Use of a non-coplanar half-beam block on the lower spinal field to decrease the maximum bowel and cumulative dose in craniospinal irradiation.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 2039-2039
Author(s):  
Madeera Kathpal ◽  
Rihan Davis
Keyword(s):  
Cumulative Dose ◽  
Therapeutic Dose ◽  
Maximum Dose ◽  
Conventional Technique ◽  
Craniospinal Irradiation ◽  
En Bloc ◽  
Cat Scan ◽  
Spinal Axis ◽  
Treatment Plans ◽  
Geometric Techniques

2039 Background: To develop and compare a non-coplanar half beam block technique that can be used in both prone and supine treatment positions with conventional beam matching for craniospinal irradiation (CSI) in order to decrease the maximum cumulative dose and dose to the bowel, while maintaining the therapeutic dose to the spinal axis. Methods: Ten treatment plans from five patients who underwent CSI were analyzed. The bowel was contoured en bloc for each patient on their simulation cat scan. Two different geometric techniques for each patient were planned and analyzed. The first technique consisted of the conventional method for CSI utilizing two coplanar beams to cover the entire spinal axis. The other technique used a non-coplanar half beam block on the lower spinal beam to exactly match the upper spinal beam’s divergence. Four “featherings” between the two spinal beams for each technique were still necessary to minimize under and overdosing which occur at abutting beam fields. Maximum doses for the plan and the bowel were compared between the two techniques on the same patient. Results: The maximum bowel dose was decreased between 10 to 35 percent when the non-coplanar half beam block was used. The maximum doses for the conventional technique were 5 to 35 percent higher than the plans using a non-coplanar half beam block. The homogeneity of the dose to the spinal axis was not altered with the use of the non-coplanar half beam block. Conclusions: Use of a non-coplanar half beam block to match the two spinal fields in craniospinal irradiation significantly reduces the maximum dose to the bowel and of the entire plan possibly resulting in reduced gastrointestinal toxicity while maintaining therapeutic dose to the spinal axis.

scholarly journals Transition from conformal to advanced radiotherapy techniques in treatment planning of gynecological cancer patients

2021 ◽  
pp. 77-77
Author(s):  
Borislava Petrovic ◽  
Olivera Ivanov ◽  
Milana Marjanovic ◽  
Jelena Licina ◽  
Ivan Gencel ◽  
...  
Keyword(s):  
At Risk ◽  
Cancer Patients ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Gynecological Cancer ◽  
Conformal Radiation Therapy ◽  
Significant Difference ◽  
Treatment Plans ◽  
Radiation Induced ◽  
Risk Treatment

Background/ Aim. Transition from standard to highly conformal radiation therapy techniques, requires implementation of complex advanced dosimetry. The aim of the work was comparison of dosimetric parameters of 3DCRT and VMAT plan, as well as complications after treatment in relation to dosimetric parameters at gynecological cancer patients. Methods. Forty-nine gynecological cancer patients were included in the study. All patients were planned for 3D CRT, but due to unacceptable doses to organs at risk, treatment plans for IMRT or VMAT were generated for 21 patients. The patients were prescribed 50.4 Gy/28 fractions (4) and 45 Gy/25 fractions (45 patients). The coverage of PTV and doses to organs at risk were recorded. PTV margins were evaluated for both techniques according to the Van Herk formula. Results. ICRU 83 criteria were fulfilled in all 3DCRT /VMAT/IMRT plans providing optimal coverage of PTV. Doses to OARS: in average, the V45Gy in small bowel in IMRT/VMAT plans was four times smaller than the same of 3DCRT plans. The V45Gy of small bowels was in average 49.4cm3 in IMRT/VMAT plans, while in 3DCRT plans it was 211.6 cm3. In case of femoral head, significant reduction in V30Gy (10.8 % vs. 33.1%) and mean dose in case of IMRT/VMAT plans was recorded (30.4 Gy in 3DCRT vs 23.6 Gy). Rectum was planned with significantly lower dose in terms of V30Gy (79.5% vs 95.2%) in IMRT/VMAT plans. Bladder was better spared in VMAT plans in terms of V40Gy (51% vs. 91%), but maximum dose was higher in VMAT plans than in 3DCRT (50.1 Gy to 48.1 Gy in average). For all OARs there is statistically significant difference registered at p>0.05. Toxicities recorded in VMAT and 3DCRT patients include mainly radiation induced cystitis and enteritis. Patients treated with 3DCRT generally have longer recovery time. Homogeneity index was 0.11 for VMAT plans and 0.09 for 3DCRT plans. Conclusions. Analysis of dosimetric parameters revealed significant differences in normal tissue doses for same 3DCRT and VMAT patient, which confirmed necessity for implementation of advanced techniques for as many patients as possible.

