bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comprehensive comparison study of three different planar IMRT QA techniques using MapCHECK 2
Authors: Keeling Vance P. , Ahmad Salahuddin , Jin Hosang 
Published: February 2017

The purpose of this study is to determine comparability of three different planar IMRT QA techniques: patient gantry angle composite (PGAC), single gantry angle composite (SGAC), and field by field (FBF), using MapCHECK 2 device and the γ test as performance metrics; and to assess the dependency of these techniques on intensity modulation, couch attenuation, and detector position (angular dependency). Ten highly modulated head and neck (H&N) and ten moderately modulated prostate IMRT validation plans were delivered using different techniques and were intercompared using the Student's t‐test. The IMRT QA measurements were evaluated by percentage of points passing the γ test for three different criteria: 1% (dose difference)/1 mm (distance to agreement (DTA)) (C1), 2%/2 mm (C2), and 3%/3 mm (C3). To investigate dependency of the IMRT validation on treatment couch, ionization chamber measurements, as well as the conventional MapCHECK 2 QAs, were performed with PGAC and PGAC‐WOC (without couch; using an extended tennis racket‐type insert with negligible attenuation assumed). To determine angular dependency of the MapCHECK 2, patient gantry field‐by‐field (PG‐FBF) technique was delivered and evaluated separately for each field. The differences of γ passing rates between SGAC and FBF were statistically insignificant, while these were statistically significant when compared to PGAC. SGAC and FBF techniques showed statistically insignificant differences between different levels of intensity modulation (H&N vs. Prostate) at C2 and C3 criteria, while PGAC could not for any criteria. The treatment couch has a significant impact on γ passing rates (PGAC vs. PGAC‐WOC), but an ionization chamber‐based IMRT validations showed clinically insignificant dose errors (< 2%) in all cases. This study showed that the MapCHECK 2 device has large angular dependency, especially at gantry angles of 90° and 270°, which dramatically affected the γ passing rates of PGAC. With proper consideration of couch attenuation and beam arrangement, the MapCHECK 2 will produce clinically comparable QA results using the three different planar IMRT QA techniques.PACS numbers: 87.55.km, 87.55.Qr, 87.56.Fc
A comparison of anatomical and dosimetric variations in the first 15 fractions, and between fractions 16 and 25, of intensity‐modulated radiotherapy for nasopharyngeal carcinoma*
Authors: Yang Haihua , Tu Yu , Wang Wei , Hu Wei , Ding Weijun , Yu Changhui , Zhou Chao 
Published: February 2017

The purpose of this study was to compare anatomical and dosimetric variations in first 15 fractions, and between fractions 16 and 25, during intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Twenty‐three NPC patients who received IMRT in 33 fractions were enrolled. Each patient had two repeat computed tomography (CT) scans before the 16th and 25th fraction. Hybrid IMRT plans were generated to evaluate the dosimetric changes. There was a significant decrease of the transverse diameter of nasopharyngeal and neck as well as gross tumor volume (GTV) in the primary nasopharyngeal carcinoma (GTVnx) and involved lymph nodes (GTVnd) during the first 15 fractions, and between fraction 16 and 25 . Consequently, there was a significant reduction of the percentage of the volume receiving the prescribed dose of CTV1 and GTVnd, which was more prominent after the first 15 fractions treatment compared to that between fraction 16 and 25 . Additionally, there was a significant increase in the mean dose (Dmean) and percentage of volume receiving to the bilateral parotid in the first 15 fractions , but not between fraction 16 and 25. While the maximum dose to the spinal cord was significantly increased both in the first 15 fractions, and between fraction 16 and 25 , the increase of the percent of spinal cord volume receiving was significantly higher in the first 15 fractions compared to that between fraction . Based on the dose constraint criterion in the RTOG0225 protocol, a total of phantom plan 1 (generated by applying the beam configurations of the original IMRT treatment plan to the anatomy of the second CT scan) and of phantom 2 (generated by applying the beam configurations of the replan 1 to the anatomy of the third CT scan) were out of limit for the dose to the normal critical structures. In conclusion, our data indicated that anatomic changes resulted in more predominant dosimetric effects in the first 15 fractions, and between fractions 16 and 25, of IMRT.PACS number: 87.53.Bn, 87.55.de, 87.55.Qr
Review of online educational resources for medical physicists
Authors: Prisciandaro Joann I. 
Published: February 2017

