Prowess Panther Research Articles

Quality Assurance Plan on a Linear Accelerator (LINAC) Plane on Nasopharynx Cancer (NFC) by using Prowess Panther 5.10 at Radiotherapy Installation Ken Saras Hospital

Radiotherapy is the treatment of cancer by using electromagnetic and particle radiation. Nasopharyngeal Cancer (NPC) is one of the difficult case to be treated in radiotherapy because its anatomical location. Precision of radiation dose is part of Quality Assurance Program as the key factor in this treatment. Thus, it is very important to ensure that the output dose of Linear Accelerator (LINAC) matched with result of Treatment Planning System (TPS). This study used Siemens LINAC Type Primus MACH Series 5633 and a set of detectors for Nasopharynx Cancer analysis with 8 field. The total dose of 5,000 cGy divided into 25 fractions with 200 cGy dose per fraction. The 8 fields are irradiated with a target on a detector device. It is then accumulated with PTW-Verisoft software by plotting the results obtained from the detector tool with PTW (phantom) which we have CT Scanned first in PTW-Verisoft. From the total detectors exposed to the radiation, the detector corresponding to PTW is 372 detectors (100%) with unsuitable detector of 0 detectors (0.00%). It is proved that the planning is 100% match for NPC with 8 fields of radiation. Thus, this method is recomended to be implemented for NPC treatment

Comparison of Electrons and Photons Treatment Plans in Medulloblastoma Patients

Background: The treatment of medulloblastoma involves surgery, radiotherapy, and adjuvant chemotherapy. In radiotherapy, craniospinal irradiation (CSI) is prescribed, where two lateral cranial fields and one or two spinal beams are applied in CSI. Different multi-field techniques (coplanar and/or noncoplanar) are used to register the prescribed dose. The purpose of this study was to assess plan quality in terms of dose coverage of the spine with both photon and electron beam therapy and the sparing of organs at risks (OARs).Methods: Ten pediatric patients (ages 6 to 10 years) were immobilized in the prone position for simulation. The Clinical Target Volume (CTV) of the organ under treatment, Planning Target volume (PTV) of the organ under treatment, and OARs were contoured. Prowess Panther (v4.71) was used for dose computations. Two lateral parallel-opposed 6 MV photon cranial fields with the spinal beam(s) (either 6 Photons or 21 MeV electrons) were used in planning. Electron beams were added posteriorly on the spine with parallel-opposed cranial fields. The treatment plans were computed for 3600 c Gy in 21 fractions.Results: For comparable conformity number of electron versus photons beam plans (0.68 ± 0.41 versus 0.66 ± 0.47, is not significantly different at p < 0.05) and homogeneity index (1.22 ± 0.03 versus 1.25 ± 0.04, is significantly different at p < 0.05), the photon doses were higher for underlying OARs (heart, liver, and thyroid) and were lower for partially in-field organs (lungs and kidneys) compared to electrons.Conclusions: The underlying organs i.e., thyroid, heart, and liver receive a lesser dose in case of electrons, while partially in-field organs are exposed more compared to photons mainly due to the ballooning effect in electrons. The study shows that both electrons and photons can be used for CSI. However, the electron may be preferred due to its better sparing of underlying structures.

Dosimetric and radiobiological comparison in head-and-neck radiotherapy using JO-IMRT and 3D-CRT

