International Journal of Cancer Therapy and Oncology
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Analysis of low dose level volumes in intensity modulated radiotherapy and 3-D conformal radiotherapy
Get PDFPurpose: To analyze the low dose volume regions in four facets: Analysis 1: low dose volume regions were compared between 3-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT) plans for each case; Analysis 2: the effect on low dose volume in 3DCRT as the number of fields are increased; Analysis 3: the same effect in IMRT, and Analysis 4: above two analysis were inter-compared between the two modalities. Methods: For this work 18 patients were taken for which both 3DCRT and IMRT plans with varying number of beams were planned using Anisotropic Analytical Algorithm (AAA) in Eclipse 10 Version Treatment Planning System with two to nine beams and five to nine beams, respectively. The plans were analyzed on the basis of conformity index and dose to the critical structures.Results: In Analysis 1, 5 Gy volume region was greater for IMRT than for 3DCRT but the 10 Gy, 15 Gy and 20 Gy volume regions were smaller for IMRT plans. In Analysis 2 and 3 shows that as the number of fields increases the low dose volume regions also increases. In Analysis 4, the effect pronounced due to increase in the beam portals is similar in 3DCRT as well as IMRT. Also it was seen that with same number of beams for both IMRT and 3DCRT, low dose volume region is higher in 3DCRT than IMRT. Conclusion: Low dose volume regions are a major concern in 3DCRT and IMRT plans with multiple beams because of its risk of secondary cancer incidence. This study concludes that by increasing number of beams low dose volume regions increases in 3DCRT and IMRT. It shows that the low dose volume regions are slightly higher in IMRT than 3DCRT, however with proper optimization the volume of tissue receiving 10 Gy, 15 Gy and 20 Gy can be reduced.-----------------------Cite this article as: Ekambaram V, Velayudham R. Analysis of low dose level volumes in intensity modulated radiotherapy and 3-D conformal radiotherapy. Int J Cancer Ther Oncol 2014; 2(3):02032. DOI: 10.14319/ijcto.0203.
Evaluation of the peripheral dose and the conformity index for three stereotactic radiotherapy techniques: Arcs, noncoplanar fixed fields and intensity modulation
Get PDFPurpose: The main aim of this work is to compare the conformity index and the peripheral doses absorbed during stereotactic treatment of a brain lesion delivered using three stereotactic techniques; Arcs, noncoplanar fixed conformal fields (3DCRT) and intensity modulation (IMRT). Methods: Ten patients with brain lesions who were previously treated with Stereotaxy radiosurgery (SRS) using the cones (Arcs technique), were re-planned both non-coplanar 3D Conformal fixed fields (3DCRT) and non-coplanar intensity modulated radiotherapy fixed fields (IMRT) with the same arrangement and orientation of the fields as the Arcs technique. To facilitate direct comparison between the competing techniques, the primary planning object was to cover 95% of the volume of PTV by 95% of the prescribed dose (1200 cGy). Results: The IMRT technique shows the highest dose conformity, Arcs technique is the next homogeneity followed by 3DCRT. The differences were statistically significant among the three different techniques (P < 0.01) for PITV (defined as the ratio of the prescription isodose volume (PI) and Target Volume (TV)) and Conformal Number (CN). The mean integral dose using the 3 different techniques for all studied patients were: 2.44 ± 0.36J, 2.31 ± 0.37J and 2.6 ± 0.37J in the Arcs, IMRT and 3DCRT techniques respectively, the differences were not statistically significant (p = 0.326). The results show that Arcs technique has the lowest volume of the body that received 2 Gy, IMRT is the next followed by 3DCRT and IMRT technique has the lowest volume of the body that received 5 Gy, Arcs technique is the next followed by 3DCRT. The differences were not statistically significant p = 0.126 for V2 and p = 0.118 for V5, but these differences might be clinically significant that need more clinical discussion and investigation. IMRT plan delivery time almost has two folded more than the two others techniques, and the arc the technique has the lowest estimated time compared to both IMRT and Conformal techniques. The differences were statistically significant (P < 0.01). Conclusion: The conformity index, dose homogeneity and the outfield dose are important aspects of plan quality, although they do not always receive clinically attention. Our results have been showed that the superiority of the IMRT in conformity, dose homogeneity and the lowest volume that received 5 Gy, Arcs technique has the superiority in lower treatment delivery time than IMRT and the lowest volume that received 2 Gy. The 3DCRT don't present a significant advantage among the competing techniques. Oncologist should be alert of the possibility of significantly increasing the secondary cancer risk particularly for pediatric patients, because children are more susceptible to the risk of second cancers.---------------------------------------Cite this article as: Ammar H, Eldebawy E, Maarouf E, Khalil W, Zaghloul MS. Evaluation of the peripheral dose and the conformity index for three stereotactic radiotherapy techniques: Arcs, noncoplanar fixed fields and intensity modulation. Int J Cancer Ther Oncol 2014; 2(4):02042. DOI: 10.14319/ijcto.0204.
