The use of scattering foil compensators in electron beam therapy

Ulin, Kenneth; Palisca, Madeline G.

doi:10.1016/0360-3016(96)00153-8

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…Technical factors also limit the use of electron beam therapy in body areas where superficial radiotherapy is particularly effective. For example, dose inhomogeneity on curved surfaces can be a problem when treating the nose 18 . For lesions around the eye, protection of the eye itself is a problem for two reasons.…”

Section: Discussionmentioning

confidence: 99%

“…Secondly, the ‘bowl’ isodose effect means that the area treated beneath the surface is greater than the area treated at the surface. More recently, better shielding has been available, 18 but this may not always be optimal. In addition, electron beam therapy is not ideal for treating small fields, 20,21 as dosing is less accurate in fields smaller than 4 cm × 4 cm in size.…”

Section: Discussionmentioning

confidence: 99%

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Three‐year retrospective review of superficial radiotherapy for skin conditions in a Perth radiotherapy unit

Thom¹,

Heywood²,

Cassidy³

et al. 2003

Aust J Dermatology

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Western Australia has only two superficial radiotherapy units, one of which is located at Fremantle Hospital, and run by the radiation oncologists of Perth Radiation Oncology Centre. A 3-year retrospective review was undertaken of all patients who underwent treatment at this unit from 1999 to 2001. Patients were identified from the unit's log book, and data was collected from their files. For malignant skin conditions, 369 lesions were treated in 259 patients over the study period. The patients' median age was 76 years. A wide variety of conditions were treated, but the most common diagnoses were basal cell carcinoma (237 lesions) and squamous cell carcinoma (92 lesions), most commonly located in the head region. The most frequently used treatment schedule was 36 Gy in six fractions over a 3-week period. Where radiotherapy was administered as primary treatment, the diagnoses had been biopsy-proven in only 53% of cases. Fifty-four patients underwent treatment of benign skin disease over the study period; most commonly keloid scars (41 patients) followed by warts (six patients). We conclude that superficial radiotherapy has a distinct role in dermatology, particularly for skin carcinomas around the nose and eyes, which cannot presently be superseded by electron beam therapy.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Three‐year retrospective review of superficial radiotherapy for skin conditions in a Perth radiotherapy unit

Thom¹,

Heywood²,

Cassidy³

et al. 2003

Aust J Dermatology

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“…However, previous discussions of surface irregularities have addressed: (1) angled beam incidence upon a flat surface, (2) developing conformal bolus or compensation techniques to reduce surface irregularities and improve dose homogeneity for sites with irregular surfaces such as the nose or ear, and (3) irregularities in the proximal surface of an electron conformal therapy bolus that result in hot and cold spots. 10,[17][18][19][20][21][22] There is limited prior investigation focused on the dosimetric effects of clinical electron beams incident perpendicularly to regular curved surfaces. 23 Still, knowledge of these dosimetric effects can be helpful in clinical cases in which curvature is present.…”

Section: Introductionmentioning

confidence: 99%

Effects of surface curvature on electron Monte Carlo (eMC) calculation results

Polignani

2023

J Applied Clin Med Phys

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Some clinical situations in radiotherapy require electron beams to be incident on curved patient surfaces. This study presents central-axis dose output (cGy/MU) and percent dose versus depth (PDD) data that show the effects of curvature on results computed by the Varian eMC v15.6 algorithm using 6, 9, 12, 16, and 20 MeV electron beams incident on virtual phantoms with curved surfaces. The phantoms were designed to simulate common treatment sites. The dose outputs at the depth of maximum dose (dmax) on the central axis were observed to decrease 0%-14%, and several features of the PDDs for the A10 applicator changed, including up to 12% increased entrance dose. These dosimetric changes have the greatest effect on treatment sites with a radius of curvature of 10 cm or less, such as the scalp, nose, neck, and extremities. The concept of applying a curvature correction factor based on relative output data is presented to help clinical users mitigate discrepancies between calculations performed by simple monitor unit verification systems and accurate treatment planning dose algorithms. K E Y W O R D Scurved patient surfaces, electron beam physical effects, electron curvature, electron monitor unit verification, electron monte carlo, electron radiotherapy, electron surface contour, Varian eMC

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“…The dosimetric effects of matching electron and photon fields have been studied by many authors. [1][2][3] Several methods have been proposed to reduce the dose inhomogeneity in the abutting regions of photon/photon, 4,5 electron/electron, [6][7][8][9][10] or photon/electron 11 fields and to reduce the sensitivity of the dose inhomogeneity to positioning errors. Most of these techniques used specially designed beam spoilers to broaden the penumbrae in the abutting regions.…”

Section: Introductionmentioning

confidence: 99%

Matching photon and electron fields with dynamic intensity modulation

Liu

Boyer

et al. 1999

Med. Phys.

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A technique was developed to reduce the size and magnitude of the hot and cold spots in the abutting regions of photon and electron fields. The photon and electron fields were set up such that the photon field extended approximately 2 cm into the electron field in the abutting region. The region of the photon beam that overlapped the electron field was modulated using a multileaf collimator, effectively broadening the photon penumbra to make it complimentary to the electron penumbra. The computer calculations were verified using film measurements for abutting a 6 MV photon beam with a 9 MeV electron beam. A uniform dose was achieved at a prespecified depth of 2 cm, and dose uniformity was improved at the specified depth and beyond compared with unmodulated photon beams. A slight increase in dose inhomogeneity was seen at shallower depths. The overall areas of the hot and cold spots were significantly reduced. The technique also reduced the sensitivity of dose homogeneity to setup errors such that the magnitudes of the hot and cold spots were about half of those produced with unmodulated photon beam when an overlap or gap of 4 mm was introduced. The technique was applied to the treatment of a head and neck cancer and a lymphoma involving the right pleura with markedly reduced dose inhomogeneity in the abutting regions.

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The use of scattering foil compensators in electron beam therapy

Cited by 8 publications

References 8 publications

Three‐year retrospective review of superficial radiotherapy for skin conditions in a Perth radiotherapy unit

Three‐year retrospective review of superficial radiotherapy for skin conditions in a Perth radiotherapy unit

Effects of surface curvature on electron Monte Carlo (eMC) calculation results

Matching photon and electron fields with dynamic intensity modulation

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