IntroductionDosimetric and radiobiological evaluations for the Jaws-only Intensity-modulated radiotherapy (JO-IMRT) technique for head and neck jaws-only intensity-modulated radiation therapy (JO-IMRT) and 3D conformal radiation therapy (3D-CRT). To compare the head-and-neck therapeutic approaches utilizing JO-IMRT and 3D-CRT techniques, different radiation dose indices were calculated, including: conformity index (CI), homogeneity index (HI), and radiobiological variables like Niemierko's equivalent uniform dose based tumor control probability (TCP) of planning target volume (PTV), normal tissue complication probability (NTCP) of organs at risk (OAR) (brainstem, spinal cord, and parotid grand). Materials and methodsTwenty-five nasopharynx patients were studied using the Prowess Panther Treatment Planning System (Prowess Inc). The results were compared with the dose distribution obtained using 3D-CRT. ResultsRegarding tumor coverage and CI, JO-IMRT showed better results than 3D-CRT. The average doses received by the PTVs were quite similar: 72.1 ± 0.8 Gy by 3D-CRT and 72.5 ± 0.6 Gy by JO-IMRT plans (p > 0.05). The mean doses received by the parotid gland were 56.7 ± 0.7 Gy by 3D-CRT and 26.8 ± 0.3 Gy by JO-IMRT (p > 0.05). The HI and CI were 0.13 ± 0.01 and 0.14 ± 0.05 and (p > 0.05) by 3D-CRT and 0.83 ± 0.05 and 0.73 ± 0.10 by JO-IMRT (p < 0.05). The average TCP of PTV was 0.82 ± 0.08 by 3D-CRT and 0.92 ± 0.02 by JO-IMRT. Moreover, the NTCP of the parotid glands, brain stem, and spinal cord were lower using the JO-IMRT than 3D-CRT plans. In comparison to the 3D-CRT approach, the JO-IMRT technique was able to boost dose coverage to the PTV, improve the target's CI and HI, and spare the parotid glands. This suggests the power of the JO-IMRT over 3D-CRT in head-and-neck radiotherapy.

Dose Variation To Critical Points In Low Dose Rate Intracavitary Brachytherapy Of Cervical Cancer As Justification For Incident Learning

Background: Low Dose Rate (LDR) brachytherapy necessitates a more extended treatment duration. This technique maintains the patient on the treatment machine for a longer length of time, which may cause changes in the applicators' position due to vaginal packing soaking and patient movement for incident learning justification.&#x0D; Objective: The purpose of this study is to evaluate pre- and post-dosage variation to points 'A' and 'B,' as well as vital organs (i.e. bladder and rectum), for low dose rate (LDR) brachytherapy at Komfo Anokye Teaching Hospital and justify the need for incident learning system.&#x0D; Method: Forty (40) patients with invasive cervical cancer were treated with LDR brachytherapy equipment (A Curietron Cesium Manuel (AMRA)-France, CA 98.22) to point 'A' at doses ranging from 30 to 35 Gy. Adult patients selected for the study ranged from 25 to 60 years simulated. For each patient, orthogonal images of anterior-posterior (AP) and (LAT) were taken by positioning the patient on the Varian Acuity Simulator Couch at 00 and 900, respectively, and two sets of orthogonal images (before and after treatment), in each case, were considered. The treatment was then planned using the AP and LAT images obtained based on the four arrangements used, namely 1-2-5, 1-3-5, 1-4-5, and 1-5. The treatment planning system used for the study was the Prowess Panther system 4.6.&#x0D; Results: The dosage disparity at point 'A' was determined to be 1.16 per cent, which is highly commendable compared to previous research that established dose variations of 2%, 35%, 8%, and 20%. In this study, the dosage variation at point B was 0.75 per cent. The bladder and rectum had average alterations of 2.32 per cent and 0.30 per cent, respectively.&#x0D; Conclusion: The difference observed between prescribed, and deposited dosage was 2.11 per cent for quality assurance and incident learning reasons. Unrealistic expectations, reliance on reminders and quick remedies, and faults in the systemic view of failure were discovered and addressed as managerial issues. It is critical not to underestimate these difficulties because they are frequently significantly more severe than the technical issues being addressed. Incident issues were not recorded per patients under review, but near misses and non-conformance were observed. The geometric variances between the Intracavitary Brachytherapy Treatment (ICBT) applicators and the essential organs change during the treatment process, resulting in dosage changes. Does variance is within the required standard limits; it can be stated that Komfo Anokye Teaching Hospital's practice satisfies the international standard and is an intrusion into the Directorate Incident Learning System.

