed dose rate (PDR) monobrachytherapy of primary or recurrent cancr of the lip.Patients and methods: Between 1995 and 2007 we treated 43 patients with primary or recurrent T1-T3 lip cancers. The clinical stage was T1N0 for 22 patients (51 %), T2N0 for 16 patients (37 %) and T3N0 for 5 patients (12 %). A median dose of 60 (55-66) Gy was given, depending on the tumour volume. The PDR treatment was given with 0.83 Gy/pulse every second hour for 5.5-6.5 days. The patients were followed for a median of 55 (1-158) months.Results: The 2-, 5- and 10-years rates of actuarial local control were 97.6 %, 94.5 % and 94.5 %, overall survival 88.0 %, 58.9 % and 39.1 %, disease free survival 92.7 %, 86.4 % and 86.4 % respectively. The regional control rate was 93 %. One patient (2 %) developed distant metastases. A dosimetrical analysis showed a mean treated volume of 14.9 (3.0-56.2) cm3. In a review of late complications we found 1 (2 %) soft tissue necrosis and 1 (2 %) osteoradionecrosis. Long-term side effects were very mild and the cosmetic outcome excellent.Conclusions: Local outcome is excellent and very similar to other published studies of continuous low dose rate (cLDR) brachytherapy.
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| 19. |
- Karlsson, Leif, et al.
(author)
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3D image-based adapted high-dose-rate brachytherapy in cervical cancer with and without interstitial needles : measurement of applicator shift between imaging and dose delivery
- 2017
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In: Journal of Contemporary Brachytherapy. - : Termedia Publishing House. - 1689-832X .- 2081-2841. ; 9:1, s. 52-58
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Journal article (peer-reviewed)abstract
- Purpose: Using 3D image-guided adaptive brachytherapy for cervical cancer treatment, it often means that patients are transported and moved during the treatment procedure. The purpose of this study was to determine the intra-fractional longitudinal applicator shift in relation to the high risk clinical target volume (HR-CTV) by comparing geometries at imaging and dose delivery for patients with and without needles.Material and methods: Measurements were performed in 33 patients (71 fractions), where 25 fractions were without and 46 were with interstitial needles. Gold markers were placed in the lower part of the cervix as a surrogate for HR-CTV, enabling distance measurements between HR-CTV and the ring applicator. Shifts of the applicator relative to the markers were determined using planning computed tomography (CT) images used for planning, and the radiographs obtained at dose delivery. Differences in the physical D-90 for HR-CTV due to applicator shifts were simulated individually in the treatment planning system to provide the relative dose variation.Results: The maximum distances of the applicator shifts, in relation to the markers, were 3.6 mm (caudal), and-2.5 mm (cranial). There was a significant displacement of-0.7 mm (SD = 0.9 mm) without needles, while with needles there was no significant shift. The relative dose variation showed a significant increase in D-90 HR-CTV of 1.6% (SD = 2.6%) when not using needles, and no significant dose variation was found when using needles.Conclusions: The results from this study showed that there was a small longitudinal displacement of the ring applicator and a significant difference in displacement between using interstitial needles or not.
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| 20. |
- Karlsson, Leif, 1954-, et al.
(author)
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The impact of activating source dwell positions outside the CTV on the dose to treated normal tissue volumes in TRUS guided 3D conformal interstitial HDR brachytherapy of prostate cancer
- 2014
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In: Journal of Contemporary Brachytherapy. - : Termedia Publishing House. - 1689-832X .- 2081-2841. ; 6:3, s. 282-288
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Journal article (peer-reviewed)abstract
- Purpose: Dose coverage is crucial for successful treatment in mono-brachytherapy. Since few and very high dose fractions are used, there is an important balance between dwell positioning outside the clinical target volume (CTV) and possible damage on adjacent normal tissue. The purpose of this study was to evaluate the possibility of having dwell positions close to the CTV surface, while maintaining an acceptable dose distribution, and to investigate the robustness in terms of known geometrical uncertainties of the implant.Material and methods: This study included 37 patients who had received brachytherapy for prostate cancer as a monotherapy with the following schedules: 2 x 14 Gy or 3 x 11 Gy, each fraction separated by two weeks. The source dwell positions were activated 5 mm outside CTV. New optimizations were simulated for dwell positions at 3, 2, 1, and 0 mm. Inverse and graphical optimization were applied according to the relative dose constraints: V-100 CTV >= 97%, D-max,D- urethra <= 110%, and D-10 rectal mucosa <= 65%. The V-100 normal tissue outside CTV was used to evaluate dose variations caused by different dwell positions. Prostate geometries and dose distributions for the different dwell positions outside the CTV were used to investigate the impact on the CTV dose distribution due to geometrical uncertainties.Results: Both V-100,V- CTV, and V-100,V- normal tissue decreased, 98.6% to 92.2%, and 17 cm(3) to 9.0 cm(3), for dwell activation from 5 rum to 0 mm. The evaluation of both simulated longitudinal geometrical uncertainties and different source dwell activations implied that V-100,V- CTV ranged from 98.6% to 86.3%.Conclusions: It is possible to reduce the V-100,V- normal tissue by decreasing the source dwell positions outside the CTV from 5 to 3 mm, while maintaining dose constraints. In combination with the estimated geometrical uncertainties, however, the source dwell positions need to be 5 mm from the surface in order to maintain a robust implant.
