instruction: let's count the number of patients who received a head ct scan procedure during the same hospital visit after receiving a sedative agent - propofol procedure during this year.
response: SELECT COUNT(DISTINCT t1.uniquepid) FROM (SELECT patient.uniquepid, treatment.treatmenttime, patient.patienthealthsystemstayid FROM treatment JOIN patient ON treatment.patientunitstayid = patient.patientunitstayid WHERE treatment.treatmentname = 'sedative agent - propofol' AND DATETIME(treatment.treatmenttime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-0 year')) AS t1 JOIN (SELECT patient.uniquepid, treatment.treatmenttime, patient.patienthealthsystemstayid FROM treatment JOIN patient ON treatment.patientunitstayid = patient.patientunitstayid WHERE treatment.treatmentname = 'head ct scan' AND DATETIME(treatment.treatmenttime, 'start of year') = DATETIME(CURRENT_TIME(), 'start of year', '-0 year')) AS t2 WHERE t1.treatmenttime < t2.treatmenttime AND t1.patienthealthsystemstayid = t2.patienthealthsystemstayid