Examination of dosimetric verification of PROWESS Panther Treatment Planning System using Monte Carlo method for small fields

Examination of dosimetric verification of PROWESS Panther Treatment Planning System using Monte Carlo method for small fields

Calculation of Jaws-only IMRT (JO-IMRT) dose distributions based on the AAPM TG-119 test cases using Monte Carlo simulation and Prowess Panther treatment planning system

The aim of this study is to calculate the JO-IMRT dose distributions based on the AAPM TG-119 using Monte Carlo (MC) simulation and Prowess Panther treatment planning system (TPS) (Panther, Prowess Inc., Chico, CA). JO-IMRT dose distributions of AAPM TG-119 were calculated by the TPS and were recalculated by MC simulation. The DVHs and 3D gamma index using global methods implemented in the PTW-VeriSoft with 3%/3 mm were used for evaluation. JO-IMRT dose distributions calculated by TPS and MC were matched the TG-119 goals. The gamma index passing rates with 3%/3 mm were 98.7% for multi-target, 96.0% for mock prostate, 95.4% for mock head-and-neck, and 96.6% for C-shape. The dose in the planning target volumes (PTV) for TPS was larger than that for the MC. The relative dose differences in D99 between TPS and MC for multi-target are 1.52%, 0.17% and 1.40%, for the center, superior and inferior, respectively. The differences in D95 are 0.16% for C-shape; and 0.06% for mock prostate. Mock head-and-neck difference is 0.40% in D99. In contrast, the organ curve for TPS tended to be smaller than MC values. JO-IMRT dose distributions for the AAPM TG-119 calculated by the TPS agreed well with the MC.

Application of AAPM TG119 to evaluate the Intensity-Modulated radiotherapy (JO-IMRT) plan on the Prowess Panther treatment planning system

Intensity-modulated radiation therapy (IMRT), one of the modern radiotherapy techniques, is one of the most common treatments for cancer. IMRT technique can deliver higher doses to tumor and reduces the minimum dose to normal tissue. Because IMRT technique is more complex than the 3D-CRT techniques, IMRT is potential to underdose the tumor and overdose the nearby critical structures. The American Association of Physicists in Medicine (AAPM) published the TG119 report, including tests and the quality assurance QA process with the aim of to assessing the overall accuracy of planning and delivery of IMRT treatments. The purpose of this research was to study and apply TG119 to evaluate the Prowess Panther planning (TPS) system for JO-IMRT plan at Dong Nai General Hospital with 4 test cases of TG119. Four test cases of TG119 were carried out on the Prowess Panther planning (TPS) system the obtained results were compared to those results of other authors. The results showed that only the prostate plan met 100% of the dose requirements prescribed by TG119, the other plans were relatively appropriate and still met most of the requirements of TG119. From these results, we concluded that Prowess Panther was a good for JO-IMRT.

Verifying the accuracy of 3D-CRT dose distributions calculated by the Prowess Panther treatment planning system (TPS) with Monte Carlo (MC) simulation for head-and-neck (H&amp;N) patients

The purpose of this study is to verify and compare the three Dimensional Conformal Radiation Therapy (3D-CRT) dose distributions calculated by the Prowess Panther treatment planning system (TPS) with Monte Carlo (MC) simulation for head-and-neck (H&amp;N) patients. In this study, we used the EGSnrc Monte Carlo code which includes BEAMnrc and DOSXYZnrc programs. Firstly, the clinical 6 MV photon beams form Siemens Primus linear accelerator at Dong Nai General Hospital were simulated using the BEAMnrc. Secondly, the absorbed dose to patients treated by 3D-CRT was computed using the DOSXYZnrc. Finally, the simulated dose distributions were then compared with the ones calculated by the Fast Photon Effective algorithm on the TPS, using the relative dose error comparison and the gamma index using global methods implemented in PTW-VeriSoft with 3%/3 mm. There is a good agreement between the MC and TPS dose. The average gamma passing rates were 92.8% based on the 3%/3 mm. The average dose in the PTV agreed well between the TPS with 0.97% error. MC predict dose was higher than the mean dose to the parotid glands and spinal cord compared to TPS. We have implemented the EGSnrc-based Monte Carlo simulation to verify the 3D-CRT plans generated by Prowess Panther TPS. Our results showed that the TPS agreed with the one of MC.&#x0D;