A dosimetric analysis of the aeroformTM tissue expander in radiation therapy
Get PDFPurpose: The aim of this study is to evaluate the effects of the metallic reservoir and the use of gas within the Aeroform™ tissue expander with respect to the radiation dose distribution.Methods: Dosimetric effects of using a metallic reservoir within a breast tissue expander during external beam radiotherapy were investigated. To view the internal components of the reservoir, it was removed from the tissue expander and imaged on a Varian AS500 electronic portal imager. To calculate the relative density of each component within the reservoir, an ionization chamber within solid water was used to measure the dose and compared to a simulation within the Pinnacle treatment planning system (TPS). To examine the relative dose profile along the length of the reservoir, the reservoir was exposed on EBT3 film and analyzed using SNC Patient™. In-vivo Dosimetry was performed using a RANDO® Woman phantom. Thermo-luminescent dosimeters were placed within the wax bolus enveloping the tissue expander.Results: Imaging the reservoir on the electronic portal imager revealed it consists of 3 distinct components. The densities assigned in the TPS, which resulted in calculated doses which matched the measured doses were; Section 1 = 0 g/cm3, Section 2 = 2.8 g/cm3 and Section 3 = 0.7 g/cm3. Relative dose reductions were observed due to the metallic case; Section 1 = 20%, Section 2 = 40% and Section 3 = 30%. Entrance doses ranged from 2.39 - 2.53 Gy for both the medial and lateral beams. Exit doses ranging from 1.10 - 1.71 Gy were observed in both beams. There was a significant difference in measured and calculated doses at exit locations in the beam.Conclusion: Dosimetric effects due to the metallic reservoir within the Aeroform breast tissue expander have been demonstrated and have been observed to be significant. To increase the dosimetric accuracy when contouring, individual components of the reservoir should be distinguished. Our in-vivo experiment showed that dose homogeneity was difficult due to the metallic reservoir and we recommend stringent patient dose monitoring when using this expander during radiotherapy.-----------------------------Cite this article as: Tran T, Ding W, Subramanian B, Melven L, Chao M, Farrow H, Baker C. A dosimetric analysis of the aeroformTM tissue expander in radiation therapy. Int J Cancer Ther Oncol 2014; 2(3):020316. DOI: 10.14319/ijcto.0203.1
Quality control test for electronic portal imaging device using QC-3 phantom with PIPSpro
Get PDFPurpose:A Quality control (QC) test suitable for routinely daily use has been established for electronic portal imaging device (EPID) using PIPSpro software version 4.4 (Standard Imaging, Middleton, WI). It provides an objective and quantitative test for tolerable image quality on the basis of the high contrast spatial resolution, the contrast-to-noise ratio (CNR) and noise.Methods: The test uses a QC-3 phantom consisting of five sets of high contrast rectangular bar patterns with spatial frequeinces of 0.10, 0.20, 0.25, 0.43 and 0.75 lp/mm using 6MV and 15MV photon energy for accquiring high quality images. A “base line” value for the relative square wave modulation transfer function (RMTF), CNR and Noise data was obtained during a one week calibration period and one month test period.Results: Subsequent measurements shows significant deviations from baseline values, resulting in warning messages “potential problems in system performance”. The QC test uses high contrast spatial resolution and CNR for the system with acceptable performance. Conclusion: The method provides an automatic, objective, and sensitive measure of the system's imaging performance. This is a useful implementation during acceptance testing, commissioning, and routine quality control
90Y PET/CT quantitative accuracy and image quality
Get PDFPurpose: To optimize 90Y-PET/CT image reconstruction for quantitative accuracy and optimal image quality.Methods: PET/CT scans of a NEMA IEC phantom (3GBq 90YCl2, sphere uptake ratio of ~7) were acquired on 4 GE (BGO:DSTE, DST & LYSO:DRX, D690) and 1 Siemens (LSO:mCT) scanners in 3D list mode with 30 min/bed; replayed to 20, 15, 10 min/bed. Iterative reconstruction parameters explored were SUB × IT (3 – 80) and post-reconstruction filters: transaxial: 5 – 25 mm cutoff & z-axis (GE only): std vs. heavy. The effects of PSF modeling and TOF correction were evaluated for D690 and mCT. VOIs were drawn inside spheres and in adjacent background regions. The accuracy of sphere activity concentration (AC in kBq/mL) and contrast to noise ratio (CNR) was calculated as function of SUB × IT. Reconstructed PET images were also evaluated qualitatively for sphere detectability and artifacts.Results: AC converged to 70 – 90% accuracy