Medical physicists are often involved in the didactic training of graduate students, residents (both physics and physicians), and technologists. As part of continuing medical education, we are also involved in maintenance of certification projects to assist in the education of our peers. As such, it is imperative that we remain current concerning available educational resources. Medical physics journals offer book reviews, allowing us an opportunity to learn about newly published books in the field. A similar means of communication is not currently available for online educational resources. This information is conveyed through informal means. This review presents a summary of online resources available to the medical physics community that may be useful for educational purposes.PACS number: 87.10.‐e
Commissioning and validation of BrainLAB cones for 6X FFF and 10X FFF beams on a Varian TrueBeam STx
Authors: Wiant David B. , Terrell Jonathon A. , Maurer Jacqueline M. , Yount Caroline L. , Sintay Benjamin J. 
Published: February 2017

Small field dosimetry is a challenging task. The difficulties of small field measurements, particularly stereotactic field size measurements, are highlighted by the large interinstitution variability that can be observed for circular cone collimator commissioning measurements. We believe the best way to improve the consistency of small field measurements is to clearly document and share the results of small field measurements. In this work we report on the commissioning and validation of a BrainLAB cone system for 6 MV and 10 MV flattening filter‐free (FFF) beams on a Varian TrueBeam STx. Commissioning measurements consisted of output factors, percent depth dose, and off‐axis factor measurements with a diode. Validation measurements were made in a polystyrene slab phantom at depths of 5 cm, 10 cm, and 15 cm using radiochromic film. Output factors for the 6xFFF cones are 0.689, 0. 790, 0.830, 0.871, 0.890, and 0.901 for 4 mm, 6 mm, 7.5 mm, 10 mm, 12.5 mm, and the 15 mm cones, respectively. Output factors for the 10xFFF cones are 0.566, 0. 699, 0.756, 0.826, 0.864, and 0.888 for 4 mm, 6 mm, 7.5 mm, 10 mm, 12.5 mm, and the 15 mm cones, respectively. The full width half maximum values of the off‐axis factors agreed with the nominal cone size to within 0.5 mm. Validation measurements showed an agreement of absolute dose between calculation and plan of ≤ 3.6%, and an agreement of field sizes of ≤ 0.3 mm in all cases. Radiochromic film validation measurements show reasonable agreement with beam models for circular collimators based on diode commissioning measurements.PACS numbers: 87.53.Ly, 87.53.Bn, 87.56.nk, 87.55.D‐, 87.55.km
A two‐point scheme for optimal breast IMRT treatment planning
Authors: Yao Weiguang 
Published: February 2017

We propose an approach to determining optimal beam weights in breast/chest wall IMRT treatment plans. The goal is to decrease breathing effect and to maximize skin dose if the skin is included in the target or, otherwise, to minimize the skin dose. Two points in the target are utilized to calculate the optimal weights. The optimal plan (i.e., the plan with optimal beam weights) consists of high energy unblocked beams, low energy unblocked beams, and IMRT beams. Six breast and five chest wall cases were retrospectively planned with this scheme in Eclipse, including one breast case where CTV was contoured by the physician. Compared with 3D CRT plans composed of unblocked and field‐in‐field beams, the optimal plans demonstrated comparable or better dose uniformity, homogeneity, and conformity to the target, especially at beam junction when supraclavicular nodes are involved. Compared with nonoptimal plans (i.e., plans with nonoptimized weights), the optimal plans had better dose distributions at shallow depths close to the skin, especially in cases where breathing effect was taken into account. This was verified with experiments using a MapCHECK device attached to a motion simulation table (to mimic motion caused by breathing).PACS number: 87.55 de
Feasibility of using the Vero SBRT system for intracranial SRS
Authors: Burghelea Manuela , Verellen Dirk , Gevaert Thierry , Depuydt Tom , Poels Kenneth , Simon Viorica , Ridder Mark De 
Published: February 2017