Dosimetric evaluation of lung treatment plans produced by the Prowess Panther system using Monte Carlo simulation

Purpose: This study evaluated the accuracy of lung dose calculation done by the fast photon effective (FPE) and the collapsed cone convolution (CCC) algorithms of the Prowess Panther treatment planning system (TPS) using Monte Carlo (MC) simulation. Materials and methods: A set of treatment plans of test cases including an acrylic phantom, the QUASAR multi-purpose body phantom, and one lung cancer patient, were created the system to assess the accuracy of the FPE and CCC algorithms. The DICOM-RT files of the plans were imported to the EGSnrc-based Monte Carlo simulation for dose calculations. The plans generated by the TPS and Monte Carlo simulation were compared using relative dose error comparison and 3D gamma index. The gamma index, using global methods, was implemented in PTW-VeriSoft with 3%/3 mm, 2%/2 mm criteria. Results: There was a good agreement between Monte Carlo-simulated and TPS-calculated doses for both the QUASAR multi-purpose body phantom and one lung cancer patient. However, discrepancies for the FPE algorithm were found to be 10% in the inhomogeneous medium such as the lung. Conclusions: The FPE algorithm may not accurately predict the dose distributions in and near the inhomogeneous structures. Monte Carlo simulation and CCC algorithm are more accurate than the FPE algorithm in calculating the dose in an inhomogeneous medium. The FPE and CCC algorithms must be validated before clinical implementation of the system.

Evaluation of the effect of dental filling material on IMRT treatment planning in patient with nasopharyngeal cancer

Introduction: Presence of dental filling material (DFM) such as amalgam in treatment patient with nasopharyngeal cancer (NPC) is common. Streaking artifact Arising from this high density material in computed tomography (scan), may lead to perturbation in dose calculation and dose delivery. Widespread performance of intensity-modulated radiotherapy (IMRT) for NPC using anterior beams that pass through the part severely affected by artefacts prior to reaching the target volume, raise concern about the effect of dental amalgam. This study quantifies the effect of dental amalgam on dose distribution target volume and organ at risk, normal tissue complication probability (NTCP) and tumor control probability (TCP). Materials and Methods: IMRT optimization two groups of 15 early-stage NPC patients with or without dental amalgam by prescribe 70 Gy to planning target volume performed by using the prowess panther treatment planning system. We used one plan nine field arrangement (F9E) and three plan of seven field (F7, F7E, F7P) arrangement with different angle. The dose volume histograms (DVHs), monitor units (MUs), Homogeneity index (HI), conformity index (CI) and TCP of PTVs, NTCP spinal cord, brain stem and parotid gland were analyzed. Results: Mean dose PTV in F7, FVE, F7P and F9E plan were 71.25±1.55, 72.06±0.96, 71.65 ±1.28 and 71.82±0.53 respectively in patients with DFM and 71.52±1.02, 71.51 ± 0.61, 71.30 ± 0.61 and 71.95 ± 0.80 in patient without DFM, Showing slight increase in mean dose of target volume. V95 of PTV shows insignificant different in two group. Mean TCP in F7, FVE, F7P and F9E plan were 95.06±0.45%, 95.18±0.54%, 94.93 ±0.68% and 95.05±0.42% in patient with DFM and 94.86±0.62%, 94.74 ± 0.43%, 94.80 ± 0.58% and 95.50 ± 0.40% in patient without DFM that shows insignificant different in two group. Mean HI of PTV-70 in four plans in presence of DFM shows a slight decrease compared than the other. Mean and maximum dose Spinal cord, brain stem and parotid and their NTCP in presence of DFM show a slight decrease. Conclusion: According to the results, dental amalgam led to slight increase in TCP, mean dose target volume and slight decrease in mean dose some OARs and their NTCP. Average dose target volume and some organ at risk that consider for this study demonstrates no meaningful difference exist in DVH and biological parameter in two group of patient.

