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Total body irradiation with step translation and dynamic field matching.

Chen HH, Wu J, Chuang KS, Lin JF, Lee JC, Lin JC - Biomed Res Int (2013)

Bottom Line: The dose distribution in the overlapped region ranged from 98.5% to 102.8%.Lateral dose profiles at abdomen and head revealed 109.8% and 111.7% high doses, respectively, at the body edges.The results confirmed that the technique is capable of delivering a uniform dose distribution to the midline of the body in a small treatment room while keeping the lung dose within the tolerance level.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Taichung Veterans General Hospital, 1650 Taiwan Boulevard Sect. 4, Taichung 40705, Taiwan.

ABSTRACT
The purpose of this study is to develop a total body irradiation technique that does not require additional devices or sophisticated processes to overcome the space limitation of a small treatment room. The technique aims to deliver a uniform dose to the entire body while keeping the lung dose within the tolerance level. The technique treats the patient lying on the floor anteriorly and posteriorly. For each AP/PA treatment, two complementary fields with dynamic field edges are matched over an overlapped region defined by the marks on the body surface. A compensator, a spoiler, and lung shielding blocks were used during the treatment. Moreover, electron beams were used to further boost the chest wall around the lungs. The technique was validated in a RANDO phantom using GAFCHROMIC films. Dose ratios at different body sites along the midline ranged from 0.945 to 1.076. The dose variation in the AP direction ranged from 96.0% to 104.6%. The dose distribution in the overlapped region ranged from 98.5% to 102.8%. Lateral dose profiles at abdomen and head revealed 109.8% and 111.7% high doses, respectively, at the body edges. The results confirmed that the technique is capable of delivering a uniform dose distribution to the midline of the body in a small treatment room while keeping the lung dose within the tolerance level.

Show MeSH
Percentage depth dose curves of a 6-MV, 40 × 40-cm2 photon beam measured using a Markus parallel plate ionization chamber inserted in a 20 cm thick solid water phantom on the floor. A 1 cm thick acrylic beam spoiler was placed above the floor at a distance of 30 cm. The gantry angle was set at (a) 0° without a spoiler, (b) 0° with a spoiler, and (c) 11° with a spoiler.
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fig10: Percentage depth dose curves of a 6-MV, 40 × 40-cm2 photon beam measured using a Markus parallel plate ionization chamber inserted in a 20 cm thick solid water phantom on the floor. A 1 cm thick acrylic beam spoiler was placed above the floor at a distance of 30 cm. The gantry angle was set at (a) 0° without a spoiler, (b) 0° with a spoiler, and (c) 11° with a spoiler.

Mentions: A spoiler placed in front of the phantom provides extra scattered dose to the buildup region and improve the dose uniformity. The percentage depth doses of the vertical treatment field with or without the spoiler and those of the 11° oblique field with the spoiler were measured at the treatment distance, as shown in Figure 10. The use of the spoiler in the beam increased the surface dose from 57% to 99% and shifted the depth of maximum dose toward the surface from 1.3 cm to 2 mm. No significant difference was observed between the 11° oblique beam and the vertical beam with the spoiler.


Total body irradiation with step translation and dynamic field matching.

Chen HH, Wu J, Chuang KS, Lin JF, Lee JC, Lin JC - Biomed Res Int (2013)

Percentage depth dose curves of a 6-MV, 40 × 40-cm2 photon beam measured using a Markus parallel plate ionization chamber inserted in a 20 cm thick solid water phantom on the floor. A 1 cm thick acrylic beam spoiler was placed above the floor at a distance of 30 cm. The gantry angle was set at (a) 0° without a spoiler, (b) 0° with a spoiler, and (c) 11° with a spoiler.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713376&req=5

fig10: Percentage depth dose curves of a 6-MV, 40 × 40-cm2 photon beam measured using a Markus parallel plate ionization chamber inserted in a 20 cm thick solid water phantom on the floor. A 1 cm thick acrylic beam spoiler was placed above the floor at a distance of 30 cm. The gantry angle was set at (a) 0° without a spoiler, (b) 0° with a spoiler, and (c) 11° with a spoiler.
Mentions: A spoiler placed in front of the phantom provides extra scattered dose to the buildup region and improve the dose uniformity. The percentage depth doses of the vertical treatment field with or without the spoiler and those of the 11° oblique field with the spoiler were measured at the treatment distance, as shown in Figure 10. The use of the spoiler in the beam increased the surface dose from 57% to 99% and shifted the depth of maximum dose toward the surface from 1.3 cm to 2 mm. No significant difference was observed between the 11° oblique beam and the vertical beam with the spoiler.

Bottom Line: The dose distribution in the overlapped region ranged from 98.5% to 102.8%.Lateral dose profiles at abdomen and head revealed 109.8% and 111.7% high doses, respectively, at the body edges.The results confirmed that the technique is capable of delivering a uniform dose distribution to the midline of the body in a small treatment room while keeping the lung dose within the tolerance level.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Taichung Veterans General Hospital, 1650 Taiwan Boulevard Sect. 4, Taichung 40705, Taiwan.

ABSTRACT
The purpose of this study is to develop a total body irradiation technique that does not require additional devices or sophisticated processes to overcome the space limitation of a small treatment room. The technique aims to deliver a uniform dose to the entire body while keeping the lung dose within the tolerance level. The technique treats the patient lying on the floor anteriorly and posteriorly. For each AP/PA treatment, two complementary fields with dynamic field edges are matched over an overlapped region defined by the marks on the body surface. A compensator, a spoiler, and lung shielding blocks were used during the treatment. Moreover, electron beams were used to further boost the chest wall around the lungs. The technique was validated in a RANDO phantom using GAFCHROMIC films. Dose ratios at different body sites along the midline ranged from 0.945 to 1.076. The dose variation in the AP direction ranged from 96.0% to 104.6%. The dose distribution in the overlapped region ranged from 98.5% to 102.8%. Lateral dose profiles at abdomen and head revealed 109.8% and 111.7% high doses, respectively, at the body edges. The results confirmed that the technique is capable of delivering a uniform dose distribution to the midline of the body in a small treatment room while keeping the lung dose within the tolerance level.

Show MeSH