The Vero SBRT system was benchmarked in a planning study against the Novalis SRS system for quality of delivered dose distributions to intracranial lesions and assessing the Vero system's capacity for SRS. A total of 27 patients with one brain lesion treated on the Novalis system, with 3 mm leaf width MLC and C‐arm gantry, were replanned for Vero, with a 5 mm leaf width MLC mounted on an O‐ring gantry allowing rotations around both the horizontal and vertical axis. The Novalis dynamic conformal arc (DCA) planning included vertex arcs, using 90° couch rotation. These vertex arcs cannot be reproduced with Vero due to the mechanical limitations of the O‐ring gantry. Alternative class solutions were investigated for the Vero. Additionally, to distinguish between the effect of MLC leaf width and different beam arrangements on dose distributions, the Vero class solutions were also applied for Novalis. In addition, the added value of noncoplanar IMRT was investigated in this study. Quality of the achieved dose distributions was expressed in the conformity index (CI) and gradient index (GI), and compared using a paired Student's t‐test with statistical significance for p‐values . For lesions larger than 5 cm3, no statistical significant difference in conformity was observed between Vero and Novalis, but for smaller lesions, the dose distributions showed a significantly better conformity for the Novalis mainly due to the smaller MLC leaf width. Using IMRT on Vero reduces this conformity difference to nonsignificant levels. The cutoff for achieving a GI around 3, characterizing a sharp dose falloff outside the target volume was 4 cm3 for Novalis and 7 cm3 for Vero using DCA technique. Using noncoplanar IMRT, this threshold was reduced to 3 cm3 for the Vero system. The smaller MLC and the presence of the vertex fields allow the Novalis system to better conform the dose around the lesion and to obtain steeper dose falloff outside the lesion. Comparable dosimetric characteristics can be achieved with Vero for lesions larger than 3 cm3 and using IMRT.PACS number: 87.55.D
Reproducibility of the external surface position in left‐breast DIBH radiotherapy with spirometer‐based monitoring
Authors: Fassi Aurora , Ivaldi Giovanni B. , Meaglia Ilaria , Porcu Patrizia , de Fatis Paola Tabarelli , Liotta Marco , Riboldi Marco , Baroni Guido 
Published: February 2017

Deep inspiration breath hold (DIBH) in left‐sided breast cancer radiotherapy treatments allows for a reduction in cardiac and pulmonary doses without compromising target coverage. The selection of the most appropriate technology for DIBH monitoring is a crucial issue. We evaluated the stability and reproducibility of DIBHs controlled by a spirometric device, by assessing the variability of the external surface position within a single DIBH (intra‐DIBH) and between DIBHs performed in the same treatment session (intrafraction) or in different sessions (interfraction). The study included seven left‐breast cancer patients treated with spirometer‐based DIBH radiotherapy. Infrared optical tracking was used to record the 3D coordinates of seven to eleven passive markers placed on the patient's thoraco‐abdominal surface during 29‐43 DIBHs performed in six to eight treatment sessions. The obtained results showed displacements of the external surface between different sessions up to 6.3 mm along a single direction, even at constant inspired volumes. The median value of the interfraction variability in the position of breast passive markers was 2.9 mm (range 1.9‐4.8 mm) in the latero‐lateral direction, 3.6 mm (range 2.2‐4.6 mm) in the antero‐posterior direction, and 4.3 mm (range 2.8‐6.2 mm) in the cranio‐caudal direction. There were no significant dose distribution variations for target and organs at risk with respect to the treatment plan, confirming the adequacy of the applied clinical margins (15 mm) to compensate for the measured setup uncertainties. This study demonstrates that spirometer‐based control does not guarantee a stable and reproducible position of the external surface in left‐breast DIBH radiotherapy, suggesting the need for more robust DIBH monitoring techniques when reduced margins and setup uncertainties are required for improving normal tissue sparing and decreasing cardiac and pulmonary toxicity.PACS number: 87.55.Km
Comparison of an anthropomorphic PRESAGE® dosimeter and radiochromic film with a commercial radiation treatment planning system for breast IMRT: a feasibility study
Authors: Iqbal Khalid , Gifford Kent A , Ibbott Geoffrey , Grant Ryan L , Buzdar Saeed Ahmad 
Published: February 2017