Evaluation of Thyroid Gland Irradiation in Women with Breast Cancer during Radiotherapy with different Radiation Energies at Supraclavicular Region

Introduction: During treatment of breast cancer, Radiotherapy to the Supraclavicular fossa region results in absorption of radiation by the thyroid gland and consequently leads to hypothyroidism in 40% of patients. The aim of this study was to compare thyroid gland radiation absorption during radiotherapy with different anterior-posterior beam radiation of 6-15 and 15-15 MV photon beam energies. Materials and Methods: 29 patients with breast cancer were recruited to this study. Adjuvant radiotherapy with a total dose of 50 Gy was performed for each participant. Thyroid gland dosimetric measurements were evaluated including, mean dose, minimum and maximum dose, and V20, V30, V40, and V50 (percentage of thyroid volume receiving ≥20 Gy, ≥30 Gy, ≥40 Gy, and ≥50 Gy, respectively). The irradiation delivered doses were measured using Prowess Panther treatment planning system (Version 5.5). All data were evaluated using SPSS software. Results: 29 subjects with mean age of 53.4±9.4 were studied. According to the obtained results, at 15- 15 MV energies, a significantly lower dose was absorbed by the thyroid gland, was observed in contrast to their counterparts who were treated with 6-15 MV photon beam energies. Conclusion: Using 15-15 MV photon beam energies field can significantly reduce the absorbed dose to the thyroid gland and consequently can reduce the risk of developing hypothyroidism in breast cancer patients treated with radiotherapy.

Comparing different techniques of Post Axillary field in Breast Cancer Treatment

As we know breast cancer is the second death reason in Iran. One step of treatment process is radiotherapy, which needs careful consideration of contouring and therapeutic techniques Lung, thyroid, spinal cord, trachea and humerus are sensitive organs in breast cancer radiation therapy. The most clinical studies recommended two ways for delivering 95 percent of dose to supraclavicular and axillary nodes, one of them is an anterior field with a posterior axillary boost (AP-PAB) technique for the axillary lymph nodes and supraclavicular treatment and another one is an anterior to posterior parallel pair (AP-PA) technique, at Reza Radiotherapy and Oncology Center in Mashhad an anterior to posterior parallel pair (AP-PA) technique was used. The aim of this study is comparing and evaluating delivered dose for all organs in these techniques. The study population comprised breast cancer patient in Reza Radiation and Oncology Center (2016). Prowess panther version 5.2 was used as a treatment planning software. Plans for 20 breast cancer cases were done with (AP-PAB) technique and (AP-PA) technique. In each techniques delivered dose was investigated for lung, spinal cord, humerus, thyroid, trachea, supraclavicular lymph node, axillary lymph node and the hot spot. Organ at risk and nodes delivered dose were compared. By comparing two technique dose volume histogram for each breast cancer case, based on the analysis of data collected by software SPSS (p value=0.7 for average dose at 30% of lung volume, p value=0.2 for average dose at 95% of axillary lymph nodes volume, p value=0.8 for average dose at thyroid, p value=0.8 for average dose at humerus, p value=0.6 for average dose at trachea, p value=0.5 for average of maximum dose at spinal cord and p value=0.08 for average dose at 95% of supraclavicular lymph nodes volume. According to the results there is not significant difference between these techniques because p value is higher than 0.05 for all organs in the other hand average dose at 30% of lung volume is 2% lower in (AP- PAB) technique, average dose at thyroid is 1% lower in (AP-PAB) technique, average dose at trachea is 4% lower and average of maximum dose at spinal cord is 4% lower in (AP-PAB) technique. Average dose at 95% of axillary lymph nodes volume is 0.9% higher in (AP-PAB) technique also average dose at 95% of supraclavicular lymph nodes volume is 1.2% higher and average dose at humerus is 1.7% lower in (AP-PA) technique. This study shows (AP- PAB) technique is acceptable for patients with critical conditions (cases with high dose constrain of organ at risk.

