A novel investigational preclinical model to assess fluence rate for dental oral craniofacial tissues.

OBJECTIVE: Photodynamic Therapy (PDT) and Photobiomodulation (PBM) are recognized for their potential in treating head and neck conditions. The heterogeneity of human tissue optical properties presents a challenge for effective dosimetry. The porcine mandible cadaver serves as an excellent model and has several similarities to human tissues of the dental oral craniofacial complex. This study aims to validate a novel modeling system that will help refine PDT and PBM dosimetry for the head and neck region. METHODS AND MATERIALS: Light transmission was analyzed through several tissue combinations at distances of 2 mm to 10 mm. Maximum light fluence rates (mW/cm2) were compared across tissue types to reveal the effects of tissue heterogeneity. RESULTS: The study revealed that light fluence is affected by tissue composition, with dentin/enamel showing reduced transmission and soft tissue regions exhibiting elevated values. The porcine model has proven to be efficient in mimicking human tissue responses to light, enabling the potential to optimize future protocols. CONCLUSION: The porcine mandible cadaver is a novel model to understand the complex interactions between light and tissue. This study provides a foundation for future investigations into dosimetry optimization for PDT and PBM.

Three-dimensional printing of the human lung pleural cavity model for PDT malignant mesothelioma.

OBJECTIVE: The primary aim was to investigate emerging 3D printing and optical acquisition technologies to refine and enhance photodynamic therapy (PDT) dosimetry in the management of malignant pleural mesothelioma (MPM). MATERIALS AND METHODS: A rigorous digital reconstruction of the pleural lung cavity was conducted utilizing 3D printing and optical scanning methodologies. These reconstructions were systematically assessed against CT-derived data to ascertain their accuracy in representing critical anatomic features and post-resection topographical variations. RESULTS: The resulting reconstructions excelled in their anatomical precision, proving instrumental translation for precise dosimetry calculations for PDT. Validation against CT data confirmed the utility of these models not only for enhancing therapeutic planning but also as critical tools for educational and calibration purposes. CONCLUSION: The research outlined a successful protocol for the precise calculation of light distribution within the complex environment of the pleural cavity, marking a substantive advance in the application of PDT for MPM. This work holds significant promise for individualizing patient care, minimizing collateral radiation exposure, and improving the overall efficiency of MPM treatments.

Clinical PDT dose dosimetry for pleural Photofrin-mediated photodynamic therapy.

Significance: Photodynamic therapy (PDT) is an established cancer treatment utilizing light-activated photosensitizers (PS). Effective treatment hinges on the PDT dose-dependent on PS concentration and light fluence-delivered over time. We introduce an innovative eight-channel PDT dose dosimetry system capable of concurrently measuring light fluence and PS concentration during treatment. Aim: We aim to develop and evaluate an eight-channel PDT dose dosimetry system for simultaneous measurement of light fluence and PS concentration. By addressing uncertainties due to tissue variations, the system enhances accurate PDT dosimetry for improved treatment outcomes. Approach: The study positions eight isotropic detectors strategically within the pleural cavity before PDT. These detectors are linked to bifurcated fibers, distributing signals to both a photodiode and a spectrometer. Calibration techniques are applied to counter tissue-related variations and improve measurement accuracy. The fluorescence signal is normalized using the measured light fluence, compensating for variations in tissue properties. Measurements were taken in 78 sites in the pleural cavities of 20 patients. Results: Observations reveal minimal Photofrin concentration variation during PDT at each site, juxtaposed with significant intra- and inter-patient heterogeneities. Across 78 treated sites in 20 patients, the average Photofrin concentration for all 78 sites is 4.98 µM, with a median concentration of 4.47 µM. The average PDT dose for all 78 sites is 493.17 µMJ/cm2, with a median dose of 442.79 µMJ/cm2. A significant variation in PDT doses is observed, with a maximum difference of 3.1 times among all sites within one patient and a maximum difference of 9.8 times across all patients. Conclusions: The introduced eight-channel PDT dose dosimetry system serves as a valuable real-time monitoring tool for light fluence and PS concentration during PDT. Its ability to mitigate uncertainties arising from tissue properties enhances dosimetry accuracy, thus optimizing treatment outcomes and bolstering the effectiveness of PDT in cancer therapy.

