<p>Purpose: The aim of this thesis is to study the European (ESTRO/EAU/EORTC) and American (ABS) guidelines how to report the permanent seed implant and the most significant dosimetric parameters. It will also report on the permanent seed implant at Södersjukhuset, Karolinska University Hospital according to the guidelines. A large number of studies on pre- and post-implant dosimetry on permanent seed implants have recently been published but none is considered a standard. This makes it difficult, if not impossible, to compare data from different centres. The differences in reporting will also be discussed in this thesis. Another part of the study is to investigate how the morbidity correlates with the dose. The results in this report will give an overview of the experience at Södersjukhuset.</p><p>Matherials and Methods: This study includes 198 patients who received implants between 2004-2007 with I-125 seeds under transperineal ultrasound at Södersjukhuset (to a prescribed dose of 145 Gy). The dose-planning system VariSeed 7.1 was used with an online connection to the ultrasound system with real-time verification. Dose constraints for the planning system are V(100)>99%, V(150)>60%, V(200)>25%, UrD(10)<130% and UrD(30)<125%. Outer and inner wall of rectum was outlined for 55 patients as recommended by ESTRO/EAU/EORTC and doses to rectum were also computed.</p><p>Results: The median value for dosimetric parameters at Södersjukhuset, Karolinska University Hospital are for the prostate; D(90)=174Gy (153-194Gy), V(100)= 99% (93-100%), V(150)= 57% (40-74%), for the urethra; UrD(30) = 130% (112-147%), UrD(10) = 124% (107-142%) and for the rectum; RD2cc= 98Gy (73-128Gy), RD0.1cc=164Gy (119-240Gy), RV(100)=0.3cc (0.0-1.3cc), RV(150)=0.0cc (0.0-0.2cc). These values correspond to recommended data, except for the V(150) value. Regarding the clinically observed results, 3 patients had a relapse in their cancer, 2 patients had mild proctitis and 15 patients had urinary problems.</p><p>Discussion and Conclusions: The significant dosimetric parameters for reporting according to ESTRO/EAU/EORTC and ABS for prostate are D90[Gy], V(100)[%] and V(150)[%], for urethra are D(30) and D(10), and for rectum RD2cc and RD0.1cc. These parameters consider as a minimum to use and they further recommend secondary parameters to report. Other authors have also recommended to report RV(100) and RV(150) for rectum. This study did not show any relationship between UrD(10), UrD(30) and urinary morbidity. According to the recommendations every patient should undergo a CT-based evaluation. Further investigations are needed on whether a post-implant CT-study is necessary for real-time implantation, as there is not enough published data on this aspect.</p>

<p>One of the most used irradiation techniques in modern radiation therapy is step-and-shoot IMRT. The accuracy of this technique when delivering complex dose distributions strongly depends on the size of the subfields. The aims of this study is to determine the minimum size of subfields that can be used efficiently in Step-and-Shoot IMRT, to investigate the validation process for beam delivery and treatment planning dose calculations, and to find recommendations for practical clinical implementations.</p><p>Two different detectors, a CC04 ion chamber and a SFD stereotactic diode, have been used for measuring head scatter factors in air (Sc), total output factors (Scp) and dose profiles in water for a wide range of field sizes. The measurements were compared to calculations done with a pre-release version of the Nucletron MasterPlanTM v 3.1 treatment planning system that employs a novel, high resolution fluence modelling for both its pencil beam and collapsed cone dose calculation algorithms. Collimator settings were explicitly checked using FWHM film measurements with a build-up sheet of tungsten placed close to the treatment head to reduce the influence from lateral electron transport and geometrical penumbra. An analysis of the influence and sensitivity of Scp for small fields with respect to the linear accelerator source size and shape was also made.</p><p>The measurements with the ionization chamber and the stereotactic diode showed good agreements with each other and with the treatment planning system calculations for field sizes larger than 2×2 cm2. For small field sizes, measurements with different detectors yielded different results. Calculations showed agreements with measurements with the smallest detector, provided careful field size calibration and commissioning of calculation parameters. Uncertainties in collimator settings and source characteristics were shown to yield large uncertainties in Scp for fields smaller than 2×2 cm2.</p><p>The treatment planning system was found to properly handle small subfields but results were very sensitive to uncertainties in source size, as well as calibration and reproducibility of the collimator settings. Therefore if subfields smaller than 2×2 cm2 are to be used in IMRT extra care should be taken to determine the source characteristics and to calibrate the collimators. The volume of the detectors used for validation of such small fields and the loss of charged particle equilibrium conditions also have to be taken into consideration.</p>

