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Purpose: A commercial proton eyeline has been developed to treat ocular disease. Radiotherapy of intraocular lesions (e.g., uveal melanoma, age-related macular degeneration) requires sharp dose gradients to avoid critical structures like the macula and optic disc. A high dose rate is needed to limit patient gazing times during delivery of large fractional dose. Dose delivery needs to be accurate and predictable, not in the least because current treatment planning algorithms have limited dose modeling capabilities. The purpose of this paper is to determine the dosimetric properties of a new proton eyeline. These properties are compared to those of existing systems and evaluated in the context of the specific clinical requirements of ocular treatments. Methods: The eyeline is part of a high-energy, cyclotron-based proton therapy system. The energy at the entrance of the eyeline is 105 MeV. A range modulator (RM) wheel generates the spread-out Bragg peak, while a variable range shifter system adjusts the range and spreads the beam laterally. The range can be adjusted from 0.5 up to 3.4 g/cm2; the modulation width can be varied in steps of 0.3 g/cm2 or less. Maximum field diameter is 2.5 cm. All fields can be delivered with a dose rate of 30 Gy/min or more. The eyeline is calibrated according to the IAEA TRS-398 protocol using a cylindrical ionization chamber. Depth dose distributions and dose/MU are measured with a parallel-plate ionization chamber; lateral profiles with radiochromic film. The dose/MU is modeled as a function of range, modulation width, and instantaneous MU rate with fit parameters determined per option (RM wheel). Results: The distal fall-off of the spread-out Bragg peak is 0.3 g/cm2, larger than for most existing systems. The lateral penumbra varies between 0.9 and 1.4 mm, except for fully modulated fields that have a larger penumbra at skin. The source-to-axis distance is found to be 169 cm. The dose/MU shows a strong dependence on range (up to 4%/mm). A linear increase in dose/MU as a function of instantaneous MU rate is observed. The dose/MU model describes the measurements with an accuracy of ±2%. Neutron dose is found to be 146 ± 102 μSv/Gy at the contralateral eye and 19 ± 13 μSv/Gy at the chest. Conclusions: Measurements show the proton eyeline meets the requirements to effectively treat ocular disease. [ABSTRACT FROM AUTHOR]

Proton therapy is an expanding radiotherapy modality in the United States and worldwide. With the number of proton therapy centers treating patients increasing, so does the need for consistent, high-quality clinical commissioning practices. Clinical commissioning encompasses the entire proton therapy system's multiple components, including the treatment delivery system, the patient positioning system, and the image-guided radiotherapy components. Also included in the commissioning process are the x-ray computed tomography scanner calibration for proton stopping power, the radiotherapy treatment planning system, and corresponding portions of the treatment management system. This commissioning report focuses exclusively on intensity-modulated scanning systems, presenting details of how to perform the commissioning of the proton therapy and ancillary systems, including the required proton beam measurements, treatment planning system dose modeling, and the equipment needed., (© 2020 American Association of Physicists in Medicine.)

Purpose: To develop a Web-based application (IHE-RO Helper) to allow comprehensive review of the interconnectivity and interoperability of various radiotherapy devices established through testing sanctioned by the Integrating Healthcare Enterprise-Radiation Oncology (IHE-RO)., Material and Methods: IHE-RO is an initiative sponsored by ASTRO to improve the way computer based systems in radiation oncology share information using well-defined data exchange standards (DICOM / HL7). At the IHE-RO Connectathon events over the last 4 years, 11 vendors with 14 different products have successfully tested and identified solutions to connectivity problems in treatment planning, simulation and delivery. Because the test results are highly technical, the interconnectivity issues amongst the RT devices may get overlooked by the end users. The IHE-RO helper tool is designed to operate in simple clinical terms with queries and presentations organized based on treatment techniques and clinical features that are familiar to the practitioners. For example, if you are planning to purchase a treatment planning system capable of generating plans (e.g. Stereotactic treatments) and are concerned whether the TPS can successfully transfer such data to your treatment management system (TMS) and subsequently to your treatment delivery system (TDS), the IHE-RO Helper can identify the connectivity requirements and list vendors that have successfully passed an IHE-RO Connectathon and validated their solution to the specific requirements., Results: The IHE-RO helper tool provides a graphical and textual user interface to effectively demonstrate the solved interconnectivity problems between TPS, TMS and TDS. A report is also provided that explains the interconnectivity problems and its solutions., Conclusions: The IHE-RO helper is an effective tool to clearly identify vendor products that are IHE-RO compliant, thereby encourages vendor participation in testing and validation. Such a tool will be invaluable in procurement of new equipment to ensure a priori interoperability with anticipated RT devices deployed in the clinic. This research and development project is supported by the Bankhead-Coley Cancer Research Program grant # RC1-09BW-09-26833., (© 2012 American Association of Physicists in Medicine.)