Prosthetic treatment protocol with fixed dental constructions made on 3D printed cast patterns

2018 ◽  
Vol 1 (90) ◽  
pp. 33-40
Author(s):  
Dzh. Dzhendov ◽  
Iv. Katreva ◽  
Ts. Dikova
Keyword(s):  
Treatment Plan ◽  
Treatment Protocol ◽  
Production Method ◽  
Conventional Technique ◽  
Experimental Investigations ◽  
Treatment Protocols ◽  
Subjective Factor ◽  
Cad Cam ◽  
Treatment Plans ◽  
3D Printed

Purpose: of the present paper is to develop prosthetic treatment protocol for fixed partial dentures made of 3D printed cast patterns. Design/methodology/approach: The clinical and laboratory protocols for manufacturing of fixed prosthetic constructions upon 3D cast patterns are developed on the basis of the literature review and our previous experimental investigations. Comparison between the conventional technique and innovative approach is made. Findings: The terms "semi-digital treatment plan" and "fully digital treatment plan" are defined according to the way of obtaining data for the virtual 3D model and the production method of the fixed prostheses. A classification of treatment protocols with non-removable partial dentures produced by additive technology is developed. Protocols for "semi" and "fully" digitized treatment plans with fixed partial dentures made by casting with 3D printed models are created. Research limitations/implications: Implementation of the fully digitized protocol for manufacturing of fixed prosthetic constructions via 3D printed prototypes requires specific equipment in the dental office and dental technician laboratory – intraoral scanner and CAD/ CAM system with 3D printing machine. Practical implications: Establishing of systematic clinical and laboratory protocols helps dental specialists to implement the innovative working approach in their practice with no risk of neglecting or omitting of some important procedures which increases the quality and long lasting effect of the dental constructions. Originality/value: Following the developed protocols reduces the role of the subjective factor in production technology of fixed prosthetic constructions while saving labour and time.

scholarly journals Disección endoscópica con técnica de bolsillo submucoso. ¿Puede reemplazar a la disección convencional?

2021 ◽  
Vol 51 (3) ◽  
Author(s):  
Martín Yantorno ◽  
Gustavo Javier Correa ◽  
Sebastián Esteves ◽  
Florencia Giraudo ◽  
Agustina Redondo ◽  
...  
Keyword(s):  
High Risk ◽  
En Bloc Resection ◽  
Conventional Technique ◽  
Bloc Resection ◽  
Complete Resection ◽  
High Rate ◽  
Procedure Time ◽  
Technical Success ◽  
En Bloc

Endoscopic submucosal dissection is a complex technique that allows en bloc resection of large lesions. It is associated with long-term, technically complex procedures and a high risk of complications. The creation of a submucosal pocket is a variant of the conventional technique that reduces these difficulties, generating a high rate of complete resection with a shorter procedure time, a faster dissection speed and a lower rate of adverse events. Even though this variant was initially described in the stomach, its application has been generalized to other areas of the digestive tract. We present two cases where this variant technique was applied to treat large early lesions, with technical success.

Intermittent Intrathecal Methotrexate and Fractional Radiation (M-Imfra) plus Chemotherapy in Childhood Leukemia

1978 ◽  
Vol 64 (6) ◽  
pp. 607-611 ◽  
Author(s):  
Renato Mastrangelo ◽  
Attilio Romanini ◽  
Numa Cellini ◽  
Dante Parenti ◽  
Costantino De Renzis ◽  
...  
Keyword(s):  
Complete Remission ◽  
Childhood Leukemia ◽  
Lymphoblastic Leukemia ◽  
Slight Modification ◽  
Intrathecal Methotrexate ◽  
Hematologic Toxicity ◽  
Cns Prophylaxis ◽  
Catholic University ◽  
Cat Scan ◽  
Spinal Axis