<p>Patient dose in diagnostic radiology is usually expressed in terms of organ dose and effective dose. The latter is used as a measure of the stochastic risk. Determinations of these doses are obtained by measurements (Thermoluminescent dosemeters) or by calculations (Monte Carlo simulation).</p><p>Conversion factors for the calculation of effective dose from dose-area product (DAP) values are commonly used to determine radiation dose in conventional x-ray imaging to realize radiation risks for different investigations, and for different ages. The exposure can easily be estimated by converting the DAP into an effective dose.</p><p>The aim of this study is to determine the conversion factor in procedures by computing the ratio between effective dose and DAP for fluoroscopic cardiac procedures in adults and for conventional lung and urography examinations in children.</p><p>Thermoluminescent dosemeters (TLD) were placed in an anthropomorphic phantom (Alderson Rando phantom) and child phantom (one year old) in order to measure the organ dose and compute the effective dose. A DAP meter was used to measure dose-area product.</p><p>MC calculations of radiation transport in mathematical anthropomorphic phantoms were used to obtain the effective dose for the same conditions with DAP as input data.</p><p>The deviation between the measured and calculated data was less than 10 %. The conversion factor for cardiac procedures varies between 0.19 mSvGy-1 cm-2 and 0.18 mSvGy-1 cm-2, for TLD respective MC. For paediatric simulation of a one year old phantom the average conversion factor for urography was 1.34 mSvGy-1 cm-2 and 1,48 mSvGy-1cm-2 for TLD respective MC. This conversion factor will decrease to 1.07 mSvGy-1 cm-2 using the TLD method, if the new ICRP (ICRP Publication 103) weighting factors were used to calculate the effective dose.</p><p>For lung investigations, the conversion factor for children was 1.75 mSvGy-1 cm-2 using TLD, while this value was 1.62 mSvGy-1 cm-2 using MC simulation. The conversion value increased to 2.02 mSvGy-1 cm-2 using ICRP’s new recommendation for tissue weighting factors and child phantom.</p>

<p>The purpose of this work was to: a) Determine whether the amount of colour in a power Doppler image is dependent on the angle between the examined vessel and the soundbeam and/or on the velocity of the flow within the vessel; b) Investigate if a dependency on flow velocity could be used for the detection of volume flow differences and c) Define clinical applications utilising the improved sensitivity to low flow of PD.</p><p>In the experimental studies (study I and II) a silicon tube in a water bath was insonated, the insonation angle and the volume flow changed and the resulting images stored, transferred to a personal computer and analysed with regard to the amount of colour present in the image.</p><p>In study III and IV the ability of power Doppler to depict low flow was used to produce a map of the perfusion in well perfused organs, lack of colour in all or part of an organ taken as a sign of decreased perfusion. 150 patients with a renal transplant (study III) and 15 patients with abdominal trauma (study IV) were examined; the detected areas of decreased perfusion were correlated to other imaging modalities, laboratory and clinical records in order to determine the underlying pathology.</p><p>In study V the power Doppler sensitivity was used to look for and describe small portosystemic shunts in 141 patients with liver cirrhoses and suspected portal hypertension.</p><p>The colour representation in a power Doppler image was found to be dependent both on the insonation angle and the flow velocity. Computer analysis of the images could detect differences in volume flow down to a change of 10 ml/min.</p><p>Of the 150 renal transplants, areas of decreased perfusion were found in 12, all of which could be given a plausible explanation (2 focal infections, 4 AV fistulae, 1 kinked segmental artery and 5 with problems related to an accessory artery).</p><p>Of the 20 organs (7 livers and 13 spleens) examined in the 15 trauma patients, 5 were found to have areas without colour, corresponding to localised haematomas. Using computed tomography as gold standard, ultrasound showed neither false positive nor false negative findings.</p><p>Of the 141 patients with cirrhosis, 40 had Doppler ultrasound findings of a shunt, consistent with a portal hypertension. 7 of these 40 shunts showed a typical “ball ” or “corkscrew ” pattern.</p><p>Conclusion: The colour in a power Doppler image is dependent not only on reflector concentration (as it should be in theory) but also on the insonation angle and the velocity of the flow. This can be used to detect relative changes in volume flow. Clinical applications of power Doppler include mapping of organ perfusion and the detection of small vessels. These applications are based on the high sensitivity of power Doppler.</p>