Dosimetric and Monte Carlo verification of jaws-only IMRT plans calculated by the Collapsed Cone Convolution algorithm for head and neck cancers.

The aim of this study is to verify the Prowess Panther jaws-only intensity modulated radiation therapy (JO-IMRT) treatment planning (TP) by comparing the TP dose distributions for head-and-neck (H&N) cancer with the ones simulated by Monte Carlo (MC). To date, dose distributions planned using JO-IMRT for H&N patients were found superior to the corresponding three-dimensional conformal radiotherapy (3D-CRT) plans. Dosimetry of the JO-IMRT plans were also experimentally verified using an ionization chamber, MapCHECK 2, and Octavius 4D and good agreements were shown. Dose distributions of 15 JO-IMRT plans of nasopharyngeal patients were recalculated using the EGSnrc Monte Carlo code. The clinical photon beams were simulated using the BEAMnrc. The absorbed dose to patients treated by fixed-field IMRT was computed using the DOSXYZnrc. The simulated dose distributions were then compared with the ones calculated by the Collapsed Cone Convolution (CCC) algorithm on the TPS, using the relative dose error comparison and the gamma index using global methods implemented in PTW-VeriSoft with 3%/3mm, 2%/2mm, 1%/1mm criteria. There is a good agreement between the MC and TPS dose. The average gamma passing rates were 93.3±3.1%, 92.8±3.2%, 92.4±3.4% based on the 3%/3mm, 2%/2mm, 1%/1mm criteria, respectively. According to the results, it is concluded that the CCC algorithm was adequate for most of the IMRT H&N cases where the target was not immediately adjacent to the critical structures.

A Feasibility Study of IMRT of Lung Cancer Using Gafchromic EBT3 Film

Intensity modulated radiation therapy (IMRT) is an advanced method for delivery of three dimensional therapies, which provides optimal dose distribution with giving multiple nonuniform fluency to the patient. The complex dose distribution of IMRT should be checked to ensure that the accurate dose is delivered. Today, film dosimetry is a powerful tool for radiotherapy treatment Quality Assurance (QA) and a good method to verify dose distribution in phantoms. This study aimed to evaluate the accuracy of IMRT treatment planning system, Prowess Panther® software, with Gafchromic EBT3 films in a inhomogeneity phantom. The IMRT plan was generated by Prowess Panther® treatment planning system (TPS) version 5.2 on a inhomogeneity phantom, then it was irradiated by ONCOR linear accelerator (Linac) with 6 (MV) photon beam energy. The Gafchromic EBT3 film located between the phantom has measured the dose distribution. To compare between TPS calculated doses and film measured doses, Gamma criteria 3%/3 mm, 4%/4 mm, 5%/5 mm, 6%/6 mm and 7%/7 mm Dose Difference (DD) and Distance to Agreement (DTA), respectively were used. Gammas passing rates for PTV are obtained 67.5% for 3%/3mm, 78.8% for 4%/4mm, 86.3% for 5%/5mm, 91.2% for 6%/6mm and 94.3% for 7%/7mm and for organs at risk is 72.4% for 3%/3mm, 82.8% for 4%/4mm, 89.8% for 5%/5mm, 93.3% for 6%/6mm and 95.4% for 7%/7mm (respectively DD/DTA). By increasing the range of criteria the capability increased. The results show that the use of EBT3 film in a inhomogeneity phantoms allows us to evaluate the dose differences between the EBT3 measured dose distribution and TPS calculated dose distribution .Hence, a result Prowess Panther® TPS can be used for IMRT technique treatment.

