3D Absorbed Dose Reconstructed in the Patient from EPID Images for IMRT and VMAT Treatments

2018 ◽  
pp. 605-609
Author(s):  
Fouad Younan ◽  
Jocelyne Mazurier ◽  
Frederic Chatrie ◽  
Ana Rita Barbeiro ◽  
Isabelle Berry ◽  
...  
Keyword(s):  
Absorbed Dose

Characterization of radioiodine therapy failures in Graves’ disease

2001 ◽  
Vol 40 (01) ◽  
pp. 1-6 ◽  
Author(s):  
M. Zimny ◽  
M. Schreckenberger ◽  
P. Reinartz ◽  
B. Nowak ◽  
E. Ostwald ◽  
...  
Keyword(s):  
Radioiodine Therapy ◽  
Thyroid Volume ◽  
Absorbed Dose ◽  
Stepwise Logistic Regression ◽  
Graves Disease ◽  
Significant Variable ◽  
Absorbed Energy ◽  
Volume Function ◽  
Energy Dose

Summary Aim of this study was a characterization of radioiodine therapy (RIT) failures in Graves’ disease without simultaneous Carbimazole. Method: 226 patients with a confirmed diagnosis of Graves’ disease received 686.8 ± 376.4 MBq of iodine-131 orally for thyroid ablation. Target dose was 250 Gy. All patients were followed up for 6 months. Therapy failures were compared with successes regarding possible influencing variables initial thyroid volume, thyroid function, immune activity (TRAb), 1-131 uptake, effective half-life, absorbed energy dose, age and gender. Results: 212 of 226 patients (93.8%) were treated successfully, 14 (6.2%) showed a hyperthyroidism relapse within 6 months which required a second radioiodine therapy. A success rate of 92.5% (62/67) could also be achieved with 67 patients who were hyperthyroid at the time of RIT. Compared to the therapy successes, the 14 failures achieved significantly lower absorbed doses (223.8 ±76.6 Gyvs. 285.2 ±82.1 Gy, ρ <0.005), but with no significant differences regarding age, thyroid volume, function or TRAb (all ρ >0.2). Of the 14 failures, η = 8 reached an absorbed dose <200 Gy and η = 1 a dose <250 Gy, although 5 of the failures reached an absorbed dose of >250 Gy. Stepwise logistic regression revealed only absorbed energy dose as a variable significantly influencing therapy success (p <0.005), but no influence of initial thyroid volume, function, TRAb value, age (all ρ >0.2) or gender (p = 0.13). Two-tailed Fisher’s exact test showed no significant influence of gender on success rates (failures/successes: male 1 /36, female 13/176, ρ = 0.48). Conclusions: Except for the absorbed energy dose, no other significant variable influencing the outcome of radioiodine therapy in Graves’ disease without simultaneous Carbimazole could be found. It should be noted, though, that 5 therapy failures (2.2%) reached an absorbed energy dose of >250 Gy.

Dosimetry with 188Re-labelled monoclonal anti-CD66 antibodies

2006 ◽  
Vol 45 (03) ◽  
pp. 134-138 ◽  
Author(s):  
T. Kull ◽  
N. M. Blumstein ◽  
D. Bunjes ◽  
B. Neumaier ◽  
A. K. Buck ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Bone Marrow ◽  
Gamma Camera ◽  
Absorbed Dose ◽  
Correlation Coefficients ◽  
Residence Times ◽  
Reliable Prediction ◽  
Red Bone Marrow ◽  
Antibody Preparation ◽  
Simplified Method

SummaryAim: For the therapeutic application of radiopharmaceuticals the activity is determined on an individual basis. Here we investigated the accuracy for a simplified assessment of the residence times for a 188Re-labelled anti-CD66 monoclonal antibody. Patients, methods: For 49 patients with high risk leukaemia (24 men, 25 women, age: 44 ± 12 years) the residence times were determined for the injected 188Re-labelled anti-CD66 antibodies (1.3 ± 0.4 GBq, 5–7 GBq/mg protein, >95% 188Re bound to the antibody) based on 5 measurements (1.5, 3, 20, 26, and 44 h p.i.) using planar conjugate view gamma camera images (complete method). In a simplified method the residence times were calculated based on a single measurement 3 h p.i. Results: The residence times for kidneys, liver, red bone marrow, spleen and remainder of body for the complete method were 0.4 ± 0.2 h, 1.9 ± 0.8 h, 7.8 ± 2.1 h, 0.6 ± 0.3 h and 8.6 ± 2.1 h, respectively. For all organs a linear correlation exists between the residence times of the complete method and the simplified method with the slopes (correlation coefficients R > 0.89) of 0.89, 0.99, 1.23, 1.13 and 1.09 for kidneys, liver, red bone marrow, spleen and remainder of body, respectively. Conclusion: The proposed approach allows reliable prediction of biokinetics of 188Re-labelled anti-CD66 monoclonal antibody biodistribution with a single study. Efficient pretherapeutic estimation of organ absorbed dose may be possible, provided that a more stable anti-CD66 antibody preparation is available.