AAPM Task Group Report 311: Guidance for performance evaluation of fluorescence-guided surgery systems.

The last decade has seen a large growth in fluorescence-guided surgery (FGS) imaging and interventions. With the increasing number of clinical specialties implementing FGS, the range of systems with radically different physical designs, image processing approaches, and performance requirements is expanding. This variety of systems makes it nearly impossible to specify uniform performance goals, yet at the same time, utilization of different devices in new clinical procedures and trials indicates some need for common knowledge bases and a quality assessment paradigm to ensure that effective translation and use occurs. It is feasible to identify key fundamental image quality characteristics and corresponding objective test methods that should be determined such that there are consistent conventions across a variety of FGS devices. This report outlines test methods, tissue simulating phantoms and suggested guidelines, as well as personnel needs and professional knowledge bases that can be established. This report frames the issues with guidance and feedback from related societies and agencies having vested interest in the outcome, coming from an independent scientific group formed from academics and international federal agencies for the establishment of these professional guidelines.

Fractionated Photofrin-Mediated Photodynamic Therapy Significantly Improves Long-Term Survival.

This study investigates the effect of fractionated (two-part) PDT on the long-term local control rate (LCR) using the concentration of reactive oxygen species ([ROS]rx) as a dosimetry quantity. Groups with different fractionation schemes are examined, including a 2 h interval between light delivery sessions to cumulative fluences of 135, 180, and 225 J/cm2. While the total treatment time remains constant within each group, the division of treatment time between the first and second fractionations are explored to assess the impact on long-term survival at 90 days. In all preclinical studies, Photofrin is intravenously administered to mice at a concentration of 5 mg/kg, with an incubation period between 18 and 24 h before the first light delivery session. Fluence rate is fixed at 75 mW/cm2. Treatment ensues via a collimated laser beam, 1 cm in diameter, emitting light at 630 nm. Dosimetric quantities are assessed for all groups along with long-term (90 days) treatment outcomes. This study demonstrated a significant improvement in long-term survival after fractionated treatment schemes compared to single-fraction treatment, with the optimal 90-day survival increasing to 63%, 86%, and 100% vs. 20%, 25%, and 50%, respectively, for the three cumulative fluences. The threshold [ROS]rx for the optimal scheme of fractionated Photofrin-mediated PDT, set at 0.78 mM, is significantly lower than that for the single-fraction PDT, at 1.08 mM.

Characterization of Cherenkov imaging parameters and positional constraints on an O-ring linear accelerator.

Objective. With the introduction of Cherenkov imaging technology on the Halcyon O-ring linear accelerator platform, we seek to demonstrate the imaging feasibility and optimize camera placement.Approach. Imaging parameters were probed by acquiring triggering data Cherenkov image frames for simplistic beams on the Halcyon and comparing the analyzed metrics with those from the TrueBeam platform. Camera position was analyzed by performing 3D rendering of patient treatment plans for various sites and iterating over camera positions to assess treatment area visibility.Main results. Commercial Cherenkov imaging systems are compatible with the pulse timing of the Halcyon, and this platform design favorably impacts signal to noise in Cherenkov image frames. Additionally, ideal camera placement is treatment site dependent and is always within a biconical zone of visibility centered on the isocenter. Visibility data is provided for four treatment sites, with suggestions for camera placement based on room dimensions. Median visibility values were highest for right breast plans, with values of 80.33% and 68.49% for the front and rear views respectively. Head and neck plans presented with the lowest values at 26.44% and 38.18% respectively.Significance. This work presents the first formal camera positional analysis for Cherenkov imaging on any platform and serves as a template for performing similar work for other irradiation platforms. Additionally, this study confirms the Cherenkov imaging parameters do not need to be changed for optimal imaging on the Halcyon. Lastly, the presented methodology provides a framework which could be further expanded to other optical imaging systems which rely on line of sight visibility to the patient.

Evaluation of Fractionated Photofrin-mediated Photodynamic Therapy Using Different Light Fluences with Reactive Oxygen Species Explicit Dosimetry (ROSED).