Preliminary results of our investigation concern 28 consecutive cases of children with acute lymphoblastic leukemia (ALL), treated between March 1974 and March 1978 at the Clinica Pediatrica of the Catholic University in Rome, with a slight modification of the ALL protocol II of the Children's Hospital of Michigan (M-IMFRA). This protocol includes intermittent low dosage radiation of the cranio-spinal axis, combined with single intrathecal injections of methotrexate for the prophylaxis of central nervous system leukemia. Of the initial 28 children, one did not achieve a complete remission and one died of viral pneumonitis, 4 months after admission, in complete remission and had no hematologic toxicity at the time of this infection. The evaluation of remission duration is based on the remaining 26 children with a period of observation of up to 48 months. Only 2 children, who belonged to the low risk group, have so far relapsed, and relapse was confined to the bone marrow. Median survival without evidence of recurrence is 21 months. Or the 28 patients investigated, 17 are high risk children, as judged by the WBC above 20,000/mm3, mediastinal mass and age below 18 months or above 12 years. Only minimal toxicity has been observed in all cases. We have been encouraged to continue the regimen described here by recent observations regarding the abnormal computed tomography (ACT) scans in children with ALL following CNS prophylaxis of 2,400 rad to the skull. The high incidence of CAT scan abnormalities found is of interest and suggests a reappraisal of the current approaches to CNS prophylaxis.

Effect of Prenatal Administration of Retinoic Acid on Developing Spinal Cord of Albino Rats

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
MarwaSaad Sherif ◽  
Mohamed TawfikKamal ◽  
Seham Refat ◽  
Mona El Gazzar ◽  
Gorge Hana ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Vitamin A ◽  
Dorsal Horn ◽  
Therapeutic Dose ◽  
Maximum Dose ◽  
Anterior Horn ◽  
Albino Rats ◽  
Daily Maximum ◽  
Group I ◽  
Developing Spinal Cord

Abstract Background Vitamin A and its derivatives (Retinoids) are essential for both normal embryonic development and maintenance of differentiation.Retinoids is a well-known teratogen when administered to embryos Aim to investigate the structural changes induced by prenatal administration of vitamin A on the developing spinal cord of albino rats. Material and methods forty pregnant albino rats were exposed to variable doses of vitamin A (retinylpalmitate) on gd 10.The pregnant albino rats were divided into three groups: Group I (control): rats received sesame oil by oral gavagedaily, till date of delivery. Group II (minimum therapeutic dose): rats were given retinylpalmitate 50 mg/kg daily. Group III (maximum therapeutic dose): rats were givenretinylpalmitate 100 mg/kg daily. The viable offspring of all groups were evaluated for changes in developing spinal cord at PND10. At the end of the experiment, rats offspring were sacrificed, the spinal cord were dissected out, and subjected to histological examination followed by computer image analysis. Results PDN10 neonates of mothers received minimum dose of vitamin A (subgroup II) revealed few immature irregular dorsal horn neurons with relatively decreased cellular density in anterior horn neurons. Meanwhile, the PDN10 neonates of mothers received daily maximum therapeutic dose of vitamin A (subgroup III) exhibited dark,pyknotic nucleiand packed dorsal horn cells while anterior horn cells were shrunkenandkaryoliticnuclei. Conclusion minimum and maximum doses of vitamin A in pregnant rats attributed to morphological changes in spinal cord of their young neonates and in long term follow up which was more obvious in maximum dose than low intake. Therefore, it might be assumed that neither minimum nor maximum dose could be used as a safe drug for their serious side effects on spinal cord morphology and consequently its functions.

scholarly journals RADI-15. CLUSTERING AND GROUPING OF BRAIN METS IN RADIOSURGERY TREATMENTS

2019 ◽  
Vol 1 (Supplement_1) ◽  
pp. i24-i24
Author(s):  
Khaled Salah ◽  
John Mckenna ◽  
Gabor Jozsef ◽  
Jonathan Knisely
Keyword(s):  
Maximum Dose ◽  
Treatment Plan ◽  
Normal Brain ◽  
Dose Distributions ◽  
Treatment Plans ◽  
Prescription Dose ◽  
Clustering Approach ◽  
Centers Of Mass ◽  
Dose Volumes ◽  
Single Isocenter

