diff --git a/app/src/main/java/com/medithings/vesiscan/managers/AlignmentAdvisorV3.kt b/app/src/main/java/com/medithings/vesiscan/managers/AlignmentAdvisorV3.kt
index 3a369b3..05d6ca1 100644
--- a/app/src/main/java/com/medithings/vesiscan/managers/AlignmentAdvisorV3.kt
+++ b/app/src/main/java/com/medithings/vesiscan/managers/AlignmentAdvisorV3.kt
@@ -197,16 +197,25 @@ class CenterAligner(
                 r?.let { Pair(it.ant, it.post) }
             }
             val bv = estimateBladderVolume6ch(allWalls)
-            bv?.volumeMl?.let { if (it.isFinite() && it > 0) bvs.add(it) }
+            // Python `position_records`: `if bv is not None: bvs.append(float(bv.volume_ml))`
+            //   nan/0 필터 없이 그대로 추가. nan 발생 시 std/mean 모두 nan → bv_cv=null →
+            //   `selectCm` tie 정렬에서 +inf 로 취급되어 뒷순위로 밀림 (Python 과 동일 동작).
+            bv?.let { bvs.add(it.volumeMl) }
         }
+        // Python: `float(np.std(bvs) / np.mean(bvs)) if len(bvs)>=2 and np.mean(bvs) else nan`
+        //   nan 이 하나라도 있으면 std/mean 모두 nan → 결과 nan (Kotlin: null).
         val bvCv: Double? = if (bvs.size >= 2) {
             val m = bvs.average()
-            if (m != 0.0) {
+            if (m != 0.0 && m.isFinite()) {
                 val sd = sqrt(bvs.map { (it - m) * (it - m) }.average())
-                sd / m
+                val cv = sd / m
+                if (cv.isFinite()) cv else null
             } else null
         } else null
-        val meanBv = if (bvs.isNotEmpty()) bvs.average() else null
+        val meanBv = if (bvs.isNotEmpty()) {
+            val m = bvs.average()
+            if (m.isFinite()) m else null
+        } else null
 
         return AlignPositionRecord(
             alignCm = cm, nch = nch, ch3Detected = ch3Detected,