Photodynamic therapy (PDT) is an established modality for cancer treatment, and reactive oxygen species explicit dosimetry (ROSED), based on direct measurements of in-vivo light fluence (rate), in-vivo photofrin concentration, and tissue oxygenation concentration, has been proved to provide the best dosimetric quantity which can be used to predict non-fractionated PDT outcome. This study performed ROSED for Photofrin-mediated PDT for mice bearing radiation-induced fibrosacorma (RIF) tumor. As demonstrated by our previous study, fractionated PDT with a 2-hour time interval can significantly improve the long-term cure rate (from 15% to 65% at 90 days), and it tends to increase as the light dose for the first light fraction gets larger. This study focused on further improving the long-term cure rate without introducing apparent toxicity using combinations of different first light fraction lengths and total light fluences. Photofrin was injected through the mouse tail vein at a concentration of 5 mg/kg. After 18~24 hours, treatment was delivered with a collimated laser beam of 1 cm diameter at 630 nm. Mice were treated using two fractions of light fluences with a 2-hour dark interval. Different dose metrics were quantified, including light fluence, PDT dose, and [ROS]rx. In addition, the total reacted [ROS]rx and treatment outcomes were evaluated and compared to identify the optimal light fraction length and total light fluence.

Evaluation of the cumulative Cherenkov converted dose on TSET patients with multiple Cherenkov cameras.

Cherenkov images can be used for the quality assurance of dose homogeneity in total skin electron therapy (TSET). For the dose mapping purpose, this study reconstructed the patient model from 3D scans using registration algorithms and computer animation techniques. The Cherenkov light emission of the patient's surface was extracted from multi-view Cherenkov images, converted into dose distribution, and projected onto the patient's 3D model, allowing for dose cumulation and evaluation. The projected result from multiple Cherenkov cameras provides additional information about Cherenkov emission on the sides of the patients, which improves the agreement between the Cherenkov converted dose and the OSLD measurements.

Validating Homogeneity for a Novel 3-Dimensional Tissue Phantom Modeling System of the Human Maxilla.

Silicon phantom models have been utilized to calculate light fluence in patients being treated with Photodynamic Therapy (PDT). This application can be utilized for other non-ionizing wavelength therapies such as Photobiomodulation (PBM). We have developed a novel protocol to validate homogeneity for 3-dimensional silicon phantom models of the human maxilla. Accurately quantifying the light profiles of human tissue can accommodate for varying optical properties that occur between subjects. More importantly, this can help optimize light fluence dosimetry calculations to achieve intended results. Silicon models of identical composition were fabricated into two different shapes: 1 flat-planar cylindrical shaped model, 2) non-flat planar (3-dimensional) mold of the human maxilla. Fabricating homogenous silicon phantom models continues to be a challenge as micro-bubbles can contaminate the compound during the curing process. Integrating both proprietary CBCT and handheld surface acquisition imaging devices confirmed our results to be within 0.5mm of accuracy. This protocol was specifically used to cross-reference and validate homogeneity at various depths of penetration. These results present the first known successful validation of identical silicon tissue phantoms with a flat-planar surface vs. a non-flat 3D planar surface. This proof-of-concept phantom validation protocol is sensitive to the specific variations of 3-dimensional surfaces and can be applied to a workflow used to capture accurate light fluence calculations in the clinical setting.

PDT Light Fluence Phantom Modeling of the Human Pleural Cavity: A Proof-of-Concept Pre-Clinical Study.

We have developed a novel scanning protocol for a life-sized human phantom model using handheld three-dimensional (3D) surface acquisition devices. This technology will be utilized to develop light fluence modeling of the internal pleural cavity space during Photodynamic Therapy (PDT) of malignant mesothelioma. The external aspect of the chest cavity phantom was prefabricated of a hardened synthetic polymer resembling ordinary human anatomy (pleural cavity space) and the internal aspect remained hollow without any characterizations. Both surfaces were layered with non-reflective adhesive paper to create non-uniformed surface topographies. These surface characteristics were established in randomized X-Y-Z coordinates ranging in dimensions from 1-15mm. This protocol utilized the handheld Occipital Scanner and the MEDIT i700. The Occipital device required a minimum scanner-to-surface distance of 24cm and the MEDIT device 1cm respectively. The external and internal aspects of the phantom model were successfully scanned acquiring digital measurements in actual value and converted into a digital image file. The initial surface rendering was acquired by the Occipital device and applied with proprietary software to guide the MEDIT device to fill voided areas. This protocol is accompanied by a visualization tool that allows for real-time inspection of surface acquisition in 2D and 3D. This scanning protocol can be utilized to scan the pleural cavity for real-time guidance for light fluence modeling during PDT, which will be expanded to ongoing clinical trials.