Abstract INTRODUCTION: Radiosurgical treatment of numerous lesions in the brain with ‘single-isocenter’ radiosurgery on a linac often requires using multiple isocenters. With our TPS (Elements, Brainlab) multiple plans need to be generated for each set of lesions, and a sum plan calculated. We investigated how to distribute multiple lesions into two groups for two isocenters to achieve a good summed dose distribution. METHODS: The DICOM RS file is exported and the PTV data is extracted by a MATLAB program that calculates the convex hulls, estimated radii, and the centers of mass for each PTV. Two approaches were tried: (1) Lesions close to each other (closer than a certain limit) are put in different groups and (2) Create clusters by kMeans clustering, which allows close lesions but the groups are distant from each other. MATLAB programs were written for all approaches. Treatment plans were generated for three patients (20, 13, 15 lesions) using each method and compared with the actual treatment plan used to treat the patient based on the intuitive grouping of lesions by the planners. Dose maximums outside the lesions, and volumes in the normal tissue exceeding 75, 50 and 25% of the prescription dose were evaluated. RESULTS AND DISCUSSION: The coverage of all lesions for all plans were 95% of the prescription dose. The first approach allowed lowering the maximum dose between lesions, but with summing dose distributions this advantage disappeared. The maximum dose and the 75, 50 and 25% dose volumes were also all worse than in plans generated by experienced planners and higher normal brain doses are delivered if closely spaced lesions are separated into different isocenters for treatment. However, the clustering approach resulted in the same or better values of these same parameters, i.e. improved dose distributions over the dosimetrist’s intuitively chosen separation.

scholarly journals Automatic Radiotherapy Planning for Glioblastoma Radiotherapy With Sparing of the Hippocampus and nTMS-Defined Motor Cortex

2022 ◽  
Vol 12 ◽  
Author(s):  
Michaela Schuermann ◽  
Yvonne Dzierma ◽  
Frank Nuesken ◽  
Joachim Oertel ◽  
Christian Rübe ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Maximum Dose ◽  
Organs At Risk ◽  
Target Volume ◽  
Brain Regions ◽  
Additional Treatment ◽  
Radiotherapy Planning ◽  
Plan Quality ◽  
Planning Algorithm ◽  
Treatment Plans

BackgroundNavigated transcranial magnetic stimulation (nTMS) of the motor cortex has been successfully implemented into radiotherapy planning by a number of studies. Furthermore, the hippocampus has been identified as a radiation-sensitive structure meriting particular sparing in radiotherapy. This study assesses the joint protection of these two eloquent brain regions for the treatment of glioblastoma (GBM), with particular emphasis on the use of automatic planning.Patients and MethodsPatients with motor-eloquent brain glioblastoma who underwent surgical resection after nTMS mapping of the motor cortex and adjuvant radiotherapy were retrospectively evaluated. The radiotherapy treatment plans were retrieved, and the nTMS-defined motor cortex and hippocampus contours were added. Four additional treatment plans were created for each patient: two manual plans aimed to reduce the dose to the motor cortex and hippocampus by manual inverse planning. The second pair of re-optimized plans was created by the Auto-Planning algorithm. The optimized plans were compared with the “Original” plan regarding plan quality, planning target volume (PTV) coverage, and sparing of organs at risk (OAR).ResultsA total of 50 plans were analyzed. All plans were clinically acceptable with no differences in the PTV coverage and plan quality metrics. The OARs were preserved in all plans; however, overall the sparing was significantly improved by Auto-Planning. Motor cortex protection was feasible and significant, amounting to a reduction in the mean dose by >6 Gy. The dose to the motor cortex outside the PTV was reduced by >12 Gy (mean dose) and >5 Gy (maximum dose). The hippocampi were significantly improved (reduction in mean dose: ipsilateral >6 Gy, contralateral >4.6 Gy; reduction in maximum dose: ipsilateral >5 Gy, contralateral >5 Gy). While the dose reduction using Auto-Planning was generally better than by manual optimization, the radiated total monitor units were significantly increased.ConclusionConsiderable dose sparing of the nTMS-motor cortex and hippocampus could be achieved with no disadvantages in plan quality. Auto-Planning could further contribute to better protection of OAR. Whether the improved dosimetric protection of functional areas can translate into improved quality of life and motor or cognitive performance of the patients can only be decided by future studies.

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