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Hip replacement is a common orthopedic surgery in the aging population. With the rising incidence of prostate cancer, metallic hip prosthetics can cause considerable beam hardening and streak artifacts, leading to difficulty in identifying the target volumes and planning process for radiation treatment. The growing use of Stereotactic Body Radiation Therapy (SBRT) to treat prostate cancer is now well established. However, the use of this treatment modality in the presence of a hip prosthesis is poorly understood. There is enough literature on planning for external beam radiation treatment without any difficulties in the presence of hip prosthesis with conventional or Hypofractionated treatment. However, there is a shortage of literature on the impact of the prosthesis in SBRT planning, and there is a need for further understanding and measures to mitigate the obstacles in planning for SBRT in the presence of hip prosthesis. We present our review of the intricacies that need to be understood while considering SBRT in the presence of hip prostheses in prostate cancer treatment.

Leptospirosis is frequently misdiagnosed as a result of its protean and nonspecific presentation. Leptospirosis, a zoonosis with global distribution, commonly occurs in tropical and subtropical regions; most reported cases in the United States occur in Hawaii. All laboratory-confirmed leptospirosis cases in the State of Hawaii from 1974 through 1998 (n = 353) were clinically evaluated. The most common presentation involved nonspecific signs or symptoms, including fever, myalgia, and headache. Jaundice occurred in 39% of cases; conjunctival suffusion was described in 28% of these cases. Initiation of antibiotics before the seventh day of symptoms was associated with a significantly shortened duration of illness. Because early recognition and initiation of antibiotic therapy are important, clinicians should familiarize themselves with the clinical presentation of leptospirosis, and when evaluating a patient with a febrile illness, they should obtain exposure and travel histories and entertain the possibility of leptospirosis in the differential diagnosis.

Knowledge‐based planning (KBP) can be used to estimate dose–volume histograms (DVHs) of organs at risk (OAR) using models. The task of model creation, however, can result in estimates with differing accuracy; particularly when outlier plans are not properly addressed. This work used RapidPlan™ to create models for the prostate and head and neck intended for large‐scale distribution. Potential outlier plans were identified by means of regression analysis scatter plots, Cook's distance, coefficient of determination, and the chi‐squared test. Outlier plans were identified as falling into three categories: geometric, dosimetric, and over‐fitting outliers. The models were validated by comparing DVHs estimated by the model with those from a separate and independent set of clinical plans. The estimated DVHs were also used as optimization objectives during inverse planning. The analysis tools lead us to identify as many as 7 geometric, 8 dosimetric, and 20 over‐fitting outliers in the raw models. Geometric and over‐fitting outliers were removed while the dosimetric outliers were replaced after re‐planning. Model validation was done by comparing the DVHs at 50%, 85%, and 99% of the maximum dose for each OAR (denoted as V50, V85, and V99) and agreed within −2% to 4% for the three metrics for the final prostate model. In terms of the head and neck model, the estimated DVHs agreed from −2.0% to 5.1% at V50, 0.1% to 7.1% at V85, and 0.1% to 7.6% at V99. The process used to create these models improved the accuracy for the pharyngeal constrictor DVH estimation where one plan was originally over‐estimated by more than twice. In conclusion, our results demonstrate that KBP models should be carefully created since their accuracy could be negatively affected by outlier plans. Outlier plans can be addressed by removing them from the model and re‐planning.

Purpose This case series represents an initial experience with implementing 3‐dimensional (3D) surface scanning, digital design, and 3D printing for bolus fabrication for patients with complex surface anatomy where traditional approaches are challenging. Methods and Materials For 10 patients requiring bolus in regions with complex contours, bolus was designed digitally from 3D surface scanning data or computed tomography (CT) images using either a treatment planning system or mesh editing software. Boluses were printed using a fused deposition modeling printer with polylactic acid. Quality assurance tests were performed for each printed bolus to verify density and shape. Results For 9 of 10 patients, digitally designed boluses were used for treatment with no issues. In 1 case, the bolus was not used because dosimetric requirements were met without the bolus. QA tests revealed that the bulk density was within 3% of the reference value for 9 of 12 prints, and with more judicious selection of print settings this could be increased. For these 9 prints, density uniformity was as good as or better than our traditional sheet bolus material. The average shape error of the pieces was less than 0.5 mm, and no issues with fit or comfort were encountered during use. Conclusions This study demonstrates that new technologies such as 3D surface scanning, digital design and 3D printing can be safely and effectively used to modernize bolus fabrication.

Background Single field Orthovoltage radiation is an acceptable modality used for the treatment of nasal cutaneous cancer. However, this technique has dosimetric pitfalls and unnecessary excessive exposure of radiation to organs at risk (OAR). We present the clinical outcome of a case series of cutaneous nasal tumours using a novel technique incorporating an optical scanner and a 3-dimensional (3D) printer to deliver treatments using parallel opposed (POP) fields. Materials and methods The POP delivery method was validated using ion chamber and phantom measurements before implementation. A retrospective chart review of 26 patients treated with this technique between 2015 and 2019 was conducted. Patients’ demographics and treatment outcomes were gathered and tabulated. These patients first underwent an optical scan of their faces to collect topographical data. The data were then transcribed into 3D printing algorithms, and positive impressions of the faces were printed. Custom nose block bolus was made with wax encased in an acrylic shell; 4 cm thick using the printed face models. Custom lead shielding was also generated. Treatments were delivered using 250 KeV photons POP arrangement with 4 cm diameter circle applicator cone and prescribed to the midplane. Dose and fractionation were as per physician discretion. Results Phantom measurements at mid-plane were found to match the prescribed dose within ±0.5%. For the 26 cases in this review, the median age was 78.5 years, with 15 females and 11 males. 85% of cases had Basal cell carcinoma (BCC); 1 had squamous cell carcinoma (SCC), one had synchronous BCC + SCC, and 1 had Merkel cell carcinoma. Twenty-one cases had T1N0 disease, 4 had T2N0, and 1 had T3N0. Dose and fractionation delivered were 40Gy in 10 fractions for the majority of cases. The complete response rate at a median follow-up of 6 months was 88%; 1 patient had a refractory tumour, and one patient had a recurrence. Toxicities were minor with 81% with no reported side effects. Three patients experienced grade 3 skin toxicity. Conclusions Utilization of optic scanner and 3D printing technology, with the innovative approach of using POP orthovoltage beams, allows an effective and efficient way of treatment carcinomas of the nose with a high control rate and low toxicity profiles.