Purpose: The authors we evaluate the uncertainty in proton therapy dose distribution for prostate cancer due to organ displacement, varying penumbra width of proton beams, and the amount of rectal gas inside the rectum., Methods and Materials: Proton beam treatment plans were generated for ten prostate patients with a minimum dose of 74.1 cobalt gray equivalent (CGE) to the planning target volume (PTV) while 95% of the PTV received 78 CGE. Two lateral or lateral oblique proton beams were used for each plan. The authors we investigated the uncertainty in dose to the rectal wall (RW) and the bladder wall (BW) due to organ displacement by comparing the dose-volume histograms (DVH) calculated with the original or shifted contours. The variation between DVHs was also evaluated for patients with and without rectal gas in the rectum for five patients who had 16 to 47 cc of visible rectal gas in their planning computed tomography (CT) imaging set. The uncertainty due to the varying penumbra width of the delivered protons for different beam setting options on the proton delivery system was also evaluated., Results: For a 5 mm anterior shift, the relative change in the RW volume receiving 70 CGE dose (V70) was 37.9% (5.0% absolute change in 13.2% of a mean V70). The relative change in the BW volume receiving 70 CGE dose (V70) was 20.9% (4.3% absolute change in 20.6% of a mean V70) with a 5 mm inferior shift. A 2 mm penumbra difference in beam setting options on the proton delivery system resulted in the relative variations of 6.1% (0.8% absolute change) and 4.4% (0.9% absolute change) in V70 of RW and BW, respectively. The data show that the organ displacements produce absolute DVH changes that generally shift the entire isodose line while maintaining the same shape. The overall shape of the DVH curve for each organ is determined by the penumbra and the distance of the target in beam's eye view (BEV) from the block edge. The beam setting option producing a 2 mm sharper penumbra at the isocenter can reduce the magnitude of maximal doses to the RW by 2% compared to the alternate option utilizing the same block margin of 7 mm. The dose to 0.1 cc of the femoral head on the distal side of the lateral-posterior oblique beam is increased by 25 CGE for a patient with 25 cc of rectal gas., Conclusion: Variation in the rectal and bladder wall DVHs due to uncertainty in the position of the organs relative to the location of sharp dose falloff gradients should be accounted for when evaluating treatment plans. The proton beam delivery option producing a sharper penumbra reduces maximal doses to the rectal wall. Lateral-posterior oblique beams should be avoided in patients prone to develop a large amount of rectal gas.

Stereotactic angiography is the preferred imaging modality in the radiosurgical treatment of arteriovenous malformations (AVM). A major limitation of this technique is the inability to determine the three-dimensional shape and the volume of the AVM. We developed a technique for reconstructing the AVM from multiple stereotactic angiograms. The fiducial marks and the identified target area are digitized for each view. The 2-D target area is then stereotactically backprojected into a 3-D volume. The spatial boundary of the target volume is defined by superimposing the backprojections from each of the views. In feasibility studies with a phantom, this technique accurately reconstructed complex 3-D structures, depicting fine details as small as 1 mm. Clinical studies in two patients indicated that this novel technique is very useful for the 3-D reconstruction of AVM for radiosurgical treatment. The number of views required depends on the complexity of the object. In general, six to eight views appear adequate. The accuracy of the reconstruction can be compromised if the view angles are limited as with the current radiographic frame. A new frame design with practically unlimited view angles is proposed to avoid this potential limitation. However, structures that are always obscured (such as concavity) could not be accurately reconstructed, leading to overestimates of the object size. This "limitation" has a positive side, in that the technique will not underestimate the actual target volume. The ability to delineate both the shape and volume of the lesion should facilitate optimal target coverage while sparing a significant amount of normal tissue.

A commercial linear accelerator with a factory-fitted multileaf collimator (MLC) was commissioned for clinical use. Measurements made of dosimetric parameters included central axis depth-dose, field-size factors, wedge factors, penumbra, and leaf leakage for the 6-MV and 15-MV photon beams available on this accelerator. The depth-dose characteristics, output factors, and transmission factors were similar to those reported in the literature for a machine by the same manufacturer with a standard treatment head. Because of scalloping, the effective penumbra for the MLC was 3 to 4 mm wider than that for the conventional collimator jaws. The output for the fields shaped by the MLC was generally lower than that for similar fields shaped with Lipowitz's metal (Cerrobend). The magnitude of the difference was field-size dependent and ranged from 0.5% to 4.5% for open shaped fields, increasing to 1% to 5% in the presence of wedges. Further analysis of this observation has shown it to be primarily due to differences in the scattered radiation from the collimator head.