Evaluating dose to thyroid gland in women with breast cancer during radiotherapy with different radiation energies at supraclavicular fossa region

AbstractBackground and aimDuring the treatment of breast cancer, radiotherapy to the supraclavicular fossa region results in absorption of radiation by the thyroid gland and consequently leads to hypothyroidism in 40% of patients. The aim of this study was to compare thyroid gland radiation absorption during radiotherapy with different anterioposterior beam radiation of 6–15 and 15–15 MV photon beam energies.Materials and methodsIn total, 29 patients with breast cancer were recruited to this study. Adjuvant radiotherapy with a total dose of 50 Gy was performed for each participant. Thyroid gland dosimetric measurements were evaluated including, mean dose, minimum and maximum dose, and V20, V30, V40 and V50 (percentage of thyroid volume receiving ≥20, ≥30, ≥40 and ≥50 Gy, respectively). The irradiation delivered doses were measured using Prowess Panther treatment planning system (Version 5.5). All data were evaluated using SPSS software.ResultsIn total, 29 subjects with mean age of 53·4±9·4 were studied. According to the obtained results, at 15–15 MV energies, a significantly lower dose was absorbed by the thyroid gland, was observed in contrast to their counterparts who were treated with 6–15 MV photon beam energies.FindingsUsing 15–15 MV photon beam energies field can significantly reduce the absorbed dose to the thyroid gland and consequently can reduce the risk of developing hypothyroidism in breast cancer patients treated with radiotherapy.

Planning comparison between intensity modulated radiation therapy and intensity modulated proton therapy in a case of head and neck cancer

In this work, we made the comparison between IMRT plan and IMPT plan for a head and neck case. We used Prowess Panther to perform IMRT plan and LAP- CERR for IMPT plan. The result showed that IMPT plan had better coverage than IMRT plan. In the IMRT plan, normal structures received higher dose with higher volume. Especially, the maximum dose of spinal cord is 31.5 Gy (RBE) using IMRT technique compared to 13.5 Gy (RBE) using IMPT technique. These results showed that IMPT is beneficial for head and neck cancer compared to IMRT technique.

Imaging and Dosimetric Consideration for Titanium Prosthesis Implanted within the Irradiated Region by Cobalt-60 Teletherapy Unit

The aim of this research is to observe dose distributions in the vicinity of titanium prosthetic implants during radiotherapy procedures on 60Co teletherapy machine, Prowess Panther treatment planning system (TPS). Data were obtained using a locally fabricated tissue equivalent phantom CT images with titanium prosthesis which was irradiated with 60Co gamma radiation. Prowess TPS (1.25 MeV) estimated less variations. Proximal ends of the metal recorded slight increase in doses as a result of backscatter with dose increment below acceptable tolerance of ±3%. Doses measured decreases on the distal side of the prosthesis at a distance less than dmax from the plate on each beam energy. The depth dose increases marginally after a certain depth level which generally originated from the unperturbed dose due to increase in the electron fluence. The percentage of depth doses decrease with the increase in plate thickness. A reduction in the above trend was also noticed with an increase in beam energy primarily because scattered photons are more forwardly directed. Prowess TPS (convolution superposition algorithm) was found to be better at reducing dose variation when correction for artifact. Manual calculations on blue phantom data agree with results from Prowess. This treatment system is capable of simulating dose around titanium prosthesis as its range of densities, 0.00121 to 2.83, excludes titanium density (rED for titanium is 3.74).

Assessment the accuracy of dose calculation in build-up region for two radiotherapy treatment planning systems.

