dctopgm8: 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/dctopgm8 - from package: dicom3tools

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

Error in other languages:
dctopgm8: bevel nie gevind nie
dctopgm8: comandă negăsită
dctopgm8: comando não encontrado
dctopgm8: commande introuvable
dctopgm8: command not found
dctopgm8: käsku ei ole
dctopgm8: không tìm thấy lệnh
dctopgm8: komanda nerasta
dctopgm8: Kommando nicht gefunden.
dctopgm8: kommandot finns inte
dctopgm8: komut yok
dctopgm8: nie znaleziono polecenia
dctopgm8: níor aimsíodh an t-ordú
dctopgm8: no se encontró la orden
dctopgm8: no s'ha trobat l'ordre
dctopgm8: opdracht niet gevonden
dctopgm8: parancs nem található
dctopgm8: perintah tidak ditemukan
dctopgm8: príkaz nenájdený
dctopgm8: příkaz nenalezen
dctopgm8: команда не найдена
dctopgm8: командата не е открита
dctopgm8: 命令找不到
dctopgm8: コマンドが見つかりません