SU-E-T-378: Limits and Possibilities of a Simplistic Approach to Whole Breast Radiation Therapy Planning

Abstract

Purpose: Challenges for radiation therapy in developing countries include unreliable infrastructure and high patient load. We propose a system to treat whole breast in the prone position without computed tomography and/or planning software. Methods: Six parameters are measured using calipers and levels with the patient prone in the treatment position. (1) The largest separation; (2) the angle that separation makes with the horizontal; (3) the separation 2 cm posterior to the nipple; (4) the vertical distance between these two separations; (5) the sup/inf length and (6) angle of the desired posterior field edge. The data in (5) (6) and (2) provide field length, collimator and gantry angles. Isocenter is set to the midpoint of (1), anterior jaw setting is 20cm (half‐beam setup), and the dose is prescribed to a point 1.5 cm anterior to isocenter. MUs and wedge angles are calculated using an MU calculator and by requiring 100% dose at that point and 100‐105% at the midpoint of (3). Measurements on 30 CT scans were taken to obtain the data 1‐6. To test the resulting MU/wedge combinations, they were entered into Eclipse (Varian) and dose distributions were calculated. The MU/wedge combinations were recorded and tabulated. Results: Performing a dose volume histogram analysis, the contoured breast V95 was 90.5%, and the average V90 was 94.1%. The maximum dose never exceeded 114.5%, (average 108%). The lung V20 was <5% for 96.7%, and the heart V5 was <10% for 93.3% of our sample. Conclusion: A method to provide prone whole breast treatment without CT‐planning was developed. The method provides reasonable coverage and normal tissue sparing. This approach is not recommended if imaging and planning capabilities are available; it was designed to specifically avoid the need for CT planning and should be reserved to clinics that need to avoid that step.

<i>Hosios</i>

“…As is explained in the prologue, the group had been driven away from every city they sought protection in, for Eurystheus had threatened all of these cities with war (15)(16)(17)(18)(19)(20)(21)(22)(23)(24). As Iolaus says, the poleis who did not wish to accept the suppliants 'are honoring the mightier' (τοὺς κρείσσονας σέβοντες).…”

“…22 They have also tried to make sense of the utterance. Some commentators have argued that it is merely motivated by Euripides' fondness of repetition of the same word (in different grammatical forms); 23 or that Apollo is referring to his human manifestation as Admetus' slave. 24 Others have proposed a meaning extension from the more common, prototypical applications of ὅσιος used for humans, to make it meaningful in application to a god.…”

“…22 Experimental work in psychology showed that this is not how humans actually conceive of categories. 23 It seems to be the case that category membership is not a yes/no question, but has various degrees. People consider some entities to be 'better' or 'more prototypical' examples of categories than others.…”

“…22 Medea's utterance is a bitter parody on limitations that any cult might have, restricting attendance at (particular) sacrifices. 23 She also parodies another formula that sometimes appears in sacred law: '(if someone transgresses anyway), let it weigh upon his consciousness': …”

“…First of all, ὅσιος and ἀνόσιος qualify body parts, 17 the place where humans live, 18 and the Cyclops' meal of Odysseus' comrades. 19 Furthermore, ὅσιος evaluates murders 20 or deaths, 21 things that pertain to the rituals of worship, 22 marriage 23 or purity (or the opposite), 24 and sometimes other matters. 25 In this dissertation we will examine what kind of evaluation ὅσιος represents in these cases.…”