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| 21. |
- Messner, Karola, 1956-, et al.
(author)
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Radiographic joint space narrowing and histologic changes in a rabbit meniscectomy model of early knee osteoarthrosis
- 2001
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In: American Journal of Sports Medicine. - 0363-5465 .- 1552-3365. ; 29:2, s. 151-160
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Journal article (peer-reviewed)abstract
- The purpose of this study was to compare weightbearing radiographs with histologic cartilage evaluation in a rabbit meniscectomy model of the early stage of osteoarthrosis. Fifteen rabbits had a medial meniscectomy performed in one knee and a sham operation in the other knee. Five rabbits each were sacrificed at 13, 25, and 40 weeks after surgery. Radiographic joint space width and histologic cartilage changes of the medial knee compartment were quantified. Five nonoperated knees and five knees in which the meniscus had been removed immediately before the evaluations served as control specimens. Overall, the joint space of the peripheral part of the medial knee compartment was narrower in knees operated on for meniscus removal than in sham-operated knees (P < 0.003). In the knees with the meniscus removed, more cartilage changes were seen at the joint surface area of contact on radiographs than in the sham-operated knees (P < 0.0015). Indeed, the area of contact had cartilage changes similar to those in the whole medial compartment. However, there was no correlation between the degree of histologic cartilage change and the corresponding joint space measurements. Joint space width as measured on weightbearing radiographs is reduced after meniscectomy in the rabbit, but it does not reflect the degree of cartilage damage of the loaded joint surfaces in early stages of osteoarthrosis.
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| 22. |
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| 23. |
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| 24. |
- Persliden, Jan, 1950-
(author)
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Patient and staff doses in interventional X-ray procedures in Sweden
- 2005
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In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 150-157
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Journal article (peer-reviewed)abstract
- Interventional procedures in radiology are of concern because of irradiation doses to the patients and also to the staff. A questionnaire sent to all radiology departments in Sweden showed that 11,350 procedures were performed annually 1996-1997. In a follow-up study, data from patient procedures were recorded. Type of procedure, dose-area product (DAP) values, fluoroscopy times, number of radiography series and patient data were recorded. For some procedures, staff doses were measured. Skin doses to the patients were also calculated where possible. Results: A total of 380 interventional procedures were described. The procedures were grouped into cranial, neck and thorax, intestine and abdominal, uro/genital and pelvis and extremities. DAP and fluoroscopy times (mean values) were 200 Gy cm2 for 57 min, 57 Gy cm2 for 16 min, 270 Gy cm2 for 35 min, 212 Gy cm2 for 37 min, 67 Gy cm2 for 21 min, respectively, for the named procedures. Maximum patient skin doses exceeded threshold values for erythema (2 Gy) in cranial, neck/thorax and intestine/abdominal procedures. Effective doses to the patients could be high, 200 mSv. Conclusion: It was found that patient doses could exceed threshold values for skin erythema (2 Gy) and temporary epilation (3 Gy). Hence, the procedures require immediate improvement. © The Author 2005. Published by Oxford University Press. All rights reserved.
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- Sandborg, Michael, 1961-, et al.
(author)
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A voxel phantom based Monte Carlo computer program for optimisation of chest and lumbar spine X ray imaging systems
- 2000
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In: Radiation Protection Dosimetry. - 0144-8420 .- 1742-3406. ; 90:1-2, s. 105-108
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Journal article (peer-reviewed)abstract
- A Monte Carlo computer model of X ray imaging systems has been developed which uses a voxel phantom to simulate the patient. Image details were selected in accordance with the European quality criteria document. Contrast and signal-to-noise ratio for these details were calculated to estimate image quality. Effective dose was computed to enable optimisation. The program was validated with measurements on phantoms, patients and digitised patient images. It was demonstrated that the computational model of the imaging system provides predictions of entrance dose and contrast that lie within the range of values measured on patients. To illustrate the importance of using a realistic model of the patient, scatter-to-primary ratios, S/P, in a chest PA examination were calculated. It was found that the S/P varied by a factor of 10 in the image and that a grid was slightly more efficient than an air gap in removing the scatter behind the heart.
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