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- Title
Effect of Bolus Type and Air Gaps on Patient Dose.
- Authors
Alford, Kelsey
- Abstract
Purpose To increase awareness of the importance of proper bolus application and improve clinical knowledge on the effects improper bolus contouring and air gaps have on patient dose during external beam radiation therapy. Methods Two independent tests were completed. In 1 test, 9 types of bolus were tested at 0.3 cm or 0.5 cm thickness, 10 cm by 10 cm field size, and 6 MeV to determine its effect on expected surface dose. In another test, the size of air gaps between a nonsticky sheet bolus and a phantom's surface were adjusted to determine the effect on desired surface dose; variations were made in air-gap depth, energy, and bolus thickness. Results for both tests were measured with an optically stimulated luminescent dosimeter radiation measuring device, and percent differences were recorded. Results For the 9 types of tested bolus, the damp gauze bolus had the greatest variation in dose--a decrease of 10% of the desired surface dose. For the air-gap tests, minimal (<15%) differences in dose were recorded for all variations except 6 cm air-gap photons. This energy and depth resulted in the largest dose differentiation of approximately 40% for the 0.3 cm and 1 cm bolus thickness. Discussion An undesired variation in patient dose can be caused by commonly used types of bolus, such as damp gauze. The amount of water in the gauze plays a vital role in adequate patient dose, and there is no consistent amount of water to put in the gauze, nor is there an adequate way to determine how many pieces of gauze equal the desired bolus thickness. Many of the air-gap findings were minimal; however, the large variations are prevalent enough to affect a patient's cumulative dose and skin reactions. Conclusion Proper bolus application in the oncology profession has an important role in many patients' treatment. Fabricated bolus, such as damp gauze, often is not reliable in clinical application. Proper measures must be taken to ensure the quality of fabricated bolus, or it should not be fabricated in-house. Air gaps from improper bolus application might lead to inadequate dose delivery to patients. Attention must be given to the application of bolus, and adequate measures should be taken to ensure no air gaps exist between the bolus and the patient.
- Subjects
SKIN disease prevention; RADIATION therapy equipment; AIR; PROTECTIVE clothing; PATIENT safety; RADIATION doses; TUMORS; TREATMENT effectiveness; DATA analysis software; DESCRIPTIVE statistics
- Publication
Radiation Therapist, 2019, Vol 28, Issue 2, p117
- ISSN
1084-1911
- Publication type
Academic Journal