<p>Percutaneous nephrostomy (PCN) is a well-established intervention performed to divert urine from the collecting system in ureteric obstruction or as a prelude to interventional procedures such as stent placement or percutaneous nephrolithotripsy (PCNL). The aim of this thesis is to enhance planning for an optimal insertion of PCN, investigate complications, long-term management, follow-up and outcome in patients with PCN treatment and to increase accuracy in CT-guided punctures.</p><p>To enhance planning for an optimal insertion of PCN prior to PCNL, biomodels from CT data were performed. Eight patients with complex urinary calculi were selected. Multislice CT of the kidney was performed and the CT data were transformed into a biomodel. The biomodels visualised unique structures before surgery, which aided the planning of endourological procedures.</p><p>PCNL is an essential procedure for treating complex urinary calculi. A subcostal approach is preferred to avoid laceration to the lung and pleura. However, a supracostal approach is often preferable, as it gives a better passage to the renal pelvis. The nature and frequency of complications after supra- versus subcostal punctures were studied in 85 patients treated with PCNL. In 63 patients, a subcostal track was established. In 22, a supracostal puncture was chosen. The main difference in preoperative complications was the higher number of patients in the supracostal group complaining of respiratory correlated pain (32%). In the subcostal group, this was (5%). </p><p>401 patients were reviewed retrospectively regarding underlying disease, subsequent management and complications of PCN treatment. The number of major complications was 4%. Minor complications were recorded in 38%, urinary tract infection being the most common. 151/401patients suffered from malignancy. 84/151 of the malignant patients died with the catheter. The median survival time of the patients with malignancies was 255 days and the median catheterisation time was 62 days. </p><p>In order to increase accuracy when performing CT guided punctures, a new puncture guide was evaluated. In 15/17 patients the puncture was successful on the first attempt. The benefits of the puncture guide were the artefact from the needle guide pointing at the target indicating the puncture path and the needle support enhancing an accurate puncture.</p>

<p>The purpose of this thesis was to investigate the utility of the Ultrasmall Superparamagnetic Iron Oxide Particle (USPIO), NC100150 Injection for assessment of macro- and microvascular morphology and function using magnetic resonance imaging. The feasibility of NC100150 Injection was tested for the following applications: Coronary angiography, Thrombus detection, Cardiac function, Myocardial perfusion, Assessment of myocardial blood volume and water exchange and finally assessment of endothelial integrity of the myocardium.</p><p>The test method included computer simulations, in vitro, animal and clinical experiments. The computer simulations included propagation of longitudinal magnetization in non-steady state acquisitions. Animal models used were coronary artery stenosis in pigs, thrombus formation in the jugular vein in pigs, normal pig myocardium and transplanted hearts in rats. A human study of patients with suspected coronary artery disease was also performed.</p><p>The results showed that angiography using an USPIO is less efficient in the coronary arteries than in the peripheral arteries. Direct targeting to thrombus using an USPIO is possible but will be limited by the spatial resolution. An USPIO will enhance gradient echo imaging of cardiac function. T2-weighted myocardial perfusion imaging is feasible as well as assessment of myocardial blood volume and endothelial integrity.</p><p>Due to physiological limitations and technical development the utility of NC100150 Injection for assessment of the macrovascular morphology is limited.However for the assessment of microvascular function, especially perfusion and permeability, NC100150 Injection may contribute to a successful implementation of these methods.</p>

Investigations of radon in natural water and its relation to physical and chemical parameters are outlined in this thesis. In particular, a method for measuring 222Rn in water at low concentrations (~20 mBq.l-1) is described, followed by discussions concerning the design and its application to study both radon and parameters influencing radon levels in natural waters. A topic considered is the impact of fluoride and other aquatic parameters on radon in water. Moreover, variables such as uranium series radionuclides and stable elements in water, bedrock and sediment radioactivity and geology are investigated in two case studies. This was performed by employing radiometric-, chemical-, statistical- and GIS &amp; geostatistical- analyses. The general water chemistry and presence of some elements such as fluoride was observed to influence radon levels in water. Health aspects of radon in drinking water are discussed based on radiation dose assessments. The radiation doses are compared with and added to doses incurred from ingestion of uranium, radium and polonium isotopes in drinking water and inhalation of radon in air in order to estimate total exposures for different age categories. The results may have a potential for future epidemiological studies.