A real-time IR navigation system for pleural photodynamic therapy with a 3D surface acquisition system.

Photodynamic therapy (PDT) has been used intraoperatively to treat patients with malignant pleural mesothelioma. For the efficiency of PDT, it is crucial to deliver light doses uniformly. The current procedure utilizes eight light detectors placed inside the pleural cavity to monitor the light. An updated navigation system, combined with a novel scanning system, is developed to provide real-time guidance for physicians during pleural PDT to improve light delivery. The scanning system consists of two handheld three-dimensional (3D) scanners to capture the pleural cavity's surface topographies quickly and precisely before PDT so that the target surface can be identified for real-time light fluence distribution calculation during PDT. An algorithm is developed to further process the scanned volume to denoise for accurate light fluence calculation and rotate the local coordinate system into any desired direction for a clear visualization during the real-time guidance. The navigation coordinate system is registered to the patient coordinate system utilizing at least three markers to track the light source point position within the pleural cavity throughout the treatment. During PDT, the light source position, the scanned pleural cavity, and the light fluence distribution for the cavity's surface will be displayed in 3D and 2D, respectively. For validation, this novel system is tested using phantom studies with a large chest phantom and 3D-printed lung phantoms of different volumes based on a personal CT scan, immersed in a liquid tissue-simulating phantom with different optical properties, and treated with eight isotropic detectors and the navigation system.

Photobiomodulation in dental extraction therapy: Postsurgical pain reduction and wound healing.

BACKGROUND: This scoping review and analysis were designed to assess the amount of time spent delivering photobiomodulation (PBM) light therapy after dental extraction to improve postoperative pain and wound healing. TYPES OF STUDIES REVIEWED: The scoping review was performed according to the Cochrane Collaboration and Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Publications were specific for human randomized controlled clinical trials, PBM after dental extraction therapy, and related clinical outcomes. Online databases searched included PubMed, Embase, Scopus, and Web of Science. Analyses were conducted to analyze the prescribed intervals of time (seconds) per application of PBM. RESULTS: Of the 632 studies initially identified, 22 studies fulfilled the inclusion criteria. Postoperative pain and PBM were reported in 20 articles for 24 treatment groups, with treatment times ranging from 17 through 900 seconds and wavelengths from 550 through 1,064 nm. Clinical wound healing outcomes were reported in 6 articles for 7 groups with treatment times ranging from 30 through 120 seconds and wavelengths from 660 through 808 nm. PBM therapy was not associated with adverse events. CONCLUSIONS AND PRACTICAL IMPLICATIONS: There is future potential to integrate PBM after dental extraction therapy to improve postoperative pain and clinical wound healing. The amount of time spent delivering PBM will vary by wavelength and the type of device. Further investigation is needed to translate PBM therapy into human clinical care.

Comparison of surface dose during whole breast radiation therapy on Halcyon and TrueBeam using Cherenkov imaging.

The emergence of the Halcyon linear accelerator has allowed for increased patient throughput and improved treatment times for common treatment sites in radiation oncology. However, it has been shown that this can lead to increased surface dose in sites like breast cancer compared with treatments on conventional machines with flattened radiation beams. Cherenkov imaging can be used to estimate surface dose by detection of Cherenkov photons emitted in proportion to energy deposition from high energy electrons in tissue. Phantom studies were performed with both square beams in reference conditions and with clinical treatments, and dosimeter readings and Cherenkov images report higher surface dose (25% for flat phantom entrance dose, 5.9% for breast phantom treatment) from Halcyon beam deliveries than for equivalent deliveries from a TrueBeam linac. Additionally, the first Cherenkov images of a patient treated with Halcyon were acquired, and superficial dose was estimated.

Improving Titanium Implant Stability with Photobiomodulation: A Review and Meta-Analysis of Irradiation Parameters.

