External Radiotherapy Techniques Research Articles

Teknik Terapi Radiasi 3DCRT Pada Kasus Kanker Serviks Dengan Studi Literatur

Research with literature studies is still rarely carried out, therefore in this article we want to know about the External Radiation Radiotherapy Technique in Cervical Cancer Cases with 3D-CRT (3-Dimensional Conformal Radiation Therapy): This literature discusses the application of the 3D-CRT external radiation radiotherapy technique in treatment cervical cancer. 3D-CRT is a method that allows external radiation exposure from more than one side,possiblemore appropriate radiation dose according to the shape and location of the tumor. This study also lists other techniques such as Brachytherapy, IMRT, and 2D in the treatment of cervical cancer. Photon Dose Distribution Using 3D-CRT and IMRT Techniques in Cervical Cancer Therapy: This research discusses photon dose distribution in the Treatment Planning System (TPS) using 3DCRT and IMRT techniques for cervical cancer therapy. This provides insight into the comparison between the two techniques in delivering appropriate radiation doses to the tumor target. 6 MV Energy Linac Radiotherapy Against Cervical Cancer: This journal discusses the use of radiotherapy on a Linac aircraft with a 6 MV energy photon beam using the 3DCRT technique in the treatment of cervical cancer. This technique helps deliver the right dose of radiation according to the target area. The literature above provides information about external radiotherapy techniques, including 3D-CRT, in the treatment of cervical cancer. They help understand the role and application of this technique in cervical cancer treatment.

External Radiotherapy for Locoregional Control in Thyroid Carcinoma.

Most patients with well-differentiated thyroid cancers (WDTC) are adequately treated with surgery, radioactive iodine, and TSH suppressionby thyroxine. External radiotherapy (ERT) is reserved for selected cases and for older patients. Some of the indications for ERT to neck include adjuvant treatment for gross or microscopic disease after surgery, palliation of locally advanced unresectable tumor, or as salvage for recurrent disease which is not amenable to surgery or does not uptake radioactive iodine. High radiation dose of at least 60Gy is required for locoregional control of gross or microscopic residual disease. As even patients with recurrent or metastatic disease can have long survival, it is important to minimize late radiation-induced morbidity without compromising local control. Modern ERT technique like intensity-modulated radiotherapy allows high radiation dose to be delivered to the large, complex target volume while protecting the adjacent critical normal structures like the trachea, larynx, esophagus, and cervical spinal cord.

Heuristic estimation of the α/β ratio for a cohort of Mexican patients with prostate cancer treated with external radiotherapy techniques.

The aim of the study was to Estimate and compare the radiobiological ratio α/β with the heuristic method for a cohort of Mexican patients with prostate cancer (PCa) who were treated with external radiotherapy (RT) techniques at three Hospital Institutions in Mexico City. With the Kaplan-Meier technique and the Cox proportional hazards model, the biochemical relapse-free survival (bRFS) is determined and characterized for cohorts of Mexican patients with PCa who received treatment with external RT. Using these clinical outcomes, the radiobiological parameter α/β is determined using the heuristic methodology of Pedicini et. al. The α/β is calculated from the survival curves for different treatment schemes implemented at three distinct hospitals. The Pedicini's techniques allow to determine the parameters α/β, k and N 0 when treatments are not radiobiologically equivalent, therefore, are built up of a set of curved pairs for the biologically effective dose (BED) versus the ratio α/β, where the ratio is given by the intersection for each pair of curves. Six different values of α/β were found: the first α/β = 2.46 Gy, the second α/β = 3.30 Gy, the third for α/β = 3.25 Gy, the fourth α/β = 3.24 Gy, the fifth α/β = 3.38 Gy and the last α/β = 4.08 Gy. These values can be explained as follows: a) The bRFS of the schemes presents a statistical variation; b) The absorbed doses given to the patient present uncertainties on the physical dosimetry that are not on the modeling; c) Finally, in the model for the bRFS of Eq. (3), there are parameters that have to be considered, such as: the number of clonogenic tumor cells N 0 , the overall treatment time (OTT), the kick-off time for tumor repopulation T k and the repopulation doubling time. Therefore, the mean value to α/β for all schemes has an average value of 3.29 (± 0.52) Gy. The value of is determined from cohorts of Mexican patients with PC a treated with external radiotherapy using the time-dependent LQ model, which is a higher value with respect to the "dogma" value of α/β 1.5 Gy obtained with the LQ model without temporal dependence. Therefore, there is a possibility of optimizing treatments radiobiologically and improving the results of bRFS in Mexican patients with PCa treated with external radiotherapy.

Dosimetric comparison of AP/PA and bilateral geometries for total body irradiation treatment.

