Proton radiography with a commercial range telescope detector using dedicated post processing methods.

Proton transmission imaging uses protons with high enough energy to fully traverse the phantom/patient and to be captured in a suitable detector placed behind it. The measured residual energy or residual range provide a direct estimate of the water equivalent thickness (WET) of the image volume. Requirements for proton imaging to be exploitable in clinical practice include: sufficient WET accuracy and integrability into the treatment room and the clinical workflow, as well as an acceptably low dose to the patient and a sufficient spatial resolution. In this work, we report on experiments performed at the Institut Curie-Proton therapy center in Orsay (IC-CPO), France, using a commercial range telescope commonly employed for quality assurance measurements. The purpose was to keep the experimental set-up as simple as possible and to achieve nonetheless high WET accuracy radiographies by developing and applying dedicated post processing methods. We explain these methods in detail and discuss their performance. We assess the WET accuracy based on two different reference phantoms: a CIRS electron density phantom with tissue equivalent inserts and a homogeneous step phantom. We find an agreement between the measured and the reference WET values of 0.2-0.5 mm. The lowest investigated dose was 10 mGy per acquisition. It could be lowered by modifying the irradiation plan and lowering the beam current, though the latter would impose slight optimisations of the detector hardware. Our work suggests that proton radiographies with good WET accuracy can be obtained with a reasonable experimental effort that would facilitate integration into clinical routine.

Estudio biométrico de la arterias femoral, poplítea y tibial posterior en relación a los implantes de stents / Biometric study of the femoral, popliteal and posterior tibial arteries in relation to the stents

Los aneurismas de la arteria poplítea son los más frecuentes entre los aneurismas periféricos, pudiendo ser tratados con stents a través de cirugía endovascular. Sin embargo, tales stents poseen el mismo diámetro en la parte proximal y distal, no siendo compatible con la anatomía vascular de ese segmento. El objetivo del presente estudio fue determinar la diferencia entre el diámetro del tercio distal de la arteria femoral y el diámetro de la arteria tibial posterior, además de obtener el diámetro de otras arterias del miembro inferior. Se utilizaron 28 cadáveres formolizados de individuos adultos, de ambos sexos, los que fueron disecados en la región correspondiente. Los diámetros registrados fueron los siguientes: en el tercio distal de la arteria femoral (inicio de la arteria poplítea), parte final de la arteria poplítea antes de su bifurcación en arterias tibial anterior y posterior, arterias tibial anterior y posterior (tronco tibiofibular). En el sexo masculino, desde el tercio distal de la arteria femoral hasta la arteria tibial posterior hubo una reducción del diámetro de 27,92% (p<0,0001). En el femenino, la reducción fue de 52,61% (p < que 0,0001). Al comparar el diámetro del tercio distal de la arteria femoral entre ambos sexos, se obtuvo una diferencia estadísticamente significativa (p < 0,0497), así como entre los diámetros de las arterias tibiales posteriores (p< 0,0142). Estos datos son de importancia clínica para los procedimientos de cirugía endovascular, pudiendo reducir las complicaciones en tales procedimientos. Las endoprotésis deberán adaptarse a estas diferencias de diámetro.

The popliteal artery aneurysms are the most common among peripheral aneurysms and can be treated with stents through endovascular surgery. However, these stents have the same diameter at the proximal and distal part , not being compatible with the vascular anatomy of that segment. The aim of this study was determine the difference between the diameter of the distal third of the femoral artery and the diameter of the posterior tibial artery, and to obtain the diameter of others arteries of the lower limb. We study 28 formalized cadavers of adult individuals of both sexes, which were dissected in the corresponding region. The following arterial diameters were recorded: the distal third of the femoral artery, distal part of the popliteal artery, anterior tibial artery and posterior tibial artery. In males from the distal third of the femoral artery to the posterior tibial artery there was a narrowing of 27.92% (p < 0.0001). In women , the reduction was 52.61 % (p<0.0001). By comparing the diameter of the distal third of the femoral artery between the sexes, a statistically significant difference was obtained (p<0.0497), as well as between the posterior tibial artery diameters (p < 0.0142). These data are of clinical importance for endovascular surgery procedures and may reduce complications in such procedures. Stents must adapt to these differences in diameter.

Postoperative incidence of deep vein thrombosis after major lower extremity amputation.

AIM: To determine the incidence of deep vein thrombosis of lower extremities up to the seven day after major lower extremity amputation in the amputated and contralateral limbs using color Doppler ultrasound. METHODS: One hundred and twenty-eight patients (67 men) underwent major lower extremity amputation (69 above-knees and 59 below-knees). All participants received unfractioned subcutaneous heparin (5000 IU TID) as prophylaxis and were evaluated using color Doppler ultrasound immediately before amputation and on the second and seventh days after amputation. The sample was composed of patients with critical limb ischemia and a primary or secondary amputation. Prophylaxis was initiated at the time of hospitalization, discontinued 12 hours before operation, and resumed 12 hours postoperatively. The primary variable was postoperative venous thrombosis. Secondary variables were: age, obesity, myocardial infarction, heart failure, immobilization and level of amputation. RESULTS: Of the 128 patients evaluated (age range: 44 to 97 years), 12 (9.4%) had venous thrombosis; in 8 (6.3%), thrombosis was ipsilateral, and in 4 (3.1%), contralateral to the amputated limb. Thrombosis was found in the thigh stump of 5 patients (3.9%); the other cases were found in the following venous segments: proximal in 2 (1.6%) patients; distal in 4 (3.1%); and proximal/distal in 1 (0.8%). CONCLUSIONS: The incidence of deep vein thrombosis of lower extremities was 9.4% in a group of patients with ischemia who underwent primary or secondary major lower extremity amputation and received prophylaxis with unfractioned heparin.