for 37 mm sphere and further degraded for smaller spheres. Spheres at max CNR might not reach AC convergence yet. Smaller spheres have slower convergence but reach CNR max together with other spheres. Scan duration did not strongly affect sphere convergence but shorter scans increased noise and reduced detectability; 13 mm spheres were not visible going from 30 to 15 min/bed. Heavy z-axis (GE) and transaxial filter with 10 – 15 mm cutoff helped suppress noise and increase sphere detectability at the expense of accuracy. Images with PSF+TOF corrections had higher sphere detectability and converged faster. Hot cluster artifacts 5 – 7 times the background were seen in some cases with SUB × IT near convergence and lower filtration.Conclusion: Accurate 90Y AC was not achieved even at convergence and noise is a major concern. 90YPET/CT reconstruction parameters are different than those for 18F and benefit substantially from PSF+TOF corrections. Optimum image quality and accurate AC may not be simultaneously achievable.----------------------------------------Cite this article as: Siman W, Mawlawi O, Kappadath SC. 90Y PET/CT quantitative accuracy and image quality. Int J Cancer Ther Oncol 2014; 2(2):020235. DOI: 10.14319/ijcto.0202.3
Utility of CT angiography in cervical spine trauma: analysis of radiation and cost
Get PDFPurpose: Vertebral artery injuries (VAIs) can be seen in cervical injuries. This investigation was conducted to assess the impact of head and neck computed tomography (CT) angiography (CTA) on planning treatment of vertebral artery injuries, if these tests were ordered appropriately, and to estimate cost and associated exposure to radiation and contrast material. Methods: This retrospective review included all patients who underwent CT of the cervical spine and CTA of the head and neck from March 2011 to October 2012 at a single institution. Patients were divided into two groups, those with and those without cervical spine fracture appreciated on CT of the cervical spine. The frequency of vascular injury on CTA in those with a cervical fracture was assessed. The frequency of vascular injury treatment and modifications owed to a positive CTA of head and neck were also assessed. A study was considered appropriate if it was ordered in accordance with the modified Denver Screening criteria. Effective radiation dose (mSv) was calculated by multiplying dose length product (DLP) from the scanner with the standard conversion coefficient (k) (k = 0.0021 mSv/mGy x cm).Results: In the 387 CTAs of head and neck, a cervical injury was recorded in 128 patients. Twenty CTA scans were correctly ordered for non-spinal indications, and 19 were ordered off protocol. CTA was found positive in 1 patient for whom the imaging was off protocol and 1 for whom the clinical indication was non-cervical. There were 19 positive CTA cases of head and neck, none of which underwent surgical intervention. CTA was positive in 13 of 48 patients who had suffered a C2 fracture; this accounted for 13 of the 19 positive CTA studies (p < 0.01). Estimated fee for CTA was $3783, and radiation exposure was 4 mSv with a standard deviation (±1.3). Conclusion: CTA of head and neck ordered off an institutional imaging protocol has a low probability of being positive. Adherence to protocols for CTA of head and neck can reduce costs and decrease unnecessary exposure to radiation and contrast medium.---------------------------------------Cite this article as:Shuaib W, Khan AA, Mehta AS, Vijayasarathi A, Hidalgo J. Utility of CT angiography in cervical spine trauma: analysis of radiation and cost. Int J Cancer Ther Oncol 2014; 2(4):02043. DOI: 10.14319/ijcto.0204.
Relapse of unusual localization of classic seminoma with post-chemotherapy transformation
Get PDFGerm cell tumor is the most common cancer among males in the 20–39 year-old age range, representing 21% of invasive cancer diagnose. The vast majority of testicular tumors in this age range are germ cell tumors. There are two types of malignant tumors, the pure seminoma cell and non-seminomatous germinal cell tumors (NGCT). We present the case of a patient who underwent a testicular tumor surgery, classic seminoma stage I, receiving two cycles of adjuvant carboplatin chemotherapy. During the follow up, an elevation on the alpha-fetoprotein level was observed, thus the final diagnosis was adenopatic recurrence of the Yolk Sac tumor.-----------------------------------------------------------------Cite this article as: Urena MD, Legeren M, Galvez F, Villaescusa A, Aparicio J, Jurado JM, Blancas I, Sanchez MJ, Romera AL, Martinez AP, Quiñonez E, Dulcey I, Puche JL. Relapse of unusual localization of classic seminoma with post-chemotherapy transformation. Int J Cancer Ther Oncol 2014; 2(1):02016.DOI: http://dx.doi.org/10.14319/ijcto.0201.