The purpose of this work was to: a) Determine whether the amount of colour in a power Doppler image is dependent on the angle between the examined vessel and the soundbeam and/or on the velocity of the flow within the vessel; b) Investigate if a dependency on flow velocity could be used for the detection of volume flow differences and c) Define clinical applications utilising the improved sensitivity to low flow of PD. In the experimental studies (study I and II) a silicon tube in a water bath was insonated, the insonation angle and the volume flow changed and the resulting images stored, transferred to a personal computer and analysed with regard to the amount of colour present in the image. In study III and IV the ability of power Doppler to depict low flow was used to produce a map of the perfusion in well perfused organs, lack of colour in all or part of an organ taken as a sign of decreased perfusion. 150 patients with a renal transplant (study III) and 15 patients with abdominal trauma (study IV) were examined; the detected areas of decreased perfusion were correlated to other imaging modalities, laboratory and clinical records in order to determine the underlying pathology. In study V the power Doppler sensitivity was used to look for and describe small portosystemic shunts in 141 patients with liver cirrhoses and suspected portal hypertension. The colour representation in a power Doppler image was found to be dependent both on the insonation angle and the flow velocity. Computer analysis of the images could detect differences in volume flow down to a change of 10 ml/min. Of the 150 renal transplants, areas of decreased perfusion were found in 12, all of which could be given a plausible explanation (2 focal infections, 4 AV fistulae, 1 kinked segmental artery and 5 with problems related to an accessory artery). Of the 20 organs (7 livers and 13 spleens) examined in the 15 trauma patients, 5 were found to have areas without colour, corresponding to localised haematomas. Using computed tomography as gold standard, ultrasound showed neither false positive nor false negative findings. Of the 141 patients with cirrhosis, 40 had Doppler ultrasound findings of a shunt, consistent with a portal hypertension. 7 of these 40 shunts showed a typical “ball ” or “corkscrew ” pattern. Conclusion: The colour in a power Doppler image is dependent not only on reflector concentration (as it should be in theory) but also on the insonation angle and the velocity of the flow. This can be used to detect relative changes in volume flow. Clinical applications of power Doppler include mapping of organ perfusion and the detection of small vessels. These applications are based on the high sensitivity of power Doppler.

Percutaneous nephrostomy (PCN) is a well-established intervention performed to divert urine from the collecting system in ureteric obstruction or as a prelude to interventional procedures such as stent placement or percutaneous nephrolithotripsy (PCNL). The aim of this thesis is to enhance planning for an optimal insertion of PCN, investigate complications, long-term management, follow-up and outcome in patients with PCN treatment and to increase accuracy in CT-guided punctures. To enhance planning for an optimal insertion of PCN prior to PCNL, biomodels from CT data were performed. Eight patients with complex urinary calculi were selected. Multislice CT of the kidney was performed and the CT data were transformed into a biomodel. The biomodels visualised unique structures before surgery, which aided the planning of endourological procedures. PCNL is an essential procedure for treating complex urinary calculi. A subcostal approach is preferred to avoid laceration to the lung and pleura. However, a supracostal approach is often preferable, as it gives a better passage to the renal pelvis. The nature and frequency of complications after supra- versus subcostal punctures were studied in 85 patients treated with PCNL. In 63 patients, a subcostal track was established. In 22, a supracostal puncture was chosen. The main difference in preoperative complications was the higher number of patients in the supracostal group complaining of respiratory correlated pain (32%). In the subcostal group, this was (5%). 401 patients were reviewed retrospectively regarding underlying disease, subsequent management and complications of PCN treatment. The number of major complications was 4%. Minor complications were recorded in 38%, urinary tract infection being the most common. 151/401patients suffered from malignancy. 84/151 of the malignant patients died with the catheter. The median survival time of the patients with malignancies was 255 days and the median catheterisation time was 62 days. In order to increase accuracy when performing CT guided punctures, a new puncture guide was evaluated. In 15/17 patients the puncture was successful on the first attempt. The benefits of the puncture guide were the artefact from the needle guide pointing at the target indicating the puncture path and the needle support enhancing an accurate puncture.

The purpose of this thesis was to investigate the utility of the Ultrasmall Superparamagnetic Iron Oxide Particle (USPIO), NC100150 Injection for assessment of macro- and microvascular morphology and function using magnetic resonance imaging. The feasibility of NC100150 Injection was tested for the following applications: Coronary angiography, Thrombus detection, Cardiac function, Myocardial perfusion, Assessment of myocardial blood volume and water exchange and finally assessment of endothelial integrity of the myocardium. The test method included computer simulations, in vitro, animal and clinical experiments. The computer simulations included propagation of longitudinal magnetization in non-steady state acquisitions. Animal models used were coronary artery stenosis in pigs, thrombus formation in the jugular vein in pigs, normal pig myocardium and transplanted hearts in rats. A human study of patients with suspected coronary artery disease was also performed. The results showed that angiography using an USPIO is less efficient in the coronary arteries than in the peripheral arteries. Direct targeting to thrombus using an USPIO is possible but will be limited by the spatial resolution. An USPIO will enhance gradient echo imaging of cardiac function. T2-weighted myocardial perfusion imaging is feasible as well as assessment of myocardial blood volume and endothelial integrity. Due to physiological limitations and technical development the utility of NC100150 Injection for assessment of the macrovascular morphology is limited.However for the assessment of microvascular function, especially perfusion and permeability, NC100150 Injection may contribute to a successful implementation of these methods.