dcposn: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/dcposn - from package: dicom3tools

You may install the required package with command apt-get install {package}

Error in other languages:
dcposn: bevel nie gevind nie
dcposn: comandă negăsită
dcposn: comando não encontrado
dcposn: commande introuvable
dcposn: command not found
dcposn: käsku ei ole
dcposn: không tìm thấy lệnh
dcposn: komanda nerasta
dcposn: Kommando nicht gefunden.
dcposn: kommandot finns inte
dcposn: komut yok
dcposn: nie znaleziono polecenia
dcposn: níor aimsíodh an t-ordú
dcposn: no se encontró la orden
dcposn: no s'ha trobat l'ordre
dcposn: opdracht niet gevonden
dcposn: parancs nem található
dcposn: perintah tidak ditemukan
dcposn: príkaz nenájdený
dcposn: příkaz nenalezen
dcposn: команда не найдена
dcposn: командата не е открита
dcposn: 命令找不到
dcposn: コマンドが見つかりません