Superselective Radioembolization of Hepatocellular Carcinoma: 5-Year Results of a Prospective Study

1994 ◽  
Vol 33 (05) ◽  
pp. 206-214 ◽  
Author(s):  
J. Triller ◽  
H. U. Baer ◽  
Livia Geiger ◽  
H. F. Beer ◽  
C. Becker ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Survival Rates ◽  
Absorbed Dose ◽  
Pulmonary Complications ◽  
Pulmonary Shunt ◽  
Recurrent Tumour ◽  
Activity Distribution ◽  
A Prospective Study ◽  
Overall Survival Rates

SummaryTwenty patients with unresectable hepatocellular carcinoma (HCC) were followed up to 5 years after transarterial radiotherapy with 90Y-resin particles. Diagnostic radioembolizations of 99mTc-macroaggregates facilitated scintigraphic assessment of activity distribution, dose evaluation and final procedural verification. The overall survival rates were 56, 38 and 14% (after 1, 2 and 3 years, resp.). Patients with unifocal HCC and a single feeding artery (n = 7) even presented 83, 67 and 40% (2 alive after 2.75 and 4 years). With multiple arteries (n = 7), the longest survival was 26 months. Patients with multifocal HCC survived up to 33 months after selective radioembolization. Quality of life was improved in all. Survival was positively correlated with absorbed dose but residual/recurrent tumour occurred even after ≥300 Gy. Post-treatment symptoms were minimal (35 applications), pulmonary shunt rates were correctly predicted and pulmonary complications avoided.

Skin exposure: requirements to methods determining active ingredient of pesticides in washings

2019 ◽  
pp. 43-48
Author(s):  
V. N. Rakitskii ◽  
N. E. Fedorova ◽  
I. V. Bereznyak ◽  
N. G. Zavolokina ◽  
L. P. Muhina
Keyword(s):  
Lower Limit ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Absorbed Dose ◽  
Ambient Air ◽  
Safety Coefficient ◽  
Limit Value ◽  
Calculated Risk ◽  
Nature Studies ◽  
Active Substances

The article presents results of studies exemplified by diquat on analysis concerning influence of lower limit value of quantitative assessment in washing sample for safety coefficient in exposure and in absorbed dose, if acting substance is absent in workplace ambient air samples and in dermal washings of workers. To control diquat in dermal washings, there is a method based on ion-pair liquid chromatography with ultraviolet detection (working wavelength 310 nm). To concentrate sample, cartridges for solid-phase extraction, containing ion exchange sorbent (Oasis MCX 6cc/500 mg), are used. Lower limit of assessment in washing sample — 0,15 micrograms. Experimentally set washing completeness is within range of 80–92%, standard deviation of repetition is 7,0% at most. The method created was tested in nature studies determining dermal exposure in workers subjected to 5 various preparations based on diquat dibromide when used for surface spraying from tractor and from aircraft. For lower limit of detection in washing sample (0,15 micrograms/washing), calculated risk value of exposure varied within 0,26–0,36; risk of absorbed dose was low — 0,23 (the allowable one ≤1). Findings are that present measuring methods which provide lower limit of detection 1 and 5 micrograms in washing sample could result in unallowable risk establishment even with absence of the substance in all samples of workplace air and dermal washings. The calculation formula suggested enables to give theoretic basis for requirements to lower limit of detecting active substances in dermal washing samples for evaluating risk of pesticides use in agriculture.

Absorbed dose and image quality in examinations of the colon with digital and analogue techniques

1997 ◽  
Vol 38 (6) ◽  
pp. 1010-1014
Author(s):  
J. Persliden ◽  
P. Larsson ◽  
B. Noren ◽  
S. Wirell
Keyword(s):  
Image Quality ◽  
Absorbed Dose

New dosimetric approach for multidimensional dose evaluation in gamma knife radiosurgery

2000 ◽  
Vol 93 (supplement_3) ◽  
pp. 239-242 ◽  
Author(s):  
R. Foroni ◽  
G. Gambraini ◽  
U. Danesi ◽  
M. Mauri ◽  
E. Pompilio ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Metal Ion ◽  
Light Transmission ◽  
Xylenol Orange ◽  
Ferrous Sulphate ◽  
Gamma Knife Radiosurgery ◽  
Absorbed Dose ◽  
Content Type ◽  
3D Representation ◽  
Fine Print

✓ During the past two decades, the progress in computerized treatment planning systems has led to more accurate imaging and therapy by using the gamma knife, especially with the smallest collimators (4 mm). However, the ionization chambers that have been used to calibrate the gamma knife are not useful with the smallest collimators because the chambers are too big compared with the irradiated volume. Therefore, it is important to develop more suitable dosimeters. This study proposes a new dosimeter method. The FriXyGel method proposed here is based on a phantom dosimeter, an acquisition chain, and dedicated software. This dosimeter uses an agarose gel into which a ferrous sulphate solution (Fricke solution) and a metal ion indicator (xylenol orange) are incorporated. The absorbed dose is detected through measurements of visible light transmission, imaged by means of a charge-coupled device camera provided with a suitable optical filter. Gel layers are imaged before and after irradiation, and the differences in light absorption are related to the absorbed dose. By choosing convenient thickness of gel layers and by building up a phantom with different gel slices, it is possible to obtain a three-dimensional (3D) representation of the absorbed dose. The final 3D representation is reached after several mathematical processes have been applied to the images. The first step identifies and reduces all factors that could alter the original data, such as nonuniformity in illumination. Then, after calibration procedures, it is possible to obtain absorbed dose values and to discover their 3D representation. This goal has been reached by developing appropriate software that performs all the calculations necessary for spatial representation routines and prompt comparison with theoretical calculations.

Sign in / Sign up

Export Citation Format

Share Document