Total body irradiation (TBI) is an external radiotherapy technique. Its aim is to deliver a therapeutic dose uniformly within ± 10% of the absorbed dose to the prescription point. In the present study, the TBI technique was implemented in anterior/posterior (AP/PA), and bilateral geometry with photons from a 6 [Formula: see text] and 18 [Formula: see text] accelerator. The TBI technique was implemented on an Alderson Rando phantom at 312 [Formula: see text] source surface distance. During bilateral fraction, rice bags were applied as tissue compensators. To reduce the lung's absorbed dose to the acceptance level, in AP/PA geometry lung blocks made of Cerrobend were used. The required monitor unit (MU) for each fraction was calculated regarding depending on the prescribed dose and beam output. Gafchromic EBT3 films were used for dosimetry between the phantom layers in eight selected points. It is demonstrated that dose uniformity for AP/PA geometry with 6 [Formula: see text] and 18 [Formula: see text] photons was within ± 10%. In contrast, for the bilateral geometry the dose uniformity was not acceptable for both studied energies; However, the results for 18 [Formula: see text] were better than those for 6 [Formula: see text]. Dose accuracy for all measurements was within ± 5 of the prescribed dose. The absorbed dose to the lungs was successfully reduced using the lung blocks. By combining different therapeutic geometries and energies over six fractions, the results of uniformity and accuracy of dose delivery could be improved. It is concluded that the introduced TBI method achieved good dose accuracy and acceptable dose uniformity. Lungs absorbed dose was lower than 10 [Formula: see text] using the lungs blocks. Based on these results, the TBI technique can now be implemented in radiotherapy at Tehran's Imam Hospital. The approach developed in the present study can be used and adapted to match with the conditions at other hospitals.

Evaluation of the surface dose for total body irradiation (TBI) technique with parallel-opposed anterior posterior geometry

AbstractAim:Total body irradiation (TBI) is an external radiotherapy technique in which the whole body including the superficial regions is required to receive the therapeutic dose. The purpose of this study is to evaluate the received surface dose during TBI technique.Methods and materials:The anterior/posterior (AP/PA) TBI was implemented with 18-MV photon beam at 312-cm treatment distance for human-like phantom. The GAFCHROMIC-EBT3 films were used for superficial dose measurements.Results and discussion:The percentage of surface-absorbed dose relative to the prescription point for 8 points of measurements was between 102·78–121·48% and 104·51–127·43% at 5 and 10 mm depth, respectively. In the chest wall region due to the presence of lung blocks, the absorbed dose was below the acceptable level, so an electron boost was required to increase the chest wall absorbed dose.Conclusions:According to the results, the implemented technique was able to deliver sufficient dose to the shallow surface of phantom’s body.

AB007. S2-1. Liver-directed therapy for cholangiocarcinoma

: Surgical resection remains the optimal curative option for cholangiocarcinoma. Unfortunately, <25% of patients will present with resectable disease leading to a significant clinical opportunity for non-surgical therapy. Due to the high frequency of intrahepatic disease recurrence or progression, liver directed therapy hold significant potential therapeutic benefit either alone or in combination with systemic therapy. While endoscopic therapies have been largely used to relieve biliary obstruction, techniques including intra-arterial therapy, ablation and external radiotherapy have been suggested as primary tumour therapy for liver-limited disease. Intra-arterial techniques include bland and trans-arterial chemo-embolization, radioembolization (Y90) and hepatic arterial infusion chemotherapy. Tumour ablation techniques include radiofrequency and microwave ablation as well as irreversible electroporation. External radiotherapy techniques such as stereotactic body radiotherapy (SBRT) and proton therapy are being applied with increasing precision and efficacy. To date the results of liver directed therapy are based on retrospective case series and systematic reviews as prospective comparative data is currently lacking. The future prospects of liver directed therapy include generation of prospective data as well as potential combination regimens of liver-directed and systemic therapy.

Effective heuristics for beam angle optimization in radiation therapy

In radiation therapy, the main challenge is to deliver the dose to the tumor while sparing healthy tissues around the tumor. One important decision to make is the beam configuration. The corresponding mathematical problem, known as beam angle optimization (BAO), is a large-scale problem. We propose three novel heuristic approaches to reduce the computation time and find high-quality treatment plans for BAO. The first heuristic is based on the fact that the beams that are geometrically close to each other (i.e., ‘adjacent’ beams) have similar impacts, and hence are less likely to be used in the optimal configuration simultaneously. Therefore, in this heuristic, referred to as ‘neighbor cuts’, their use is limited. The second heuristic is to eliminate the beams with small contribution to dose delivery in the ideal plan when all candidate beams can be used. Finally, the number of beams is reduced in the third heuristic while ensuring the quality of the plan remains within a pre-specified range. These heuristics can be applied to any formulation for BAO for various external radiation therapy techniques. We evaluate these heuristics by applying them to a mixed integer programming (MIP) formulation of BAO for a phantom liver case and a clinical liver case.

