Screen: 5
Birjoo Vaishnav, PhD, DABR
Mayo Clinic College of Medicine and Science Rochester
Baltimore, MD
Materials/
Methods: Patchy alopecia is a known side effect of stereotactic radiosurgery (SRS) especially for Arteriovenous malformations that are closer to the scalp. There is no clear consensus about scalp constraints for prevention of alopecia for such large doses. This patient population is relatively sparse at our institution. Over the last year out of ~ 4000 patients treated across three sites, there were 117 SRS/fSRT patients of which 4 were treated for AVM. From 2019-2023, 23 patients were treated for AVM, out of which 15 were treated with 32.5 Gy in 5 fractions, of which 14 were women, many of whom had requested keeping the hair loss as low as possible during the initial consult. Owing to not much clear consensus on scalp sparing for SRS AVM available, this investigation was initiated, to be able to inform the planning process and to help prevent hair loss to the patients. A retrospective chart review of these patients revealed at least mild hair loss at 6/8 week follow up, which resolved within the year. To better understand the dosimetry that may be associated with this, the scalp was contoured 5 mm deep from the external contour of the head. Various dose-volume quantities were evaluated to try and find the discriminator.
Results: The difference that stood out between alopecia/no alopecia was the distance of the AVM lesion from the external surface, those who reported no hair loss had the lesion 2.5 cm or more from the surface. However, one patient with lesion over 4 cm away from the surface nevertheless reported mild hair loss, due to the large volume. Parameters such as max dose and D2cc to the scalp show a clear difference in mean and median between the cohorts as shown in the table below. More data is needed to establish statistical significance.
Conclusion: Alopecia in AVM patients who have a longer survival than other SRS patients, can significantly impact quality of life. In this initial study, we investigated the dose delivered to the scalp, informed by patient reported hair loss outcomes. This lays the groundwork for a future systematic, prospective, multi-institutional trial to better understand the scalp constraints that can prevent alopecia and enhance the patients quality of life. Abstract 2896 – Table 1
| Mean (Std deviation) | Median | |||
| Scalp Parameter | No hair loss | Hair loss | No hair loss | Hair Loss |
| V100cGy (cc) | 110.3 (61.9) | 187.8 (102.6) | 100.8 | 146.7 |
| V500cGy (cc) | 9.1 (8.7) | 34 (25.7) | 6.4 | 23.4 |
| Max (cGy) | 1296.1 (782.5) | 1962 (759.5) | 975.1 | 1897 |
| D0.035cc (cGy) | 1205.4 (754.2) | 1819.4 (721) | 888.8 | 1726 |
| D0.1cc (cGy) | 1156.1 (733.9) | 1749.1 (701.5) | 843.2 | 1627.7 |
| D2cc (cGy) | 839.9 (501.7) | 1317.8 (579.6) | 629 | 1152 |
| D5cc (cGy) | 649.5 (340.1) | 1069 (486.4) | 561.5 | 907 |
| D10cc (cGy) | 494 (225.9) | 840.2 (320.4) | 425.5 | 740.6 |