The Canadian Organization of Medical Physicists (COMP), in close partnership with the Canadian Partnership for Quality Radiotherapy (CPQR) has developed a series of Technical Quality Control (TQC) guidelines for radiation treatment equipment. These guidelines outline the performance objectives that equipment should meet in order to ensure an acceptable level of radiation treatment quality. The TQC guidelines have been rigorously reviewed and field tested in a variety of Canadian radiation treatment facilities. The development process enables rapid review and update to keep the guidelines current with changes in technology. This announcement provides an introduction to the guidelines, describing their scope and how they should be interpreted. Details of recommended tests can be found in separate, equipment specific TQC guidelines published in the JACMP (COMP Reports), or the website of the Canadian Partnership for Quality Radiotherapy (www.cpqr.ca).

Deep Inspiration Breath Hold (DIBH) is a respiratory‐gating technique adopted in radiation therapy to lower cardiac irradiation. When performing DIBH treatments, it is important to have a monitoring system to ensure the patient's breath hold level is stable and reproducible at each fraction. In this retrospective study, we developed a system capable of monitoring DIBH breast treatments by utilizing cine EPID images taken during treatment. Setup error and intrafraction motion were measured for all fractions of 20 left‐sided breast patients. All patients were treated with a hybrid static‐IMRT technique, with EPID images from the static fields analyzed. Ten patients had open static fields and the other ten patients had static fields partially blocked with the multileaf collimator (MLC). Three image‐processing algorithms were evaluated on their ability to accurately measure the chest wall position (CWP) in EPID images. CWP measurements were recorded along a 61‐pixel region of interest centered along the midline of the image. The median and standard deviation of the CWP were recorded for each image. The algorithm showing the highest agreement with manual measurements was then used to calculate intrafraction motion and setup error. To measure intrafraction motion, the median CWP of the first EPID frame was compared with that of the subsequent EPID images of the treatment. The maximum difference was recorded as the intrafraction motion. The setup error was calculated as the difference in median CWP between the MV DRR and the first EPID image of the lateral tangential field. The results showed that the most accurate image‐processing algorithm can identify the chest wall within 1.2 mm on both EPID and MV DRR images, and measures intrafraction motion and setup errors within 1.4 mm.

Bolus, formed by a sheet of material, covers on tumors of patient skins to generate the desired dose distribution in a process of the high-energy radiotherapy. The existing methods of bolus shaping use a manual process to cut the commercial material into the shape, which can cause air gaps between the patient skin surface and bolus in the reduced effect of cancer care treatment. A method of automatic bolus shaping can improve the accuracy and reduce air gaps of bolus shaping, which uses a process of first segmenting 3D patient skin surface models into several patches and then unfolding the patches into 2D patterns for material cutting before folding the cut sheet into the bolus. However, air gaps between the bolus and patient skin surface cannot be directly evaluated to find the bolus accuracy. This paper proposes a method to improve model flattenability and evaluate the air gaps using a particle swarm optimizer (PSO). A 3D surface shape is unfolded only if the air gap and surface flattenability meet the requirement of accuracy. Otherwise, the surface will be segmented into several patches to improve the flattenability and reduce air gaps. The objective and constraint are identified to search for an optimal solution for the 3D surface with a high flattenability. A strategy of the dimension reduction is proposed for the selection of local nodes on a meshed surface to increase the searching efficiency of surface flattenability. A local node selection based PSO (L-PSO) method is developed to search for the optimal solution. The proposed method is verified in two case studies of bolus shaping.

Accurate tracking of organ motion during treatment is needed to improve the efficacy of radiation therapy. This work investigates the feasibility of tracking an uncontoured target using the motion detected within a moving treatment aperture. Tracking was achieved with a weighted optical flow algorithm, and three different techniques for updating the reference image were evaluated. The accuracy and susceptibility of each approach to the accumulation of position errors were verified using a 3D-printed tumor (mounted on an actuator) and a virtual treatment aperture. Tumor motion up to 15.8 mm (peak-to-peak) taken from the breathing patterns of seven lung cancer patients was acquired using an amorphous silicon portal imager at ~ 7.5 frames/s. The first approach (INI) used the initial image detected, as a fixed reference, to determine the target motion for each new incoming image, and performed the best with the smallest errors. This method was also the most robust against the accumulation of position errors. Mean absolute errors of 0.16, 0.32, and 0.38 mm were obtained for the three methods, respectively. Although the errors are comparable to other tracking methods, the proposed method does not require prior knowledge of the tumor shape and does not need a tumor template or contour for tracking.