A treatment planning code for inverse planning and 3D optimization in hadrontherapy.

The therapeutic use of protons and ions, especially carbon ions, is a new technique and a challenge to conform the dose to the target due to the energy deposition characteristics of hadron beams. An appropriate treatment planning system (TPS) is strictly necessary to take full advantage. We developed a TPS software, ANCOD++, for the evaluation of the optimal conformal dose. ANCOD++ is an analytical code using the voxel-scan technique as an active method to deliver the dose to the patient, and provides treatment plans with both proton and carbon ion beams. The iterative algorithm, coded in C++ and running on Unix/Linux platform, allows the determination of the best fluences of the individual beams to obtain an optimal physical dose distribution, delivering a maximum dose to the target volume and a minimum dose to critical structures. The TPS is supported by Monte Carlo simulations with the package GEANT3 to provide the necessary physical lookup tables and verify the optimized treatment plans. Dose verifications done by means of full Monte Carlo simulations show an overall good agreement with the treatment planning calculations. We stress the fact that the purpose of this work is the verification of the physical dose and a next work will be dedicated to the radiobiological evaluation of the equivalent biological dose.

Prevalence of peripheral arterial occlusive disease in patients referred to a tertiary care hospital in Salvador, Bahia, Brazil, for coronary angiography.

The presence of peripheral arterial occlusive disease increases the morbidity and mortality of patients with coronary artery disease. The objective of the present study was to calculate the prevalence of peripheral arterial occlusive disease in patients referred for coronary angiography. This prevalence study was carried out at the Hemodynamics Unit of Hospital Santa Isabel, Salvador, Brazil, from December 2004 to April 2005. After approval by the Ethics Committee of the hospital, 397 patients with angiographic signs of coronary artery disease were enrolled. Diagnosis of peripheral arterial occlusive disease was made using the ankle-brachial blood pressure index (< or =0.90). Statistical analyses were performed using the z test and a level of significance of alpha = 5%, 95%CI, the chi-square test and t-test, and multiple logistic regression analysis. The prevalence of peripheral arterial occlusive disease was 34.3% (95%CI: 29.4-38.9). Mean age was 65.7 +/- 9.4 years for patients with peripheral arterial occlusive disease, and 60.3 +/- 9.8 years for patients without peripheral arterial occlusive disease (P = 0.0000003). The prevalence of peripheral arterial occlusive disease was 1.57 times greater in patients with hypertension (P = 0.007) and 2.91 times greater in patients with coronary stenosis > or =50% (P = 0.002). Illiterate patients and those with little education had a 44% higher chance of presenting peripheral arterial occlusive disease probably as a result of public health prevention policies of limited effectiveness. The prevalence of peripheral arterial occlusive disease in patients referred to a tertiary care hospital in Salvador, Bahia, for coronary angiography, was 34.3%.

Prevalence of peripheral arterial occlusive disease in patients referred to a tertiary care hospital in Salvador, Bahia, Brazil, for coronary angiography

The presence of peripheral arterial occlusive disease increases the morbidity and mortality of patients with coronary artery disease. The objective of the present study was to calculate the prevalence of peripheral arterial occlusive disease in patients referred for coronary angiography. This prevalence study was carried out at the Hemodynamics Unit of Hospital Santa Isabel, Salvador, Brazil, from December 2004 to April 2005. After approval by the Ethics Committee of the hospital, 397 patients with angiographic signs of coronary artery disease were enrolled. Diagnosis of peripheral arterial occlusive disease was made using the ankle-brachial blood pressure index (£0.90). Statistical analyses were performed using the z test and a level of significance of a = 5 percent, 95 percentCI, the chi-square test and t-test, and multiple logistic regression analysis. The prevalence of peripheral arterial occlusive disease was 34.3 percent (95 percentCI: 29.4-38.9). Mean age was 65.7 ± 9.4 years for patients with peripheral arterial occlusive disease, and 60.3 ± 9.8 years for patients without peripheral arterial occlusive disease (P = 0.0000003). The prevalence of peripheral arterial occlusive disease was 1.57 times greater in patients with hypertension (P = 0.007) and 2.91 times greater in patients with coronary stenosis ³50 percent (P = 0.002). Illiterate patients and those with little education had a 44 percent higher chance of presenting peripheral arterial occlusive disease probably as a result of public health prevention policies of limited effectiveness. The prevalence of peripheral arterial occlusive disease in patients referred to a tertiary care hospital in Salvador, Bahia, for coronary angiography, was 34.3 percent.

Anatomical study of the gastrocnemius venous network and proposal for a classification of the veins.

OBJECTIVES: To present a detailed description of the gastrocnemius venous network. DESIGN: Anatomical study in cadavers. MATERIAL AND METHODS: Forty lower limbs from 20 adult male cadavers were studied. All gastrocnemius veins were dissected from the gastrocnemius muscle heads proximally toward their drainage site. RESULTS: Eighty heads of 40 gastrocnemius muscles showed 438 gastrocnemius veins. The number of veins per muscle head varied between 2 and 12. There were 221 gastrocnemius trunks distributed as 95 main gastrocnemius trunks, 81 axial and 45 collateral ones. From the 95 main gastrocnemius trunks, 83 (87%) drained into the popliteal vein. Direct observation of the gastrocnemius venous network allowed us to classify the anatomical distribution as four distinct types. CONCLUSIONS: The majority of main gastrocnemius venous trunks drain into the popliteal vein. There is wide variability in the number of gastrocnemius veins. We propose a classification of four distinct types of anatomical pattern.