Objective: This analysis was designed to present a summary of available evidence that will inform practice and guide future research for photobiomodulation (PBM) after titanium implant placement procedures. Materials and methods: A systematic review was performed according to the Cochrane Collaboration and in line with Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) criteria. Two investigators screened the titles and abstracts, and reviewed articles for risk of bias. Online databases searched included PubMed, Embase, Scopus, and Web of Science. Terms were specific to the effects of PBM on dental implant stability. Results: Eight hundred fifty-six studies were identified, and 15 studies fulfilled the inclusion criteria. Light sources included both laser and light emitting diode (LED) devices. Wavelengths ranged from 618 to 1064 nm. The meta-analysis concluded that all 15 published studies were able to safely apply PBM near dental implants without adverse events. Laser and LED wavelengths that reported significant results included 618, 626, 830, 940 (2 × ), and 1064 nm. Conclusions: The use of adjunctive PBM can be safely prescribed after surgical placement of titanium implants. Six groups reported statistical significance for improving implant stability (four laser diode, two LED) in wavelengths ranging from 618 to 1064 nm. The amount of time spent delivering PBM was not a variable that differentiated whether a study reported significant results.

Dose prescription and reporting in stereotactic body radiotherapy: A multi-institutional study.

BACKGROUND AND PURPOSE: Radiation dose prescriptions are foundational for optimizing treatment efficacy and limiting treatment-related toxicity. We sought to assess the lack of standardization of SBRT dose prescriptions across institutions. MATERIALS & METHODS: Dosimetric data from 1298 patients from 9 academic institutions treated with IMRT and VMAT were collected. Dose parameters D100, D98, D95, D50, and D2 were used to assess dosimetric variability. RESULTS: Disease sites included lung (48.3 %) followed by liver (29.7 %), prostate (7.5 %), spine (6.8 %), brain (4.1 %), and pancreas (2.5 %). The PTV volume in lung varied widely with bimodality into two main groups (22.0-28.7 cm3) and (48.0-67.1 cm3). A hot spot ranging from 120-150 % was noted in nearly half of the patients, with significant variation across institutions. A D50 ≥ 110 % was found in nearly half of the institutions. There was significant dosimetric variation across institutions. CONCLUSIONS: The SBRT prescriptions in the literature or in treatment guidelines currently lack nuance and hence there is significant variation in dose prescriptions across academic institutions. These findings add greater importance to the identification of dose parameters associated with improved clinical outcome comparisons as we move towards more hypofractionated treatments. There is a need for standardized reporting to help institutions in adapting treatment protocols based on the outcome of clinical trials. Dosimetric parameters are subsequently needed for uniformity and thereby standardizing planning guidelines to maximize efficacy, mitigate toxicity, and reduce treatment disparities are urgently needed.

Evaluation of Detector Position and Light Fluence Distribution Using an Infrared Navigation System during Pleural Photodynamic Therapy†.

Photodynamic therapy (PDT) has been used to treat malignant pleural mesothelioma. Current practice involves delivering light to a prescribed light fluence with a point source, monitored by eight isotropic detectors inside the pleural cavity. An infrared (IR) navigation system was used to track the location of the point source throughout the treatment. The recorded data were used to reconstruct the pleural cavity and calculate the light fluence to the whole cavity. An automatic algorithm was developed recently to calculate the detector positions based on recorded data within an hour. This algorithm was applied to patient case studies and the calculated results were compared to the measured positions, with an average difference of 2.5 cm. Calculated light fluence at calculated positions were compared to measured values. The differences between the calculated and measured light fluence were within 14% for all cases, with a fixed scattering constant and a dual correction method. Fluence-surface histogram (FSH) was calculated for photofrin-mediated PDT to be able to cover 80% of pleural surface area to 50 J cm-2 (83.3% of 60 J cm-2 ). The study demonstrates that it will be possible to eliminate the manual measurement of the detector positions, reducing the patient's time under anesthesia.

Multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated Photodynamic Therapy.

Direct detection of singlet-state oxygen ([1O2]) constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). However, the short lifetime and extremely weak nature of the singlet oxygen signal produced has given rise to a need to improve MSOLD signal-to-noise ratio. This study examines methods for optimizing MSOLD signal acquisition, specifically employing an orthogonal arrangement between detection and PDT treatment light, consisting of two fiber optics - connected to a 632-nm laser and an InGaAs detector respectively. Light collected by the InGaAs detector is then passed through a filter wheel, where spectral emission measurements are taken at 1200 nm, 1240 nm, 1250 nm, 1270 nm, and 1300 nm. The data, after fitting to the fluorescence background and a gaussian-fit for the singlet oxygen peak, is established for the background-subtracted singlet oxygen emission signal. The MSOLD signal is then compared with the singlet oxygen explicit dosimetry (SOED) results, based on direct measurements of in-vivo light fluence (rate), in-vivo Photofrin concentration, and tissue oxygenation concentration. This study focuses on validating the sensitivity and minimum detectability of MSOLD signal in various in-vitro conditions. Finally, the MSOLD device will be tested in Photofrin-mediated PDT for mice bearing Radiation-Induced Fibrosarcoma (RIF) tumors.