TREATMENT OF RADIOTHERAPY FOR SERVIKS CANCER WITH SEPARATION MORE THAN 20 CENTIMETERS USING COBALT-60 AT UNIT RADIOTHERAPY INSTALLATION RADIOLOGY RSUP DR. KARIADI SEMARANG

Background: Cervical cancer is a type of cancer that emerges from the cervix. In the early stages of the tumor, treatment therapy will be performed surgically on organs affected by cancer cells, at an advanced stage will be done adjuvant therapy with curative goals through a combination of chemotherapy, surgery, and radiotherapy. In radiotherapy treatment is done with several techniques such as Brachyterapi, IMRT, 3DCRT, and 2D with external aircraft radiation modality with Linac (Linear Accelator) and Cobalt-60. For Brachyterapi (internal radiation) technique, the radiation source is directly placed on the target tumor by using the after loading technique generally, whereas the external radiation techniques of 3DCRT and IMRT are generally performed on external radiation plane using MLC (Multi leaf Collimator) by following the target shape tumors resulting from CT Simulator and TPS (Treatment Planning System) calculations. For IMRT alone the technique used is almost the same as 3DCRT technique. In cobalt-60 is generally used for the treatment of radiation therapy has an average energy of 1.25 MV. At 1.25 MV cobalt energy with 10x10 cm field area will get maximal energy at depth (d max) 0.5 cm and energy will decrease to half (d half) at a depth of 11 centimeter on water media. So that in planning of radiation using cobalt-60 plane have limited separation diameter less than 20centimeter. Methods : This type of research is qualitative with case study approach. the data was collected in October-December 2017 at radiotherapy Installation of Dr. Kariadi General Hospital Semarang by observation methodology, interview with Radiation Oncologist Specialist, Medical Physiciast and Radiographer. the data obtained from the study were analyzed by an interactive model, creating the interview transcripts subsequently reduced and processed within the type of open coding, given within the type of quotations then are often drawn conclusions. Result: The results of this study demonstrate that the management of cervix cancer radiation utilizing 2D procedure in radiotherapy installation of Dr. Kariadi General Hospital Semarang includes patient examination, planning medical physics, verification and radiation treatments. 2D techniques are used pupose to paliative radiation, homogenity of dose and the location of the target volume is close to the Organ at Risk. Field radiation evaluation was performed before first and third irradiation, patient evaluation after five times of radiation and evaluation after 25rd radiation. Conclusion: The reason for doing the external radiation exposure of cervical cancer with tumor stage further consideration according to the Anatomical Pathology with pT3aN0M0 stage. So the purpose of palliative external radiation. with cervical cancer using cobalt-60 teletherapy air as much as 50 Gy with a fractionation s25 times, and each fractionation with doses of 2Gy. The reason for doing the external radiation exposure of cervical cancer with tumor stage further consideration according to the Anatomical Pathology with pT3aN0M0 stage. So the purpose of palliative external radiation. with cervical cancer using cobalt-60 teletherapy air as much as 50 Gy with a fractionation 25 times, and each fractionation with doses of 2Gy. The reason for doing the external radiation exposure of cervical cancer with tumor stage further consideration according to the Anatomical Pathology with pT3aN0M0 stage. So the purpose of palliative external radiation

Evaluation of Different External Radiation Therapy Techniques for the Treatment of Malignant Pleural Mesothelioma After Extrapleural Pleuropneumonectomy

ratio and beam output. Finally, a hypothetical treatment of a 2-cm diameter target located at a depth of 11 cm and near the pancreas was simulated on patient CT images using an optimized kV x-ray source and compared to a dose distribution generated with a 6 MV beam. Results: MC simulated depth-dose curves of the existing large-area x-ray source agreed with film measurements to within 5%. Beam energy and filtration, target thickness, collimator hole geometry, and treatment SSD had the largest effect on the quality of dose distributions in terms of both target-to-skin ratio and beam output. An optimized kV x-ray source design for the 4-cm diameter target resulted in target-to-skin ratio of 5.2 and D50 of 19.5 Gy delivered in 30 minutes. For the 5 mm-diameter target, the target-to-skin ratio increased to 11.2 and D50 in 30 minutes exceeded 35 Gy. The MC models of treatment coverage for a target near the pancreas demonstrated that optimized kV and 6 MV treatment plans delivered comparable doses to critical structures. The integral dose delivered by the kV x-ray source was similar to the integral dose delivered by the 6 MV beam due to the fast fall-off of kV beams. Conclusion: A novel radiation therapy kilovoltage x-ray source has been modeled and optimized using Monte Carlo simulations. Due to its unique design, the source delivers conformal doses of radiation to deep-seated tumors with dosimetric parameters and treatment times acceptable for clinical use. A hypothetical clinical scenario showed that treatment plans with the novel cost-effective kV x-ray source have the potential to match treatment plans generated with commonly used 6 MV beams. Author Disclosure: M. Bazalova: None. E. Graves: None. B. Wilfley: None. M. Weil: P. Ownership Other; yes. Q. Leadership; yes.

