Surface dose measurements and comparison of unflattened and flattened photon beams

Sigamani, Ashokkumar; Nambiraj, Arunai; Yadav, Garima; Giribabu, Ananda; Srinivasan, Karthikeyan; Gurusamy, Venkadamanickam; Raman, Kothanda; Karunakaran, Kaviarasu; Thiyagarajan, Rajesh

doi:10.4103/0971-6203.181648

Cited by 14 publications

(10 citation statements)

References 43 publications

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“…The maximum surface dose in maximum field size 30x30 cm 2 for 6FF is 52.84 ± 0.011 (LA1) in SSD setup and 51.68 ± 0.005 (LA1) in SAD setup. For 6FFF the maximum to the surface dose (Sigamani et al, 2016). In general, there is no model in treatment planning system accurately accounting for surface dose measurements.…”

Section: Discussionmentioning

confidence: 99%

Verification of Surface Dose for Flattening Filter and Flattening Filter Free Beams in Beam-Matched Medical Linear Accelerators

Sushma

Kaginelli

Palanivel

et al. 2021

Asian Pac J Cancer Prev

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Depending on the doses delivered, the basal skin layer will experience a number of problems ranging from mild (erythema/epilation) to severe (desquamation/necrosis) reactions. According to the ICRP and the ICRU, the skin depth prescribed for realistic dosage measurements is 0.07 cm, which refers to the skin's interface between the epidermis and dermis layers ("Report 24, ICRU" 1976; Venselaar et al., 2001). At the same time, precise doses

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Section: Discussionmentioning

confidence: 99%

Verification of Surface Dose for Flattening Filter and Flattening Filter Free Beams in Beam-Matched Medical Linear Accelerators

Sushma

Kaginelli

Palanivel

et al. 2021

Asian Pac J Cancer Prev

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“…Skin doses were measured using a Gafchromic EBT3 film (Ashland Inc, New Jersey, USA) from 5 cm inside the medial edge of the medial beam and across the contralateral breast. Gafchromic films have been shown to be suitable for accurate skin dosimetry 18, 19. Again, the measurements were repeated six times for reproducibility and uncertainty analysis.…”

Section: Methodsmentioning

confidence: 99%

Characterization of a novel scale maille contralateral breast shield: SMART Armor

Butson¹,

Carroll

Butson

et al. 2017

J Applied Clin Med Phys

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During breast radiotherapy treatment, the contralateral breast receives radiation doses to the skin and subcutaneous tissue caused mainly from incident electron contamination and low energy photon scatter radiation. Measurements have shown that for a typical hybrid tangential treatment, these dose levels can be up to 17% of maximum applied prescription dose if no shielding is used during the treatment process. This work examined the use of different shielding metals, aluminum, copper, and lead to reduce peripheral radiation dose to evaluate the optimal metal to form the basis of a contralateral breast radiation shield. This work also shows a simple but novel method to substantially reduce this unwanted radiation dose with the use of a copper scale maille sheet which can be easily and accurately draped over a patient's contralateral breast during treatment. The copper scale maille is flexible and can thus conform around typical breast shapes. It can also form irregular shaped edges to match those outlined by typical tangential treatment fields. As the shield is made from copper, it is nontoxic and can potentially be used directly on patients for treatment. The designed copper scale maille has shown to reduce contralateral breast skin and subcutaneous dose by up to 80% for typical radiation fields used in breast radiotherapy.

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“…Unfortunately, accurate measurement of dose at the surface and in the build-up region is a difficult task involving a specific type of dosimeters and procedures. [7][8][9][10][11][12] However, applying a bolus over phantom surface reduces or removes build-up region and enhances the accuracy of a measurement obtained using an ordinary ionisation chamber available in the clinical environment for radiation dosimetry and quality assurance measurements. The impact of air-gaps under a bolus on the dose distribution is one of the major challenges in photon beam external radiation therapy, but it is nevertheless essential for proper treatment patient.…”

Section: Introductionmentioning

confidence: 99%

Enhancing benefits of bolus use through minimising the effect of air-gaps on dose distribution in photon beam radiotherapy

et al. 2020

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Introduction: Bolus material is frequently used on patient’s skin during radiation therapy to reduce or remove build-up effect for high-energy beams. However, the air-gaps formed between the bolus and the skin’s irregular surface reduce the accuracy of treatment planning. To achieve a good treatment outcome using bolus, experimental investigations are required to choose its thickness and to quantify the air-gap effect. Material and methods: Measurements for a 6 MV photon beam with a fixed source surface distance were carried out using the 31021 Semiflex 3D chamber into the water phantom. Firstly, the depth of maximum dose (R100) and the dose value at surface (Ds) were evaluated as a function of bolus thickness for some square fields. Secondly, to test the effect of the air-gaps ranged from 5 to 30 mm with a step of 5 mm between the bolus and the phantom surface, a water-equivalent RW3 (Goettingen White Water) slab form of 10 mm thickness was considered as a bolus. Results: We observed that the linear behaviour of R100 in terms of the bolus thickness makes the choice of this parameter more convenient depending on field size. In addition, increasing the air-gaps widens the penumbra and created electrons that have a greater probability to quit the radiation field borders before reaching the surface. The dose spread of the off-field area could have a significant influence on the patient treatment. Conclusion: Based on dose distribution comparisons between the measurements with and without air-gaps for the field size of 100 mm × 100 mm, it has been demonstrated that a maximum air-gap value lower than 5 mm would be desirable for an efficient use of the bolus technique.

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Surface dose measurements and comparison of unflattened and flattened photon beams

Cited by 14 publications

References 43 publications

Verification of Surface Dose for Flattening Filter and Flattening Filter Free Beams in Beam-Matched Medical Linear Accelerators

Verification of Surface Dose for Flattening Filter and Flattening Filter Free Beams in Beam-Matched Medical Linear Accelerators

Characterization of a novel scale maille contralateral breast shield: SMART Armor

Enhancing benefits of bolus use through minimising the effect of air-gaps on dose distribution in photon beam radiotherapy

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