Measurement of exposure to personnel performing shielding evaluations
Get PDFPurpose: Determine the exposure to personnel accrued while performing shielding evaluations of diagnostic facilities.Methods: Shielding inspections were performed at three sites: a small animal imaging facility, an imaging center consisting of general x-ray, CT, and PET/CT rooms, and a cardiac catheterization lab. The small animal facility was evaluated using two 20 mCi Tc-99m uncollimated sources. The imaging center was evaluated using a 20 mCi source of F-18 for the PET/CT room and a collimated 25 mCi source of Tc-99m for the CT and x-ray rooms. The catheterization lab was evaluated using an uncollimated 35 mCi vial of Tc-99m. Electronic personal dosimeters (Rados RAD-60R, RADOS Technology Oy Turku, Finland) were worn by each of the personnel involved in performing shielding inspections. The cumulative exposure reading from the dosimeter for each surveyor was recorded.Results: The surveyor who positioned the open source at the small animal facility had an exposure reading of 3.5 mR in 5.5 hours. Those who were outside the room surveying the barriers had readings of 0 and 0.1 mR in 5 hours. For the cath lab, the surveyor positioning the source had a reading of 0.4 mR in 30 minutes, while those outside had readings of 0 mR. At the imaging center all personnel surveying the PET/CT room with an open F-18 source had readings of 2.0, 1.1, and 2.9 mR in 4 hours. Surveys of the CT and general radiography rooms with a collimated Tc-99m source had readings of 1.2, 0.9, and 0.2mR in 5 hours.Conclusion: The surveyors who were in the room with the sources had the highest exposures. Using a higher energy source (F-18) also led to higher exposures. By using a collimated source, the time to measure each barrier for penetrations was increased, but the surveyors’ exposures were lower.---------------------------------------Cite this article as: Page L, Dodge C, Li G, Wendt R. Measurement of exposure to personnel performing shielding evaluations. Int J Cancer Ther Oncol 2014; 2(2):020230. DOI: 10.14319/ijcto.0202.3
Investigating magnetic field dose effects in small animals: a Monte Carlo study
Get PDFPurpose: In MRI-linac treatments, radiation dose distributions are affected by magnetic fields, especially at high-density/low-density interfaces. Radiobiological consequences of magnetic field dose effects are presently unknown and preclinical studies are desirable. This study investigates the optimal combination of beam energy and magnetic field strength needed for preclinical murine studies.Methods: The Monte Carlo code MCNP6 was used to simulate the effects of a magnetic field when irradiating a mouse lung phantom with a 1.0 cm × 1.0 cm photon beam. Magnetic field dose effects were examined using various beam energies (225 kVp, 662 keV [Cs-137], and 1.25MeV [Co-60]) and magnetic field strengths (0.75 T, 1.5 T, and 3 T). The resulting dose distributions were compared to Monte Carlo results for humans with various field sizes and patient geometries using a 6MV/1.5T MRI-linac.Results: In human simulations, the addition of a 1.5 T magnetic field causes an average dose increase of 49% (range: 36% - 60%) to lung at the soft tissue-lung interface and an average dose decrease of 30% (range: 25% - 36%) at the lung-soft tissue interface. In mouse simulations, no magnetic field dose effects were seen with the 225 kVp beam. The dose increase for the Cs-137 beam was 12%, 33%, and 49% for 0.75 T, 1.5 T, and 3.0 T magnetic fields, respectively while the dose decrease was 7%, 23%, and 33%. For the Co-60 beam the dose increase was 14%, 45%, and 41%, and the dose decrease was 18%, 35%, and 35%.Conclusion: The magnetic field dose effects observed in mouse phantoms using a Co-60 beam with 1.5 T or 3 T fields or a Cs-137 beam with a 3T field fall within the range seen in humans treated with an MRI-linac. These irradiator/magnet combinations are therefore suitable for preclinical studies investigating potential biological effects of delivering radiation therapy in the presence of a magnetic field.---------------------------Cite this article as: Rubinstein A, Guindani M, Hazle JD, Court LE. Investigating magnetic field dose effects in small animals: a Monte Carlo study. Int J Cancer Ther Oncol 2014; 2(2):020233. DOI: 10.14319/ijcto.0202.3
Giant fibroadenoma of the breast in a pre-pubertal girl: a case report
Get PDFJuvenile fibroadenoma comprises about 4% of the total fibroadenomas. The incidence of giant juvenile fibroadenomas is merely 0.5% of all the fibroadenomas. Bilateral giant juvenile fibroadenomas are extremely rare. We are presenting a case of giant juvenile fibroadenomas in an 11-year-old pre-pubertal girl. The diagnosis was made on fine-needle aspiration cytology which was confirmed on histopathology. As these tumors are mostly benign, breast-conserving surgery is done so that patient can lead a normal life without psychological trauma.-----------------------------------Cite this article as: Goyal S, Garg G, Narang S. Giant fibroadenoma of the breast in a pre-pubertal girl: a case report. Int J Cancer Ther Oncol 2014; 2(1):020113.DOI: http://dx.doi.org/10.14319/ijcto.0201.1