This work presents a comparison of an anthropomorphic PRESAGE® dosimeter and radiochromic film measurements with a commercial treatment planning system to determine the feasibility of PRESAGE® for 3D dosimetry in breast IMRT. An anthropomorphic PRESAGE® phantom was created in the shape of a breast phantom. A five‐field IMRT plan was generated with a commercially available treatment planning system and delivered to the PRESAGE® phantom. The anthropomorphic PRESAGE® was scanned with the Duke midsized optical CT scanner (DMOS‐RPC) and the OD distribution was converted to dose. Comparisons were performed between the dose distribution calculated with the Pinnacle3 treatment planning system, PRESAGE®, and EBT2 film measurements. DVHs, gamma maps, and line profiles were used to evaluate the agreement. Gamma map comparisons showed that Pinnacle3 agreed with PRESAGE® as greater than 95% of comparison points for the PTV passed a criterion when the outer 8 mm of phantom data were discluded. Edge artifacts were observed in the optical CT reconstruction, from the surface to approximately 8 mm depth. These artifacts resulted in dose differences between Pinnacle3 and PRESAGE® of up to 5% between the surface and a depth of 8 mm and decreased with increasing depth in the phantom. Line profile comparisons between all three independent measurements yielded a maximum difference of 2% within the central 80% of the field width. For the breast IMRT plan studied, the Pinnacle3 calculations agreed with PRESAGE® measurements to within the gamma criterion. This work demonstrates the feasibility of the PRESAGE® to be fashioned into anthropomorphic shape, and establishes the accuracy of Pinnacle3 for breast IMRT. Furthermore, these data have established the groundwork for future investigations into 3D dosimetry with more complex anthropomorphic phantoms.PACS number: 87.53.Jw, 87.55.D‐, 87.55.dk
Teflon cylindrical phantom for delivery quality assurance of SBRT
Authors: Lack Danielle W. , Kakakhel Ali , Starin Ross , Snyder Michael 
Published: February 2017

At our institution the standard delivery quality assurance (DQA) procedure for tomotherapy plans is accomplished with a water‐equivalent phantom, EDR2 film, and ion chamber point‐dose measurements. Most plans deliver at most 5 Gy to the dose plane; however, recently a stereotactic body radiotherapy (SBRT) protocol has produced plans delivering upwards of 12 Gy to the film plane. EDR2 film saturates at a dose of , requiring a modification of our DQA procedure for SBRT plans. To reduce the dose to the film plane and accommodate a possible move to SBRT using Varian RapidArc, a Teflon phantom has been constructed and tested. Our Teflon phantom is cylindrical in shape and of a similar design to the standard phantom. The phantom was MVCT scanned on the TomoTherapy system with images imported into the TomoTherapy and Varian Eclipse planning systems. Phantom images were smoothed to reduce artifacts for treatment planning purposes. Verification SBRT plans were delivered with film and point‐dose benchmarked against the standard procedure. Verification tolerance criteria were 3% dose difference for chamber measurements and a gamma pass rate for film (criteria: 3 mm DTA, 3% dose difference, 10% threshold). The phantom sufficiently reduced dose to the film plane for DQA of SBRT plans. Both planning systems calculated accurate point doses in phantom, with the largest differences being 2.4% and 4.4% for TomoTherapy and Rapid Arc plans. Measured dose distributions correlated well with planning system calculations (). These results were comparable to the standard phantom. The Teflon phantom appears to be a potential option for SBRT DQA. Preliminary data show that the planning systems are capable of calculating point doses in the Teflon, and the dose to the film plane is reduced sufficiently to allow for a direct measured DQA without the need for dose rescaling.PACS numbers: 87.56.‐V, 87.56.N‐, 87.55.‐X, 87.55.Qr.
First clinical implementation of the Capri applicator
Authors: Gloi Aime M. 
Published: February 2017