Our objective is to quantify dose calculation accuracy in the build-up region using TiGRT and Prowess Panther treatment planning systems (TPSs). Thermoluminescent dosimeter-100 chips were used in a phantom for dose measurement. TiGRT Version 1.2 (LinaTech, Sunnyvale, CA, USA) and Prowess Panther version 5.1 (Prowess Inc., Concord, CA, USA) TPSs were also used for dose calculations. Finally, the confidence limit values obtained to quantify dose calculation accuracy of the TPSs at build-up region for different field sizes and various gantry angles. For 8 cm × 10 cm, 10 cm × 10 cm, and 15 cm × 10 cm field sizes, the confidence limit values for TiGRT TPS were 16.64, 16.56, and 25.85; for Prowess TPS with fast photon effective (FPE) algorithm were 15.17, 14.22, and 9.73; and for Prowess TPS with collapsed cone convolution superposition (CCCS) algorithm were 10.53, 9.97, and 9.76, respectively. For wedged field with gantry angles of 15°, 30°, and 60°, the confidence limit values for TiGRT TPS were 12.11, 12.96, and 22.69 and for Prowess TPS with FPE algorithm were 24.50, 22.07, and 7.82, respectively. It is concluded that for open field sizes without gantry angulation, dose calculation accuracy in Prowess TPS with CCCS algorithm is better than TiGRT and Prowess TPSs with FPE algorithm. Furthermore, it is concluded that for wedged field with large gantry angle, dose calculation accuracy of Prowess TPS with FPE algorithm is better than TiGRT TPS while, for medium and small gantry angles, dose calculation accuracy of TiGRT TPS is better than Prowess TPS with FPE algorithm.

Application of Monte-Carlo Code to dose distribution calculation in a case of lung cancer by the emitted photon beams from Linear Accelerator

The dose distribution calculation is one of the major steps in radiotherapy. In this paper the Monte Carlo code MCNP5 has been applied for simulation 15MV photon beams emitted from linear accelerator in a case of lung cancer of the General Hospital of Kien Giang. The settings for beam directions, field sizes and isocenter position used in MCNP5 must be the same as those in treatment plan at the hospital to ensure the results from MCNP5 are accurate. We also built a program CODIM by using MATLAB­® programming software. This program was used to construct patient model from lung CT images obtained from cancer treatment cases at the General Hospital of Kien Giang and then MCNP5 code was used to simulate the delivered dose in the patient. The results from MCNP5 show that there is a difference of 5% in comparison with Prowess Panther program – a semi-empirical simulation program which is being used for treatment planning in the General Hospital of Kien Giang. The success of the work will help the planners to verify the patient dose distribution calculated from the treatment planning program being used at the hospital.

SU‐E‐T‐481: In Vivo and Post Mortem Animal Irradiation: Measured Vs. Calculated Doses

Purpose:Computerized radiation therapy treatment planning is performed on almost all patients today. However it is seldom used for laboratory irradiations. The first objective is to assess whether modern radiation therapy treatment planning (RTP) systems accurately predict the subject dose by comparing in vivo and decedent dose measurements to calculated doses. The other objective is determine the importance of using a RTP system for laboratory irradiations.Methods:5 MOSFET radiation dosimeters were placed enterically in each subject (2 sedated Rhesus Macaques) to measure the absorbed dose at 5 levels (carina, lung, heart, liver and rectum) during whole body irradiation. The subjects were treated with large opposed lateral fields and extended distances to cover the entire subject using a Varian 600C linac. CT simulation was performed ante‐mortem (AM) and post‐mortem (PM). To compare AM and PM doses, calculation points were placed at the location of each dosimeter in the treatment plan. The measured results were compared to the results using Varian Eclipse and Prowess Panther RTP systems.Results:The Varian and Prowess treatment planning system agreed to within in +1.5% for both subjects. However there were significant differences between the measured and calculated doses. For both animals the calculated central axis dose was higher than prescribed by 3–5%. This was caused in part by inaccurate measurement of animal thickness at the time of irradiation. For one subject the doses ranged from 4% to 7% high and the other subject the doses ranged 7% to 14% high when compared to the RTP doses.Conclusions:Our results suggest that using proper CT RTP system can more accurately deliver the prescribed dose to laboratory subjects. It also shows that there is significant dose variation in such subjects when inhomogeneities are not considered in the planning process.