http://www.revmaterialeplastice.ro MATERIALE PLASTICE ♦54♦No. 4 ♦2017 731 Treatment Planning Optimization in Radiotherapy Using the Bolus ANCA MUNTEANU 1,2 , FLORINA DANIELA IVAN 3,4 , ALEXANDRU PATRASCU 1,5 *, VERA BALAN 4 , CATALINA URSACHE 2 , LILIANA VERESTIUC 4 1 Grigore T.Popa University of Medicine and Pharmacy Iasi, Faculty of Medicine, Department of Medical Oncology-Radiotherapy, 16 Universitatii Str., 700115, Iasi, Romania 2 Regional Institute of Oncology, Department of Radiotherapy, 2-4 General Henry Mathias Berthelot Str., 700483, Iasi, Romania 3 Gheorghe Asachi Tehnical University of Iaºi, Faculty of Chemical Engineering and Environmental Protection, 67 Dimitrie Mangeron Blvd. 7000050, Iasi, Romania 4 Grigore T.Popa University of Medicine and Pharmacy Iasi, Faculty of Medical Bioengineering, 9-13 Mihail Kogalniceanu Str., 700454, Iasi, Romania 5 Clinical Recovery Hospital, 12-14 Pantelimon Halipa Str.,700614, Iasi, Romania The present paper presents the results of the research regarding the bolus structure (Bio-Rad Win-IR instrument), the elasticity modulus, the bioadhesiveness properties (TA-XT2 Plus analyzer) and the clinical applications of the bolus in the adjuvant irradiation after radical mastectomy (Treatment Plan System Eclipse). The dose-volume histogram has made a comparative evaluation for with and without bolus treatment plans and confirmed the importance of bolus utilisation in selected patients. Conclusions: the thickness of the applied bolus is dependent on the skin dose required, on the treatment technique and must be equal to the depth of the build-up region for the removal of the skin-sparing effect of a high energy radiation. Keywords: radiotherapy, planning, bioadhesive, bolus, histogram Achieving a treatment plan that respects both the homogeneous distribution of the prescribed dose in the target volume and the dose constraints for adjacent risk organs requires choosing the appropriate irradiation technique, but in some cases, it also requires the application of a bolus to the surface of the irradiated volume. The irradiation of the chest wall after radical mastectomy often requires the application of a bolus to obtain the optimal parameters of the treatment plan. The type and thickness of the bolus must be included in the calculation algorithm [1, 2]. The bolus allows irradiation of the skin with 100% of the prescribed dose, while without the bolus, the skin (in which almost all local relapses occur in breast cancer [3-9]) receives about 70% of the prescribed dose, and the non- target tissues (muscles, ribs) receive 100% of the dose. Similarly, the bolus is indicated for irradiation of laryngeal tumors with extension at the anterior commissure or primary vulvar tumors [6,7]. Depending on the total dose irradiation and dose fractionation, when the bolus is used, the late cutaneous atrophy may occur more frequently. Experimental part Materials and methods Structure ATR-IR spectrum was measured using a Bio-Rad Win- IR instrument with the range of 4000 to 400 cm -1 in the ATR mode: mono reflection device, using a diamond crystal with incidence angle of 45 °. Elasticity modulus measurements The texture analyzer TA-XT2 Plus (Stable micro systems UK) was used for testing the elasticity of the gel, by using a cylinder of 12 mm diameter and compression speeds of 1mm/s. The slopes from the stress-strain curves at 50% deformations were used to calculate an apparent compression modulus. Ten samples were measured; the * e m a il: patrascu_alex@yahoo.com samples height was of 9.4 mm and their area was between 95 mm 2 and 105 mm 2 . An initial fast deformation of 50 % at 1 mm/s was kept constant for 60 s. Bioadhesive properties The same texture analyzer TA-XT2 (Stable micro systems UK) was used for testing the adhesive properties of the material. The efficiency of the gel adhesion (8 mm diameter; 2 mm height) on to a chicken fresh skin (cleaned with diluted SDS solution (0.1%, w/vol) and rinsed with distilled water, wiped with filter paper to remove the water) was evaluated at room temperature. The texture analyser has a moving arm, a cylinder probe, a heavy duty platform and a holed plate. The sample is attached to the probe which is then pressed on to the receiving surface until the trigger force is detected. The gel samples were attached to the probe in such a way that the probe was fully covered so as to avoid any errors due to interaction. The biological tissue was used as a receiver and placed between the platform and the plate. 1 ml of phosphate buffer was introduced into the formed inlet above the membrane. This was repeated eight times. The work of adhesion (TWA) and the maximum detachment force (MDF) were recorded. The settings of the texture analyser were (table 1): Table 1 THE SETTINGS OF THE PARAMETERS