This study was to assess the Capri applicator for patients with endometrial cancer undergoing high‐radiation dose treatments following external‐beam radiation therapy. The Capri applicator is an inflatable vaginal cylinder with multiple channels. It is used to tailor the dose distribution to an asymmetric vaginal disease, and better spare organs at risk. Five patients with high‐risk endometrial cancer were selected for this study. The patients were treated with a high dose of radiation using the Capri applicator: daily fraction of 7 Gy was prescribed for a total dose of 21 Gy. The treatment plans included radiobiological parameters such as equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and tumor control probability (TCP). Based on the dose‐volume histograms (DVH), we also calculated four quality factors: conformity index (CI), dose homogeneity index (DHI), dose nonuniformity index (DNR), and overdose index (OI). The TCP values range from 82.26% to 95.92%. Very low values of NTCP were observed for the bladder and rectum. The EUDs to organs at risk ranged from 4.65 Gy to 18.22 Gy for the bladder, and from 3.41 Gy from to 6.56 Gy for the rectum. The mean CI was . The mean DNR was . The mean OI was . The DHIs were in the range of . The use of a multichannel vaginal cylinder may not only help cover extensive vaginal disease, but also reduce the dose to the rectum. This dosimetric analysis shows that rectal doses could be reduced using a multichannel cylinder. However, the dose delivered to the bladder based on EUD calculation may be higher than that obtained with other methods. Each patient must be evaluated independently to determine if a multichannel treatment is appropriate. Clinical followup will show whether this rectal dose sparing translates into a real toxicity improvement.PACS number: 3.6.96.0
Dosimetry of small bone joint calculated by the analytical anisotropic algorithm: a Monte Carlo evaluation using the EGSnrc
Authors: Chow James C. L. , Jiang Runqing , Owrangi Amir M. 
Published: February 2017

This study compared a small bone joint dosimetry calculated by the anisotropic analytical algorithm (AAA) and Monte Carlo simulation using megavoltage (MV) photon beams. The performance of the AAA in the joint dose calculation was evaluated using Monte Carlo simulation, and dependences of joint dose on its width and beam angle were investigated. Small bone joint phantoms containing a vertical water layer (0.5‐2 mm) sandwiched by two bones () were irradiated by the 6 and 15 MV photon beams with field size equal to . Depth doses along the central beam axis in a joint (cartilage) were calculated with and without a bolus () added on top of the phantoms. Different beam angles (0°‐15°) were used with the isocenter set to the center of the bone joint for dose calculations using the AAA (Eclipse treatment planning system) and Monte Carlo simulation (the EGSnrc code). For dosimetry comparison and normalization, dose calculations were repeated in homogeneous water phantoms with the bone substituted by water. Comparing the calculated dosimetry between the AAA and Monte Carlo simulation, the AAA underestimated joint doses varying with its widths by about 6%‐12% for 6 MV and 12%‐23% for 15 MV without bolus, and by 7% for 6 MV and 13%‐17% for 15 MV with bolus. Moreover, joint doses calculated by the AAA did not vary with the joint width and beam angle. From Monte Carlo results, there was a decrease in the calculated joint dose as the joint width increased, and a slight decrease as the beam angle increased. When bolus was added to the phantom, it was found that variations of joint dose with its width and beam angle became less significant for the 6 MV photon beams. In conclusion, dosimetry deviation in small bone joint calculated by the AAA and Monte Carlo simulation was studied using the 6 and 15 MV photon beam. The AAA could not predict variations of joint dose with its width and beam angle, which were predicted by the Monte Carlo simulations.PACS numbers: 87.55.K‐; 87.53.Bn; 87.53.‐j
The CT number accuracy of a novel commercial metal artifact reduction algorithm for large orthopedic implants
Authors: Hilgers Guido , Nuver Tonnis , Minken André 
Published: February 2017

Philips Healthcare released a novel metal artifact reduction algorithm for large orthopedic implants (O‐MAR). Little information was available about its CT number accuracy. Since CT numbers are used for tissue heterogeneity corrections in external beam radiotherapy treatment planning, we performed a phantom study to assess the CT number accuracy of O‐MAR. Two situations were simulated: a patient with a unilateral metallic hip prosthesis and a patient with bilateral metallic hip prostheses. We compared the CT numbers in the O‐MAR reconstructions of the simulations to those in the nonO‐MAR reconstruction and to those in a metal‐free baseline reconstruction. In both simulations, the CT number accuracy of the O‐MAR reconstruction was better than the CT number accuracy of the nonO‐MAR reconstruction. In the O‐MAR reconstruction of the unilateral simulation, all CT numbers were accurate within (AAPM criterion). In the O‐MAR reconstruction of the bilateral simulation, CT numbers were found that differed more than from the metal‐free baseline values. However, none of these differences were clinically relevant.PACS numbers: 87.57.Q‐, 87.57.cp