Khan's the physics of radiation therapy

Semwal, Manoj Kumar

doi:10.4103/jmp.jmp_17_20

Cited by 9 publications

(11 citation statements)

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“…The reported case shows that even extremely complex targets can be irradiated thanks to more and more new performing radiotherapy techniques [17]. The dose delivery characteristics of VMAT allow for a superficial circumferential irradiation while sparing organs at risk centered within the target (femur and tibia in our case) by exploiting the tangential effect [13].…”

Section: Discussionmentioning

confidence: 86%

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Volumetric Modulated Arc Therapy Capabilities for Treating Lower-Extremity Skin Affected by Several Merkel Cell Carcinoma Nodules: When Technological Advances Effectively Achieve the Palliative Therapeutic Goal while Minimising the Risk of Potential Toxicities

Ferini¹,

Valenti²,

Puliafito³

et al. 2021

Medicina

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The peculiar and rare clinical condition below clearly requires a customized care approach in the context of personalized medicine. An 80-year-old female patient who was subjected in 2018 to surgical removal of a cutaneous Merkel cell carcinoma (MCC) nodule located on the posterior surface of the left thigh and to three subsequent palliative radiotherapy treatments developed a fourth relapse in October 2020, with fifteen nodular metastases located in the left thigh and leg. Since the overall macroscopic disease was still exclusively regionally located and microscopic spread was likely extended also to clinically negative skin of the thigh and leg, we performed an irradiation of the whole left lower extremity. For this purpose the total target (65.5 cm) was divided into three sub-volumes. Dose prescription was 30 Gy in 15 daily fractions. A sequential boost of 10 Gy in 5 daily fractions was planned for macroscopic nodules. Plans were calculated by means of volumetric modulated arc therapy (VMAT) with the field overlap technique. Thanks to this, we obtained a homogeneous dose distribution in the field junction region; avoidance structures were delineated in the central part of the thigh and leg with the aim of achieving an optimal superficial dose painting and to reduce bone exposure to radiation. This case study demonstrates that VMAT allows for a good dose coverage for circumferential cutaneous targets while sparing deeper organs at risk. A reproducible image-guided set-up is fundamental for an accurate and safe dose delivery. However, local treatments such as radiotherapy for very advanced MCC of the lower extremities might have limited impact due to the high probability of systemic progression, as illustrated in this case. Radiation is confirmed as being effective in preventing MCC nodule progression toward skin wounding.

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Section: Discussionmentioning

confidence: 86%

“…These facts could make radiation oncologists reconsider the usefulness of palliative extended field radiotherapy for locoregional control even in massive limb involvement. The wide extension and irregular shape of such a target make irradiation particularly challenging [13].…”

Section: Introductionmentioning

confidence: 99%

Volumetric Modulated Arc Therapy Capabilities for Treating Lower-Extremity Skin Affected by Several Merkel Cell Carcinoma Nodules: When Technological Advances Effectively Achieve the Palliative Therapeutic Goal while Minimising the Risk of Potential Toxicities

Ferini¹,

Valenti²,

Puliafito³

et al. 2021

Medicina

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“…2. For closed-ended applicators, Table 1 shows the mean of FSD eff , where the effective distance (FSD eff ) was calculated using methods described in literature [14,15]. Thus, for these applicators FSD eff was used in Eq.…”

Section: Methodsmentioning

confidence: 99%

A New Standoff-Factor Formula for Orthovoltage Radiotherapy Treatments

Elawadi

AlGendy

AlMohsen

et al. 2023

Preprint

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Orthovoltage x-rays are useful for the treatment of some superficial cancers and benign conditions. An orthovoltage machine has numerous different applicators (open and closed ended) and energies that require measurements for all different applicator-energy combinations in addition to patient-specific Standoff Factor (SF) measurements, which is arduous and time-consuming. This study aimed to introduce a simple, accurate, and practical method to calculate SF. This factor is usually calculated based on the inverse square law (ISL), which is not an accurate approximation for closed-ended applicators. In this work, we introduced a simple, accurate, and practical method to calculate SF that is valid for both open-ended and closed-ended applicators. Xstrahl 300 therapy unit was used with two sets of Open-ended and Closed-ended applicators with energies up to 300 kVp. The proposed SF empirical formula and ISL were evaluated against the measurements. For open-ended applicators, the maximum Percentage Differences (PD) in calculated SF using the suggested formula and ISL were 2.2% and 3.4% relative to the measurement, respectively. For closed-ended applicators, the maximum PD was 3.2% and -8.1% using the suggested formula and ISL relative to the measurement, respectively. The results demonstrated satisfactory accuracy compared to the measured standoff factor values and superior accuracy when compared to the commonly used ISL method, particularly for closed-ended applicators. The study concluded that SF calculated using the proposed formula was in agreement with measured SF at clinically relevant standoff distances for all energies and applicators combinations. Thus, we recommend using this proposed formula for SF calculations.

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“…Once the calibration curve is established, the HU of the phantom material can be measured and converted to electron density using the equation: Where: ρ water is the electron density of water, HUwater is the HU of water, HUair is the HU of air, and HU is the HU of the phantom material [18].…”

Section: Calibration Curve For Relation Of Ed Versus Ct Numbersmentioning

confidence: 99%

Optimizing 3D-printed workpieces for radiotherapy application: modelling the CT number and print time

Kadiri,

Jakupi,

Dukovski

et al. 2024

Biomed. Phys. Eng. Express

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Objective: This study aims to analyze the influence of specific printing parameters, including infilling, print speed, and layer height, on the CT numbers and printing time of 3D-printed workpieces fabricated from Polylactic Acid (PLA). The primary objective is to optimize these parameters to attain desired CT numbers and print time for radiotherapy applications.Approach: To achieve this objective, we employed the Taguchi experimental design and regression analysis methodologies. A series of experiments were conducted to systematically assess the effects of varying infilling, print speed, and layer height values on the CT numbers and printing time of the PLA workpieces. The resulting data were then used to create mathematical models for predicting optimal parameter settings.Main Results: Our investigations revealed that specific adjustments to infilling and layer height significantly influence the CT numbers and printing time of 3D-printed workpieces. By leveraging the developed mathematical models, precise predictions can be made to optimize independent parameters for the desired CT numbers and printing times, enhancing the efficacy of 3D-printed workpieces for radiotherapy applications.Significance: This research contributes to the advancement of 3D-printed workpieces utilized in radiotherapy, offering a pathway to enhance the accuracy and efficiency of treatment delivery. The optimization of printing parameters outlined in this study provides a valuable tool for clinicians and researchers in the field, ultimately benefiting patients undergoing radiotherapy treatments.

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Khan's the physics of radiation therapy

Cited by 9 publications

References 0 publications

Volumetric Modulated Arc Therapy Capabilities for Treating Lower-Extremity Skin Affected by Several Merkel Cell Carcinoma Nodules: When Technological Advances Effectively Achieve the Palliative Therapeutic Goal while Minimising the Risk of Potential Toxicities

Volumetric Modulated Arc Therapy Capabilities for Treating Lower-Extremity Skin Affected by Several Merkel Cell Carcinoma Nodules: When Technological Advances Effectively Achieve the Palliative Therapeutic Goal while Minimising the Risk of Potential Toxicities

A New Standoff-Factor Formula for Orthovoltage Radiotherapy Treatments

Optimizing 3D-printed workpieces for radiotherapy application: modelling the CT number and print time

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