Surgical placement of biologic mesh spacers prior to external beam radiation for retroperitoneal and pelvic tumors

PurposeTo determine the feasibility of surgical placement of biologic mesh spacers to displace bowel and other radiation-sensitive organs prior to external beam radiation for difficult retroperitoneal and pelvic tumors. Methods and MaterialsTumors were resected if possible, and intraoperative electron radiation therapy (IOERT) was directed to the tumor or tumor bed in selected patients. Biologic mesh spacers comprised of cadaveric human skin treated to remove cells and preserve extracellular matrix (Alloderm; Lifecell, Branchburg, NJ) were then placed around the tumor or tumor bed. External radiation techniques included proton beam radiation therapy (PBRT) and intensity modulated radiation therapy (IMRT). ResultsPatients had primary sarcomas (n = 2), radiation-associated sarcomas (n = 1), or isolated metastases (n = 2) in the retroperitoneum or pelvis. One patient received preoperative radiation. Three tumors were marginally resected (R1 resection) while 2 tumors were left in situ, and 3 patients received IOERT (10-17 Gy) to the tumor or tumor bed. Up to 4 sheets of biologic mesh were used as spacers around the tumor or tumor bed to displace small bowel, colon, ureter, bladder, or pancreas. The average distance of the 4 closest organs prior to mesh placement was 1.3-9 mm and after mesh placement was 8.0-23.5 mm. Preoperative or postoperative radiation 36-76 Gy was delivered by IMRT or PBRT. There were no early complications from mesh placement and late complications possibly related to radiation included 1 vertebral body compression fracture and 1 deep vein thrombosis. There were no mesh-related infections and none of the meshes required removal. All 5 patients currently remain free of disease progression after 3-38 months. ConclusionsBiologic mesh spacers can be placed around tumors or tumor beds to displace radiation-sensitive organs and may allow for safer delivery of external beam radiation.

Conservation of salivary function and new external head and neck radiation techniques

New radiation therapy techniques seek to adapt dose distribution to three-dimensional tumor geometry, so as to deliver the lowest possible dose to normal tissue and at-risk organs. This is expected to enhance locoregional control and survival and to reduce complications and thereby improve quality of life. Post-radiation xerostomia significantly deteriorates quality of life. New external radiation techniques (such as intensity-modulated conformal radiation therapy, RapidArc VMAT arc therapy, tomotherapy, CyberKnife(®), protontherapy, use of carbon ions) applicable in ENT are reviewed. Preliminary data show interesting results in terms of salivary function with highly conformal techniques. In France, assessment is ongoing, financed under the Health Ministry's "Support for Expensive Innovatory Techniques" scheme (STIC [Soutien aux techniques innovantes coûteuses]), as routine use is growing rapidly.

Impact of clinical and therapeutic factors on major late complications after radiotherapy with or without concomitant chemotherapy for anal carcinoma

To investigate factors potentially influencing major late morbidity after sphincter-conserving treatment for anal carcinoma. Grade 3-4 complications were retrospectively analyzed in 144 evaluable patients (pts), 55 pts after split-course radiotherapy (RT), and 89 after concomitant chemo-RT. First sequence RT delivered a median dose of 39.6 Gy using megavoltage photon beams. Boost treatment used either 192Ir implantation or external beam RT (median dose 20 Gy). Chemotherapy started on day 1 and in 83% of pts consisted of Mitomycin-C (10 mg/m2) and a 5-day infusion of 5-fluorourcil (600-800 mg/m2/day). Uni- and multivariate analyses tested the association of following factors with complication rate: age, gender, stage, anatomic tumor extent, type of biopsy, external RT technique (dose, fraction size, field arrangement), boost type (brachytherapy vs. external), brachytherapy dose and dose rate, overall treatment time, and addition of chemotherapy. Five-year actuarial complication rate was 16%. Two variables were significantly associated with complication rate: anatomic tumor extent (canal or margin vs. both +/- rectum; 10 vs. 31% complications, p = 0.0004) and first sequence prescribed dose (< 39.6 Gy vs. > or = 39.6 Gy; 7 vs. 23% complications, p = 0.012), confirmed as independent factors by Cox analysis. Grade 4 anal morbidity correlated significantly with prior local excision. All six bone complications were observed in pts treated by chemo-RT using large pelvic fields, five occurring in pts older than 66. Pts with tumors involving more than one anatomic subsite or treated with the higher first sequence RT dose are at greater risk of major complications. Prior tumor excision and combined modality therapy in older pts appear to favor major anal and bone complications, respectively.