In vivo spectroscopic evaluation of human tissue optical properties and hemodynamics during HPPH-mediated photodynamic therapy of pleural malignancies.

Significance: Dosimetry for photodynamic therapy is dependent on multiple parameters. Critically, in vivo tissue optical properties and hemodynamics must be determined carefully to calculate the total delivered light dose. Aim: Spectroscopic analysis of diffuse reflectance measurements of tissues taken during a clinical trial of 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a-mediated photodynamic therapy for pleural malignancies. Approach: Diffuse reflectance measurements were taken immediately before and after photodynamic therapy. Measurements were analyzed with a nonlinearly constrained multiwavelength, multi-distance algorithm to extract tissue optical properties, tissue oxygen saturation, StO2, and total hemoglobin concentration (THC). Results: A total of 25 patients were measured, 23 of which produced reliable fits for optical property extraction. For all tissue types, StO2 ranged through [24, 100]% and [22, 97]% for pre-photodynamic therapy (PDT) and post-PDT conditions, respectively. Mean THC ranged through [ 69,152 ] µM and [ 48,111 ] µM, for pre-PDT and post-PDT, respectively. Absorption coefficients, µa, ranged through [ 0.024 , 3.5 ] cm - 1 and [ 0.039 , 3 ] cm - 1 for pre-PDT and post-PDT conditions, respectively. Reduced scattering coefficients, µs', ranged through [ 1.4 , 73.4 ] cm - 1 and [ 1.2 , 64 ] cm - 1 for pre-PDT and post-PDT conditions, respectively. Conclusions: There were similar pre- and post-PDT tissue optical properties and hemodynamics. The high variability in each parameter for all tissue types emphasizes the importance of these measurements for accurate PDT dosimetry.

Skin dose distributions between Stanford and rotational techniques in total skin electron therapy (TSET).

PURPOSE: Total skin electron therapy (TSET) has proven to be one of the most effective treatments for advanced-stage cutaneous T-cell lymphoma. Two most used techniques are the Stanford six-field and rotational techniques. This study compares patient skin dose distributions as a function of depth between these two techniques. METHODS: The EGSnrc system was used to simulate electron beams and calculate patient dose distributions. The calculations assumed the same patient standing on a platform, and the patient's different postures were ignored for the Stanford technique in the comparison of dose distributions. The skin doses were analyzed as a function of skin depth-dose coverage and evaluated using dose-volume-histograms (DVH). The comparisons were performed in three realistic clinical settings in which dual-field were used for patients treated at extended distances of 316 and 500 cm, and a single field was used at 700 cm. In all cases the realistic patient treatment beam delivery geometry was simulated. RESULTS: Although small dose differences were observed in some local areas, no clinically significant differences were found in the patient 3D dose distributions between the Stanford and rotational techniques. Virtually the same DVH curves between two the techniques were observed for mean dose to skin depth of 0-5, 5-10, and 10-15 mm from the skin surface, respectively. It is found that the skin depth dose coverage is 2 mm shallower for patient treatment at 500 cm compared to at 316 cm due to the additional air attenuation. However, very similar dose coverage and uniformity can be achieved at these two different extended treatment distances by adjusting the thickness of acrylic scatter plate. Adequate thickness of a scattering plate improves the skin dose uniformity. CONCLUSION: Both the Stanford and rotational techniques deliver very similar skin dose coverage in DVH plots, and only small differences are seen in local areas. It is worth to emphasize that the DVH is a graphical representation of the distribution of dose within a structure, and it does not contain spatial information. Therefore, comparison of entire skin dose using DVH may mask some variations at different locations of the surface area. In addition, the comparison did not consider different patient postures of the Stanford technique. Including the different patient postures in the calculation may affect the result of doses to the limbs.